CRYSTAL GROWTH & DESIGN 2008 VOL. 8, NO. 4 1094–1096
Communications A Novel Interpenetrating Diamondoid Network from Self-Assembly of N,N′-Di(4-pyridyl)adipoamide and Copper Sulfate: An Unusual 12-Fold, [6 + 6] Mode Yi-Fen Hsu,† Chia-Her Lin,† Jhy-Der Chen,*,† and Ju-Chun Wang‡ Department of Chemistry, Chung-Yuan Christian UniVersity, Chung-Li, Taiwan, R.O.C., and Department of Chemistry, Soochow UniVersity, Taipei, Taiwan, R.O.C. ReceiVed December 10, 2007; ReVised Manuscript ReceiVed February 17, 2008
ABSTRACT: The polymeric complex [CuSO4(L)(H2O)2]∞, 1, which was prepared by the reaction of a flexible ligand N,N′-di(4pyridyl)adipoamide), L, and copper sulfate forms a 12-fold diamondoid network showing an unusual [6 + 6] mode of interpenetration. The L ligands in 1 adopt the AAA trans and GAG trans conformations which also differ in the dihedral angle between the two pyridyl rings. Considerable effort has been devoted to understanding the selfassembly of organic and inorganic molecules in the past decade, because it extends the range of new solids that can be designed to have particular physical and chemical properties.1 The crystal engineering of coordination polymeric frameworks has attracted great attention due to their potential properties as novel zeolitelike materials.2 One of the most common and important types of topology in polymeric networks is related to the structure of diamond,3 which is, in general, formed by propagating a tetrahedral nodal point in all four directions by coordinating a topological linear bidentate ligand. There are a number of diamondoid-like networks involved in interpenetrating phenomena and the fold-interpenetrating number ranges from 2 to 11.4 The complex [Ag(ddn)2]NO3 (ddn ) 1,12-dodecanedinitrile) shows the highest degree of 10-fold interpenetration ever found for diamondoid nets exclusively based on coordination bonds, while the complex [Ag(ddn)2]PF6 shows an 8-fold diamondoid network with an unusual [4 + 4] mode of interpenetration.5 The 11-fold interpenetration of diamondoid frames has been reported for the hydrogen-bonded complex of tetrakis[4(3-hydroxyphenyl)phenyl]methane and benzoquinone.6 We are currently exploring the roles of ligand conformations in the structural types.7 Recently, we have reported a series of onedimensional (1-D) Ag(I) coordination polymers containing a flexible ligand N,N′-di(2-pyridyl)adipoamide).7c The GAG trans, AAA trans, GGG cis, and AGA cis conformations were found, which also differ in the dihedral angle between the two pyridyl rings. We report herein our investigation of the self-assembly of copper sulfate with the flexible ligand N,N′-di(4-pyridyl)adipoamide), L, which results in a 12-fold diamondoid network showing an unusual [6 + 6] mode of interpenetration. The synthesis, structure, and ligand conformations of [CuSO4(L)(H2O)2]∞, 1, form the subject of this report. * To whom correspondence should be addressed. † Chung-Yuan Christian University. ‡ Soochow University.
The ligand L was prepared by the reaction of adipoyl chloride,
4-aminopyridine, and triethylamine in dimethylformamide (DMF).8 An ethanol solution of L was layered on top of an aqueous solution of CuSO4 · 5H2O to afford needle-like crystals,9 which was characterized as [CuSO4(L)(H2O)2]∞, 1, by X-ray crystallography.10 Complex 1 is very stable in air at ambient temperature. The thermal gravimetric analyses (TGA) curve shows that 1 is stable up to 40 °C. A total weight loss of 7.26% occurred in the temperature range 40–80 °C, presumably due to the removal of the water molecules per formula unit (calcd. 7.2%). A weight loss of 76.62% occurred in the temperature range 81–554 °C, corresponding to the removal of L ligands and SO3 per formula unit (calcd. 76.6%). Finally, the residual product weight of 16.02% was found in the temperature range 554–800 °C, corresponding to the formation of CuO (calcd. 16.1%). Complex 1 emits at λmax ) 394 nm, upon excitation at 247 nm, which is the same as that of the free L. Since there is no significant energy shift observed upon coordinating L ligands to the Cu atoms, the emission bands in 1 may be tentatively assigned as intraligand (IL) π f π* transitions. The crystal structure of 1 was solved in the space group Pna21, and Figure 1a depicts a molecular structure showing the arrangements about the two Cu(II) metal centers. There are two crystallographically independent copper atoms in the structure, and both Cu atoms adopt the distorted square pyramidal geometry, with a Cu(1)---Cu(2) distance of 4.681 (4) Å. Two SO42- anions which adopt the µ2-η1:η1-bridging coordination mode bridge the two Cu(II) atoms to form an eight-membered metallocycle. The structure of 1 consists of a three-dimensional (3D) framework with the extended diamondoid topology. A single adamantanoid framework is il-
10.1021/cg701209k CCC: $40.75 2008 American Chemical Society Published on Web 03/15/2008
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Figure 1. (a) A molecular structure showing the environments of the two copper centers. (b) A diagram showing a single adamantanoid framework.
