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Varying the frameworks of coordination polymers with (CuI)4 cubane cluster by altering terminal groups of thioether ligands
Journal of Molecular Structure 921 (2009) 132–136
Contents lists available at ScienceDirect
Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc
Varying the frameworks of coordination polymers with (CuI)4 cubane cluster by altering terminal groups of thioether ligands Chuang Xie, Lina Zhou, Wenxiu Feng, Jingkang Wang, Wei Chen * The State Research Center of Industrialization for Crystallization Technology, Tianjin University, Tianjin 300072, PR China
a r t i c l e
i n f o
Article history: Received 16 October 2008 Received in revised form 16 December 2008 Accepted 19 December 2008 Available online 30 December 2008 Keywords: (CuI)4 complexes Dithioether Terminal groups 4(6).6(4) topology Synthesis
a b s t r a c t Two Cu(I) coordination architectures, [(CuI)4(L1)2]n (1) and [(CuI)4(L2)1.5]n (2) with two structurally related flexible dithioether ligands, 1,4-bis(ethylsulfanyl)butane (L1) and 1,4-bis(benzylsulfanyl)butane (L2) have been synthesized and structurally characterized by element analysis and X-ray diffraction. In both complexes, (CuI)4 cubane cluster acts as a secondary building unit and dithioether ligands as a ditopic bridge to generate two distinct frameworks. 1 has a two-dimensional (4,4) network, while 2 is a three-dimensional framework with rare 4(6).6(4) topology, being the first example in (CuI)4 complexes. The difference of frameworks can be attributed to the variation of the terminal groups of the two ligands. Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction The design, syntheses, and characterization of novel metal–organic coordination architectures has attracted great attention in recent years, not only because of their intriguing structural topologies but also their potential applicable properties [1–3]. Many efforts have been devoted to the rational design of specific complexes including 1D chains and ladders, 2D grids, 3D microporous networks, interpenetrated nets, and chiral frameworks [4–6]. In fact, the formation of these complexes is influenced by many factors such as coordination environment of metal center (or clusters as secondary building units), the choice of rigid or flexible ligand, solvent, template, counterion [7–9]. In this context, complex construction between copper(I) halides and sulfur containing organic compounds has great current interest for their potential use in the rational design and synthesis of new polymeric metal–organic coordination architectures [10,11]. As the tendency of copper(I) to form clusters often leading to short metal–metal bonds and the large size of the S atom to make it easier to adopt different angles at this atom in complexes, such compounds display intriguing structural diversities in architectures and potentially useful properties, including ion-exchange capacity, electronic, and optical properties. For example, CuI complex with flexible 1,3-bis(4-pyridyl)propane shows a chiral triple-interpenetrated, quartz net[12]. The coordination polymers form between CuI and bis(4-pyridyl)disulfide (bpds) illustrated solvent depen* Corresponding author. Tel.: +86 22 27405754; fax: +86 22 23502458. E-mail address: [email protected] (W. Chen). 0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2008.12.043
dent topological isomerism [13] while the solvothermal reactions of CuI with bpds result in situ cleavage of both S–S and S–C(sp2) bonds and temperature-dependent in situ ligand rearrangement [14,15]. On the other hand, although the flexible dithioether ligands have been investigated widely in Ag(I) complexes by us and others [16,17], the Cu(I) complexes with these ligands are still rarely explored [18]. As a continuous effort in the investigation of the coordination complexes of dithioether ligands, we report herein the construction of two Cu(I) coordination polymers by using two structurally closely related dithioether ligands, 1,4-bis(ethylsulfanyl)butane (L1) and 1,4-bis(benzylsulfanyl)butane (L2) (see Chart 1), with aiming to examine the influence of sterichindrance of the ligands on the resultant structures of their metal complexes. 2. Experimental 2.1. Materials and general methods All commercially available chemicals were of reagent grade and used as received without further purification. Elemental analyses of C and H were performed on a Perkin-Elmer 240C analyzer. The emission/excitation spectra were measured on an Varian Cary Eclipse spectrophotometer equipped with a continuous Xe-900 Xenon lamp, a íF900 nanosecond flash lamp. The ligands 1,4-bis(ethylsulfanyl)butane (L1) and 1,4-bis(benzylsulfanyl)butane (L2) were synthesized according to a reported procedure [17]. The X-ray powder diffraction (XRPD) patterns of 1 and 2 were registered with a Rigaku D/Max-2500 diffractometer, operated at 40 kV and 100 mA, using a Cu target tube and a graphite
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onto the specific atoms and refined isotropically with fixed thermal factors. Further details for structural analysis are summarized in Table 1. Selected bond lengths and angles for 1 and 2 are compared in Table 2. Visualization and analysis of topological networks of complexes were carried out by the freeware OLEX program [22,23]. CCDC reference numbers is 642854 and 642855. 3. Results and discussion
Chart 1.
