Synthesis and characterizations of Zn(II) and Co(II) coordination polymers based on 5-acetamidoisophthalate

Inorganica Chimica Acta 442 (2016) 187–194

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Synthesis and characterizations of Zn(II) and Co(II) coordination polymers based on 5-acetamidoisophthalate Xiaofei Sun a,b, Yanqing Su b, Hui Pan b, Xiaoju Li a,b,⇑ a b

College of Chemistry and Chemical Engineering, Fujian Normal University, Fuzhou, Fujian 350007, China Fujian Key Laboratory of Polymer Materials, College of Material Science and Engineering, Fujian Normal University, Fuzhou, Fujian 350007, China

a r t i c l e

i n f o

Article history: Received 26 October 2015 Received in revised form 29 November 2015 Accepted 1 December 2015 Available online 19 December 2015 Keywords: Cobalt(II) Zinc(II) Crystal structure Carboxylate Fluorescence

a b s t r a c t Seven Zn(II) and Co(II) coordination polymers based on 5-acetamidoisophthalate (AcAIP) and flexible bis (imidazolyl) ligands, [Zn(H2O)0.5(AcAIP)]n (1), [Zn(AcAIP)(o-BIMB)]n
3nH2O (2), [Co(AcAIP)(o-BIMB)]n
3nH2O (3), [Zn(AcAIP)(m-BIMB)]n
3nH2O (4), [Co(AcAIP)(m-BIMB)]n
3nH2O (5), [Zn(AcAIP)(p-BIMB)]n (6) and [Co(AcAIP)(p-BIMB)]n (7) (o-BIMB = 1,2-bis(imidazol-1-yl-methyl)benzene, m-BIMB = 1,3-bis(imidazol-1-yl-methyl)benzene and p-BIMB = 1,4-bis(imidazol-1-yl-methyl)benzene), were synthesized and well characterized. In complex 1, AcAIP serves as a l4-bridge through l2,g2-carboxylate, monodentate carboxylate and acetamido, and connects Zn(II) ions into a 3-D network, while acetamido group of AcAIP in 2–7 is not involved in coordination with metal ions owing to the presence of bis(imidazolyl) ligands. Notably, AcAIP in 2–6 bridges two metal ions through two monodentate carboxylate groups. AcAIP in 2–5 connects Zn(II) and Co(II) ions into 1-D chain, subsequent bridge by o-BIMB generates a 2-D corrugated layer, while m-BIMB connects two intra-chained metal ions to form [Zn2(AcAIP)(mBIMB)] macrocycles. Interestingly, AcAIP in 6 links two Zn(II) ions into a 16-membered [Zn2(AcAIP)2] macrocycle, and subsequent bridge by anti-conformationed p-BIMB forms a 2-D layer. However, two carboxylate groups of AcAIP in 7 function in l2,g2-bridging and chelating modes, AcAIP and gauche-conformationed p-BIMB bridge Co(II) ions to form a twofold interpenetrating framework consisting of dinuclear Co(II)-carboxylate units. Magnetic analysis of complex 7 shows that the existence of antiferromagnetic interactions. Fluorescent properties of Zn(II) coordination polymers in solid state were also investigated. Ó 2015 Published by Elsevier B.V.

1. Introduction The design and synthesis of metal–organic coordination polymers have attracted considerable interest in supramolecular chemistry and material science due to their intriguing structure topologies and potential applications in adsorption, separation, magnetism, luminescence and catalysis [1–6]. Organic ligands are well known to have crucial influences on the formation of desirable structures, a slight variation in length, type and substituent of linkers between coordination groups may generate coordination polymers with different structures and performances [7–9]. Many efforts have been devoted to constructing coordination polymers through deliberate modification of organic ligands in order to provide a solid foundation for understanding how molecules can be organized and how functions can be achieved. In the context, 5-substituted isophthalate derivatives are one type of promising ⇑ Corresponding author at: College of Chemistry and Chemical Engineering, Fujian Normal University, Fuzhou, Fujian 350007, China. E-mail address: [email protected] (X. Li). http://dx.doi.org/10.1016/j.ica.2015.12.010 0020-1693/Ó 2015 Published by Elsevier B.V.

