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Copper 3,4-pyridinedicarboxylate mixed ligand coordination polymers with diverse topologies and aqueous Congo Red degradation catalytic properties
Polyhedron 180 (2020) 114427
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Copper 3,4-pyridinedicarboxylate mixed ligand coordination polymers with diverse topologies and aqueous Congo Red degradation catalytic properties Ellese C. Jaddou, Robert L. LaDuca 1 Lyman Briggs College and Department of Chemistry, Michigan State University, East Lansing, MI 48825, USA
a r t i c l e
i n f o
Article history: Received 7 January 2020 Accepted 31 January 2020 Available online 7 February 2020 Keywords: Copper Coordination polymer Crystal structure Topology Dye degradation catalysis
a b s t r a c t Hydrothermal reaction of copper nitrate, 3,4-pyridinedicarboxylic acid (34pdcH2), and a variety of ditopic dipyridyl ligands afforded six new coordination polymer solids with diverse 2D and 3D topologies as characterized via single-crystal X-ray diffraction. {[Cu(34pdc)(dpa)]H2O}n (1, dpa = 4,40 -dipyridylamine) reveals a 3,5-connected layered net with a (426)(42678) topology. [Cu(34pdc)(3pina)]n (2, 3pina = 3pyridylisonicotinamide) manifests a 2-fold interpenetrated 3,5-connected 3D net with (426)(426583) topology. [Cu2(34pdc)2(bbn)(H2O)2]7H2O}n (3, bbn = bis(butane-1,4-diyl)nicotinamide) shows a 3D trinodal network with {(63)2(6.102)(64102)} topology, with looped pairs of bbn ligands acting as single connectors. [Cu4(34pdc)4(bbin)(H2O)4]8H2O}n (4, bbin = bis(butane-1,4-diyl)isonicotinamide) displays a quite complicated 3D multinodal network with {(63)2(628)(6282102)(668310)} topology. [Cu2(34pdc)2(pebn)(H2O)]8H2O}n (5, pebn = bis(pentane-1,5-diyl)nicotinamide) shows a 3,4,4-connected 2D network with {(63)2(6472)(6.74.11)} topology, along with entrapped chair-centered 14-water molecule clusters. [Cu4(34pdc)4(hbn)(H2O)4]3H2O}n (6, hbn = bis(hexane-1,6-diyl)nicotinamide) showed the same {(63)2(6.102)(64102)} topology as 3, but with single dipyridylamide ligands instead of looped pairs. Thermal decomposition of these six new materials are also probed, along with their catalytic behavior for the aqueous degradation of Congo Red dye in the presence of ultraviolet radiation and hydrogen peroxide. Ó 2020 Elsevier Ltd. All rights reserved.
1. Introduction Coordination polymers constructed from metal cations and anionic aromatic dicarboxylate ligands have shown exciting properties in many technologically relevant applications [1], such as carbon dioxide sequestration [2], shape-selective hydrocarbon separation [3], antibacterial coatings [4], heterogeneous catalysis for key industrial organic transformations [5], non-linear optics [6], and temperature and field-dependent magnetism [7]. Due to their flexible coordination environments, divalent copper coordination polymers manifest a tremendous diversity of different structural topologies depending on the specific dicarboxylate ligand used, along with the presence of other structure-directing neutral dipyridyl or bis(imidazolyl) coligands [8]. Recent studies have shown that many divalent copper coordination polymers have significant utility as heterogeneous catalysts for the ultraviolet-induced
1 Mailing address: Lyman Briggs College, E-30 Holmes Hall, 919 East Shaw Lane, Michigan State University, East Lansing, MI 48825, USA. E-mail address: [email protected] (R.L. LaDuca)
https://doi.org/10.1016/j.poly.2020.114427 0277-5387/Ó 2020 Elsevier Ltd. All rights reserved.
degradation of toxic dyestuffs in the presence of an inexpensive or free oxidant (e.g. hydrogen peroxide or atmospheric oxygen) [9]. The most commonly used ligands for inducing neutral charge and crystallization in divalent metal coordination polymers are the aromatic dicarboxylates such as phthalate [10], isophthalate [11], terephthalate [12], and related derivatives such as 5-position substituted isophthalates [13]. Less commonly used have been pyridyldicarboxylate ligands, such as 2,3-pyridinedicarboxylate and 3,4-pyridinedicarboxylate (34pdc, Scheme 1) [14–20]. {[Cu2(34pdc)2(dpp)2(H2O)4]5H2O}n (dpp = 1,3-(di-4-pyridyl)propane) shows 1D [Cu(34pdc)(H2O)2]n chain motifs pillared into a 2D (4,4) grid coordination polymer by the dipodal dpp tethers, in which the 34pdc ligands serve as simple linkers. This material undergoes a reversible single-crystal-to-amorphous morphological transition upon dehydration and rehydration, and has water-bearing incipient channels comprising over 25% of the unit cell volume [14]. A series of copper hydroxide cluster-bearing 34pdc coordination polymer chains with variable ferromagnetic or antiferromagnetic properties was prepared in the presence of the capping ligand 1,10-phenanthroline [15]. Due to the presence of the pyridyl
2
E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427
Scheme 1. Organic precursors used in this study.
nitrogen donor atom, the 34pdc ligand can serve as a 3-connected node in some cases, instead of a simple linker, thereby instilling an even greater variety of structural variability in the resulting coordination polymer. A previously reported example where this is the case is {(NMe4)2[Cu3(34pdc)4(H2O)4]4H2O}n, which possesses an anionic 3D coordination polymer network with{(63)4(6282102) (648.10)} 3,4,4-connected topology [16]. {[Cd(34pdc)(dpp)] 0.5H2O}n manifests a 3,5-connected 3D coordination polymer network, again with the 34pdc ligand serving as a 3-connected node [17]. In this study we have aimed to expand the scope of divalent copper 3,4-pyridyldicarboxylate coordination polymers by including hydrogen-bonding capable dipyridylamine or dipyridylamide ligands in the hydrothermal synthetic scheme. Herein we report the synthesis and single-crystal X-ray structural characterization of six new divalent copper 3,4-pyridyldicarboxylate coordination polymers with 2D and 3D topologies as characterized via single-crystal X-ray diffraction: {[Cu(34pdc)(dpa)]H2O}n (1, dpa = 4,40 -dipyridylamine, Scheme 1), [Cu(34pdc)(3pina)]n (2, 3pina = 3-pyridylisonicotinamide, Scheme 1), [Cu2(34pdc)2(bbn) (H2O)2]7H2O}n (3, bbn = bis(butane-1,4-diyl)nicotinamide, Scheme 1), [Cu4(34pdc)4(bbin)(H2O)4]8H2O}n (4, bbin = bis(butane-1,4-diyl)isonicotinamide, Scheme 1), [Cu2(34pdc)2(pebn) (H2O)]8H2O}n (5, pebn = bis(pentane-1,5-diyl)nicotinamide, Scheme 1), and [Cu4(34pdc)4(hbn)(H2O)4]3H2O}n (6, hbn = bis (hexane-1,6-diyl)nicotinamide, Scheme 1). Thermal dehydration and/or decomposition of these six new materials have also been investigated, along with their heterogeneous catalytic behavior towards the aqueous degradation of Congo Red dye in the presence of ultraviolet radiation and hydrogen peroxide.
2.2. Preparation of {[Cu(34pdc)(dpa)]H2O}n (1) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), dpa (62 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 80 °C for 48 h, and then cooled slowly to 25 °C. Blue crystals of 1 (65 mg, 42% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C17H14CuN4O5 1: C, 48.86; H, 3.38; N, 13.41% Found: C, 48.29; H, 3.21; N, 13.12%. IR (cm1): 1596 (s) , 1516 (m) , 1385 (m), 1366 (s) , 1340 (m), 1210 (s) , 1050 (w), 1027 (m) , 816 (s), 790 (w), 683 (s).
2.3. Preparation of [Cu(34pdc)(3pina)]n (2) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), 3pina (75 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 100 °C for 24 h, and then cooled slowly to 25 °C. Blue crystals of 2 (84 mg, 53% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C18H12CuN4O5 2: C, 50.53; H, 2.83; N, 13.09% Found: C, 50.23; H, 2.68; N, 13.08%. IR (cm1): 1681 (m), 1613 (s), 1581 (s), 1541 (m), 1502 (w), 1433 (m), 1396 (s), 1365 (s), 1340 (m) 1286(m), 1196 (w), 1111 (w) , 1054 (w), 1027 (w), 945 (w), 861 (w), 836 (w), 807 (w), 791 (w), 761 (m), 696 (s), 680 (s).
2. Experimental section 2.4. Preparation of [Cu2(34pdc)2(bbn)(H2O)2]7H2O}n (3) 2.1. General considerations Copper nitrate and 3,4-pyridinedicarboxylic acid were purchased commercially. The 4,40 -dipyridylamine ligand was prepared according to a literature procedure [21], as were the various dipyridylamide ligands [22]. Reported yields are for optimized procedures to obtain the maximum amount of monophasic product. Water was deionized above 3 MX-cm in-house. IR spectra were recorded on powdered samples using a Perkin Elmer Spectrum One instrument. Thermogravimetric analysis was performed under flowing N2 on a TA Instruments TGA Q50 Thermogravimetric Analyzer with a heating rate of 10 °C/min up to 600 °C.
Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), bbn (110 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 80 °C for 48 h, and then cooled slowly to 25 °C. Blue crystals of 3 (52 mg, 31% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C30H42Cu2N6O19 3: C, 39.26; H, 4.61; N, 9.16% Found: C, 38.97; H, 4.03; N, 8.98%. IR (cm1): 3260 (w), 2349 (w), 2341 (w), 2316 (w), 1660 (m), 1650 (m), 1543 (s), 1377 (s), 1305 (m), 1191 (w), 831 (m), 696 (s).
E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427 Table 1 Crystal and structure refinement data for 1–6. Data
1
2
3
Empirical Formula Formula Weight Crystal system Space group
C17H14CuN4O5 417.86 Triclinic
C18H12CuN4O5 427.86 Orthorhombic Pbca
C30H42Cu2N6O19 917.77 Monoclinic P21/c
8.897(4) 19.066(10) 20. 5(11) 90 90 90 3450(3) 8 1.648 1.307 0.8092 0 h 10, 0 k 23, 0 l 24 71,555 3188 0.0931 253 0.1155 0.0702 0.1921 0.1669 1.806/–0.571
13.368(2) 11.8607(18) 24.035(4) 90 92.717(2) 90 3806.7(10) 4 1.601 1.205 0.8968 10 h 11, 23 k 23, 19 l 19 29,716 7004 0.0640 543 0.0924 0.0766 0.1741 0.1672 1.324/–0.680
a (Å) b (Å) c (Å) a(°) b (°) c(°) V (Å3) Z Dcalc (g cm3) l(mm1) Min./max. trans. hkl ranges
Total reflections Unique reflections R(int) Parameters R1 (all data) R1 (I > 2r (I)) wR2 (all data) wR2 (I > 2 r (I)) Max/min residual (e/Å3) G.O.F.
P1 8.9225(6) 10.3928(7) 10.5604(7) 118.931(1) 97.995(1) 100.902(1) 810.73(9) 2 1.712 1.388 0.9192 10 h 10, 12 k 12, 12 l 12 13,262 2988 0.0247 247 0.0278 0.0254 0.0669 0.0650 0.332/–0.248 1.079
1.081
1.153
Data
4
5
6
Empirical Formula Formula Weight Crystal system Space group a (Å) b (Å) c (Å) a(°) b (°) c(°) V (Å3) Z Dcalc (g cm3) l (mm1) Min./max. trans. hkl ranges
C44H54Cu4N8O30 1429.1 Monoclinic P21/c 13.300(3) 11.272(3) 18.699(5) 90 106.805(3) 90 2683.5(12) 2 1.769 1.669 0.8269 16 h 15, 12 k 13, 22 l 22 16,904 4901 0.1894 366 0.1884 0.0715 0.1643 0.1170 0.815/–0.705
C31H44Cu2N6O19 931.80 Monoclinic P21/c 13.244(14) 11.682(12) 25.95(2) 90 96.206(15) 90 3991(7) 4 1.551 1.151 0.3321 16 h 15, 13 k 14, 31 l 31 31,449 7427 0.2280 536 0.2121 0.1156 0.3310 0.2743 1.390/–1.631
C46H48Cu4N8O25 1367.08 Monoclinic P21/c 13.7686(9) 11.0964(7) 18.4979(15) 90 111.587(1) 90 2627.9(3) 2 1.728 1.693 0.9117 16 h 16, 13 k 13, 22 l 22 20,663 4815 0.0392 387 0.0487 0.0381 0.1032 0.0949 0.685/–0.629
0.942
1.031
1.036
Total reflections Unique reflections R(int) Parameters R1 (all data) R1 (I > 2 r (I)) wR2 (all data) wR2 (I > 2 r (I)) Max/min residual (e/Å3) G.O.F.