3.1. The effect of molar ratio of CuI:L monochromater. Fixed scatter and divergence slits of 0.5 l and a 0.15 mm receiving slit were used. The intensity data were recorded by continuous scan in a 2h/h mode from 2° to 50° with a step size of 0.02° and a scan speed of 4°/min. Simulation of the XRPD spectra was carried out by the single-crystal data and diffraction-crystal module of the commercially available Cerius2 program[19]. 2.2. Synthesis of complexes 1 and 2 [(CuI)4(L1)2]n (1) and [(CuI)4(L2)1.5]n (2) as single colourless crystal samples were obtained by a similar methods: 10 mL of dichloromethane solution of the ligand L (2.0 mmol) was slowly added to a solution of CuI (0.380 g, 2.0 mmol) in acetonitrile (10 mL) and stirred for 30 min, and then filtrated to give colourless solution. The solution is maintained undisturbed at ambient temperature. After six days, colourless crystals were collected. For 1 with yield of 40%. Anal. Calcd for C16H36S4Cu4I4 (1118.50): C 17.18, H 3.24; Found C 17.02, H 3.55. For 2 with yield of 50%. Anal. Calcd for C27H33S3Cu4I4 (1215.54): C 26.68, H 2.74; Found C 26.43, H 2.92. 2.3. X-ray crystallographic studies of complexes X-ray single-crystal diffraction data for 1 and 2 were collected on a Bruker Smart 1000 CCD diffractometer at 293(2) K with Mo Ka radiation (k = 0.71073 Å) by x scan mode. The program SAINT [20] was used for integration of the diffraction profiles. All the structures were solved by direct methods using the SHELXS program of the SHELXTL package and refined by full-matrix least-squares methods with SHELXL (semi-empirical absorption corrections were applied using SADABS program) [21]. Metal atoms in each complex were located from the E-maps and other non-hydrogen atoms were located in successive difference Fourier syntheses and refined with anisotropic thermal parameters on F2. The hydrogen atoms of the ligands were generated theoretically
Table 1 Crystallographic data and structure refinement summary for complexes 1 and 2. Formula Formula weight Crystal system Space group Z a/Å c/Å V/Å3 Dcalc/g cm 3 l/mm 1 F(0 0 0) Reflections collected/unique Ra & wRb (I > 2r(I)) GOF on F2 (Dq)max/eÅ 3 (Dq)min/eÅ 3 a b
C16H36S4Cu4I4 (1) 1118.45 Tetragonal P42/n 2 11.936(2) 10.964(2) 1561.9(4) 2.378 6.911 1048 15132/1788 0.0374, 0.0969 1.060 0.392 0.490
R = R||F0| |FC||/R|F0|. wR = [Rw(F02 FC2)2/Rw(F02)2]1/2.
C13.5H16.5S1.5Cu2I2 (2) 607.74 Hexagonal P3 4 16.895(2) 7.0151(14) 1734.1(5) 2.328 6.178 1142 16570/2652 0.0225, 0.0501 1.087 0.711 0.852
The crystals were obtained as 4:2 and 8:3 binary compounds, although both of them were carried out with an equimolar amount of the starting reagent by the same method. As the metal-to-ligand ratio plays an important role in construction of supramolecular architectures [24], we also tried to generate different structures by modification the molar ratios of CuI to L in a similar synthetic route to that used for 1 and 2. Changing the reagent molar ratio to 4:1, 2:1, and 1:2 caused compound 1 and 2 in pure form while the molar ratio to 1:4 with further excessive ligands just resulted in some oil residues. The negative results indicate that it is still a challenge to predict and control the ligand reactions toward target products. 