ligands in the assembly of coordination polymers [10–12], their steric and electronic effects of the coordination-inert 5-positioned substituents may exert important influences on the dimensions and topologies of final frameworks. In our previous study, we have mainly focused on the construction of coordination polymers based on 5-hydroxyisophthalate [12], the electron-donating hydroxyl doesn’t take part in coordination with transition metal ions, but the strong hydrogen bonds between hydroxyl and carboxylate oxygen atoms may induce the formation of the interpenetrating architectures. Subsequent researches have shown that the replacement of hydroxyl by alkyloxyl group may generate coordination polymers with different structures, even under the same reaction conditions [13,14]. In comparison with 5-hydroxyisophthalate, amino in 5-aminoisophthalate (AIP) not only serves as a hydrogen bonding donor, but also may coordinate to metal ions in a nonlinear mode, which results in distinct coordination polymers [15,16]. Furthermore, amino is reactive group, it is ready to be chemically modified or protected, which greatly increases the diversity of organic ligands. Recently, amino-containing MOFs have been applied in the post-synthetic

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modification of coordination polymers [17], resulting in the conversion from one solid state material to another material. Although amino modification is widely used in organic synthesis [18], but it is seldom explored in the assembly of coordination polymers. With the aim of developing new materials and investigating the effects of steric and electronic nature in 5-positioned substituents of isophthalate on structures and properties of coordination polymers, we are interested in aceto-modified AIP. Herein, we report syntheses, structures and properties of seven Zn(II) and Co(II) coordination polymers based on 5-acetamidoisophthalate (AcAIP), [Zn (H2O)0.5(AcAIP)]n (1), [Zn(AcAIP)(o-BIMB)]n
3nH2O (2), [Co(AcAIP) (o-BIMB)]n
3nH2O (3), [Zn(AcAIP)(m-BIMB)]n
3nH2O (4), [Co (AcAIP)(m-BIMB)]n
3nH2O (5), [Zn(AcAIP)(p-BIMB)]n (6) and [Co (AcAIP)(p-BIMB)]n (7) (o-BIMB = 1,2-bis(imidazol-1-yl-methyl) benzene, m-BIMB = 1,3-bis(imidazol-1-yl-methyl)benzene and p-BIMB = 1,4-bis(imidazol-1-yl-methyl)benzene). 2. Results and discussion 2.1. Synthesis The hydrothermal reaction of AcAIP and Zn(NO3)2
6H2O gave rise to a 3-D framework, in which acetamido takes part in coordination, the variation from Zn(NO3)2
6H2O to Zn(CH3COO)2
2H2O has no obvious effect on the formation of complex 1. However, when o-BIMB was introduced into the reaction system, complex 2 was obtained, in which o-BIMB serves as an exo-bidentate ligand, and acetamido is not involved in coordination owing to the competitive coordination between AcAIP and o-BIMB. The change of metal ions from Zn(II) to Co(II) have not obvious effect on the corrugated 2-D frameworks of the resultant coordination polymers. It is known that the different orientation of imidazolyl groups at the

aromatic ring can generate coordination polymers with different structures and performances [19]. The replacement of o-BIMB by m-BIMB in 4 and 5 gave 1-D chain structures. However, the use of p-BIMB in 6 and 7 generates a 2-D layer and a twofold interpenetrating 3-D network, respectively. It should be mentioned that AcAIP is not deprotected in the preparation of 1–7, and acetamido is not involved in coordination in 2–7 owing to the presence of bis (imidazolyl) ligands. 2.2. Structural descriptions 2.2.1. Crystal structure of [Zn(H2O)0.5(AcAIP)]n (1) Single crystal X-ray diffraction analysis shows that complex 1 crystallizes in the monoclinic space group P2/c. As shown in Fig. 1a, there are two crystallographically independent Zn(II) ions. Zn1 is in a distorted trigonal-bipyramid geometry. Two acetamido oxygen atoms from different AcAIP (O5B and O5C) and water molecule (O1W) comprise the equatorial plane, Zn1 resides in the equatorial plane. The Zn1–O1W and Zn1–O5B bond distances are 1.940(3) and 1.9649(14) Å, respectively. Two symmetry-related oxygen atoms from different l2,g2-carboxylate groups occupy the axial positions with the O1–Zn1–O1A bond angle being 173.89(9)°. Zn–O1 bond distance is 2.1160 (16) Å, which is much longer than the Zn–O bond distances in equatorial plane, suggesting an enlongated trigonal bipyramid. Zn2 takes a distorted tetrahedral geometry, and is coordinated by four carboxylate oxygen atoms from different AcAIP. The Zn2–O2 and Zn2–O3E bond distances are 1.968 (14) and 1.951 (14) Å, respectively. AcAIP serves as a l4-bridge through one l2,g2-carboxylate group, one monodentate carboxylate group and acetamido coordinating to four Zn(II) ions (Scheme 1a). Zn1 and Zn2 are alternatively connected by l2,g2-carboxylate into a 1-D chain with Zn(1)