2.5. Preparation of [Cu4(34pdc)4(bbin)(H2O)4]8H2O}n (4) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), bbin (110 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 100 °C for 24 h, and then cooled slowly to 25 °C. Blue crystals of 4 (62 mg, 47% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C44H54Cu4N8O30 4: C, 36.98; H, 3.81; N,
3
7.84% Found: C, 37.13; H, 3.60; N, 7.69%. IR (cm1): 3300 (w, br), 1640 (w), 1614 (m), 1570 (m), 1555 (m), 1386 (s), 1166 (w), 1123 (w), 1068 (w), 945 (w), 843 (w), 819 (w), 723 (w), 684 (s). 2.6. Preparation of [Cu2(34pdc)2(pebn)(H2O)]8H2O}n (5) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), pebn (111 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 100 °C for 24 h, and then cooled slowly to 25 °C. Blue crystals of 5 (63 mg, 37% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C31H44Cu2N6O19 5: C, 39.96; H, 4.76; N, 9.02% Found: C, 39.40; H, 4.66; N, 9.24%. IR (cm1): 3298 (w), 1640 (m), 1619 (s), 1551 (m), 1373 (s), 1197 (w), 1172 (w), 1125 (w), 1058 (w), 884 (w), 838 (w), 816 (w), 786 (w), 728 (m), 701 (s), 683 (s). 2.7. Preparation of [Cu4(34pdc)4(hbn)(H2O)4]3H2O}n (6) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), hbn (121 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 120 °C for 24 h, and then cooled slowly to 25 °C. Blue crystals of 6 (47 mg, 37% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C46H48Cu4N8O25 6: C, 40.41; H, 3.54; N, 8.20% Found: C, 40.82; H, 3.43; N, 8.39%. IR (cm1): 3236 (w), 1660 (w), 1640 (w), 1594 (m), 1525 (w), 1492 (w), 1444 (w), 1408 (m), 1382 (s), 1350 (m), 1198 (w), 1118 (w), 836 (w), 814 (w), 779 (m), 722 (m), 686 (s). 2.8. Congo Red degradation experiments 50 mg of copper coordination complexes 1–6 were dispersed in 100 mL deionized water in 250 mL beakers open to ambient air. A 5 mg portion of solid Congo Red dye was added to each beaker, along with 10 mL 30% H2O2 solution. Each mixture was stirred at 25 °C under an Electron Microscopy Sciences 100 W High-Intensity Ultraviolet lamp with maximum wavelength of 365 nm. A 5 mL aliquot was taken prior to irradiation and its UV–VIS spectrum was acquired. Small aliquots (5 mL) were withdrawn from each mixture at different elapsed time values, and their UV–VIS spectra were acquired. 3. X-ray crystallography Single crystal X-ray diffraction on crystals of 1–6 was performed using a Bruker-AXS ApexII CCD instrument at 173 K. Reflection data were acquired using graphite-monochromated Mo-Ka radiation (k = 0.71073 Å). The data was integrated via SAINT [23]. Lorentz and polarization effect and empirical absorption corrections were applied with SADABS [24]. The structures were solved using direct methods and refined on F2 using SHELXTL [25] within the OLEX2 crystallographic software suite [26]. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were placed in calculated positions and refined isotropically with a riding model. The R(int) values for the crystals of 4 and 5 were rather high due to small crystal size and weaker diffraction at high angles. Nevertheless all atoms refined well and the connectivity and topology are unambiguous. Relevant crystallographic data for 1–6 are listed in Table 1.
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E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427
Fig. 1. a) Coordination environment in 1. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 2. b) [Cu(34pdc)]n ribbon submotif in 1.
Table 2 Selected bond distance (Å) and angle (°) data for 1. Cu1–O1 Cu1–O4#1 Cu1–N1 Cu1–N3#2 Cu1–N4#3 O1–Cu1–O4#1 O1–Cu1–N1 O1–Cu1–N3#2
1.9556(13) 2.0078(13) 2.0213(16) 2.3582(17) 2.0388(16) 89.73(6) 87.06(6) 90.11(6)
O1–Cu1–N4#3 O4#1–Cu1–N1 O4#1–Cu1–N3#2 O4#1–Cu1–N4#3 N1–Cu1–N3#2 N1–Cu1–N4#3 N4#3–Cu1–N3#2
177.26(6) 171.88(6) 88.94(6) 87.57(6) 98.51(6) 95.67(6) 89.40(6)
Symmetry transformations: #1 x + 1, y, z; #2 x, y 1, z 1; #3 x + 1, y, z.
4. Results and discussion 4.1. Synthesis and spectral characterization Compounds 1–6 were prepared by hydrothermal reaction of copper nitrate, 3,4-pyridinedicarboxylic acid, and the requisite dipyridyl ligand in the presence of aqueous base (in order to deprotonate the carboxylic acid precursors). The infrared spectra of 1–6 were consistent with structural components determined by singlecrystal X-ray diffraction. Intense, slightly broadened asymmetric and symmetric carboxylate CAO stretching bands for the cyclohexyldicarboxylate ligands were observed at 1596 and 1366 cm1 for 1, 1541 and 1396 cm1 for 2, 1543 and 1377 cm1 for 3, 1570 and 1386 cm1 for 4, 1551 and 1373 cm1 for 5, and 1594 and 1382 cm1 for 6. Sharp and medium intensity bands in the range of ~1600 cm1 to ~1300 cm1 were attributed to stretching mode of the pyridyl rings of the ligands in 1–6. The C@O
carbonyl stretching frequency for the dipyridylamide ligands appeared at 1681 cm1 (for 2), 1660 cm1 (for 3), 1640 cm1 (for 4), 1640 cm1 (for 5), and 1660 cm1 (for 6). 4.2. Structural description of {[Cu(34pdc)(dpa)]H2O}n (1) The asymmetric unit of compound 1 contains a divalent copper atom, a fully deprotonated 34pdc ligand, a dpa ligand, and a water molecule of crystallization. A square pyramidal {CuN3O2} coordination environment is observed at copper (s = 0.09) [27], with a pyridyl nitrogen donor atom from a dpa ligand placed in the elongated apical position. The base of the square pyramid contains cis carboxylate oxygen donor atoms belonging to two 34pdc ligands, while a pyridyl nitrogen donor atom belonging to a third 34pdc ligand fills one position (Fig. 1a). The final position, cis to the 34pdc nitrogen donor atom, is taken up by a pyridyl nitrogen donor atom from a second dpa ligand. The three nitrogen donors are arranged in a facial fashion within the coordination environment. Bond lengths and angles within the coordination sphere are listed in Table 2. The 34pdc ligands in 1 act as exotridentate donor atoms, binding to three copper atoms via single oxygen atoms from both carboxylate groups, and the pyridyl nitrogen atom. Through this l3-j3-N:O:O0 bridging mode in which one oxygen atom from each carboxylate group does not bind to copper, [Cu(34pdc)]n coordination polymer ribbons are formed (Fig. 1b). These ribbon motifs are oriented along the a crystal axis, with the Cu Cu distance linked through 34pdc pyridyl nitrogen atoms and 4-position carboxylate groups measuring 8.922(2) Å.
Fig. 2. [Cu(34pdc)(dpa)]n coordination polymer layer in 1.The 34pdc ligands are drawn in red and the dpa ligands are drawn in blue. The Cu atoms are shown in green. a) Face view. b) Side view. ((Colour online.))
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E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427 Table 3 Selected bond distance (Å) and angle (°) data for 2. Cu1–O1 Cu1–O3#1 Cu1–N1 Cu1–N3#2 Cu1–N4#3 O1–Cu1–O3#1 O1–Cu1–N1 O1–Cu1–N3#2
1.980(4) 2.171(4) 2.005(5) 2.023(5) 2.010(5) 90.48(16) 89.67(17) 89.05(17)
O1–Cu1–N4#3 N1–Cu1–O3#1 N1–Cu1–N3#2 N1–Cu1–N4#3 N3#2–Cu1–O3#1 N4#3–Cu1–O3#1 N4#3–Cu1–N3#2
175.86(18) 109.55(18) 161.1(2) 90.33(18) 89.36(17) 93.42(18) 89.62(18)
Symmetry transformations: #1 x + 1/2, y + 3/2, z + 1; #2 x + 1, y + 1/2, z + 1/2; #3 x + 1, y, z.
Fig. 3. Simplified (426)(42678) binodal topology in 1, otherwise known as the 3,5-L2 net. The 34pdc ligand nodes are drawn in teal, while the Cu atom nodes are drawn in dark blue. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Parallel [Cu(34pdc)]n ribbons are connected into [Cu(34pdc) (dpa)]n coordination polymer layers by the dipodal dpa ligands (Fig. 2a); these span a CuCu internuclear distance of 10.64(1) Å. As seen in Fig. 2b, the dpa ligands (drawn in blue) are situated above and below the plane defined by the parallel [Cu(34pdc)]n ribbon submotifs. From a topological perspective, the exotridentate 34pdc ligands can be considered 3-connected nodes, and the copper atoms can be considered 5-connected nodes. A topological calculation performed by TOPOS [28] reveals a 3,5-connected binodal layered net (Fig. 3) with a Schläfli symbol of (426)(42678), otherwise known as the 3,5L2 net. A previous example of a coordination polymer exhibiting this network is [Co(2,5-thiophenedicarboxylate)(3pna)]n (3pna = 3-pyridylnicotinamide) [29]. Adjacent [Cu(34pdc)(dpa)]n coordination polymer layers stack in an AAA pattern along the c crystal direction, with the supramolecular impetus provided by NAH O hydrogen bonding between dpa central amine moieties and unbound 34pdc carboxylate oxygen atoms (Fig. S1, Table S1). Water molecules of crystallization are held to the coordination polymer layers by donating hydrogen bonds to unligated 34pdc carboxylate oxygen atoms. 4.3. Structural description of [Cu(34pdc)(3pina)]n (2) The asymmetric unit of compound 2 contains a divalent copper atom, a fully deprotonated 34pdc ligand, and a 3pina ligand. A rather distorted square pyramidal {CuN3O2} coordination environment is observed at copper (s = 0.24), but dissimilar to 1, a carboxylate oxygen donor from a 34pdc ligand is located in the elongated apical position. The base of the square pyramid contains trans pyridyl nitrogen donor atoms from two 3pina ligands, a pyridyl nitrogen donor atom from a second 34pdc ligand, and a carboxylate oxygen atom belonging to a third 34pdc ligand. The
three nitrogen donors are arranged in a meridional fashion within the coordination environment, dissimilar to the facial arrangement seen in 1 (Fig. 4a). Bond lengths and angles within the coordination sphere in 2 are listed in Table 3. The 34pdc ligands in 2 act as exotridentate ligands with a l3-j3-N:O:O0 bridging mode, similar to that seen in 1. As a result, similar [Cu(34pdc)]n coordination polymer ribbons are seen in 2 (Fig. 4b), with some variances in the carboxylate twist angles. Unlike the 2D coordination polymer net of 1, 3D [Cu(34pdc) (3pina)]n coordination polymer networks are caused by the pillaring of the ribbon submotifs by the dipyridylamide 3pina ligands, which span a CuCu distance of 11.72(1) Å (Fig. 5a). The incipient voids in a single [Cu(34pdc)(3pina)]n network contain a second [Cu(34pdc)(3pina)]n network, resulting in 2-fold interpenetration (Fig. 5b). As in 1, from a topological perspective, the exotridentate 34pdc ligands in 2 can be considered 3-connected nodes, and the copper atoms can be considered 5-connected nodes. The resulting 2-fold interpenetrated 3,5-connected binodal net has a (426) (426583) topology (Fig. 6) as calculated by TOPOS. A previous example of this network is {[Cd2(sip)2(4-bpmpH2)(4-bpmp)]4H2O}n (sip = 5-sulfoisophthalate, 4-bpmp = bis(4-pyridylmethyl)piperazine), in which the sip ligand acts as 3-connected ligand nodes [30]. 4.4. Structural description of [Cu2(34pdc)2(bbn)(H2O)2]7H2O}n (3) The asymmetric unit of compound 3 contains two divalent copper atoms (Cu1, Cu2), two 34pdc ligands, one complete bbn ligand, two bound water molecules and seven water molecules of crystallization (with some of those being disordered). The Cu1 atoms display a distorted {CuN2O3} square pyramidal coordination environment with s = 0.22. A carboxylate oxygen atom donor from a 34pdc ligand occupies the elongated apical position. The basal plane at Cu1 contains cis disposed pyridyl nitrogen donor atoms from two bbn ligands, a bound water molecule, and a carboxylate oxygen atom donor from a second 34pdc ligand. The Cu2 atoms display a much less distorted {CuN2O3} square pyramidal coordination environment with s = 0.04. Here, a bound water molecule occupies the Jahn-Teller elongated apical position. In the basal
Fig. 4. a) Coordination environment in 2. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 2. b) [Cu(34pdc)]n ribbon submotif in 2.
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Fig. 5. a) A single [Cu(34pdc)(3pina)]n network in 2, with [Cu(34pdc)]n ribbon submotifs drawn in red going into the plane of the page. b) 2-fold interpenetration of 3D networks in 2. ((Colour online.))
Table 5 Selected bond distance (Å) and angle (°) data for 4. Cu1–O3 Cu1–O8#1 Cu1–O9 Cu1–O10 Cu1–N3 O3–Cu1–O10 O8#1–Cu1–O3 O8#1–Cu1–O10 O9–Cu1–O3 O9–Cu1–O8#1 O9–Cu1–O10 O9–Cu1–N3 N3–Cu1–O3 N3–Cu1–O8#1 N3–Cu1–O10
2.012(6) 2.011(6) 1.961(6) 2.243(6) 2.000(8) 103.8(3) 152.8(3) 103.0(3) 92.5(3) 84.1(3) 88.1(3) 177.5(3) 87.8(3) 94.5(3) 94.3(3)
Cu2–O1 Cu2–O5 Cu2–O11#2 Cu2–N1#3 Cu2–N2#4 O1–Cu2–O5 O1–Cu2–O11#2 O1–Cu2–N1#3 O1–Cu2–N2#4 O5–Cu2–O11#2 O5–Cu2–N1#3 N1#3–Cu2–O11#2 N2#4–Cu2–O5 N2#4–Cu2–O11#2 N2#4–Cu2–N1#3
1.963(6) 2.008(6) 2.370(6) 2.014(7) 1.988(8) 164.2(3) 87.4(2) 91.2(3) 91.7(3) 108.3(2) 87.5(2) 87.9(2) 90.0(3) 90.9(3) 176.8(3)
Fig. 6. Schematic perspective of the 2-fold interpenetrated (426)(426583) topology network in 2.