3.2. Description of the crystal structures Single-crystal X-ray analysis of 1 revealed the formation of a (4,4) two-dimensional polynuclear assembly with a substructure of Cu4I4 clusters. The Cu4I4 core, resembles a cubane-like arrangement with an internal tetrahedral Cu4 core (Fig. 1a). Each copper(I) is tetrahedrally coordinated by three I and a sulfur from the L1 with Cu–I and Cu–S distances of 2.664(1)– 2.708(1) and 2.284(2) Å, respectively. The Cu–Cu distances are 2.645(2)–2.739(2) Å, being similar to those of other reported Cu4I4 tetramer units (Fig. 1b) [18]. Each cluster core is bonded to four different bridging L1 by Cu–S bonds forming a layer structure (Fig. 2). The network topology can be simplified to a (4,4) net by considering a Cu4I4 cluster as a node and a ligand as a bisdentate linker. The distance is 11.93(1) Å between the neighboring nodes in a square-grid. The ligand L1 adopts a
Table 2 Selected bond distances (Å) and angles (deg) for complexes 1a and 2b. Compound 1 Cu(1)–S(1) Cu(1)–I(1)#1 I(1)–Cu(1)#1 Cu(1)–Cu(1)#3 S(1)–Cu(1)–I(1)#1 I(1)#1–Cu(1)–I(1)#2 I(1)#1–Cu(1)–I(1) S(1)–Cu(1)–Cu(1)#1 I(1)#2–Cu(1)–Cu(1)#1
2.284(2) 2.6643(9) 2.6643(9) 2.7380(16) 107.89(7) 112.05(3) 113.07(3) 146.33(6) 108.904(19)
Cu(1)–I(1) Cu(1)–I(1)#2 I(1)–Cu(1)#3
2.7076(9) 2.6893(11) 2.6893(11)
S(1)–Cu(1)–I(1)#2 S(1)–Cu(1)–I(1) I(1)#2–Cu(1)–I(1) I(1)#1–Cu(1)–Cu(1)#1 I(1)–Cu(1)–Cu(1)#1
104.74(7) 107.93(6) 110.70(3) 60.14(3) 58.58(3)
Compound 2 Cu(1)–I(1) Cu(1)–I(2)#1 Cu(2)–S(1) Cu(2)–I(1)#3 I(2)–Cu(1)–I(2)#1 I(2)–Cu(1)–I(1) S(1)–Cu(2)–Cu(1) I(1)#3–Cu(2)–I(2)#2
2.7485(10) 2.6385(4) 2.2866(10) 2.6977(6) 113.780(13) 104.715(16) 149.45(3) 109.241(18)
Cu(1)–I(2) Cu(1)–Cu(2)#1 Cu(2)–I(2)
2.6385(4) 2.7247(8) 2.6680(6)
I(2)–Cu(1)–Cu(2)#1 S(1)–Cu(2)–I(2) Cu(1)–I(2)–Cu(2)
60.700(14) 111.52(3) 61.787(17)
a Symmetry code: #1: x, z + 1/2. b Symmetry code: #1:
x + 1/2,
y + 1/2, z. #2: y, x + 1/2, z + 1/2. #3:
y + 1, x
y + 1, z. #2:
x + y,
y + 1/2,
x + 1, z. #3: x, y, z + 1.
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Fig. 2. The 2D (4,4) net in 1 (left) and its schematic presentation with nodes collided from the Cu4I4 units (right).
Fig. 1. (a) The tetrahedral connectivity of the Cu4I4 unit and (b) coordination environment of 1 (symmetry code A: 1/2 x, 3/2 y, z).
cis-conformation with the pseudo-torsion angle (C2–S1. . .S1A– C2A) of 17.4(2)°. Although the structure of Cu4I4 core in complex 2 is similar to that in 1 while the Cu–Cu, Cu–I, and Cu–S fall in the range 2.725(1)–2.898(1), 2.638(1)–2.748(1), and 2.287(1) Å, respectively (Fig. 3a), a quite different framework has been constructed by substituting benzyl of L2 for ethyl of L1. It is worth noting that each cluster core plays the role as a five-connected node (Fig. 3b). Three Cu(I) ions (Cu2, Cu2A, and Cu2B) locate in the diagonal plane of the cubane-like Cu4I4 core in which each Cu(I) ion is tetrahedrally corner-connected to three l3-iodide atoms and one sulfur donor of L2. Each L2 ligand, adopting a centrosymmetric arrangement, bridges two adjacent cluster cores and extends along the crystallographic a and b directions. The inorganic-organic hybrid layers feature as (6,3) topological sheets
Fig. 3. (a) Coordination environment of 2 and (b) the pentahedral connectivity of the Cu4I4 unit.
C. Xie et al. / Journal of Molecular Structure 921 (2009) 132–136
135
Fig. 4. View of (a) the framework in 2 along c- direction and (b) the 3D 4(6).6(4) network, the (6,3) net in ab plane outlined in green. Each Cu4I4 unit was collided into a node.