Zn(2) distance being

Fig. 1. (a) View of coordination environment of Zn(II) with thermal ellipsoid at 50% level in 1; (b) view of 2-D layer constructed through carboxylate of AcAIP bridging Zn(II) in 1; (c) view of 3-D network along the b axis in 1.

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Scheme 1. Coordination mode of AcAIP and bis(imidazolyl) ligands used in this work.

4.290 Å. Further coordination of monodentate carboxylate to Zn(2) results in the formation of 2-D layer (Fig. 1b). Acetamido locates two sides of 2-D layers, and coordinates to Zn1 to generate a 3-D network (Fig. 1c). The strong hydrogen bonds between acetamido and uncoordinated oxygen atom of monodentate carboxylate [N1-H1


O4i 2.790(2) Å, symmetry code: (i) x, y + 1, z + 1/2] as well as between water molecule and coordinated oxygen atom of monodentate carboxylate [O1W–H1W1


O3ii 2.790(2) Å, symmetry code: (ii) x, y + 2, z + 1/2] further stabilize the framework. 2.2.2. Crystal structure of [Zn(AcAIP)(o-BIMB)]n
3nH2O (2) and [Co(AcAIP)(o-BIMB)]n
3nH2O (3) Single crystal X-ray diffraction analyses show that complexes 2 and 3 are isostructural, and crystallize in the monoclinic space

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group P21/c. Both of them are the corrugated 2-D layer. Herein, we only describe crystal structure of 2 in detail as an example. The asymmetric unit of 2 contains one Zn(II), one AcAIP, one o-BIMB and three free water molecules. As shown in Fig. 2a, Zn1 has a distorted tetrahedral geometry, and is coordinated by two carboxylate oxygen atoms from different AcAIP and two imidazolyl nitrogen atoms from different BIMB. The average Zn–O and Zn–N bond distances are 1.987 and 2.008 Å, respectively. Different from complex 1, acetamido group in AcAIP is not involved in coordination, and AcAIP acts as a bis-monodentate bridge through two monodentate carboxylate groups (Scheme 1b). As shown in Fig. 2b, AcAIP connects Zn(II) into a charge-neutral [Zn(AcAIP)]n chain, where the adjointing Zn


Zn separation across AcAIP is 9.420 Å. The 1-D chains are further extended by exo-bidentate o-BIMB to form a corrugated 2-D layer, in which Zn


Zn distance across o-BIMB is 10.067 Å. Interestingly, each layer is threaded into the void of the adjacent layers in an offset mode to fill with void space of 2-D layer (Fig. 2c). The extensive hydrogen bonds between acetamido and water [N


O2W 2.956 Å], between water and uncoordinated carboxylate oxygen atoms [O1W


O4 2.748 Å] as well as between water molecules [O


O 2.648–2.980 Å] further stabilize the framework. 2.2.3. Crystal structure of [Zn(AcAIP)(m-BIMB)]n
3nH2O (4) and [Co(AcAIP)(m-BIMB)]n
3nH2O (5) Complexes 4 and 5 are also isostructural, we only describe crystal structure of complex 4 in detail as an example. The asymmetric unit of complex 4 contains one Zn(II), one AcAIP, one m-BIMB and three free water molecules. As shown in Fig. 3a, Zn(II) is in a distorted tetrahedral geometry, and is coordinated by two monodentate carboxylate oxygen atoms from different AcAIP and two imidazolyl nitrogen atoms from different m-BIMB. The Zn–O and

Fig. 2. (a) View of coordination environment of Zn(II) with thermal ellipsoid at 50% level in 2; (b) view of the correuagted 2-D layer in 2; (c) view of the packing diagram along the a axis in 2.