lustrated in Figure 1b, which exhibits maximum dimensions of 2a × 6b × 2c (37.36 × 82.27 × 32.61 Å3). Because of the formation of two different conformations for the L ligands, AAA trans and GAG trans,7c the adjoining nodes (the node is assumed to be the midpoint of the independent copper atoms) are separated by two different distances that are 24.46 (AAA trans) and 23.62 (GAG trans), respectively. These ligand conformations also differ in the dihedral angle (4.4 and 7.2°) between the two pyridyl rings, that is, the two rings twisted about the C-N bonds. Twelve independent equivalent cages interpenetrate in the crystal structure by selfclathration along the b-axis (12-fold interpenetration), Figure 2a. This interpenetration mode differs from the normal mode and can be described as two sets of normal 6-fold net, Figure 2b, that is, an unusual [6 + 6] mode of interpenetration, and the independent equivalent cages are separated from each other by 13.71 Å. Figure 2c shows a view looking down the b axis. The two sets of 6-fold nets are translationally equivalent and are generated by a unique interpenetration vector5 Ti ) a/2 + b/2 with a relative displacement distance of 11.65 Å. Noticeably, the framework is supported by extensive N-H---O (N---O ) 2.850–2.881 Å) and C-H---O (C---O ) 3.267 Å) interactions, originating from the amine hydrogen and pyridyl hydrogen atoms of the L ligands, respectively, to the uncoordinated oxygen atoms of the bridged SO42- anions, while different C-H---O interactions from the pyridyl hydrogen atoms (C---O ) 3.121 Å) and the methylene hydrogen atoms (C---O ) 3.272 Å) to the oxygen atoms of the cocrystallized water molecules are observed. The framework is also supported by the O-H---O (O---O ) 2.718–2.893) hydrogen bonds, which are involved in the cocrystallized water molecules and the SO42- anions. To our best knowledge, compound 1 shows the maximum number of interpenetration presently known for interpenetrating nets. The degree of interpenetration is strongly related to the length of the spacer ligand.5 There are, however, other factors that can affect interpenetration, such as the bulkiness of the ligands and the counterions, the number and type of solvated molecules, the π–π interactions between the aromatic bridging ligands, and the coordination geometry at the pseudotetrahedral centers.5 In the present complex, combination of a long flexible ligand with a node located at the midpoint of dinuclear copper centers which are bridged by two SO42- anions do extend the number of interpenetration. Thus, the flexibility of the spacer ligand as well as the diversities of
Figure 2. (a) A schematic view of the 12-fold interpenetration in 1. (b) Another view showing the [6 + 6] interpenetration. (c) A view looking down the b axis.
geometrical arrangements of the metal centers and the counteranions which compose the node are essential in determining the structural type, and the spacer ligand adopts the conformation that maximizes the intra- and intermolecular forces. The nature of the L ligands and the packing of the water molecules which result in the formation of the N-H---O, C-H---O, and O-H---O interactions may help direct the unusual interpenetration topology. Increasing both the length of a flexible spacer ligand like L and the M---M distance of the dinuclear metal centers may possibly further extend the number of interpenetration.
Acknowledgment. We are grateful to the National Science Council of the Republic of China for support. Supporting Information Available: Crystallographic data (CIF files, excluding structure factors) for complex 1 have been deposited with the Cambridge Crystallographic Data Centre, CCDC no.
1096 Crystal Growth & Design, Vol. 8, No. 4, 2008
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670216. This material is available free of charge via the Internet at http://pubs.acs.org.