with edges of 11.17(1) Å (Fig. 4a). Then the fourth Cu(I) (Cu1) in Cu4I4 core interconnects another core related by symmetric relation 1 y, 1 + x y, z 1 through Cu–I bond, so that the 2D nets were jointed in c-direction to generate a 3D framework (Fig. 4b). Such a net structure can be characterized by the short vertex symbol 4(6).6(4); the long Schäfli symbol is 4.4.4.4.4.4.6.6.6 (Fig. 4c) [22]. Although a large number of examples of threeor four-connected networks based on d-block metal ions have been reported, five-connected networks are still rare [25,26]. The present net is the first case of Cu4I4 complexes with such a five-connected topology. A similar BN topological net also could be found in the manganese(II) complex with pyridine2,4,6-tricarboxylate [26]. An analysis of the voids [27] shows only 0.6% of the space empty in 2 for the inner cavity of each hexagon-unit is accommodated with six benzyl end-groups. 3.3. XRPD results X-ray powder diffraction (XRD) was used to check the purity of complexes 1 and 2 as shown in Fig. 5. Although there are a few unindexed diffraction lines in the experimental patterns, it still can be considered that the peaks displayed in the measured patterns closely match those in the simulated patterns generated from
single-crystal diffraction data, indicating complexes 1 and 2 are isolated as single phases. 3.4. Luminescent properties The emission spectra of complexes 1 and 2 in the solid state are investigated at room temperature under the same situations. The em excitation and emission maxima (kex max and kmax ) at room temperature are shown in Fig. 6. Upon excitation at 342 and 344 nm, 1 and 2 in the solid state exhibit strong photoluminescence with emission maxima at 517 and 499 nm, respectively, in conformity with photoluminescent properties of Cu4I4 cluster complexes[28]. Since the L1 and L2 are non-fluorescent, the emission band might be assigned to a combination of a cluster centered transition and halideto-metal charge-transfer (XMCT)[29]. In summary, two copper(I) metal–organic supramolecular architectures 1 and 2 have been constructed by the direct reactions of CuI with flexible thioether ligands L1 and L2 in similar reaction conditions, respectively. Although L1 and L2 are closely related in structure, 1 and 2 form quite different frameworks induced by terminal group variation. Comparing the structures of 1 and 2, the different character of the Cu4I4 clusters in1 and 2, as fourand five-connected nodes, results in a 2D (4,4) and a rare 3D
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4(6).6(4) network, respectively. Since a complex framework has a tendency to be such an architecture with the least free volume in cell and sterichindrance in geometry [30], the terminal group of the analogous ligands becomes a determining factor in modifying the conformation of ligand in complex, so as to control structural topology of the metal–organic supramolecular network.
Acknowledgments We gratefully acknowledge the financial support from the National Natural Science Foundation of China (No. 20576089) and Tianjin Natural Science Foundation (05YFJZJC02000 and 05YFGHHZ01100).
References [1] [2] [3] [4] [5] [6] [7] [8] [9]
Fig. 5. Simulated (solid line) and experimental (red point) XRPD patterns of (a) complex 1 and (b) complex 2. (For interpretation of colour mentioned in this figure the reader is referred to the web version of the article.) 1000
Intensity/a.u.
900
[10] [11] [12] [13]
[14] [15]
800
1
700
2
[16] [17] [18]
600
[19] [20] [21]
500 400 300
[22]
200
[23]
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[24] [25]
0 250
300
350
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450
500
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600
650
700
Wavelength/nm Fig. 6. Emission and excitation spectra of 1 (red) and 2 (blue). (For interpretation of colour mentioned in this figure the reader is referred to the web version of the article.)
[26] [27] [28] [29] [30]
C.L. Cahill, D.T. Lill, M. Frisch, Cryst. Eng. Comm. 9 (2007) 15. B.H. Ye, M.L. Tong, X.M. Chen, Coord. Chem. Rev. 249 (2005) 545. J.P. Wang, W. Wang, J.Y. Niu, J. Mol. Struct. 