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Fig. 3. (a) View of the coordination environment of Zn(II) with thermal ellipsoid at 50% level in 4; (b) view of 1-D chain in 4; (c) view of the packing diagram along the a axis in 4.

Zn–N bond distances are very close to those in complex 2. Similar to AcAIP in complex 2, AcAIP bridges two Zn(II) ions through bismonodentate carboxylate groups, and links Zn(II) into a chargeneutral [Zn(AcAIP)]n chain. The Zn


Zn separation across AcAIP is 9.408 Å. Notably, further coordination of m-BIMB to two Zn(II) ions does not give higher dimensional framework, and generates a 20-membered macrocycle consisting of two AcAIP, two m-BIMB and two Zn(II), the Zn


Zn separation in the macrocycle is 9.408 Å. The fuse of these macrocycles in an almost perpendicular mode gives rise to a 1-D chain (Fig. 3b). The adjacent chains are arranged in an offset manner through phenyl ring of m-BIMB penetrating into adjacent chains (Fig. 3c) The extensive hydrogen bonds between acetamido and carboxylate oxygen atoms [N1


O2W 2.897 Å], between water and acetamido [O1W


O1 2.874 Å], between water and uncoordinated carboxylate oxygen atoms [O1W


O1 2.801 Å] as well as between water molecules [O


O 2.841–2.891 Å] are formed and further stabilize the structure. 2.2.4. Crystal structure of [Zn2(AcAIP)2(p-BIMB)2]n (6)  The asymComplex 6 crystallizes in the triclinic space group P1. metric unit consists of one Zn(II), one AcAIP and two half of p-BIMB. As shown in Fig. 4a, Zn1 takes a distorted tetrahedral geometry, and is coordinated by two carboxylate oxygen atoms from different AcAIP and two imidazolyl nitrogen atoms from different p-BIMB. The average Zn–O and Zn–N bond distances are 1.945 and 1.990 Å, respectively, which are very close to those in 2 and 4. AcAIP serves as a bis-monodentate ligand, and links two Zn(II) ions into a 16-membered [Zn2(AcAIP)2] macrocycle (A), Zn


Zn separation in the macrocycle is 7.364 Å. p-BIMB adopts an anti conformation, two imidazolyl rings are parallel with each other owing to center symmetry. Interestingly, p-BIMB links [Zn2 (AcAIP)]2 into a 2-D layer containing the other type of macrocycle (Fig. 4b). The macrocycle is composed of four p-BIMB, two AcAIP and six Zn(II) ions, the largest Zn


Zn separation in the macrocycle is 30.887 Å. The acetamido of AcAIP locates two sides of 2D layer, and is threaded into this type of macrocycles of the adjacent layers to preclude void space (Fig. 4c). The hydrogen bonds between acet-

amido of different 2-D layers [N5-H5


O2i 2.896(2) Å, symmetry code: (i) x + 1, y, z] further consolidate the whole framework. 2.2.5. Crystal structure of [Co(AcAIP)(p-BIMB)]n (7) Complex 7 crystallizes in the orthorhombic space group Pbca, and is a twofold interpenetrating 3-D network consisting of dinuclear Co(II)-carboxylate units. The asymmetric unit contains one Co(II), one AcAIP and one p-BIMB. As shown in Fig. 5a, Co1 is in a distorted octahedral geometry, and is coordinated by one l2,g2carboxylate oxygen atom and one imidazolyl nitrogen atom at the axial positions with the O4B–Co1–N2 bond angle being 176.13(11)°. One imidazolyl nitrogen atom from p-BIMB (N5C), two chelating carboxylate oxygen atoms (O2A and O3A) and one l2,g2-carboxylate oxygen atom (O5) from different AcAIP comprise the equatorial plane. Co1 and one symmetry-related Co(II) are bridged by two l2,g2-carboxylate groups from different AIP to form a dinuclear Co(II)-carboxylate unit, the Co1


Co1A distance in the dinuclear unit is 4.619 Å. In AcAIP, acetamido is not involved in coordination, two carboxylate groups function in l2,g2-bridging and chelating modes, respectively, to bridge three Co(II) ions (Scheme 1c). AcAIP links the dinuclear Co(II) units into a chargeneutral [Co2(AcAIP)2]n chain (Fig. 5b), the Co