Symmetry transformations: #1 x, y + 1, z; #2 x 1/2, y + 3/2, z 1/2; #3 x + 1/2, y + 1/2, z + 1/2; #4 x + 3/2, y 1/2, z + 1/2.
plane lie trans pyridyl nitrogen donor atoms belonging to two 34pdc ligands, along with trans carboxylate oxygen atoms from two other 34pdc ligands. Bond lengths and angles within the disparate coordination spheres are listed in Table 4. A thermal ellipsoid plot of the copper atoms with their respective ligand sets is shown in Fig. 7. As in 1 and 2, all of the 34pdc ligands in 3 act as exotridentate ligands with a l3-j3-N:O:O0 bridging mode. However, dissimilar to the [Cu(34pdc)]n ribbon submotifs in 1 and 2, compound 3 possesses [Cu2(34pdc)2(H2O)2]n coordination polymer layers arranged parallel to the ab crystal planes (Fig. 8a). Parallel [Cu2(34pdc)2(H2-
O)2]n layers are connected into a non-interpenetrated 3D [Cu2(34pdc)2(bbn)(H2O)2]n coordination polymer network (Fig. 8b) by pairs of curled conformation bbn ligands (Fig. S2). The bbn ligands have a gauche-gauche-gauche conformation of their central butanediamine tethers, with torsion angles of 63.0°, 70.9°, and 74.4°. The underlying topology of 3 can be probed by considering each of the exotridentate 34pdc ligands as 3-connected nodes, the Cu1 atoms as 3-connecting nodes, and the Cu2 atoms as 4-connected nodes. Each 34pdc ligand connects to one Cu1 atom and two Cu2 atoms. Each Cu1 atom connects to two 34pdc ligands, and another Cu1 atom via a looped pair of bbn ligands. Each Cu2 atom connects
Table 4 Selected bond distance (Å) and angle (°) data for 3. Cu1–O1 Cu1–O8#1 Cu1–O10 Cu1–N3 Cu1–N6#2 O1–Cu1–O8#1 O1–Cu1–O10 O1–Cu1–N3 O1–Cu1–N6#2 O10–Cu1–O8#1 O10–Cu1–N3 O10–Cu1–N6#2 N3–Cu1–O8#1 N3–Cu1–N6#2 N6#2–Cu1–O8#1
1.969(5) 2.222(4) 1.998(5) 2.015(6) 2.020(5) 100.26(18) 88.01(19) 89.5(2) 162.0(2) 90.32(17) 174.9(2) 92.2(2) 94.50(19) 88.8(2) 97.8(2)
Cu2–O4 Cu2–O5 Cu2–O9 Cu2–N1#3 Cu2–N2#4 O4–Cu2–O9 O4–Cu2–N1#3 O4–Cu2–N2#4 O5–Cu2–O4 O5–Cu2–O9 O5–Cu2–N1#3 O5–Cu2–N2#4 N1#3–Cu2–O9 N1#3–Cu2–N2#4 N2#4–Cu2–O9
1.992(4) 1.970(4) 2.291(4) 2.016(5) 2.021(5) 91.28(17) 88.04(19) 89.69(19) 176.44(18) 86.17(17) 89.56(19) 92.95(19) 92.19(19) 174.1(2) 93.31(19)
Symmetry transformations: #1 x, y + 1, z; #2 x + 1, y + 1, z + 1; #3 x + 2, y 1/ 2, z + 1/2; #4 x + 1, y + 1/2, z + 1/2.
Fig. 7. Coordination environments in 3. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 4.
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Fig. 8. a) [Cu2(34pdc)2(H2O)2]n coordination polymer layer in 3. b) Non-interpenetrated 3D [Cu2(34pdc)2(bbn)(H2O)2]n coordination polymer network, with [Cu2(34pdc)2 (H2O)2]n layer submotifs drawn in red. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 9. a) Simplified [Cu2(34pdc)2(H2O)2]n layer submotif in 3, representing 34pdc ligand nodes as light green spheres, connecting to Cu1 atoms (blue) and Cu2 atoms (dark green). b) 3,3,4-connected trinodal network with {(63)2(6.102)(64102)} topology in 3. Connections mediated by 34pdc ligands are shown in red, and the bbn-mediated connections are shown in blue. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 10. Coordination environments in 4. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 5.
to four 34pdc ligands. According to TOPOS, the 3,3,4-connected trinodal network has {(63)2(6.102)(64102)} topology (Fig. 9). To the best of our knowledge this network has not yet been reported. Discrete co-crystallized water molecule chains (Fig. S3) with D(14) classification [31] occupy pockets within the 3D structure of 3. 4.5. Structural description of [Cu4(34pdc)4(bbin)(H2O)4]8H2O}n (4) The asymmetric unit of compound 4 contains two divalent copper atoms (Cu1, Cu2), two doubly deprotonated 34pdc ligands (pdc-A, pdc-B), half of a bbin ligand whose central CAC single bond is sited over a crystallographic inversion center, two aqua ligands, and four water molecules of crystallization. The Cu1 atoms display
a very distorted {CuO4N} square pyramidal geometry (s = 0.41) with bound water molecules in the elongated apical site and also in the basal plane. In trans positions in the basal plane are located a single carboxylate oxygen atom donor from a pdc-A ligand and a single carboxylate oxygen atom donor from a pdc-B ligand. The sole remaining basal coordination site is taken up by a pyridyl nitrogen donor atom from a bbin ligand. In contrast, the Cu2 atoms display a less distorted {CuO3N2} square pyramidal geometry (s = 0.21) with pyridyl nitrogen donor atoms from pdc-A and pdc-B ligands occupying two trans basal positions. The other two trans positions in the basal plane are filled by a single carboxylate oxygen atom donor from a pdc-A ligand and a single carboxylate oxygen atom donor from a pdc-B ligand. The elongated apical posi-
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Fig. 11. [Cu4(34pdc)4(H2O)4]n layer motif in 4.
Fig. 12. [Cu4(34pdc)4(bbin)(H2O)4]n 3D coordination polymer network in 4. [Cu4(34pdc)4(H2O)4]n layer motifs (red) are connected by bbin ligands, whose bound formyl oxygen atoms are shown in orange. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
tion at Cu2 is taken up by a formyl oxygen atom donor from a bbin ligand. A thermal ellipsoid representation of the coordination environments and full ligand set is depicted in Fig. 10. All pdc-A and pdc-B ligands adopt an exotridentate binding mode, connecting to three different copper atoms via monodentate carboxylate oxygen atoms and a pyridyl nitrogen atom. Both the pdc-A and pdc-B ligands connect to two Cu2 atoms and one Cu1 atom. Through this binding mode, [Cu4(34pdc)4(H2O)4]n layer motifs are formed (Fig. 11); these are oriented parallel to the ab crystal planes. In turn the layer motifs are aggregated into a non-
interpenetrated [Cu4(34pdc)4(bbin)(H2O)4]n 3D coordination polymer network (Fig. 12) by exotetradentate bbn ligands. These have an anti-anti-anti conformation of their central tetramethylenediamine tethers, with torsion angles 177.0, 180, and 177.0°. Cu1 atoms in adjacent layer motifs are connected between basal coordination sites through the full span of the bbn ligands via the pyridyl nitrogen donor atoms, with a through-ligand internuclear distance of 12.30(1) Å. Cu2 atoms in adjacent layer motifs are connected between apical coordination sites through the two carbonyl oxygen atoms of the bbn ligands at a distance of 9.739(2) Å.
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The Cu2 atoms connect to two pdc-A ligand nodes, two pdc-B ligand nodes, and a bbn ligand node (via a carbonyl oxygen donor atom). The resulting complicated 3,3,4,5-connected multinodal network has an unprecedented {(63)2(628)(6282102)(668310)} topology, where the first term represents the pdc ligand nodes (Fig. 13). Discrete D(4) water molecule chains [31] are located in small pockets within the 3D coordination polymer network, anchored via hydrogen bonding mechanisms between the co-crystallized water molecules and bound water molecules and unligated pdc carboxylate oxygen atoms (Table S1).
4.6. Structural description of [Cu2(34pdc)2(pebn)(H2O)]8H2O}n (5)
Fig. 13. 3,3,4,5-connected multinodal network with {(63)2(628)(6282102)(668310)} topology in 4. The Cu1 and Cu2 atom nodes are shown in dark blue and green, respectively. The pdc-A and pdc-B ligand nodes are shown in gray and light blue. The bbn ligand nodes are shown in orange. Connections mediated by the pdc ligands are drawn in red; connections mediated by the bbn ligands are drawn in green. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Table 6 Selected bond distance (Å) and angle (°) data for 5. Cu1–O1 Cu1–O8#1 Cu1–N3 Cu1–N6#2 O1–Cu1–O8#1 O1–Cu1–N3 O1–Cu1–N6#2 O8#1–Cu1–N3 O8#1–Cu1–N6#2 N6#2–Cu1–N3 O5#3–Cu2–N1#4 O5#3–Cu2–N2 N1#4–Cu2–O9
1.949(8) 1.981(8) 2.000(10) 1.986(10) 94.7(3) 86.8(4) 162.1(4) 161.0(4) 87.7(4) 96.8(4) 89.1(3) 90.7(3) 90.3(3)
Cu2–O3 Cu2–O5#3 Cu2–O9 Cu2–N1#4 Cu2–N2 O3–Cu2–O9 O3–Cu2–N1#4 O3–Cu2–N2 O5#3–Cu2–O3 O5#3–Cu2–O9 N2–Cu2–O9 N2–Cu2–N1#4
1.962(8) 1.954(7) 2.187(9) 1.998(9) 1.986(9) 97.5(3) 91.0(3) 89.3(3) 164.5(4) 98.0(3) 89.4(4) 179.6(4)
Symmetry transformations: #1 x, y 1/2, z + 3/2; #2 1, y + 1, z; #3 x, y + 1/2, z + 3/2; #4 x + 1, y + 1/2, z + 3/2.
The underlying topology of compound 4 is rather complicated, with no ligands as simple linkers. The pdc-A and pdc-B ligands act as 3-connected nodes, joining two Cu2 atoms and one Cu1 atom within the [Cu4(34pdc)4(H2O)4]n layer motifs. The bbn ligands act as 4-connected nodes, joining two Cu1 atoms and two Cu2 atoms in adjacent [Cu4(34pdc)4(H2O)4]n layer motifs. The Cu1 atoms connect to a pdc-A ligand node, a pdc-B ligand node, and a bbn ligand node (via a pyridyl nitrogen donor atom).
The asymmetric unit of compound 5 contains two divalent copper atoms (Cu1, Cu2), two pdc ligands (pdc-A, pdc-B), a complete pebn ligand, an aqua ligand, and eight water molecules of crystallization. The Cu1 atoms display a {CuN2O2} square planar coordination environment, with trans pyridyl nitrogen donor atoms belonging to two pebn ligands and trans carboxylate oxygen atom donors from one pdc-A and one pdc-B ligand. In contrast, the Cu2 atoms display a rather distorted {CuN2O3} square pyramidal coordination environment (s = 0.252) in which a bound water molecule occupies the elongated apical position. The basal plane at Cu2 contains trans pyridyl nitrogen donor atoms from pdc-A and pdc-B ligands, and trans carboxylate oxygen donor atoms from pdc-A and pdc-B ligands. Bond lengths and angles within the respective coordination environments are listed in Table 6. A thermal ellipsoid plot of the disparate coordination environments is shown in Fig. 14. The pyridyl nitrogen donors and carboxylate oxygen atom donors of the pdc-A and pdc-B ligands connect Cu1 and Cu2 atoms into [Cu2(pdc)2(H2O)]n layers that are oriented parallel to the ab crystal planes (Fig. 15). Each pdc ligand within the layer motif binds in an exotridentate fashion, binding to two Cu2 atoms and one Cu1 atom. The Cu1 atoms on the periphery of the [Cu2(pdc)2 (H2O)]n layers are connected within the layer by pedn ligands with an anti-anti-gauche-anti conformation of their central pentamethylenediamine tethers (torsion angles = 169.1, 174.5, 68.2, 175.4°), thereby forming [Cu2(34pdc)2(pebn)(H2O)]n layer motifs in 5 (Fig. 16a). The pebn ligands span a Cu1 Cu1 internuclear distance of 17.660(3) Å. The underlying topology of the [Cu2(34pdc)2(pebn)(H2O)]n layer motifs in 5 can be inferred by treating the exotridentate pdc ligands as 3-connected nodes, the Cu1 and Cu2 atoms as 4-connected nodes, and the pebn ligands as simple linkers. A calculation performed with TOPOS reveals a 3,4,4-connected network with an unprecedented {(63)2(6472)(6.74.11)} topology (Fig. 16b). Isolated water molecules and intriguing chair-centered 14-water molecule clusters (Fig. 17) occupy the interlamellar regions between
Fig. 14. Coordination environments in 4. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 5.
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Fig. 15. [Cu2(pdc)2(H2O)]n layer in 5, oriented parallel to the ab crystal plane.
Fig. 16. a) Side view of [Cu2(34pdc)2(pebn)(H2O)]n layer motif in 5. The interior [Cu2(34pdc)2(H2O)]n submotif is shown in red. b) Schematic perspective of the {(63)2(6472) (6.74.11)} topology network in 5. Gold and dark blue spheres represent the 4-connected Cu1 and Cu2 atom nodes. Light blue and green spheres represent the 3-connected 34pdc ligand nodes. Connections mediated by 34pdc ligands are shown in red, while connections mediated by pebn ligands are shown in blue. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
[Cu2(34pdc)2(pebn)(H2O)]n layer motifs in 5. The 14-water molecule clusters can be said to resemble 1,4-bis(isobutyl)cyclohexane in connectivity, and are held to the coordination polymer layers by means of extensive hydrogen bonding patterns involving the bound water molecules, 34pdc carboxylate oxygen atoms, and pebn NAH and C@O groups (Table S1).
4.7. Structural description of [Cu4(34pdc)4(hbn)(H2O)4]3H2O}n (6) The asymmetric unit of compound 6 contains two divalent copper atoms (Cu1, Cu2), two 34pdc ligands (pdc-A, pdc-B), half of an hbn ligand whose central CAC bond is sited over a crystallographic inversion center, two bound water molecules, and two water
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Fig. 17. 14-water molecule cluster found in the interlamellar regions of 5.