875 (2008) 68. H. Hofmeier, U.S. Shubert, Chem. Commun. (2005) 2423. M.V. Yigit, K. Biyikli, B. Moulton, J.C. MacDonald, Cryst. Growth Des. 6 (2006) 63. N.W. Ockwig, O. Delgado-Friedrichs, M. O’Keeffe, O.M. Yaghi, Acc. Chem. Res. 38 (2005) 176. A.M. Brown, M.V. Ovchinnikov, C.L. Stern, C.A. Mirkin, J. Am. Chem. Soc. 126 (2004) 14316. R. Carballo, B. Covelo, C. Lodeiro, E.M. Vázquez-López, Cryst. Eng. Comm. (2005) 294. K.F. Bowes, L.P. Clark, J.M. Cole, M. Gourlay, A.M.E. Griffin, M.F. Mahon, L. Ooi, A.W. Parker, P.R. Raithby, H.A. Sparkes, M. Towrie, Cryst. Eng. Comm. (2005) 269. P. Schwerdtfeger, R.P. Krawczyk, A. Hammerl, R. Brown, Inorg. Chem. 43 (2004) 6707. T.S. Lobana, R. Sharma, E. Bermejo, A. Castineiras, Inorg. Chem. 42 (2003) 7728. S. Hu, M.L. Tong, Dalton Trans. (2005) 1165. A.J. Blake, N.R. Brooks, N.R. Champness, M. Crew, A. Deveson, D. Fenske, D.H. Gregory, L.R. Hanton, P. Hubberstey, M. Schröder, Chem. Commun. (2001) 1432. J. Wang, S.L. Zheng, S. Hu, Y.H. Zhang, M.L. Tong, Inorg. Chem. 46 (2007) 795. J. Wang, Y.H. Zhang, H.X. Li, Z.J. Lin, M.L. Tong, Cryst. Growth Des. 7 (2007) 2352. M.O. Awaleh, A. Badia, F. Brisse, Cryst. Growth Des. 6 (2006) 2674. W. Chen, M. Du, X.H. Bu, R.H. Zhang, T.C.W. Mak, Cryst. Eng. Comm. (2003) 96. T.H. Kim, K.Y. Lee, Y.W. Shin, S.T. Moon, K.M. Park, J.S. Kim, Y. Kang, S.S. Lee, J. Kim, Inorg. Chem. Commun. 8 (2005) 27. Cerius2, version 4.6, Molecular Simulation Incorporated, San Diego, CA, 2001. AXS Bruker, SAINT Software Reference Manual, Madison, WI, 1998. G.M. Sheldrick, SHELXTL NT Version 5.1. Program for Solution and Refinement of Crystal Structures, University of Göttingen, Germany, 1997. O.V. Dolomanov, OLEX, Version 2.55, Wellcome Genome Campus, Hinxton, Cambridge, UK. O.V. Dolomanov, A.J. Blake, N.R. Champness, M. Schröder, J. Appl. Cryst. 36 (2003) 1283. M.L. Chen, X.F. Xu, Z.X. Cao, Q.M. Wang, Inorg. Chem. 47 (2008) 1877. D.L. Long, A.J. Blake, N.R. Champness, C. Wilson, M. Schröder, J. Am. Chem. Soc. 123 (2001) 3401. X.W. Wang, Y.R. Dong, Y.Q. Zheng, J.Z. Chen, Cryst. Growth Des. 7 (2007) 613. A.L. Spek, PLATON, A Multipurpose Crystallographic Tool, Utrecht University, Netherlands, 2005. M. Vitale, P.C. Ford, Coord. Chem. Rev. 219–221 (2001) 3. S. Hu, A.J. Zhou, Y.H. Zhang, S. Ding, M.L. Tong, Cryst. Growth Des. 6 (2006) 2543. A.I. Kitaigorodsky, Chem. Soc. Rev. 7 (1978) 133.
Contents lists available at ScienceDirect
Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc
Varying the frameworks of coordination polymers with (CuI)4 cubane cluster by altering terminal groups of thioether ligands Chuang Xie, Lina Zhou, Wenxiu Feng, Jingkang Wang, Wei Chen * The State Research Center of Industrialization for Crystallization Technology, Tianjin University, Tianjin 300072, PR China
a r t i c l e
i n f o
Article history: Received 16 October 2008 Received in revised form 16 December 2008 Accepted 19 December 2008 Available online 30 December 2008 Keywords: (CuI)4 complexes Dithioether Terminal groups 4(6).6(4) topology Synthesis
a b s t r a c t Two Cu(I) coordination architectures, [(CuI)4(L1)2]n (1) and [(CuI)4(L2)1.5]n (2) with two structurally related flexible dithioether ligands, 1,4-bis(ethylsulfanyl)butane (L1) and 1,4-bis(benzylsulfanyl)butane (L2) have been synthesized and structurally characterized by element analysis and X-ray diffraction. In both complexes, (CuI)4 cubane cluster acts as a secondary building unit and dithioether ligands as a ditopic bridge to generate two distinct frameworks. 1 has a two-dimensional (4,4) network, while 2 is a three-dimensional framework with rare 4(6).6(4) topology, being the first example in (CuI)4 complexes. The difference of frameworks can be attributed to the variation of the terminal groups of the two ligands. Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction The design, syntheses, and characterization of novel metal–organic coordination architectures has attracted great attention in recent years, not only because of their intriguing structural topologies but also their potential applicable properties [1–3]. Many efforts have been devoted to the rational design of specific complexes including 1D chains and ladders, 2D grids, 3D microporous networks, interpenetrated nets, and chiral frameworks [4–6]. In fact, the formation of these complexes is influenced by many factors such as coordination environment of metal center (or clusters as secondary building units), the choice of rigid or flexible ligand, solvent, template, counterion [7–9]. In this context, complex construction between copper(I) halides and sulfur containing organic compounds has great current interest for their potential use in the rational design and synthesis of new polymeric metal–organic coordination architectures [10,11]. As the tendency of copper(I) to form clusters often leading to short metal–metal bonds and the large size of the S atom to make it easier to adopt different angles at this atom in complexes, such compounds display intriguing structural diversities in architectures and potentially useful properties, including ion-exchange capacity, electronic, and optical properties. For example, CuI complex with flexible 1,3-bis(4-pyridyl)propane shows a chiral triple-interpenetrated, quartz net[12]. The coordination polymers form between CuI and bis(4-pyridyl)disulfide (bpds) illustrated solvent depen* Corresponding author. Tel.: +86 22 27405754; fax: +86 22 23502458. E-mail address: [email protected] (W. Chen). 0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2008.12.043