Co separation across AcAIP is 7.982 Å. Acetamido lies on two sides of the chain. p-BIMB adopts a gauche configuration, which is much different p-BIMB in 6. As shown in Fig. 5c, p-BIMB links the adjacent chains into a 3D open framework containing large cavities. The absence of large guest molecules in the void space results in the formation of a twofold interpenetrating network (Fig. 5d), acetamido groups reside in the cavities to further fill with void space of the cavities. The hydrogen bonds between acetamido from different 3-D networks [N1–H1


O1i 3.038(4) Å, symmetry code: (i) x + 1/2, y, –z + 3/2] further consolidate the whole framework, the closest Co


Co separation between the adjacent interpenetrating 3-D networks is 7.428 Å, which is much shorter than Co


Co separation of 13.514 Å across p-BIMB. To gain a better insight into the 3-D structure, topological analysis was undertaken. Taking the dinuclear Co (II) unit as one node, each dinuclear unit becomes an six-connected node, AcAIP and p-BIMB can be regarded as independent

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Fig. 4. (a) View of coordination environment of Zn(II) with thermal ellipsoid at 50% level in 6; (b) view of packing diagram along the b axis in 6; (c) view of the packing diagram along the a axis in 6.

Fig. 5. (a) View of coordination environment of Co(II) with thermal ellipsoid at 50% level in 7; (b) view of 1-D chain formed by AcAIP and Co(II) in 7; (c) view of 3-D network in 7; (d) view of the packing diagram along the a axis in 7; (e) view of six-connected topology in 7.

two-connected vertices that link two adjacent nodes. The interlinkage of six dinuclear units with two AcAIP and four p-BIMB generates a six-connected topology (Fig. 5e). The Schläfli symbol of this net is {412
63}.

2.3. X-ray powder diffraction and thermogravimetric analysis In order to check purity of complexes 1–7, the as-synthesized samples were measured by powder X-ray diffraction (XRD) at

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Fig. 6. TGA curve of complexes 1–7.

Fig. 7. Temperature dependence of magnetic susceptibility in complex 7.

room temperature. As shown in Fig. S1 in Supporting information. The experimental patterns of the bulk materials closely match the simulated ones from the single crystal X-ray structure analysis, indicating pure and homogeneous solid-state phases in 1–7. The thermal behaviors of complexes 1–7 were investigated by thermogravimetric analysis (TGA) under N2 atmosphere. As shown in Fig. 6, TGA curve of complex 1 shows a weight loss of 3.29% from 280 °C to 360 °C, which is attributed to the release of the coordinated water molecules (calcd: 3.04%), and subsequent collapse of host framework occurs. In 2 and 3, the weight loss of 9.39% before 160 °C corresponds to the removal of free water molecules (calcd: 9.33% for 1, 9.44% for 2), and their structural frameworks are stable up to 350 °C. In 4 and 5, the weight loss of 8.34% before 160 °C corresponds to the removal of lattice water molecules (calcd: 9.33% for 4, 9.44% for 5). However, there is no obvious weight loss before the host frameworks of 6 and 7 start to collapse before 375 °C and 350 °C, respectively.

3.460 cm3 mol 1 K, which is much higher than the spin-only value of 1.875 cm3 K mol 1 based on single Co(II) ion (g = 2 and s = 3/2) due to the spin–orbital coupling. The vmT value is almost constant above 70 °C, but it goes down quickly to 0.160 cm3 mol 1 K at 2 K. These results suggest the existence of antiferromagnetic interactions within dinuclear Co(II) ions. The reciprocal value of magnetic susceptibility follows Curie–Weiss law over full temperature range, Curie constant and Weiss constant are C = 3.6477 cm3 K mol 1 and h = –11.7038 K, respectively. Considering crystal structure of complex 7, the dinuclear cobalt(II) units are well separated from each other, magnetic exchange between dinuclear Co (II) units can be neglected, as a result, the dinuclear unit may be assumed to make up the basic magnetic unit. The magnetic data can be fitted using MagSaki Software [22]. The best fit to the experimental data give J = –2.262 ± 0.04 cm 1 and g = 2.763. The negative J value further confirms the presence of antiferromagnetic coupling between Co(II) ions.