Table 7 Selected bond distance (Å) and angle (°) data for 6. Cu1–O2 Cu1–O5 Cu1–O6 Cu1–O9 Cu1–N3 O2–Cu1–O5 O2–Cu1–O6 O2–Cu1–O9 O2–Cu1–N3 O6–Cu1–O5 O6–Cu1–O9 O9–Cu1–O5 N3–Cu1–O5 N3–Cu1–O6 N3–Cu1–O9
1.960(2) 2.137(2) 1.996(2) 2.096(3) 1.980(3) 144.81(9) 97.01(9) 120.80(11) 93.45(10) 63.62(8) 88.75(10) 89.45(11) 102.10(10) 165.33(10) 94.71(11)
Cu2–O4#1 Cu2–O7 Cu2–O10 Cu2–N1#2 Cu2–N2#3 O4#1–Cu2–O10 O4#1–Cu2–N1#2 O4#1–Cu2–N2#3 O7–Cu2–O4#1 O7–Cu2–O10 O7–Cu2–N1#2 O7–Cu2–N2#3 N1#2–Cu2–O10 N2#3–Cu2–O10 N2#3–Cu2–N1#2
1.986(2) 1.980(2) 2.250(3) 2.019(2) 2.006(2) 100.47(10) 84.10(9) 92.56(9) 164.23(9) 95.25(10) 92.09(9) 89.61(9) 99.50(10) 86.65(10) 173.43(10)
Symmetry transformations: #1 x, y 1, z; #2 x + 1, y 1/2, z + 1/2; #3 x, y 1/ 2, z + 1/2.
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cule occupies the Jahn-Teller elongated apical position. In the basal plane lie trans pyridyl nitrogen donor atoms belonging to a pdc-A and a pdc-B ligand, along with trans carboxylate oxygen atoms from other pdc-A and a pdc-B ligands. Bond lengths and angles within the different coordination spheres are listed in Table 7. A thermal ellipsoid plot of the copper atoms with full ligand sets is shown in Fig. 18. The 34pdc ligands in 6 are all exotridentate, connecting to two Cu2 atoms and one Cu1 atom. However, they adopt different binding modes. The pdc-A ligands link copper atoms in a l3-j3-N:O:O0 bridging mode in which both of their carboxylate ligands bind in a monodentate fashion. The pdc-B ligands link copper atoms in a l3j3-N:O:O0 ,O00 bridging mode in which one carboxylate group chelates to a Cu1 atom and the other binds in a monodentate fashion to a Cu2 atom. Via these binding modes, [Cu2(34pdc)2(H2O)2]n coordination polymer layer motifs are constructed (Fig. 19); these are oriented parallel to the ab crystal planes. These coordination polymer layer motifs have the same stoichiometry as seen in 3 and 4. However the layers in 6 are most closely related to those in 3, because each of the crystallographically distinct copper atoms possesses one bound water molecule. Parallel [Cu2(34pdc)2(H2O)2]n layers are connected into a noninterpenetrated 3D [Cu4(34pdc)4(hbn)(H2O)4]n coordination polymer network (Fig. 20) by curled conformation hbn ligands that exhibit a gauche-gauche-anti-gauche-gauche conformation of their central hexanediamine tethers (torsion angles = 60.5, 64.0, 180, 64.0, 60.5°). The hbn ligands connect Cu1 atoms in neighboring [Cu2(34pdc)2(H2O)2]n layer motif with a Cu Cu internuclear distance of 13.824(2) Å. The underlying topology of 6 can be investigated by considering each of the exotridentate 34pdc ligands as 3-connected nodes, the Cu1 atoms as 3-connecting nodes, and the Cu2 atoms as 4-connected nodes. Each 34pdc ligand connects to one Cu1 atom and two Cu2 atoms within the layer motifs. Each Cu2 atom connects to four 34pdc ligands within the layer motifs. Each Cu1 atom connects to two 34pdc ligands within one layer motif, and another Cu1 atom in another layer motif via an hbn ligand. According to TOPOS, the 3D 3,3,4-connected trinodal network has {(63)2(6.102) (64102)} topology, identical to that of 3, where looped pairs of bbn ligands acted as interlayer connectors in place of the single hbn ligand linkers seen in 6 (Fig. 9b). Isolated water molecules of crystallization occupy small pockets within the 3D structure of 6. 4.8. Thermogravimetric analysis
Fig. 18. Coordination environments in 6. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 7.
molecules of crystallization (one of which best refined at half occupancy). The Cu1 atoms display a rather distorted {CuNO4} square pyramidal coordination environment with s = 0.342. A pdc-A carboxylate group chelates to the apical site and one of the basal coordination sites. In cis basal positions are ligated a water molecule and a pyridyl nitrogen donor atom from an hbn ligand. A single carboxylate oxygen atom from a pdc-B occupies the fourth and final basal position. The Cu2 atoms display a less distorted {CuN2O3} square pyramidal coordination environment with s = 0.153. A bound water mole-
Thermogravimetric analyses were carried out on compounds 1– 6 to investigate their thermal stability and degradation behavior. Compound 1 underwent dehydration between 25 and ~150 °C, with a mass loss of 4.5% corresponding to the predicted value (4.3%) for ejection of one molar equivalent of co-crystallized water. Ligand ejection occurred above 215 °C. Compound 2 underwent ligand ejection above 240 °C. Compound 3 underwent dehydration between 25 and ~150 °C, with a mass loss of 12.8% corresponding roughly to the predicted value (13.7%) for ejection of seven molar equivalents of co-crystallized water. Ligand ejection occurred above 210 °C. Compound 4 underwent dehydration in two stages between 25 and ~210 °C, with a total mass loss of 16.0% corresponding roughly to the predicted value (15.1%) for ejection of twelve molar equivalents of bound and co-crystallized water. Ligand ejection occurred above 210 °C. Compound 5 underwent dehydration in two stages between 25 and ~205 °C, with a total mass loss of 9.3%. As this value is substantially below the predicted value of 15.5% corresponding roughly to ejection of eight molar equivalents of co-crystallized water, it is plausible that some dehydration occurred upon long term storage (~60 d) of compound 5 in ambient air. Ligand ejection occurred above 210 °C. Compound 6
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Fig. 19. [Cu2(34pdc)2(H2O)2]n coordination polymer layer in 6.
Fig. 20. Non-interpenetrated 3D [Cu4(34pdc)4(hbn)(H2O)4]n coordination polymer network in 6, with [Cu2(34pdc)2(H2O)2]n layer submotifs drawn in red and green, connected by the hbn ligands. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
underwent dehydration in three stages between 25 and ~210 °C, with a total mass loss of 9.2% corresponding exactly to the predicted value for ejection of seven molar equivalents of bound and co-crystallized water. Ligand ejection occurred above 210 °C. Thermogravimetric analysis plots for 1–6 are shown in Figs. S4–S9, respectively. 4.9. Congo Red dye degradation studies Crystalline compounds 1–6 were probed as heterogeneous Congo Red dye degradation catalysis in the presence of H2O2 and under ultraviolet irradiation. A blank control experiment without
any copper coordination polymer showed degradation of only 17% of the initial dye concentration after 120 min of irradiation in the presence of H2O2. Compound 1 showed degradation of 48% of the initial dye concentration after 30 min, and degradation of 96% of the initial dye concentration after 120 min elapsed time (Fig. 21). Compound 2 showed degradation of 81% of the initial dye concentration after 30 min, 87% after 60 min, and no detectable dye remaining after 120 min elapsed time. Compound 3 showed degradation of 49% of the initial dye concentration after 30 min, and degradation of 92% of the initial dye concentration after 120 min elapsed time. Compound 4 showed degradation of 40% of the initial dye concentration after 30 min, 70% after
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Fig. 21. Congo Red dye degradation graph for 1. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
60 min, and degradation of 99% of the initial dye concentration after 120 min elapsed time. Compound 5 showed degradation of 21% of the initial dye concentration after 30 min, 74% after 90 min, and degradation of 94% of the initial dye concentration after 120 min elapsed time. Compound 6 showed degradation of 38% of the initial dye concentration after 30 min, and degradation of 94% of the initial dye concentration after 120 min elapsed time. Thus, all six copper/34pdc coordination polymers in this study showed good activity as heterogeneous degradation catalysts for the azo dye Congo Red. Compound 2, which possesses one of the simpler topologies across this series, showed the most activity as a dye degradation catalyst. This could plausibly be ascribed to easier access to the copper centers by H2O2 molecules undergoing metal-catalyzed scission of the OAO bonds to produce hydroxyl radicals, which are the putative reactive species cleaving the azo like in the dye molecules [32].
Acknowledgments We thank Lyman Briggs College and the Honors College of Michigan State University for funding this work. Appendix A. Supplementary data Hydrogen bonding information, additional molecular graphics, TGA traces, and dye degradation catalysis plots for 2–6. Crystallographic data (excluding structure factors) for 1–6 have been deposited with the Cambridge Crystallographic Data Centre with Nos. 1934863–1934868, respectively. Copies of the data can be obtained free of charge via the Internet at
5. Conclusions A series of divalent copper coordination polymers containing the 3,4-pyridyldicarboxylate ligand and various neutral dipyridyl coligands has been synthesized and structurally characterized. Structural diversity across the series is predicated by differences in dipodal dipyridyl tether length and hydrogen-bonding facility. Several of the new compounds possess unprecedented, complicated topologies based on the 3,4-pyridyldicarboxylate ligands acting as 3-connected nodes in this system. All new compounds acted as heterogeneous catalysts for the oxidative degradation of the azo dye Congo Red in the presence of ultraviolet irradiation, with a topologically simple derivative showing the most rapid catalysis.
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
Conflicts of interest No conflicts to declare.
[15] [16] [17]
C. Janiak, J.K. Vieth, New J. Chem. 34 (2010) 2366. M. Arisi, O. Yesilel, M. Tas, H. Demiral, Cryst. Growth Des. 17 (2017) 2654. R.G. Miller, P.D. Southon, C.J. Kepert, S. Brooker, Inorg. Chem. 55 (2016) 6195. O. Gordon, T. Slenters, P.S. Brunetto, A.E. Villaruz, D.E. Sturdevant, M. Otto, R. Landmann, K.M. Fromm, Antimicrob. Agents Chemother. 54 (2010) 4208. S. Hasegawa, S. Horike, R. Matsuda, S. Furukawa, K. Mochizuki, Y. Kinoshita, S. Kitagawa, J. Am. Chem. Soc. 129 (2007) 2607. Y. He, Y. Tan, J. Zhang, Inorg. Chem. 54 (2015) 6653. X. Zhang, Y. Wang, Y. Song, E. Gao, Inorg. Chem. 50 (2011) 7284. X. Bu, M. Tong, H. Chang, S. Kitagawa, Angew. Chem., Int. Ed. 43 (2004) 192. L. Liu, D. Wu, B. Zhao, X. Han, J. Wu, H. Hou, Y. Fan, Dalton Trans. 44 (2015) 1406. A. Hossain, A. Dey, S. Seth, P. Ray, P. Ballester, R.G. Pritchard, J. Ortega-Castro, A. Frontera, S. Mukhopadhyay, ACS Omega 3 (2018) 9160. L. Gao, B. Zhao, G. Li, Z. Shi, S. Feng, Inorg. Chem. Commun. 6 (2003) 1249. J.Y. Baeg, S.W. Lee, Inorg. Chem. Commun. 6 (2003) 313. D. Sarma, K.V. Ramanujachary, N. Stock, S. Natarajan, Cryst. Growth Des. 11 (2011) 1357. A. Halder, B. Bhattacharya, R. Dey, D. Maity, D. Ghoshal, Cryst. Growth Des. 16 (2016) 4783. S. Yan, X. Zheng, L. Li, D. Yuan, L. Jin, Dalton Trans. 40 (2011) 1758. M.L. Tong, J. Wang, S. Hu, S.R. Batten, Inorg. Chem. Commun. 8 (2005) 48. Z. Fu, S. Hu, J. Dai, J. Zhang, X. Wu, Eur. J. Inorg. Chem. (2003) 2670.
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[18] H. Fei, Z. Li, X. Liu, J. Alloys Compounds 640 (2015) 118. [19] B. Bhattacharya, A. Halder, D. Maity, D. Ghoshal, CrystEngComm 18 (2016) 4074. [20] F. Semerci, O. Yesilel, F. Yüksel, O. Sahin, Polyhedron 111 (2016) 1. [21] P.J. Zapf, R.L. LaDuca, R.S. Rarig, K.M. Johnson, J. Zubieta, Inorg. Chem. 37 (1998) 3411. [22] T.S. Gardner, E. Wenis, J.J. Lee, J. Org. Chem. 19 (1954) 753. [23] SAINT, Software for Data Extraction and Reduction, Version 6.02; Bruker AXS, Inc.: Madison, WI, 2002. [24] SADABS, Software for Empirical Absorption Correction. Version 2.03; Bruker AXS, Inc.: Madison, WI, 2002. [25] G.M. Sheldrick, Acta Crystallogr. A64 (2008) 112.
[26] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H.J. Puschmann, Appl. Crystallogr. 42 (2009) 42. [27] A.W. Addison, T.N.J. Rao, J. Reedijk, J. van Rijn, G.C. Verschoor, J. Chem. Soc., Dalton Trans. (1984) 1349. [28] V.A. Blatov, A.P. Shevchenko, D.M. Proserpio, Cryst. Growth Des. 14 (2014) 3576, TOPOS software is available for download at:. [29] M.D. Torres-Salgado, C.J. Bouchey, J.A. Wilson, R.L. LaDuca, J. Coord. Chem. 68 (2015) 2029. [30] B.L. Pickwick, A.L. Pochodylo, R.L. LaDuca, Inorg. Chim. Acta 466 (2017) 618. [31] L. Infantes, S. Motherwell, CrystEngComm 4 (2002) 454. [32] L. Liu, Y. Peng, X. Lv, K. Li, B. Li, B. Wu, CrystEngComm 18 (2016) 2490.