dent topological isomerism [13] while the solvothermal reactions of CuI with bpds result in situ cleavage of both S–S and S–C(sp2) bonds and temperature-dependent in situ ligand rearrangement [14,15]. On the other hand, although the flexible dithioether ligands have been investigated widely in Ag(I) complexes by us and others [16,17], the Cu(I) complexes with these ligands are still rarely explored [18]. As a continuous effort in the investigation of the coordination complexes of dithioether ligands, we report herein the construction of two Cu(I) coordination polymers by using two structurally closely related dithioether ligands, 1,4-bis(ethylsulfanyl)butane (L1) and 1,4-bis(benzylsulfanyl)butane (L2) (see Chart 1), with aiming to examine the influence of sterichindrance of the ligands on the resultant structures of their metal complexes. 2. Experimental 2.1. Materials and general methods All commercially available chemicals were of reagent grade and used as received without further purification. Elemental analyses of C and H were performed on a Perkin-Elmer 240C analyzer. The emission/excitation spectra were measured on an Varian Cary Eclipse spectrophotometer equipped with a continuous Xe-900 Xenon lamp, a íF900 nanosecond flash lamp. The ligands 1,4-bis(ethylsulfanyl)butane (L1) and 1,4-bis(benzylsulfanyl)butane (L2) were synthesized according to a reported procedure [17]. The X-ray powder diffraction (XRPD) patterns of 1 and 2 were registered with a Rigaku D/Max-2500 diffractometer, operated at 40 kV and 100 mA, using a Cu target tube and a graphite
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onto the specific atoms and refined isotropically with fixed thermal factors. Further details for structural analysis are summarized in Table 1. Selected bond lengths and angles for 1 and 2 are compared in Table 2. Visualization and analysis of topological networks of complexes were carried out by the freeware OLEX program [22,23]. CCDC reference numbers is 642854 and 642855. 3. Results and discussion
Chart 1.
3.1. The effect of molar ratio of CuI:L monochromater. Fixed scatter and divergence slits of 0.5 l and a 0.15 mm receiving slit were used. The intensity data were recorded by continuous scan in a 2h/h mode from 2° to 50° with a step size of 0.02° and a scan speed of 4°/min. Simulation of the XRPD spectra was carried out by the single-crystal data and diffraction-crystal module of the commercially available Cerius2 program[19]. 2.2. Synthesis of complexes 1 and 2 [(CuI)4(L1)2]n (1) and [(CuI)4(L2)1.5]n (2) as single colourless crystal samples were obtained by a similar methods: 10 mL of dichloromethane solution of the ligand L (2.0 mmol) was slowly added to a solution of CuI (0.380 g, 2.0 mmol) in acetonitrile (10 mL) and stirred for 30 min, and then filtrated to give colourless solution. The solution is maintained undisturbed at ambient temperature. After six days, colourless crystals were collected. For 1 with yield of 40%. Anal. Calcd for C16H36S4Cu4I4 (1118.50): C 17.18, H 3.24; Found C 17.02, H 3.55. For 2 with yield of 50%. Anal. Calcd for C27H33S3Cu4I4 (1215.54): C 26.68, H 2.74; Found C 26.43, H 2.92. 2.3. X-ray crystallographic studies of complexes X-ray single-crystal diffraction data for 1 and 2 were collected on a Bruker Smart 1000 CCD diffractometer at 293(2) K with Mo Ka radiation (k = 0.71073 Å) by x scan mode. The program SAINT [20] was used for integration of the diffraction profiles. All the structures were solved by direct methods using the SHELXS program of the SHELXTL package and refined by full-matrix least-squares methods with SHELXL (semi-empirical absorption corrections were applied using SADABS program) [21]. Metal atoms in each complex were located from the E-maps and other non-hydrogen atoms were located in successive difference Fourier syntheses and refined with anisotropic thermal parameters on F2. The hydrogen atoms of the ligands were generated theoretically
Table 1 Crystallographic data and structure refinement summary for complexes 1 and 2. Formula Formula weight Crystal system Space group Z a/Å c/Å V/Å3 Dcalc/g cm 3 l/mm 1 F(0 0 0) Reflections collected/unique Ra & wRb (I > 2r(I)) GOF on F2 (Dq)max/eÅ 3 (Dq)min/eÅ 3 a b
C16H36S4Cu4I4 (1) 1118.45 Tetragonal P42/n 2 11.936(2) 10.964(2) 1561.9(4) 2.378 6.911 1048 15132/1788 0.0374, 0.0969 1.060 0.392 0.490
R = R||F0| |FC||/R|F0|. wR = [Rw(F02 FC2)2/Rw(F02)2]1/2.