2.4. Luminescent properties

3. Experimental section

The fluorescent properties of Zn(II) coordination polymers were studied in the solid state at room temperature. 1, 2, 4 and 6 exhibit maximum emission at 440 (kex = 341 nm), 420 (kex = 347 nm), 400 (kex = 361 nm) and 402 nm (kex = 350 nm), respectively (Fig. S2). While H2AcAIP shows the strongest emission at 400 nm upon excitation at 336 nm, and the maximum emission peaks for oBIMB, m-BIMB and p-BIMB are observed at 383, 378 and 389 nm, respectively [20]. In comparison with the free ligands, the obvious redshift is displayed in Zn(II) coordination polymers. Zn(II) is well known to be difficult to oxidize or reduce because of its d10 configuration, as a result, these emissions in 1, 2, 4 and 6 are mainly based on the luminescence of ligands, the bathochromic shift probably originates from their coordination with Zn(II) ions [21].

3.1. Materials and general methods

2.5. Magnetic study The coordination polymers consisting of dinuclear or polynuclear Co(II) units may serve as promising magnetic materials, the Co(II)


Co(II) distance in the dinuclear unit of complex 7 is 4.619 Å, suggesting the existence of magnetic exchange interaction in the dinuclear Co(II) ions. However, Co(II) ions in complexes 3 and 5 are well separated by AcAIP and bis(imidazolyl) ligands, magnetic exchange between Co(II) ions can be neglected, their magnetic behavior is similar to mononuclear metal ions. As a result, the magnetic susceptibilities of only complex 7 were measured at 2–300 K in an applied field of 1000 Oe. The temperature dependence of vmT is depicted in Fig. 7, vmT value at 300 K is

H2AcAIP [23] and BIMB [24] were prepared according to literature methods. All other chemicals were commercially available and used as purchased. IR spectra (KBr pellets) were recorded on a Magna 750 FT-IR spectrophotometer in the range of 400– 4000 cm 1. Powder X-ray diffraction data (PXRD) were recorded on a PANaytical X’pert pro X-ray diffractometer with graphitemonochromatized Cu Ka radiation (k = 1.542 Å). Thermogravimetric analyses (TGA) were carried out on a NETSCHZ STA 449C thermoanalyzer under N2 at a heating rate of 10 °C/min. Luminescent spectra were recorded on an Edinburgh Instruments FLS920 spectrofluorimeter equipped with both continuous-wave (450 W) and pulse xenon lamps. The magnetic susceptibility data were collected on a Quantum Design MPMS model 6000 magnetometer in the temperature range of 2–300 K. C, H and N elemental analyses were determined on an EA1110 CHNS-0 CE element analyzer. 3.2. Synthesis of complexes 1–7 3.2.1. Synthesis of [Zn(H2O)0.5(AcAIP)]n (1) A mixture of H2AcAIP (56 mg, 0.25 mmol), Zn(NO3)2
6H2O (73 mg, 0.25 mmol) and aqueous NaOH (0.40 mL, 1 mol
L 1) in deionized water (10 mL) was placed in a Teflon-lined stainless steel vessel (30 mL), and then heated to 130 °C for 4 days. After cooled to room temperature at a rate of 3 °C h 1, the light yellow crystals were obtained. Yield: 35 mg [47%basedonH2AcAIP]. Anal.