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Copper 3,4-pyridinedicarboxylate mixed ligand coordination polymers with diverse topologies and aqueous Congo Red degradation catalytic properties Ellese C. Jaddou, Robert L. LaDuca 1 Lyman Briggs College and Department of Chemistry, Michigan State University, East Lansing, MI 48825, USA
a r t i c l e
i n f o
Article history: Received 7 January 2020 Accepted 31 January 2020 Available online 7 February 2020 Keywords: Copper Coordination polymer Crystal structure Topology Dye degradation catalysis
a b s t r a c t Hydrothermal reaction of copper nitrate, 3,4-pyridinedicarboxylic acid (34pdcH2), and a variety of ditopic dipyridyl ligands afforded six new coordination polymer solids with diverse 2D and 3D topologies as characterized via single-crystal X-ray diffraction. {[Cu(34pdc)(dpa)]H2O}n (1, dpa = 4,40 -dipyridylamine) reveals a 3,5-connected layered net with a (426)(42678) topology. [Cu(34pdc)(3pina)]n (2, 3pina = 3pyridylisonicotinamide) manifests a 2-fold interpenetrated 3,5-connected 3D net with (426)(426583) topology. [Cu2(34pdc)2(bbn)(H2O)2]7H2O}n (3, bbn = bis(butane-1,4-diyl)nicotinamide) shows a 3D trinodal network with {(63)2(6.102)(64102)} topology, with looped pairs of bbn ligands acting as single connectors. [Cu4(34pdc)4(bbin)(H2O)4]8H2O}n (4, bbin = bis(butane-1,4-diyl)isonicotinamide) displays a quite complicated 3D multinodal network with {(63)2(628)(6282102)(668310)} topology. [Cu2(34pdc)2(pebn)(H2O)]8H2O}n (5, pebn = bis(pentane-1,5-diyl)nicotinamide) shows a 3,4,4-connected 2D network with {(63)2(6472)(6.74.11)} topology, along with entrapped chair-centered 14-water molecule clusters. [Cu4(34pdc)4(hbn)(H2O)4]3H2O}n (6, hbn = bis(hexane-1,6-diyl)nicotinamide) showed the same {(63)2(6.102)(64102)} topology as 3, but with single dipyridylamide ligands instead of looped pairs. Thermal decomposition of these six new materials are also probed, along with their catalytic behavior for the aqueous degradation of Congo Red dye in the presence of ultraviolet radiation and hydrogen peroxide. Ó 2020 Elsevier Ltd. All rights reserved.
1. Introduction Coordination polymers constructed from metal cations and anionic aromatic dicarboxylate ligands have shown exciting properties in many technologically relevant applications [1], such as carbon dioxide sequestration [2], shape-selective hydrocarbon separation [3], antibacterial coatings [4], heterogeneous catalysis for key industrial organic transformations [5], non-linear optics [6], and temperature and field-dependent magnetism [7]. Due to their flexible coordination environments, divalent copper coordination polymers manifest a tremendous diversity of different structural topologies depending on the specific dicarboxylate ligand used, along with the presence of other structure-directing neutral dipyridyl or bis(imidazolyl) coligands [8]. Recent studies have shown that many divalent copper coordination polymers have significant utility as heterogeneous catalysts for the ultraviolet-induced
1 Mailing address: Lyman Briggs College, E-30 Holmes Hall, 919 East Shaw Lane, Michigan State University, East Lansing, MI 48825, USA. E-mail address: [email protected] (R.L. LaDuca)
https://doi.org/10.1016/j.poly.2020.114427 0277-5387/Ó 2020 Elsevier Ltd. All rights reserved.
degradation of toxic dyestuffs in the presence of an inexpensive or free oxidant (e.g. hydrogen peroxide or atmospheric oxygen) [9]. The most commonly used ligands for inducing neutral charge and crystallization in divalent metal coordination polymers are the aromatic dicarboxylates such as phthalate [10], isophthalate [11], terephthalate [12], and related derivatives such as 5-position substituted isophthalates [13]. Less commonly used have been pyridyldicarboxylate ligands, such as 2,3-pyridinedicarboxylate and 3,4-pyridinedicarboxylate (34pdc, Scheme 1) [14–20]. {[Cu2(34pdc)2(dpp)2(H2O)4]5H2O}n (dpp = 1,3-(di-4-pyridyl)propane) shows 1D [Cu(34pdc)(H2O)2]n chain motifs pillared into a 2D (4,4) grid coordination polymer by the dipodal dpp tethers, in which the 34pdc ligands serve as simple linkers. This material undergoes a reversible single-crystal-to-amorphous morphological transition upon dehydration and rehydration, and has water-bearing incipient channels comprising over 25% of the unit cell volume [14]. A series of copper hydroxide cluster-bearing 34pdc coordination polymer chains with variable ferromagnetic or antiferromagnetic properties was prepared in the presence of the capping ligand 1,10-phenanthroline [15]. Due to the presence of the pyridyl
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E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427
Scheme 1. Organic precursors used in this study.
nitrogen donor atom, the 34pdc ligand can serve as a 3-connected node in some cases, instead of a simple linker, thereby instilling an even greater variety of structural variability in the resulting coordination polymer. A previously reported example where this is the case is {(NMe4)2[Cu3(34pdc)4(H2O)4]4H2O}n, which possesses an anionic 3D coordination polymer network with{(63)4(6282102) (648.10)} 3,4,4-connected topology [16]. {[Cd(34pdc)(dpp)] 0.5H2O}n manifests a 3,5-connected 3D coordination polymer network, again with the 34pdc ligand serving as a 3-connected node [17]. In this study we have aimed to expand the scope of divalent copper 3,4-pyridyldicarboxylate coordination polymers by including hydrogen-bonding capable dipyridylamine or dipyridylamide ligands in the hydrothermal synthetic scheme. Herein we report the synthesis and single-crystal X-ray structural characterization of six new divalent copper 3,4-pyridyldicarboxylate coordination polymers with 2D and 3D topologies as characterized via single-crystal X-ray diffraction: {[Cu(34pdc)(dpa)]H2O}n (1, dpa = 4,40 -dipyridylamine, Scheme 1), [Cu(34pdc)(3pina)]n (2, 3pina = 3-pyridylisonicotinamide, Scheme 1), [Cu2(34pdc)2(bbn) (H2O)2]7H2O}n (3, bbn = bis(butane-1,4-diyl)nicotinamide, Scheme 1), [Cu4(34pdc)4(bbin)(H2O)4]8H2O}n (4, bbin = bis(butane-1,4-diyl)isonicotinamide, Scheme 1), [Cu2(34pdc)2(pebn) (H2O)]8H2O}n (5, pebn = bis(pentane-1,5-diyl)nicotinamide, Scheme 1), and [Cu4(34pdc)4(hbn)(H2O)4]3H2O}n (6, hbn = bis (hexane-1,6-diyl)nicotinamide, Scheme 1). Thermal dehydration and/or decomposition of these six new materials have also been investigated, along with their heterogeneous catalytic behavior towards the aqueous degradation of Congo Red dye in the presence of ultraviolet radiation and hydrogen peroxide.
2.2. Preparation of {[Cu(34pdc)(dpa)]H2O}n (1) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), dpa (62 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 80 °C for 48 h, and then cooled slowly to 25 °C. Blue crystals of 1 (65 mg, 42% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C17H14CuN4O5 1: C, 48.86; H, 3.38; N, 13.41% Found: C, 48.29; H, 3.21; N, 13.12%. IR (cm1): 1596 (s) , 1516 (m) , 1385 (m), 1366 (s) , 1340 (m), 1210 (s) , 1050 (w), 1027 (m) , 816 (s), 790 (w), 683 (s).
2.3. Preparation of [Cu(34pdc)(3pina)]n (2) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), 3pina (75 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 100 °C for 24 h, and then cooled slowly to 25 °C. Blue crystals of 2 (84 mg, 53% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C18H12CuN4O5 2: C, 50.53; H, 2.83; N, 13.09% Found: C, 50.23; H, 2.68; N, 13.08%. IR (cm1): 1681 (m), 1613 (s), 1581 (s), 1541 (m), 1502 (w), 1433 (m), 1396 (s), 1365 (s), 1340 (m) 1286(m), 1196 (w), 1111 (w) , 1054 (w), 1027 (w), 945 (w), 861 (w), 836 (w), 807 (w), 791 (w), 761 (m), 696 (s), 680 (s).
2. Experimental section 2.4. Preparation of [Cu2(34pdc)2(bbn)(H2O)2]7H2O}n (3) 2.1. General considerations Copper nitrate and 3,4-pyridinedicarboxylic acid were purchased commercially. The 4,40 -dipyridylamine ligand was prepared according to a literature procedure [21], as were the various dipyridylamide ligands [22]. Reported yields are for optimized procedures to obtain the maximum amount of monophasic product. Water was deionized above 3 MX-cm in-house. IR spectra were recorded on powdered samples using a Perkin Elmer Spectrum One instrument. Thermogravimetric analysis was performed under flowing N2 on a TA Instruments TGA Q50 Thermogravimetric Analyzer with a heating rate of 10 °C/min up to 600 °C.
Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), bbn (110 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 80 °C for 48 h, and then cooled slowly to 25 °C. Blue crystals of 3 (52 mg, 31% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C30H42Cu2N6O19 3: C, 39.26; H, 4.61; N, 9.16% Found: C, 38.97; H, 4.03; N, 8.98%. IR (cm1): 3260 (w), 2349 (w), 2341 (w), 2316 (w), 1660 (m), 1650 (m), 1543 (s), 1377 (s), 1305 (m), 1191 (w), 831 (m), 696 (s).
E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427 Table 1 Crystal and structure refinement data for 1–6. Data
1
2
3
Empirical Formula Formula Weight Crystal system Space group
C17H14CuN4O5 417.86 Triclinic
C18H12CuN4O5 427.86 Orthorhombic Pbca
C30H42Cu2N6O19 917.77 Monoclinic P21/c
8.897(4) 19.066(10) 20. 5(11) 90 90 90 3450(3) 8 1.648 1.307 0.8092 0 h 10, 0 k 23, 0 l 24 71,555 3188 0.0931 253 0.1155 0.0702 0.1921 0.1669 1.806/–0.571
13.368(2) 11.8607(18) 24.035(4) 90 92.717(2) 90 3806.7(10) 4 1.601 1.205 0.8968 10 h 11, 23 k 23, 19 l 19 29,716 7004 0.0640 543 0.0924 0.0766 0.1741 0.1672 1.324/–0.680
a (Å) b (Å) c (Å) a(°) b (°) c(°) V (Å3) Z Dcalc (g cm3) l(mm1) Min./max. trans. hkl ranges
Total reflections Unique reflections R(int) Parameters R1 (all data) R1 (I > 2r (I)) wR2 (all data) wR2 (I > 2 r (I)) Max/min residual (e/Å3) G.O.F.
P1 8.9225(6) 10.3928(7) 10.5604(7) 118.931(1) 97.995(1) 100.902(1) 810.73(9) 2 1.712 1.388 0.9192 10 h 10, 12 k 12, 12 l 12 13,262 2988 0.0247 247 0.0278 0.0254 0.0669 0.0650 0.332/–0.248 1.079
1.081
1.153
Data
4
5
6
Empirical Formula Formula Weight Crystal system Space group a (Å) b (Å) c (Å) a(°) b (°) c(°) V (Å3) Z Dcalc (g cm3) l (mm1) Min./max. trans. hkl ranges
C44H54Cu4N8O30 1429.1 Monoclinic P21/c 13.300(3) 11.272(3) 18.699(5) 90 106.805(3) 90 2683.5(12) 2 1.769 1.669 0.8269 16 h 15, 12 k 13, 22 l 22 16,904 4901 0.1894 366 0.1884 0.0715 0.1643 0.1170 0.815/–0.705
C31H44Cu2N6O19 931.80 Monoclinic P21/c 13.244(14) 11.682(12) 25.95(2) 90 96.206(15) 90 3991(7) 4 1.551 1.151 0.3321 16 h 15, 13 k 14, 31 l 31 31,449 7427 0.2280 536 0.2121 0.1156 0.3310 0.2743 1.390/–1.631
C46H48Cu4N8O25 1367.08 Monoclinic P21/c 13.7686(9) 11.0964(7) 18.4979(15) 90 111.587(1) 90 2627.9(3) 2 1.728 1.693 0.9117 16 h 16, 13 k 13, 22 l 22 20,663 4815 0.0392 387 0.0487 0.0381 0.1032 0.0949 0.685/–0.629
0.942
1.031
1.036
Total reflections Unique reflections R(int) Parameters R1 (all data) R1 (I > 2 r (I)) wR2 (all data) wR2 (I > 2 r (I)) Max/min residual (e/Å3) G.O.F.