C13.5H16.5S1.5Cu2I2 (2) 607.74 Hexagonal P3 4 16.895(2) 7.0151(14) 1734.1(5) 2.328 6.178 1142 16570/2652 0.0225, 0.0501 1.087 0.711 0.852
The crystals were obtained as 4:2 and 8:3 binary compounds, although both of them were carried out with an equimolar amount of the starting reagent by the same method. As the metal-to-ligand ratio plays an important role in construction of supramolecular architectures [24], we also tried to generate different structures by modification the molar ratios of CuI to L in a similar synthetic route to that used for 1 and 2. Changing the reagent molar ratio to 4:1, 2:1, and 1:2 caused compound 1 and 2 in pure form while the molar ratio to 1:4 with further excessive ligands just resulted in some oil residues. The negative results indicate that it is still a challenge to predict and control the ligand reactions toward target products. 3.2. Description of the crystal structures Single-crystal X-ray analysis of 1 revealed the formation of a (4,4) two-dimensional polynuclear assembly with a substructure of Cu4I4 clusters. The Cu4I4 core, resembles a cubane-like arrangement with an internal tetrahedral Cu4 core (Fig. 1a). Each copper(I) is tetrahedrally coordinated by three I and a sulfur from the L1 with Cu–I and Cu–S distances of 2.664(1)– 2.708(1) and 2.284(2) Å, respectively. The Cu–Cu distances are 2.645(2)–2.739(2) Å, being similar to those of other reported Cu4I4 tetramer units (Fig. 1b) [18]. Each cluster core is bonded to four different bridging L1 by Cu–S bonds forming a layer structure (Fig. 2). The network topology can be simplified to a (4,4) net by considering a Cu4I4 cluster as a node and a ligand as a bisdentate linker. The distance is 11.93(1) Å between the neighboring nodes in a square-grid. The ligand L1 adopts a
Table 2 Selected bond distances (Å) and angles (deg) for complexes 1a and 2b. Compound 1 Cu(1)–S(1) Cu(1)–I(1)#1 I(1)–Cu(1)#1 Cu(1)–Cu(1)#3 S(1)–Cu(1)–I(1)#1 I(1)#1–Cu(1)–I(1)#2 I(1)#1–Cu(1)–I(1) S(1)–Cu(1)–Cu(1)#1 I(1)#2–Cu(1)–Cu(1)#1
2.284(2) 2.6643(9) 2.6643(9) 2.7380(16) 107.89(7) 112.05(3) 113.07(3) 146.33(6) 108.904(19)
Cu(1)–I(1) Cu(1)–I(1)#2 I(1)–Cu(1)#3
2.7076(9) 2.6893(11) 2.6893(11)
S(1)–Cu(1)–I(1)#2 S(1)–Cu(1)–I(1) I(1)#2–Cu(1)–I(1) I(1)#1–Cu(1)–Cu(1)#1 I(1)–Cu(1)–Cu(1)#1
104.74(7) 107.93(6) 110.70(3) 60.14(3) 58.58(3)
Compound 2 Cu(1)–I(1) Cu(1)–I(2)#1 Cu(2)–S(1) Cu(2)–I(1)#3 I(2)–Cu(1)–I(2)#1 I(2)–Cu(1)–I(1) S(1)–Cu(2)–Cu(1) I(1)#3–Cu(2)–I(2)#2
2.7485(10) 2.6385(4) 2.2866(10) 2.6977(6) 113.780(13) 104.715(16) 149.45(3) 109.241(18)
Cu(1)–I(2) Cu(1)–Cu(2)#1 Cu(2)–I(2)
2.6385(4) 2.7247(8) 2.6680(6)
I(2)–Cu(1)–Cu(2)#1 S(1)–Cu(2)–I(2) Cu(1)–I(2)–Cu(2)
60.700(14) 111.52(3) 61.787(17)
a Symmetry code: #1: x, z + 1/2. b Symmetry code: #1:
x + 1/2,
y + 1/2, z. #2: y, x + 1/2, z + 1/2. #3:
y + 1, x
y + 1, z. #2:
x + y,
y + 1/2,
x + 1, z. #3: x, y, z + 1.
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Fig. 2. The 2D (4,4) net in 1 (left) and its schematic presentation with nodes collided from the Cu4I4 units (right).