References (1) (a) Desiraju, G. R. Angew. Chem., Int. Ed. Engl. 1995, 34, 2311. (b) Desiraju, G. R. Chem. Commun. 1997, 1475. (c) Lehn, J. M. Supramolecular Chemistry; VCH: Weinheim, 1995. (2) (a) Robson, R.; Abrahams, B. E.; Batten, S. R.; Gable, R. W.; Hoskins, B. F.; Lieu, J. Supramolecular Architecture; ACS Publications, Washington, DC, 1992. (b) Batten, S. R.; Robson, R. Angew. Chem., Int. Ed. 1998, 37, 1460. (c) Yaghi, O. M.; Li, H.; Davis, C.; Richardson, D.; Groy, T. L. Acc. Chem. Res. 1998, 31, 474. (d) Gudbjartson, H.; Biradha, K.; Poirier, K. M.; Zaworotko, M. J. J. Am. Chem. Soc. 1999, 121, 2599. (e) Aakeröy, C. B.; Seddon, K. R. Chem. Soc. ReV. 1993, 397. (f) Fujita, M.; Ogura, K. Coord. Chem. ReV. 1996,148, 249. (g) Noro, S.-I.; Kitauta, R.; Kondo, M.; Kitagawa, S.; Ishii, T.; Matauzaka, H.; Yamashita, M. J. Am. Chem. Soc. 2002, 124, 2568. (h) Kitagawa, S.; Kondo, M. Bull. Chem. Soc. Jpn. 1998, 71, 1739. (3) (a) Zaworotko, M. J. Chem. Soc. ReV. 1994, 23, 283. (b) Goodgame, D. M. L.; Grachvogel, D. A.; Williams, D. J. Angew. Chem., Int. Ed. 1999, 38, 153. (4) Batten, S. R. CrystEngComm 2001, 3, 67. (5) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Rizzato, S. Chem. Eur. J. 2002, 8, 1520. (6) Reddy, D. S.; Dewa, K. E.; Aoyama, Y. Angew. Chem., Int. Ed. 2000, 39, 4266. (7) (a) Hsu, Y.-F.; Chen, J.-D. Eur. J. Inorg. Chem. 2004, 1488. (b) Hu, H.-L.; Yeh, C.-W.; Chen, J.-D. Eur. J. Inorg. Chem. 2004, 4696. (c) Chen, H.-C.; Hu, H.-L.; Chan, Z.-K.; Yeh, C.-W.; Jia, H.-W.; Wu, C.-P.; Chen, J.-D.; Wang, J.-C. Cryst. Growth Des. 2007, 7, 698. (d) Chiang, L.-M.; Yeh, C.-W.; Chan, Z.-K.; Wang, K.-M.; Chou, Y.-C.; Chen, J.-D.; Wang, J.-C.; Lai, J. Y. Cryst. Growth Des. 2008, 8, 470. (8) Adipoyl chloride (1.00 g, 5.47 mmol) was added slowly to a DMF solution of 4-aminopyridine (1.03 g, 10.94 mmol), which was stirred for 15 min, and triethylamine (1.11 g, 10.94 mmol) was then added. The mixture was refluxed for 6 h and then the volume was reduced to 10 mL by vacuum evaporation. A light yellow solid was obtained from the solution after standing at room temperature for 24 h. The solid was filtered off and washed with excess cold water to give a white powder. Yield: 1.15 g (72%). 1H NMR (DMSO-d6, ppm) 10.26
(9)
(10)
(11)
(12) (13)
(2H, s, NH), 8.36 (2H, t, H2-py), 7.51 (2H, d, H3-py), 2.34 (4H, t, COCH2), 1.58 (4H, p, COCH2CH2). Anal Calcd for C16H18O2N4 (MW ) 298.34): C, 64.41; H, 6.08; N, 18.78%. Found: C, 64.40; H, 6.10; N, 18.71%. IR (KBr disk, cm-1): ν ) 3335 (w), 3076 [br, νs(N-H)], 1693 [s, νs(CdO)], 1590 [br, νas(COO-) + ν(CdN)], 1501(s), 1465(s), 1437(s), 1160 [s, νs(COO-)], 1002(w), 827(m), 678(w), 529(w). During our preparation of the manuscript, a structure of L was shown by Biradha, et. al., but no detailed synthetic procedures and spectroscopic data were reported.13 An ethanol solution of L (0.30 g, 1.0 mmol) was layered on top of an aqueous solution of CuSO4 · 5H2O (0.25 g, 1.0 mmol). Several days later, needle-like crystals were at the interface with an 80% yield. Anal Calcd for C16H22CuN4O8S: C, 38.90; H, 4.49; N, 11.34. Found: C, 38.87; H, 4.58; N, 11.41. IR (KBr disk, cm-1): ν ) 3498 (w), 3080 [br, νs(N-H)], 1671 [s, νs(CdO)], 1517 [br, νas(COO-) + ν(CdN)], 1435(s), 1337(s), 1307(s), 1093 [s, νs(COO-)], 1024(w), 840(m), 596(w), 528(w). Crystal data for 1. C16H22CuN4O8S, Orthorhombic, space group Pna21, fw ) 493.98, a ) 18.6983(13), b ) 13.7126(12), c ) 16.305(2), R ) β ) γ ) 90°, V ) 4180.6(8), Z ) 8, dcalc ) 1.570 g cm-3, ) 1.196 mm-1, F(000) ) 2040. The diffraction data of 1 was collected on a Bruker AXS diffractometer, which was equipped with a graphite-monochromated Mo KR (λKR ) 0.71073) radiation. Data reduction was carried by standard methods with use of wellestablished computational procedures.11 The structure factors were obtained after Lorentz and polarization corrections. The positions of the heavy atoms, including the copper atoms, were located by the direct method. The remaining atoms were found in a series of alternating difference Fourier maps and least-square refinements,12 while the hydrogen atoms were added by using the HADD program and refined using a riding model. Final residuals of the final refinement were R1 ) 0.0465 and wR2 ) 0.1308 for 1, respectively, for I > 2σ(I). (a) XSCANS, Release, 2.1, Siemens Energy & Automation, Inc: Madison, Wisconsin, USA, 1995. (b) SMART/SAINT/ASTRO, Release 4.03, Siemens Energy & Automation, Inc.: Madison, Wisconsin, USA, 1995. SHELXTL 5.10; Bruker Analytical X-ray Instruments Inc.: Karlsruche, Germany, 1997. Rajput, L.; Singha, S.; Biradha, K. Cryst. Growth Des. 2007, 7, 2788.
CG701209K
