1D Tubular Chains and 3D Polycatenane Frameworks Constructed with Cu2X2 Dimers (X ) Br-, I-, CN-) and Flexible Dipyridyl Spacers Sheng Hu, Ai-Ju Zhou, Yue-Hua Zhang, Shu Ding, and Ming-Liang Tong*
CRYSTAL GROWTH & DESIGN 2006 VOL. 6, NO. 11 2543-2550
MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen UniVersity, Guangzhou 510275, China ReceiVed June 18, 2006; ReVised Manuscript ReceiVed September 4, 2006
ABSTRACT: Five new coordination polymers based on copper(I) halides or pseudohalide, [Cu2Br2(bpe)2] (1), [Cu2(CN)2(bpe)] (2), [Cu2Br2(bpp)2] (3), [Cu2I2(bpp)2]‚(toluene) (4), and [Cu2I2(bpp)2]‚(naphthalene) (5) (bpe ) 1,2-bis(4-pyridyl)ethane, bpp ) 1,3-bis(4-pyridyl)propane), have been synthesized by solvothermal methods and characterized by X-ray crystallography. All structures can be deconstructed into rhomboid Cu2X2 (X ) Br, I, CN) dimers and flexible bridged dipyridyl ligands. In 1, two sets of (4,4) layers adopt the “diagonal-diagonal” 4-fold interpenetration mode, giving high catenation and generating a novel 2D f 3D interpenetrating framework. 2 is a 3D (3,6)-connected rutile-like net of 2-fold interpenetration. Each 3D rutile-like net consists of 2D flat [Cu2(µ3-CN)(µ-CN)] layers and bpe pillars. 3 is a 2D polycatenane formed by interlocking of 1D double-stranded tubular chains. 1D double-stranded tubular chains are also present in 4 and 5, similar to that found in 3; however, the presence of toluene or naphthalene guests prevents the 1D double-stranded tubular chains from interpenetration. The photoluminescent properties of 1 and 3 in the solid state have been studied. Introduction Rational design and synthesis of net-based coordination polymers with intriguing structural features and potential useful properties, for example, magnetism, photoluminescence, electric conductivity, adsorption, and heterogeneous catalysis, are of great current interest.1 Among the different types of netassembled molecular frameworks, the networks constructed from interlocking and interweaving of individual motifs such as polycatenation, Borromean, polythreading, and polyknotting have received much attention in recent years not only for their intriguing architectures and topologies but also from the perspective of establishing useful relationships between structure and properties.2 Copper(I) halides3 have been employed as inorganic components in the construction of novel coordination polymers with various structural motifs such as a linear Cu2Cl dimer,4 square (rhomboid) Cu2X2 (X ) Br-, I-) dimers,5 cubane or step-cubane Cu4X4 tetramers,6 zigzag [CuX]n or [Cu3I4]nn- chains,5f,h,7 [Cu2X2]n ladders or ribbons,5f,h,8 and 2D [CuX]n layers.5h,9 Among those copper halide motifs, the rhombic Cu2X2 secondary building units (SBUs), formed by two X- atoms linking two neighboring Cu(I) atoms, have been found to be characteristic of excellent planar 4-connecting nodes whose remaining coordination sites of the Cu(I) atoms are bridged by the N,N′bridging ligands, being facile at constructing multidimensional coordination frameworks.5 However, most bridging ligands adopted to date to connect the Cu2X2 building blocks have been rigid, including pyrazine, pyrimidine, 2,7-diazapyrene, 4,7phenanthroline, 4,4′-bipyridine, 2,4-bis(4-pyridyl)-1,3,5-triazine, 3,5-bis(4-pyridyl)pyridine, and 5-(4-pyridyl)pyrimidine. In contrast, only a few coordination polymers based on Cu2X2 SBUs with flexible conformations have been documented so far,5i,10 probably due to the flexibility of the backbones, which makes it more difficult to predict and control the final coordination networks. We have recently investigated the assembly rule of * To whom correspondence should be addressed. E-mail: tongml@ mail.sysu.edu.cn. Tel: +86 20 8411-0966; Fax: +86 20 8411-2245.