2.5. Preparation of [Cu4(34pdc)4(bbin)(H2O)4]8H2O}n (4) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), bbin (110 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 100 °C for 24 h, and then cooled slowly to 25 °C. Blue crystals of 4 (62 mg, 47% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C44H54Cu4N8O30 4: C, 36.98; H, 3.81; N,
3
7.84% Found: C, 37.13; H, 3.60; N, 7.69%. IR (cm1): 3300 (w, br), 1640 (w), 1614 (m), 1570 (m), 1555 (m), 1386 (s), 1166 (w), 1123 (w), 1068 (w), 945 (w), 843 (w), 819 (w), 723 (w), 684 (s). 2.6. Preparation of [Cu2(34pdc)2(pebn)(H2O)]8H2O}n (5) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), pebn (111 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 100 °C for 24 h, and then cooled slowly to 25 °C. Blue crystals of 5 (63 mg, 37% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C31H44Cu2N6O19 5: C, 39.96; H, 4.76; N, 9.02% Found: C, 39.40; H, 4.66; N, 9.24%. IR (cm1): 3298 (w), 1640 (m), 1619 (s), 1551 (m), 1373 (s), 1197 (w), 1172 (w), 1125 (w), 1058 (w), 884 (w), 838 (w), 816 (w), 786 (w), 728 (m), 701 (s), 683 (s). 2.7. Preparation of [Cu4(34pdc)4(hbn)(H2O)4]3H2O}n (6) Cu(NO3)22.5H2O (87 mg, 0.37 mmol), 3,4-pyridinedicarboxylic acid (61 mg, 0.37 mmol), hbn (121 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL distilled H2O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 120 °C for 24 h, and then cooled slowly to 25 °C. Blue crystals of 6 (47 mg, 37% yield based on Cu) were isolated after washing with distilled water and acetone, and drying in air. Anal. Calc. for C46H48Cu4N8O25 6: C, 40.41; H, 3.54; N, 8.20% Found: C, 40.82; H, 3.43; N, 8.39%. IR (cm1): 3236 (w), 1660 (w), 1640 (w), 1594 (m), 1525 (w), 1492 (w), 1444 (w), 1408 (m), 1382 (s), 1350 (m), 1198 (w), 1118 (w), 836 (w), 814 (w), 779 (m), 722 (m), 686 (s). 2.8. Congo Red degradation experiments 50 mg of copper coordination complexes 1–6 were dispersed in 100 mL deionized water in 250 mL beakers open to ambient air. A 5 mg portion of solid Congo Red dye was added to each beaker, along with 10 mL 30% H2O2 solution. Each mixture was stirred at 25 °C under an Electron Microscopy Sciences 100 W High-Intensity Ultraviolet lamp with maximum wavelength of 365 nm. A 5 mL aliquot was taken prior to irradiation and its UV–VIS spectrum was acquired. Small aliquots (5 mL) were withdrawn from each mixture at different elapsed time values, and their UV–VIS spectra were acquired. 3. X-ray crystallography Single crystal X-ray diffraction on crystals of 1–6 was performed using a Bruker-AXS ApexII CCD instrument at 173 K. Reflection data were acquired using graphite-monochromated Mo-Ka radiation (k = 0.71073 Å). The data was integrated via SAINT [23]. Lorentz and polarization effect and empirical absorption corrections were applied with SADABS [24]. The structures were solved using direct methods and refined on F2 using SHELXTL [25] within the OLEX2 crystallographic software suite [26]. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were placed in calculated positions and refined isotropically with a riding model. The R(int) values for the crystals of 4 and 5 were rather high due to small crystal size and weaker diffraction at high angles. Nevertheless all atoms refined well and the connectivity and topology are unambiguous. Relevant crystallographic data for 1–6 are listed in Table 1.
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E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427
Fig. 1. a) Coordination environment in 1. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 2. b) [Cu(34pdc)]n ribbon submotif in 1.
Table 2 Selected bond distance (Å) and angle (°) data for 1. Cu1–O1 Cu1–O4#1 Cu1–N1 Cu1–N3#2 Cu1–N4#3 O1–Cu1–O4#1 O1–Cu1–N1 O1–Cu1–N3#2
1.9556(13) 2.0078(13) 2.0213(16) 2.3582(17) 2.0388(16) 89.73(6) 87.06(6) 90.11(6)
O1–Cu1–N4#3 O4#1–Cu1–N1 O4#1–Cu1–N3#2 O4#1–Cu1–N4#3 N1–Cu1–N3#2 N1–Cu1–N4#3 N4#3–Cu1–N3#2
177.26(6) 171.88(6) 88.94(6) 87.57(6) 98.51(6) 95.67(6) 89.40(6)
Symmetry transformations: #1 x + 1, y, z; #2 x, y 1, z 1; #3 x + 1, y, z.
4. Results and discussion 4.1. Synthesis and spectral characterization Compounds 1–6 were prepared by hydrothermal reaction of copper nitrate, 3,4-pyridinedicarboxylic acid, and the requisite dipyridyl ligand in the presence of aqueous base (in order to deprotonate the carboxylic acid precursors). The infrared spectra of 1–6 were consistent with structural components determined by singlecrystal X-ray diffraction. Intense, slightly broadened asymmetric and symmetric carboxylate CAO stretching bands for the cyclohexyldicarboxylate ligands were observed at 1596 and 1366 cm1 for 1, 1541 and 1396 cm1 for 2, 1543 and 1377 cm1 for 3, 1570 and 1386 cm1 for 4, 1551 and 1373 cm1 for 5, and 1594 and 1382 cm1 for 6. Sharp and medium intensity bands in the range of ~1600 cm1 to ~1300 cm1 were attributed to stretching mode of the pyridyl rings of the ligands in 1–6. The C@O
carbonyl stretching frequency for the dipyridylamide ligands appeared at 1681 cm1 (for 2), 1660 cm1 (for 3), 1640 cm1 (for 4), 1640 cm1 (for 5), and 1660 cm1 (for 6). 4.2. Structural description of {[Cu(34pdc)(dpa)]H2O}n (1) The asymmetric unit of compound 1 contains a divalent copper atom, a fully deprotonated 34pdc ligand, a dpa ligand, and a water molecule of crystallization. A square pyramidal {CuN3O2} coordination environment is observed at copper (s = 0.09) [27], with a pyridyl nitrogen donor atom from a dpa ligand placed in the elongated apical position. The base of the square pyramid contains cis carboxylate oxygen donor atoms belonging to two 34pdc ligands, while a pyridyl nitrogen donor atom belonging to a third 34pdc ligand fills one position (Fig. 1a). The final position, cis to the 34pdc nitrogen donor atom, is taken up by a pyridyl nitrogen donor atom from a second dpa ligand. The three nitrogen donors are arranged in a facial fashion within the coordination environment. Bond lengths and angles within the coordination sphere are listed in Table 2. The 34pdc ligands in 1 act as exotridentate donor atoms, binding to three copper atoms via single oxygen atoms from both carboxylate groups, and the pyridyl nitrogen atom. Through this l3-j3-N:O:O0 bridging mode in which one oxygen atom from each carboxylate group does not bind to copper, [Cu(34pdc)]n coordination polymer ribbons are formed (Fig. 1b). These ribbon motifs are oriented along the a crystal axis, with the Cu Cu distance linked through 34pdc pyridyl nitrogen atoms and 4-position carboxylate groups measuring 8.922(2) Å.
Fig. 2. [Cu(34pdc)(dpa)]n coordination polymer layer in 1.The 34pdc ligands are drawn in red and the dpa ligands are drawn in blue. The Cu atoms are shown in green. a) Face view. b) Side view. ((Colour online.))
5
E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427 Table 3 Selected bond distance (Å) and angle (°) data for 2. Cu1–O1 Cu1–O3#1 Cu1–N1 Cu1–N3#2 Cu1–N4#3 O1–Cu1–O3#1 O1–Cu1–N1 O1–Cu1–N3#2
1.980(4) 2.171(4) 2.005(5) 2.023(5) 2.010(5) 90.48(16) 89.67(17) 89.05(17)
O1–Cu1–N4#3 N1–Cu1–O3#1 N1–Cu1–N3#2 N1–Cu1–N4#3 N3#2–Cu1–O3#1 N4#3–Cu1–O3#1 N4#3–Cu1–N3#2
175.86(18) 109.55(18) 161.1(2) 90.33(18) 89.36(17) 93.42(18) 89.62(18)
Symmetry transformations: #1 x + 1/2, y + 3/2, z + 1; #2 x + 1, y + 1/2, z + 1/2; #3 x + 1, y, z.
Fig. 3. Simplified (426)(42678) binodal topology in 1, otherwise known as the 3,5-L2 net. The 34pdc ligand nodes are drawn in teal, while the Cu atom nodes are drawn in dark blue. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Parallel [Cu(34pdc)]n ribbons are connected into [Cu(34pdc) (dpa)]n coordination polymer layers by the dipodal dpa ligands (Fig. 2a); these span a CuCu internuclear distance of 10.64(1) Å. As seen in Fig. 2b, the dpa ligands (drawn in blue) are situated above and below the plane defined by the parallel [Cu(34pdc)]n ribbon submotifs. From a topological perspective, the exotridentate 34pdc ligands can be considered 3-connected nodes, and the copper atoms can be considered 5-connected nodes. A topological calculation performed by TOPOS [28] reveals a 3,5-connected binodal layered net (Fig. 3) with a Schläfli symbol of (426)(42678), otherwise known as the 3,5L2 net. A previous example of a coordination polymer exhibiting this network is [Co(2,5-thiophenedicarboxylate)(3pna)]n (3pna = 3-pyridylnicotinamide) [29]. Adjacent [Cu(34pdc)(dpa)]n coordination polymer layers stack in an AAA pattern along the c crystal direction, with the supramolecular impetus provided by NAH O hydrogen bonding between dpa central amine moieties and unbound 34pdc carboxylate oxygen atoms (Fig. S1, Table S1). Water molecules of crystallization are held to the coordination polymer layers by donating hydrogen bonds to unligated 34pdc carboxylate oxygen atoms. 4.3. Structural description of [Cu(34pdc)(3pina)]n (2) The asymmetric unit of compound 2 contains a divalent copper atom, a fully deprotonated 34pdc ligand, and a 3pina ligand. A rather distorted square pyramidal {CuN3O2} coordination environment is observed at copper (s = 0.24), but dissimilar to 1, a carboxylate oxygen donor from a 34pdc ligand is located in the elongated apical position. The base of the square pyramid contains trans pyridyl nitrogen donor atoms from two 3pina ligands, a pyridyl nitrogen donor atom from a second 34pdc ligand, and a carboxylate oxygen atom belonging to a third 34pdc ligand. The
three nitrogen donors are arranged in a meridional fashion within the coordination environment, dissimilar to the facial arrangement seen in 1 (Fig. 4a). Bond lengths and angles within the coordination sphere in 2 are listed in Table 3. The 34pdc ligands in 2 act as exotridentate ligands with a l3-j3-N:O:O0 bridging mode, similar to that seen in 1. As a result, similar [Cu(34pdc)]n coordination polymer ribbons are seen in 2 (Fig. 4b), with some variances in the carboxylate twist angles. Unlike the 2D coordination polymer net of 1, 3D [Cu(34pdc) (3pina)]n coordination polymer networks are caused by the pillaring of the ribbon submotifs by the dipyridylamide 3pina ligands, which span a CuCu distance of 11.72(1) Å (Fig. 5a). The incipient voids in a single [Cu(34pdc)(3pina)]n network contain a second [Cu(34pdc)(3pina)]n network, resulting in 2-fold interpenetration (Fig. 5b). As in 1, from a topological perspective, the exotridentate 34pdc ligands in 2 can be considered 3-connected nodes, and the copper atoms can be considered 5-connected nodes. The resulting 2-fold interpenetrated 3,5-connected binodal net has a (426) (426583) topology (Fig. 6) as calculated by TOPOS. A previous example of this network is {[Cd2(sip)2(4-bpmpH2)(4-bpmp)]4H2O}n (sip = 5-sulfoisophthalate, 4-bpmp = bis(4-pyridylmethyl)piperazine), in which the sip ligand acts as 3-connected ligand nodes [30]. 4.4. Structural description of [Cu2(34pdc)2(bbn)(H2O)2]7H2O}n (3) The asymmetric unit of compound 3 contains two divalent copper atoms (Cu1, Cu2), two 34pdc ligands, one complete bbn ligand, two bound water molecules and seven water molecules of crystallization (with some of those being disordered). The Cu1 atoms display a distorted {CuN2O3} square pyramidal coordination environment with s = 0.22. A carboxylate oxygen atom donor from a 34pdc ligand occupies the elongated apical position. The basal plane at Cu1 contains cis disposed pyridyl nitrogen donor atoms from two bbn ligands, a bound water molecule, and a carboxylate oxygen atom donor from a second 34pdc ligand. The Cu2 atoms display a much less distorted {CuN2O3} square pyramidal coordination environment with s = 0.04. Here, a bound water molecule occupies the Jahn-Teller elongated apical position. In the basal
Fig. 4. a) Coordination environment in 2. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 2. b) [Cu(34pdc)]n ribbon submotif in 2.
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Fig. 5. a) A single [Cu(34pdc)(3pina)]n network in 2, with [Cu(34pdc)]n ribbon submotifs drawn in red going into the plane of the page. b) 2-fold interpenetration of 3D networks in 2. ((Colour online.))
Table 5 Selected bond distance (Å) and angle (°) data for 4. Cu1–O3 Cu1–O8#1 Cu1–O9 Cu1–O10 Cu1–N3 O3–Cu1–O10 O8#1–Cu1–O3 O8#1–Cu1–O10 O9–Cu1–O3 O9–Cu1–O8#1 O9–Cu1–O10 O9–Cu1–N3 N3–Cu1–O3 N3–Cu1–O8#1 N3–Cu1–O10
2.012(6) 2.011(6) 1.961(6) 2.243(6) 2.000(8) 103.8(3) 152.8(3) 103.0(3) 92.5(3) 84.1(3) 88.1(3) 177.5(3) 87.8(3) 94.5(3) 94.3(3)
Cu2–O1 Cu2–O5 Cu2–O11#2 Cu2–N1#3 Cu2–N2#4 O1–Cu2–O5 O1–Cu2–O11#2 O1–Cu2–N1#3 O1–Cu2–N2#4 O5–Cu2–O11#2 O5–Cu2–N1#3 N1#3–Cu2–O11#2 N2#4–Cu2–O5 N2#4–Cu2–O11#2 N2#4–Cu2–N1#3
1.963(6) 2.008(6) 2.370(6) 2.014(7) 1.988(8) 164.2(3) 87.4(2) 91.2(3) 91.7(3) 108.3(2) 87.5(2) 87.9(2) 90.0(3) 90.9(3) 176.8(3)
Fig. 6. Schematic perspective of the 2-fold interpenetrated (426)(426583) topology network in 2.