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Calc. for C10H8NO5.5Zn (295.54): C, 40.63; H, 2.73; N, 4.74. Found: C, 40.56; H, 2.87; N, 4.92. IR (KBr, cm 1): 3079(m), 2364(vw), 1624(vs), 1560(vs), 1420(vs), 1304(s), 1247(m), 1117(vw), 1039 (w), 1002(vw), 960(vw), 910(w), 833(w), 782(m), 724(m), 696 (w), 599(vw), 547(m), 470(w). 3.2.2. Synthesis of [Zn(AcAIP)(o-BIMB)]n
3nH2O (2) A mixture of H2AcAIP (22 mg, 0.10 mmol), o-BIMB (24 mg, 0.10 mmol) and Zn(CH3COO)2
2H2O (44 mg, 0.20 mmol) in ethanol (0.5 mL) and deionized water (10 mL) was placed in a Teflon-lined stainless steel vessel (30 mL), and then heated to 120 °C for 3 days. After cooled to room temperature at a rate of 3 °C h 1, the light yellow crystals were obtained. Yield: 15 mg [25% based on H2AcAIP]. Anal. Calc. for C24H27N5O8Zn (578.88): C, 49.79; H, 4.70; N, 12.10. Found: C, 49.79; H, 4.64; N, 12.11. IR (KBr, cm 1): 3144(m), 1694(w), 1670(w), 1619(w), 1558 (vs), 1441 (s), 1412 (s), 1356(vs), 1319(w), 1272(w), 1239 (w), 1181(vw), 1108(m), 1087(m), 1029(w), 979(vw), 951(m), 900(vw), 834(vw), 813(vw), 782(m), 740(m), 684(w), 655(m), 636(vw), 568(vw). 3.2.3. Synthesis of [Co(AcAIP)(o-BIMB)]n
3nH2O (3) A mixture of H2AcAIP (22 mg, 0.10 mmol), o-BIMB (24 mg, 0.10 mmol) and Co(CH3COO)2
4H2O (75 mg, 0.30 mmol) in ethanol (2 mL) and deionized water (5 mL) was placed in a glass bottle (20 mL), and then heated to 100 °C for 1 days. After cooled to room temperature, the purple crystals were obtained. Yield: 23 mg [40% based on H2AcAIP]. Anal. Calc. for C24H27N5O8Co (572.43): C, 50.35; H, 4.75; N, 12.23. Found: C, 50.30; H, 4.77; N, 12.29. IR (KBr, cm 1): 3142(m), 1695(w), 1671(w), 1616(w), 1554(vs), 1442(m), 1413 (m), 1319(w), 1273(w), 1238(w), 1109(w), 1086(s), 1028(w), 949 (w), 900(vw), 833(w),812(vw), 782(m), 739(s), 684(vw), 655(m), 634(vw), 535(vw), 436(vw). 3.2.4. Synthesis of [Zn(AcAIP)(m-BIMB)]n
3nH2O (4) A mixture of H2AcAIP (22 mg, 0.10 mmol), m-BIMB (24 mg, 0.10 mmol) and Zn(CH3COO)2
2H2O (55 mg, 0.25 mmol) in DMF (5 mL) and deionized water (5 mL) was placed in a Teflon-lined stainless steel vessel (30 mL), and then heated to 120 °C for 3 days. After cooled to room temperature at a rate of 3 °C h 1, the colorless crystals were obtained. Yield: 13 mg [22% based on H2AcAIP]. Anal. Calc. for C24H27N5O8Zn (578.88): C, 49.79; H, 4.70; N, 12.10. Found: C, 49.88; H, 4.61; N, 12.29. IR (KBr, cm 1): 3144(m), 1692(s), 1620 (s), 1573(vs), 1437(s), 1362(vs), 1280(m), 1250(m), 1195(vw), 1109(vw), 1092(vs), 1031(m), 979(vw), 952(m), 922(vw), 902(w), 813(w), 784(s), 732(vs), 700(vw), 656(s), 629(w). 3.2.5. Synthesis of [Co(AcAIP)(m-BIMB)]n
3nH2O (5) Complex 5 was prepared through similar procedures to 3 except for replacement of o-BIMB by m-BIMB (24 mg, 0.10 mmol). Yield: 27 mg [47% based on H2AcAIP]. Anal. Calc. for C24H27N5O8Co (572.43): C, 50.35; H, 4.75; N, 12.23. Found: C, 50.50; H, 4.77; N, 12.33. IR (KBr, cm 1): 3143(w), 1693(m), 1616(m), 1569(vs), 1531(m), 1436(s), 1364(vs), 1281(w), 1250(w), 1230(w), 1107 (w), 1090(w), 1031(vw), 952(vw), 903(vw), 860(vw), 813(vw), 783(m), 733(s), 657(m), 629(vw), 528(vw), 467(vw). 3.2.6. Synthesis of [Zn(AcAIP)(p-BIMB)]n (6) A mixture of H2AcAIP (22 mg, 0.10 mmol), p-BIMB (24 mg, 0.10 mmol), Zn(CH3COO)2
2H2O (55 mg, 0.25 mmol) and NaOCH3 (0.001 g) in deionized water (10 mL) was placed in a Teflon-lined stainless steel vessel (30 mL), and then heated to 130 °C for 3 days. After cooled to room temperature at a rate of 3 °C h 1, the colorless crystals were obtained. Yield: 15 mg [25% based on H2AcAIP]. Anal. Calc. for C24H21N5O5Zn (524.83): C, 54.92; H, 4.03; N, 13.34. Found: C, 54.09; H, 4.05; N, 13.33. IR (KBr, cm 1): 3511(m), 3407(vw), 3297(vw), 3135(w), 2984 (vw), 2926 (vw), 2854(vw), 1674(vs),

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1616(vs), 1588(vs), 1568 (vs), 1426(vs), 1358(vs), 1274(m), 1240 (s), 1105(vs), 1021(w), 951(m), 901(w), 826(w), 789(vs), 740(s), 733(s), 702(m), 651(s), 597(m). 3.2.7. Synthesis of [Co(AcAIP)(p-BIMB)]n (7) A mixture of H2AcAIP (22 mg, 0.10 mmol), p-BIMB (48 mg, 0.20 mmol) and Co(CH3COO)2
4H2O (75 mg, 0.30 mmol) in deionized water (3 mL) and DMF (5 mL) was placed in a glass bottle (20 mL), and then heated to 100 °C for 3 days. After cooled to room temperature, the block crystals were obtained. Yield: 11 mg [21% based on H2AcAIP]. Anal. Calc. for C24H21N5O5Co (518.39): C, 55.60; H, 4.08; N, 13.51. Found: C, 55.07; H, 4.26; N, 13.52. IR (KBr, cm 1): 3306(w), 3039(w), 3123(vw), 1659(vs), 1621(vs), 1555(vs), 1516(m), 1445(s), 1405(m), 1381(vs), 1317(w), 1274 (m), 1247(m), 1225(w), 1206(vw), 1107(m), 1085(m), 1030(m), 938(w), 904(w), 852(w), 830(vw), 805(m), 788(m), 756(s), 719 (vw), 659(m), 636(vw), 615(w), 594(w), 535(vw), 515(vw). 3.3. X-ray crystallography Single crystals of complexes 1–7 were mounted on a glass fiber for X-ray diffraction analysis. Data sets were collected on a Rigaku AFC7R equipped with a graphite-monochromated Mo Ka radiation (k = 0.71073 Å) from a rotating anode generator at 293 K. Intensities were corrected for LP factors and empirical absorption using the w scan technique. The structures were solved by direct methods and refined on F2 with full-matrix least-squares techniques using the SHELX-97 program package [25]. All non-hydrogen atoms were refined anisotropically. The positions of hydrogen atoms were generated geometrically (C–H bond fixed at 0.96 Å), assigned isotropic thermal parameters, and allowed to ride on their parent carbon atoms before the final cycle of refinement. The selected bond distances and bond angles for complexes 1–7 are given in Table S1. Crystal data as well as details of data collection and refinement are summarized in Table S2. 4. Conclusions Seven Zn(II) and Co(II) coordination polymers based on AcAIP and flexible bis(imidazolyl) ligands have been presented. l4-Bridged AcAIP in 1 links Zn(II) ions into a 3-D network, acetamido group of AcAIP participates in coordination, while acetamido group of AcAIP in 2–7 is not involved in coordination owing to the competitive coordination of bis(imidazolyl) ligands. The orientation of bis(imidazolyl) groups at aromatic rings shows important effects on the structures of coordination polymers. AcAIP in 2–6 acts as a bis-monodentate ligand, AcAIP and o-BIMB in 2 and 3 link Zn(II) and Co(II) ions into a 2-D corruagted layer, while AcAIP and m-BIMB in 4 and 5 connect Zn(II) and Co(II) ions into a 1-D chain. AcAIP and p-BIMB in 6 and 7 bridge Zn(II) and Co(II) to form a 2-D layer containing [Zn2(AcAIP)2] macrocycles and a twofold interpenetrating framework consisting of dinuclear Co(II)-carboxylate units, respectively. Interestingly, p-BIMB in 6 and 7 adopt anti and gauche configurations, respectively. Magnetic analysis of complex 7 shows that the existence of antiferromagnetic interactions. In summary, this study has demonstrated the use of amino-substituted 5-aminoisophthalates is a useful approach to generate coordination polymers with new structures and properties, further study for the construction of coordination polymers based on other amino-modified 5-aminoisophthalates is on progress. Acknowledgements This work was supported by Provincial Education Department of Fujian (JA12070), State Key Laboratory of Structural Chemistry

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