the coordination polymers with metal clusters as building blocks; several metal cluster units, such as Ag2(RCO2)2,11a,b Cu2(RCO2)3,11c M2(RCO2)4,11d Cu4I4,6e Zn4O,11e and Mx(OH)y11f,g have been successfully introduced to act as secondary building units for the construction of two- and three-dimensional frameworks. As an extension of our study of the construction of new structural types of cluster-based coordination networks, rhombic Cu2X2 units were selected for our assembled systems, since they are excellent inorganic functional modules for their planar 4-connectivity as well as their rich photophysical properties.12 Herein, we report a series of complexes constructed from Cu2X2 units and flexible N,N′-spacers of 1,2-bis(4pyridyl)ethane (bpe) or 1,3-bis(4-pyridyl)propane (bpp) under solvothermal conditions in the presence of benzene or naphthalene molecules, in which the bridging ligand or templating molecule plays a vital role in the formation of the structures and topologies. Experimental Section Materials and Physical Measurements. The reagents and solvents employed were commercially available and used as received without further purification. The C, H, and N microanalyses were carried out with an Elementar Vario-EL CHNS elemental analyzer. The FT-IR spectra were recorded from KBr pellets in the range 4000-400 cm-1 on a Bio-Rad FTS-7 spectrometer. X-ray powder diffraction (XRD) intensities for 1 and 3 were measured at 293 K on a Rigaku D/maxIIIA diffratometer (Cu KR, λ ) 1.540 56 Å). The crushed single-crystal powder samples were prepared by crushing the crystals and scanned from 3 to 60° with a step of 0.1°/s. Calculated patterns of 1 and 3 were generated with PowderCell. The emission/excitation spectra and the lifetimes were measured on an Edinburgh FLS-920 spectrophotometer equipped with a continuous Xe-900 Xenon lamp, a µF900 nanosecond flash lamp. Solvothermal Synthesis. (a) [Cu2Br2(bpe)2] (1). A mixture of CuBr (0.5 mmol), bpe (0.5 mmol), benzene (2 mL), and MeCN (10 mL) in a 23 mL Teflon reactor was heated to 160 °C for 3 days and then cooled to room temperature at a rate of 5 °C/h. Dark red block crystals were obtained in 24% yield (based on Cu) after washing with MeCN and drying in air. Anal. Calcd for C24H24Br2Cu2N4: C, 43.98; H, 3.69; N, 8.55. Found: C, 42.96; H, 3.60; N, 8.44. IR (KBr, cm-1): 3434
10.1021/cg060370k CCC: $33.50 © 2006 American Chemical Society Published on Web 10/18/2006
2544 Crystal Growth & Design, Vol. 6, No. 11, 2006
Hu et al.
Table 1. Crystal Data and Structure Refinement Details for 1-5
formula formula wt temp/K cryst syst space group a/Å b/Å c/Å β/deg V/Å3 Z Dc/g cm-3 µ/mm-1 F(000) no. of rflns collected no. of indep rflns Rint GOF R1a (I > 2σ(I)) wR2a (all data) a
1
2
3
4
5
C24H24Br2Cu2N4 655.37 293(2) tetragonal P43212 16.622(3) 16.622(3) 17.733(6)
C28H24Cu4N8 726.71 293(2) monoclinic P21/n 13.543(1) 6.9515(5) 30.757(2) 101.314(1) 2839.4(4) 4 1.700 2.988 1456 15 205 6102 0.0342 1.014 0.0552 0.1646
C26H28Br2Cu2N4 683.42 123(2) tetragonal P43212 12.210(1) 12.210(1) 35.803(4)
C33H36Cu2I2N4 869.54 293(2) monoclinic C2/m 16.072(2) 13.100(2) 8.475(1) 94.335(3) 1779.3(5) 2 1.623 2.956 852 2691 1554 0.0173 1.034 0.0414 0.1148
C36H36Cu2I2N4 905.56 123(2) monoclinic C2/m 15.761(2) 13.149(1) 8.4107(9) 94.423(2) 1737.9(3) 2 1.731 3.031 888 3082 1678 0.0197 1.095 0.0363 0.0928
4900(2) 8 1.777 5.017 2592 14 802 5595 0.0911 0.828 0.0466 0.0814
5337.5(8) 8 1.701 4.610 2720 13 707 5162 0.0662 1.023 0.0641 0.1666
R1 ) ∑||Fo| - |Fc||/∑|Fo|; wR2 ) [∑w(Fo2 - Fc2)2/∑w(Fo2)2]1/2.
(w), 3035 (w), 2932 (w), 2864 (w), 1606 (s), 1556 (w), 1493 (w), 1451 (w), 1420 (m), 1211 (w), 1072 (w), 1013 (w), 830 (s), 812 (w), 542 (s). (b) [Cu2(CN)2(bpe)] (2). A mixture of CuI (0.5 mmol), bpe (0.5 mmol), and MeCN (10 mL) in a 23 mL Teflon reactor was heated to 160 °C for 3 days and then cooled to room temperature at a rate of 5 °C/h. Dark red block crystals were found in very low amount (