Symmetry transformations: #1 x, y + 1, z; #2 x 1/2, y + 3/2, z 1/2; #3 x + 1/2, y + 1/2, z + 1/2; #4 x + 3/2, y 1/2, z + 1/2.
plane lie trans pyridyl nitrogen donor atoms belonging to two 34pdc ligands, along with trans carboxylate oxygen atoms from two other 34pdc ligands. Bond lengths and angles within the disparate coordination spheres are listed in Table 4. A thermal ellipsoid plot of the copper atoms with their respective ligand sets is shown in Fig. 7. As in 1 and 2, all of the 34pdc ligands in 3 act as exotridentate ligands with a l3-j3-N:O:O0 bridging mode. However, dissimilar to the [Cu(34pdc)]n ribbon submotifs in 1 and 2, compound 3 possesses [Cu2(34pdc)2(H2O)2]n coordination polymer layers arranged parallel to the ab crystal planes (Fig. 8a). Parallel [Cu2(34pdc)2(H2-
O)2]n layers are connected into a non-interpenetrated 3D [Cu2(34pdc)2(bbn)(H2O)2]n coordination polymer network (Fig. 8b) by pairs of curled conformation bbn ligands (Fig. S2). The bbn ligands have a gauche-gauche-gauche conformation of their central butanediamine tethers, with torsion angles of 63.0°, 70.9°, and 74.4°. The underlying topology of 3 can be probed by considering each of the exotridentate 34pdc ligands as 3-connected nodes, the Cu1 atoms as 3-connecting nodes, and the Cu2 atoms as 4-connected nodes. Each 34pdc ligand connects to one Cu1 atom and two Cu2 atoms. Each Cu1 atom connects to two 34pdc ligands, and another Cu1 atom via a looped pair of bbn ligands. Each Cu2 atom connects
Table 4 Selected bond distance (Å) and angle (°) data for 3. Cu1–O1 Cu1–O8#1 Cu1–O10 Cu1–N3 Cu1–N6#2 O1–Cu1–O8#1 O1–Cu1–O10 O1–Cu1–N3 O1–Cu1–N6#2 O10–Cu1–O8#1 O10–Cu1–N3 O10–Cu1–N6#2 N3–Cu1–O8#1 N3–Cu1–N6#2 N6#2–Cu1–O8#1
1.969(5) 2.222(4) 1.998(5) 2.015(6) 2.020(5) 100.26(18) 88.01(19) 89.5(2) 162.0(2) 90.32(17) 174.9(2) 92.2(2) 94.50(19) 88.8(2) 97.8(2)
Cu2–O4 Cu2–O5 Cu2–O9 Cu2–N1#3 Cu2–N2#4 O4–Cu2–O9 O4–Cu2–N1#3 O4–Cu2–N2#4 O5–Cu2–O4 O5–Cu2–O9 O5–Cu2–N1#3 O5–Cu2–N2#4 N1#3–Cu2–O9 N1#3–Cu2–N2#4 N2#4–Cu2–O9
1.992(4) 1.970(4) 2.291(4) 2.016(5) 2.021(5) 91.28(17) 88.04(19) 89.69(19) 176.44(18) 86.17(17) 89.56(19) 92.95(19) 92.19(19) 174.1(2) 93.31(19)
Symmetry transformations: #1 x, y + 1, z; #2 x + 1, y + 1, z + 1; #3 x + 2, y 1/ 2, z + 1/2; #4 x + 1, y + 1/2, z + 1/2.
Fig. 7. Coordination environments in 3. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 4.
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Fig. 8. a) [Cu2(34pdc)2(H2O)2]n coordination polymer layer in 3. b) Non-interpenetrated 3D [Cu2(34pdc)2(bbn)(H2O)2]n coordination polymer network, with [Cu2(34pdc)2 (H2O)2]n layer submotifs drawn in red. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 9. a) Simplified [Cu2(34pdc)2(H2O)2]n layer submotif in 3, representing 34pdc ligand nodes as light green spheres, connecting to Cu1 atoms (blue) and Cu2 atoms (dark green). b) 3,3,4-connected trinodal network with {(63)2(6.102)(64102)} topology in 3. Connections mediated by 34pdc ligands are shown in red, and the bbn-mediated connections are shown in blue. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 10. Coordination environments in 4. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 5.
to four 34pdc ligands. According to TOPOS, the 3,3,4-connected trinodal network has {(63)2(6.102)(64102)} topology (Fig. 9). To the best of our knowledge this network has not yet been reported. Discrete co-crystallized water molecule chains (Fig. S3) with D(14) classification [31] occupy pockets within the 3D structure of 3. 4.5. Structural description of [Cu4(34pdc)4(bbin)(H2O)4]8H2O}n (4) The asymmetric unit of compound 4 contains two divalent copper atoms (Cu1, Cu2), two doubly deprotonated 34pdc ligands (pdc-A, pdc-B), half of a bbin ligand whose central CAC single bond is sited over a crystallographic inversion center, two aqua ligands, and four water molecules of crystallization. The Cu1 atoms display
a very distorted {CuO4N} square pyramidal geometry (s = 0.41) with bound water molecules in the elongated apical site and also in the basal plane. In trans positions in the basal plane are located a single carboxylate oxygen atom donor from a pdc-A ligand and a single carboxylate oxygen atom donor from a pdc-B ligand. The sole remaining basal coordination site is taken up by a pyridyl nitrogen donor atom from a bbin ligand. In contrast, the Cu2 atoms display a less distorted {CuO3N2} square pyramidal geometry (s = 0.21) with pyridyl nitrogen donor atoms from pdc-A and pdc-B ligands occupying two trans basal positions. The other two trans positions in the basal plane are filled by a single carboxylate oxygen atom donor from a pdc-A ligand and a single carboxylate oxygen atom donor from a pdc-B ligand. The elongated apical posi-
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Fig. 11. [Cu4(34pdc)4(H2O)4]n layer motif in 4.
Fig. 12. [Cu4(34pdc)4(bbin)(H2O)4]n 3D coordination polymer network in 4. [Cu4(34pdc)4(H2O)4]n layer motifs (red) are connected by bbin ligands, whose bound formyl oxygen atoms are shown in orange. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
tion at Cu2 is taken up by a formyl oxygen atom donor from a bbin ligand. A thermal ellipsoid representation of the coordination environments and full ligand set is depicted in Fig. 10. All pdc-A and pdc-B ligands adopt an exotridentate binding mode, connecting to three different copper atoms via monodentate carboxylate oxygen atoms and a pyridyl nitrogen atom. Both the pdc-A and pdc-B ligands connect to two Cu2 atoms and one Cu1 atom. Through this binding mode, [Cu4(34pdc)4(H2O)4]n layer motifs are formed (Fig. 11); these are oriented parallel to the ab crystal planes. In turn the layer motifs are aggregated into a non-
interpenetrated [Cu4(34pdc)4(bbin)(H2O)4]n 3D coordination polymer network (Fig. 12) by exotetradentate bbn ligands. These have an anti-anti-anti conformation of their central tetramethylenediamine tethers, with torsion angles 177.0, 180, and 177.0°. Cu1 atoms in adjacent layer motifs are connected between basal coordination sites through the full span of the bbn ligands via the pyridyl nitrogen donor atoms, with a through-ligand internuclear distance of 12.30(1) Å. Cu2 atoms in adjacent layer motifs are connected between apical coordination sites through the two carbonyl oxygen atoms of the bbn ligands at a distance of 9.739(2) Å.
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The Cu2 atoms connect to two pdc-A ligand nodes, two pdc-B ligand nodes, and a bbn ligand node (via a carbonyl oxygen donor atom). The resulting complicated 3,3,4,5-connected multinodal network has an unprecedented {(63)2(628)(6282102)(668310)} topology, where the first term represents the pdc ligand nodes (Fig. 13). Discrete D(4) water molecule chains [31] are located in small pockets within the 3D coordination polymer network, anchored via hydrogen bonding mechanisms between the co-crystallized water molecules and bound water molecules and unligated pdc carboxylate oxygen atoms (Table S1).
4.6. Structural description of [Cu2(34pdc)2(pebn)(H2O)]8H2O}n (5)
Fig. 13. 3,3,4,5-connected multinodal network with {(63)2(628)(6282102)(668310)} topology in 4. The Cu1 and Cu2 atom nodes are shown in dark blue and green, respectively. The pdc-A and pdc-B ligand nodes are shown in gray and light blue. The bbn ligand nodes are shown in orange. Connections mediated by the pdc ligands are drawn in red; connections mediated by the bbn ligands are drawn in green. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Table 6 Selected bond distance (Å) and angle (°) data for 5. Cu1–O1 Cu1–O8#1 Cu1–N3 Cu1–N6#2 O1–Cu1–O8#1 O1–Cu1–N3 O1–Cu1–N6#2 O8#1–Cu1–N3 O8#1–Cu1–N6#2 N6#2–Cu1–N3 O5#3–Cu2–N1#4 O5#3–Cu2–N2 N1#4–Cu2–O9
1.949(8) 1.981(8) 2.000(10) 1.986(10) 94.7(3) 86.8(4) 162.1(4) 161.0(4) 87.7(4) 96.8(4) 89.1(3) 90.7(3) 90.3(3)
Cu2–O3 Cu2–O5#3 Cu2–O9 Cu2–N1#4 Cu2–N2 O3–Cu2–O9 O3–Cu2–N1#4 O3–Cu2–N2 O5#3–Cu2–O3 O5#3–Cu2–O9 N2–Cu2–O9 N2–Cu2–N1#4
1.962(8) 1.954(7) 2.187(9) 1.998(9) 1.986(9) 97.5(3) 91.0(3) 89.3(3) 164.5(4) 98.0(3) 89.4(4) 179.6(4)
Symmetry transformations: #1 x, y 1/2, z + 3/2; #2 1, y + 1, z; #3 x, y + 1/2, z + 3/2; #4 x + 1, y + 1/2, z + 3/2.
The underlying topology of compound 4 is rather complicated, with no ligands as simple linkers. The pdc-A and pdc-B ligands act as 3-connected nodes, joining two Cu2 atoms and one Cu1 atom within the [Cu4(34pdc)4(H2O)4]n layer motifs. The bbn ligands act as 4-connected nodes, joining two Cu1 atoms and two Cu2 atoms in adjacent [Cu4(34pdc)4(H2O)4]n layer motifs. The Cu1 atoms connect to a pdc-A ligand node, a pdc-B ligand node, and a bbn ligand node (via a pyridyl nitrogen donor atom).
The asymmetric unit of compound 5 contains two divalent copper atoms (Cu1, Cu2), two pdc ligands (pdc-A, pdc-B), a complete pebn ligand, an aqua ligand, and eight water molecules of crystallization. The Cu1 atoms display a {CuN2O2} square planar coordination environment, with trans pyridyl nitrogen donor atoms belonging to two pebn ligands and trans carboxylate oxygen atom donors from one pdc-A and one pdc-B ligand. In contrast, the Cu2 atoms display a rather distorted {CuN2O3} square pyramidal coordination environment (s = 0.252) in which a bound water molecule occupies the elongated apical position. The basal plane at Cu2 contains trans pyridyl nitrogen donor atoms from pdc-A and pdc-B ligands, and trans carboxylate oxygen donor atoms from pdc-A and pdc-B ligands. Bond lengths and angles within the respective coordination environments are listed in Table 6. A thermal ellipsoid plot of the disparate coordination environments is shown in Fig. 14. The pyridyl nitrogen donors and carboxylate oxygen atom donors of the pdc-A and pdc-B ligands connect Cu1 and Cu2 atoms into [Cu2(pdc)2(H2O)]n layers that are oriented parallel to the ab crystal planes (Fig. 15). Each pdc ligand within the layer motif binds in an exotridentate fashion, binding to two Cu2 atoms and one Cu1 atom. The Cu1 atoms on the periphery of the [Cu2(pdc)2 (H2O)]n layers are connected within the layer by pedn ligands with an anti-anti-gauche-anti conformation of their central pentamethylenediamine tethers (torsion angles = 169.1, 174.5, 68.2, 175.4°), thereby forming [Cu2(34pdc)2(pebn)(H2O)]n layer motifs in 5 (Fig. 16a). The pebn ligands span a Cu1 Cu1 internuclear distance of 17.660(3) Å. The underlying topology of the [Cu2(34pdc)2(pebn)(H2O)]n layer motifs in 5 can be inferred by treating the exotridentate pdc ligands as 3-connected nodes, the Cu1 and Cu2 atoms as 4-connected nodes, and the pebn ligands as simple linkers. A calculation performed with TOPOS reveals a 3,4,4-connected network with an unprecedented {(63)2(6472)(6.74.11)} topology (Fig. 16b). Isolated water molecules and intriguing chair-centered 14-water molecule clusters (Fig. 17) occupy the interlamellar regions between
Fig. 14. Coordination environments in 4. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 5.
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Fig. 15. [Cu2(pdc)2(H2O)]n layer in 5, oriented parallel to the ab crystal plane.
Fig. 16. a) Side view of [Cu2(34pdc)2(pebn)(H2O)]n layer motif in 5. The interior [Cu2(34pdc)2(H2O)]n submotif is shown in red. b) Schematic perspective of the {(63)2(6472) (6.74.11)} topology network in 5. Gold and dark blue spheres represent the 4-connected Cu1 and Cu2 atom nodes. Light blue and green spheres represent the 3-connected 34pdc ligand nodes. Connections mediated by 34pdc ligands are shown in red, while connections mediated by pebn ligands are shown in blue. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
[Cu2(34pdc)2(pebn)(H2O)]n layer motifs in 5. The 14-water molecule clusters can be said to resemble 1,4-bis(isobutyl)cyclohexane in connectivity, and are held to the coordination polymer layers by means of extensive hydrogen bonding patterns involving the bound water molecules, 34pdc carboxylate oxygen atoms, and pebn NAH and C@O groups (Table S1).