Fig. 1. (a) The tetrahedral connectivity of the Cu4I4 unit and (b) coordination environment of 1 (symmetry code A: 1/2 x, 3/2 y, z).
cis-conformation with the pseudo-torsion angle (C2–S1. . .S1A– C2A) of 17.4(2)°. Although the structure of Cu4I4 core in complex 2 is similar to that in 1 while the Cu–Cu, Cu–I, and Cu–S fall in the range 2.725(1)–2.898(1), 2.638(1)–2.748(1), and 2.287(1) Å, respectively (Fig. 3a), a quite different framework has been constructed by substituting benzyl of L2 for ethyl of L1. It is worth noting that each cluster core plays the role as a five-connected node (Fig. 3b). Three Cu(I) ions (Cu2, Cu2A, and Cu2B) locate in the diagonal plane of the cubane-like Cu4I4 core in which each Cu(I) ion is tetrahedrally corner-connected to three l3-iodide atoms and one sulfur donor of L2. Each L2 ligand, adopting a centrosymmetric arrangement, bridges two adjacent cluster cores and extends along the crystallographic a and b directions. The inorganic-organic hybrid layers feature as (6,3) topological sheets
Fig. 3. (a) Coordination environment of 2 and (b) the pentahedral connectivity of the Cu4I4 unit.
C. Xie et al. / Journal of Molecular Structure 921 (2009) 132–136
135
Fig. 4. View of (a) the framework in 2 along c- direction and (b) the 3D 4(6).6(4) network, the (6,3) net in ab plane outlined in green. Each Cu4I4 unit was collided into a node.
with edges of 11.17(1) Å (Fig. 4a). Then the fourth Cu(I) (Cu1) in Cu4I4 core interconnects another core related by symmetric relation 1 y, 1 + x y, z 1 through Cu–I bond, so that the 2D nets were jointed in c-direction to generate a 3D framework (Fig. 4b). Such a net structure can be characterized by the short vertex symbol 4(6).6(4); the long Schäfli symbol is 4.4.4.4.4.4.6.6.6 (Fig. 4c) [22]. Although a large number of examples of threeor four-connected networks based on d-block metal ions have been reported, five-connected networks are still rare [25,26]. The present net is the first case of Cu4I4 complexes with such a five-connected topology. A similar BN topological net also could be found in the manganese(II) complex with pyridine2,4,6-tricarboxylate [26]. An analysis of the voids [27] shows only 0.6% of the space empty in 2 for the inner cavity of each hexagon-unit is accommodated with six benzyl end-groups. 3.3. XRPD results X-ray powder diffraction (XRD) was used to check the purity of complexes 1 and 2 as shown in Fig. 5. Although there are a few unindexed diffraction lines in the experimental patterns, it still can be considered that the peaks displayed in the measured patterns closely match those in the simulated patterns generated from
single-crystal diffraction data, indicating complexes 1 and 2 are isolated as single phases. 3.4. Luminescent properties The emission spectra of complexes 1 and 2 in the solid state are investigated at room temperature under the same situations. The em excitation and emission maxima (kex max and kmax ) at room temperature are shown in Fig. 6. Upon excitation at 342 and 344 nm, 1 and 2 in the solid state exhibit strong photoluminescence with emission maxima at 517 and 499 nm, respectively, in conformity with photoluminescent properties of Cu4I4 cluster complexes[28]. Since the L1 and L2 are non-fluorescent, the emission band might be assigned to a combination of a cluster centered transition and halideto-metal charge-transfer (XMCT)[29]. In summary, two copper(I) metal–organic supramolecular architectures 1 and 2 have been constructed by the direct reactions of CuI with flexible thioether ligands L1 and L2 in similar reaction conditions, respectively. Although L1 and L2 are closely related in structure, 1 and 2 form quite different frameworks induced by terminal group variation. Comparing the structures of 1 and 2, the different character of the Cu4I4 clusters in1 and 2, as fourand five-connected nodes, results in a 2D (4,4) and a rare 3D
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4(6).6(4) network, respectively. Since a complex framework has a tendency to be such an architecture with the least free volume in cell and sterichindrance in geometry [30], the terminal group of the analogous ligands becomes a determining factor in modifying the conformation of ligand in complex, so as to control structural topology of the metal–organic supramolecular network.
Acknowledgments We gratefully acknowledge the financial support from the National Natural Science Foundation of China (No. 20576089) and Tianjin Natural Science Foundation (05YFJZJC02000 and 05YFGHHZ01100).
References [1] [2] [3] [4] [5] [6] [7] [8] [9]
Fig. 5. Simulated (solid line) and experimental (red point) XRPD patterns of (a) complex 1 and (b) complex 2. (For interpretation of colour mentioned in this figure the reader is referred to the web version of the article.) 1000
Intensity/a.u.
900
[10] [11] [12] [13]
[14] [15]
800
1
700
2
[16] [17] [18]
600
[19] [20] [21]
500 400 300
[22]
200
[23]
100
[24] [25]
0 250
300
350
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500
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600
650
700
Wavelength/nm Fig. 6. Emission and excitation spectra of 1 (red) and 2 (blue). (For interpretation of colour mentioned in this figure the reader is referred to the web version of the article.)
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