4.7. Structural description of [Cu4(34pdc)4(hbn)(H2O)4]3H2O}n (6) The asymmetric unit of compound 6 contains two divalent copper atoms (Cu1, Cu2), two 34pdc ligands (pdc-A, pdc-B), half of an hbn ligand whose central CAC bond is sited over a crystallographic inversion center, two bound water molecules, and two water
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Fig. 17. 14-water molecule cluster found in the interlamellar regions of 5.
Table 7 Selected bond distance (Å) and angle (°) data for 6. Cu1–O2 Cu1–O5 Cu1–O6 Cu1–O9 Cu1–N3 O2–Cu1–O5 O2–Cu1–O6 O2–Cu1–O9 O2–Cu1–N3 O6–Cu1–O5 O6–Cu1–O9 O9–Cu1–O5 N3–Cu1–O5 N3–Cu1–O6 N3–Cu1–O9
1.960(2) 2.137(2) 1.996(2) 2.096(3) 1.980(3) 144.81(9) 97.01(9) 120.80(11) 93.45(10) 63.62(8) 88.75(10) 89.45(11) 102.10(10) 165.33(10) 94.71(11)
Cu2–O4#1 Cu2–O7 Cu2–O10 Cu2–N1#2 Cu2–N2#3 O4#1–Cu2–O10 O4#1–Cu2–N1#2 O4#1–Cu2–N2#3 O7–Cu2–O4#1 O7–Cu2–O10 O7–Cu2–N1#2 O7–Cu2–N2#3 N1#2–Cu2–O10 N2#3–Cu2–O10 N2#3–Cu2–N1#2
1.986(2) 1.980(2) 2.250(3) 2.019(2) 2.006(2) 100.47(10) 84.10(9) 92.56(9) 164.23(9) 95.25(10) 92.09(9) 89.61(9) 99.50(10) 86.65(10) 173.43(10)
Symmetry transformations: #1 x, y 1, z; #2 x + 1, y 1/2, z + 1/2; #3 x, y 1/ 2, z + 1/2.
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cule occupies the Jahn-Teller elongated apical position. In the basal plane lie trans pyridyl nitrogen donor atoms belonging to a pdc-A and a pdc-B ligand, along with trans carboxylate oxygen atoms from other pdc-A and a pdc-B ligands. Bond lengths and angles within the different coordination spheres are listed in Table 7. A thermal ellipsoid plot of the copper atoms with full ligand sets is shown in Fig. 18. The 34pdc ligands in 6 are all exotridentate, connecting to two Cu2 atoms and one Cu1 atom. However, they adopt different binding modes. The pdc-A ligands link copper atoms in a l3-j3-N:O:O0 bridging mode in which both of their carboxylate ligands bind in a monodentate fashion. The pdc-B ligands link copper atoms in a l3j3-N:O:O0 ,O00 bridging mode in which one carboxylate group chelates to a Cu1 atom and the other binds in a monodentate fashion to a Cu2 atom. Via these binding modes, [Cu2(34pdc)2(H2O)2]n coordination polymer layer motifs are constructed (Fig. 19); these are oriented parallel to the ab crystal planes. These coordination polymer layer motifs have the same stoichiometry as seen in 3 and 4. However the layers in 6 are most closely related to those in 3, because each of the crystallographically distinct copper atoms possesses one bound water molecule. Parallel [Cu2(34pdc)2(H2O)2]n layers are connected into a noninterpenetrated 3D [Cu4(34pdc)4(hbn)(H2O)4]n coordination polymer network (Fig. 20) by curled conformation hbn ligands that exhibit a gauche-gauche-anti-gauche-gauche conformation of their central hexanediamine tethers (torsion angles = 60.5, 64.0, 180, 64.0, 60.5°). The hbn ligands connect Cu1 atoms in neighboring [Cu2(34pdc)2(H2O)2]n layer motif with a Cu Cu internuclear distance of 13.824(2) Å. The underlying topology of 6 can be investigated by considering each of the exotridentate 34pdc ligands as 3-connected nodes, the Cu1 atoms as 3-connecting nodes, and the Cu2 atoms as 4-connected nodes. Each 34pdc ligand connects to one Cu1 atom and two Cu2 atoms within the layer motifs. Each Cu2 atom connects to four 34pdc ligands within the layer motifs. Each Cu1 atom connects to two 34pdc ligands within one layer motif, and another Cu1 atom in another layer motif via an hbn ligand. According to TOPOS, the 3D 3,3,4-connected trinodal network has {(63)2(6.102) (64102)} topology, identical to that of 3, where looped pairs of bbn ligands acted as interlayer connectors in place of the single hbn ligand linkers seen in 6 (Fig. 9b). Isolated water molecules of crystallization occupy small pockets within the 3D structure of 6. 4.8. Thermogravimetric analysis
Fig. 18. Coordination environments in 6. Thermal ellipsoids are drawn at 50% probability. Symmetry codes are listed in Table 7.
molecules of crystallization (one of which best refined at half occupancy). The Cu1 atoms display a rather distorted {CuNO4} square pyramidal coordination environment with s = 0.342. A pdc-A carboxylate group chelates to the apical site and one of the basal coordination sites. In cis basal positions are ligated a water molecule and a pyridyl nitrogen donor atom from an hbn ligand. A single carboxylate oxygen atom from a pdc-B occupies the fourth and final basal position. The Cu2 atoms display a less distorted {CuN2O3} square pyramidal coordination environment with s = 0.153. A bound water mole-
Thermogravimetric analyses were carried out on compounds 1– 6 to investigate their thermal stability and degradation behavior. Compound 1 underwent dehydration between 25 and ~150 °C, with a mass loss of 4.5% corresponding to the predicted value (4.3%) for ejection of one molar equivalent of co-crystallized water. Ligand ejection occurred above 215 °C. Compound 2 underwent ligand ejection above 240 °C. Compound 3 underwent dehydration between 25 and ~150 °C, with a mass loss of 12.8% corresponding roughly to the predicted value (13.7%) for ejection of seven molar equivalents of co-crystallized water. Ligand ejection occurred above 210 °C. Compound 4 underwent dehydration in two stages between 25 and ~210 °C, with a total mass loss of 16.0% corresponding roughly to the predicted value (15.1%) for ejection of twelve molar equivalents of bound and co-crystallized water. Ligand ejection occurred above 210 °C. Compound 5 underwent dehydration in two stages between 25 and ~205 °C, with a total mass loss of 9.3%. As this value is substantially below the predicted value of 15.5% corresponding roughly to ejection of eight molar equivalents of co-crystallized water, it is plausible that some dehydration occurred upon long term storage (~60 d) of compound 5 in ambient air. Ligand ejection occurred above 210 °C. Compound 6
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Fig. 19. [Cu2(34pdc)2(H2O)2]n coordination polymer layer in 6.
Fig. 20. Non-interpenetrated 3D [Cu4(34pdc)4(hbn)(H2O)4]n coordination polymer network in 6, with [Cu2(34pdc)2(H2O)2]n layer submotifs drawn in red and green, connected by the hbn ligands. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
underwent dehydration in three stages between 25 and ~210 °C, with a total mass loss of 9.2% corresponding exactly to the predicted value for ejection of seven molar equivalents of bound and co-crystallized water. Ligand ejection occurred above 210 °C. Thermogravimetric analysis plots for 1–6 are shown in Figs. S4–S9, respectively. 4.9. Congo Red dye degradation studies Crystalline compounds 1–6 were probed as heterogeneous Congo Red dye degradation catalysis in the presence of H2O2 and under ultraviolet irradiation. A blank control experiment without
any copper coordination polymer showed degradation of only 17% of the initial dye concentration after 120 min of irradiation in the presence of H2O2. Compound 1 showed degradation of 48% of the initial dye concentration after 30 min, and degradation of 96% of the initial dye concentration after 120 min elapsed time (Fig. 21). Compound 2 showed degradation of 81% of the initial dye concentration after 30 min, 87% after 60 min, and no detectable dye remaining after 120 min elapsed time. Compound 3 showed degradation of 49% of the initial dye concentration after 30 min, and degradation of 92% of the initial dye concentration after 120 min elapsed time. Compound 4 showed degradation of 40% of the initial dye concentration after 30 min, 70% after
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Fig. 21. Congo Red dye degradation graph for 1. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
60 min, and degradation of 99% of the initial dye concentration after 120 min elapsed time. Compound 5 showed degradation of 21% of the initial dye concentration after 30 min, 74% after 90 min, and degradation of 94% of the initial dye concentration after 120 min elapsed time. Compound 6 showed degradation of 38% of the initial dye concentration after 30 min, and degradation of 94% of the initial dye concentration after 120 min elapsed time. Thus, all six copper/34pdc coordination polymers in this study showed good activity as heterogeneous degradation catalysts for the azo dye Congo Red. Compound 2, which possesses one of the simpler topologies across this series, showed the most activity as a dye degradation catalyst. This could plausibly be ascribed to easier access to the copper centers by H2O2 molecules undergoing metal-catalyzed scission of the OAO bonds to produce hydroxyl radicals, which are the putative reactive species cleaving the azo like in the dye molecules [32].
Acknowledgments We thank Lyman Briggs College and the Honors College of Michigan State University for funding this work. Appendix A. Supplementary data Hydrogen bonding information, additional molecular graphics, TGA traces, and dye degradation catalysis plots for 2–6. Crystallographic data (excluding structure factors) for 1–6 have been deposited with the Cambridge Crystallographic Data Centre with Nos. 1934863–1934868, respectively. Copies of the data can be obtained free of charge via the Internet at
5. Conclusions A series of divalent copper coordination polymers containing the 3,4-pyridyldicarboxylate ligand and various neutral dipyridyl coligands has been synthesized and structurally characterized. Structural diversity across the series is predicated by differences in dipodal dipyridyl tether length and hydrogen-bonding facility. Several of the new compounds possess unprecedented, complicated topologies based on the 3,4-pyridyldicarboxylate ligands acting as 3-connected nodes in this system. All new compounds acted as heterogeneous catalysts for the oxidative degradation of the azo dye Congo Red in the presence of ultraviolet irradiation, with a topologically simple derivative showing the most rapid catalysis.
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
Conflicts of interest No conflicts to declare.
[15] [16] [17]
C. Janiak, J.K. Vieth, New J. Chem. 34 (2010) 2366. M. Arisi, O. Yesilel, M. Tas, H. Demiral, Cryst. Growth Des. 17 (2017) 2654. R.G. Miller, P.D. Southon, C.J. Kepert, S. Brooker, Inorg. Chem. 55 (2016) 6195. O. Gordon, T. Slenters, P.S. Brunetto, A.E. Villaruz, D.E. Sturdevant, M. Otto, R. Landmann, K.M. Fromm, Antimicrob. Agents Chemother. 54 (2010) 4208. S. Hasegawa, S. Horike, R. Matsuda, S. Furukawa, K. Mochizuki, Y. Kinoshita, S. Kitagawa, J. Am. Chem. Soc. 129 (2007) 2607. Y. He, Y. Tan, J. Zhang, Inorg. Chem. 54 (2015) 6653. X. Zhang, Y. Wang, Y. Song, E. Gao, Inorg. Chem. 50 (2011) 7284. X. Bu, M. Tong, H. Chang, S. Kitagawa, Angew. Chem., Int. Ed. 43 (2004) 192. L. Liu, D. Wu, B. Zhao, X. Han, J. Wu, H. Hou, Y. Fan, Dalton Trans. 44 (2015) 1406. A. Hossain, A. Dey, S. Seth, P. Ray, P. Ballester, R.G. Pritchard, J. Ortega-Castro, A. Frontera, S. Mukhopadhyay, ACS Omega 3 (2018) 9160. L. Gao, B. Zhao, G. Li, Z. Shi, S. Feng, Inorg. Chem. Commun. 6 (2003) 1249. J.Y. Baeg, S.W. Lee, Inorg. Chem. Commun. 6 (2003) 313. D. Sarma, K.V. Ramanujachary, N. Stock, S. Natarajan, Cryst. Growth Des. 11 (2011) 1357. A. Halder, B. Bhattacharya, R. Dey, D. Maity, D. Ghoshal, Cryst. Growth Des. 16 (2016) 4783. S. Yan, X. Zheng, L. Li, D. Yuan, L. Jin, Dalton Trans. 40 (2011) 1758. M.L. Tong, J. Wang, S. Hu, S.R. Batten, Inorg. Chem. Commun. 8 (2005) 48. Z. Fu, S. Hu, J. Dai, J. Zhang, X. Wu, Eur. J. Inorg. Chem. (2003) 2670.
14
E.C. Jaddou, R.L. LaDuca / Polyhedron 180 (2020) 114427
[18] H. Fei, Z. Li, X. Liu, J. Alloys Compounds 640 (2015) 118. [19] B. Bhattacharya, A. Halder, D. Maity, D. Ghoshal, CrystEngComm 18 (2016) 4074. [20] F. Semerci, O. Yesilel, F. Yüksel, O. Sahin, Polyhedron 111 (2016) 1. [21] P.J. Zapf, R.L. LaDuca, R.S. Rarig, K.M. Johnson, J. Zubieta, Inorg. Chem. 37 (1998) 3411. [22] T.S. Gardner, E. Wenis, J.J. Lee, J. Org. Chem. 19 (1954) 753. [23] SAINT, Software for Data Extraction and Reduction, Version 6.02; Bruker AXS, Inc.: Madison, WI, 2002. [24] SADABS, Software for Empirical Absorption Correction. Version 2.03; Bruker AXS, Inc.: Madison, WI, 2002. [25] G.M. Sheldrick, Acta Crystallogr. A64 (2008) 112.
[26] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H.J. Puschmann, Appl. Crystallogr. 42 (2009) 42. [27] A.W. Addison, T.N.J. Rao, J. Reedijk, J. van Rijn, G.C. Verschoor, J. Chem. Soc., Dalton Trans. (1984) 1349. [28] V.A. Blatov, A.P. Shevchenko, D.M. Proserpio, Cryst. Growth Des. 14 (2014) 3576, TOPOS software is available for download at: