- Email: [email protected]
Two novel coordination polymers with different molecular tectonics based on cobalt–succinate-organoamine systems
Inorganic Chemistry Communications 9 (2006) 273–276 www.elsevier.com/locate/inoche
Two novel coordination polymers with different molecular tectonics based on cobalt–succinate-organoamine systems Yun Gong, Changwen Hu *, Hui Li, Wang Tang Department of Chemistry, Beijing Institute of Technology, Beijing 100081,China Received 31 August 2005; accepted 15 November 2005 Available online 4 January 2006
Abstract Two novel coordination polymers with different N-donors, [Co(suc)(im)]n (1) and [Co(suc)(phen)]n (2) (suc = succinic dianion, im = imidazole, phen = 1,10-phenanthroline) were synthesized by solvothermal technique and structurally characterized by elemental analysis, IR and single crystal X-ray diffraction. Compound 1 exhibits a novel molecular tectonics like fourfold entangled catenane. Compound 2 shows a two-dimensional structure with two types of rings observed. They exhibit different photoluminescence properties. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Succinic anion; N-donor; Tectonics; Photoluminescence
The construction of coordination networks with novel topologies have been attracting considerable interest, not only because of their intriguing structural diversity but also due to their interesting properties and potential applications [1,2]. A large number of network topologies and entangled systems such as catenanes, rotaxanes, and molecular knots were elucidated by Wells, Batten and Robson in their monograph and comprehensive reviews [3–7]. Rigid ligand such as benzenecarboxylates, pyridinecarboxylates, 4,4 0 -bipyridine are usually utilized to construct network because of their symmetrical structure [8]. However, imidazole as an exo-bidentate rigid ligand is relatively rarely investigated due to its inequal electron density of two nitrogen atoms. Recently, a serial of coordination polymers based on imidazole and metal ions have been reported [9]. If dicarboxylatos such as succinic acid is introduced into such metal-imidazole systems, it is presumed novel network topologies to be built up. Succinic acid is a preference because its flexible linear ligand can make up for the rigidity of imidazole. However, it is a challenge to expect both dicarboxylatos and imidazolo act as bridging ligands *
Corresponding author. Tel./fax: +86 010 62828869. E-mail address: [email protected] (C. Hu).
1387-7003/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2005.11.018
[10]. Our strategy to solve problem is to choose solvothermal technique and adjust the molar ratio of imidazole and succinic acid. A novel coordination polymer [Co(suc)(im)]n (1) (suc = succinic dianion, im = imidazole) was obtained successfully [11], which exhibits a novel molecular tectonics like fourfold entangled catenane (Scheme 1), in which entanglement or self-penetration is happened around anode and each (4, 4) topological net is hinged with four neighboring nets. In order to investigate the role of imidazole in the construction of the molecular tectonics [Co(suc) (phen)]n (2) (phen = 1,10-phenanthroline) was synthesized in comparison with compound 1 [12]. Coordination polymers based on metal-succinate-phen systems usually exhibit a one-dimensional chain with water or excess molar ratio of phen coordinated to metal center [13]. Compound 2 exhibits a novel two-dimensional structure, which is rarely reported in previous work. Single-crystal X-ray analysis has revealed that in compound 1, the ratio of the crystallographically unique Co (II), imidazole and succinic dianion is 1:1:0.5 [14]. Each Co (II) is four coordinated by two O atoms from different succinic dianions and two N atoms from different imidazole ligands. Each Co (II) exhibits a slightly distorted ˚ , Co–O tetrahedral geometry [Co–N 1.992(2)–1.994(3) A
274
Y. Gong et al. / Inorganic Chemistry Communications 9 (2006) 273–276
Scheme 1. Molecular tectonics like fourfold entangled catenane in compound 1.
˚ , O–Co–N 101.57(10)–117.29(11)°, 1.988(2)–2.017(2) A O–Co–O 96.97(9)°, N–Co–N 116.39(11)°]. The carboxylato groups in each succinic dianion are bidentate coordination mode linking four different Co(II). Compound 1 exhibits a uniform (4, 4) net topology, in which a sixteen-membered ring is constructed by four Co (II), two bridged imidazole molecules, two carboxylato groups from two succinic dianions (Figs. 1 and 2). A succinic dianion connects the two diagonal Co (II) of the ring with two O atoms from its two carboxylato groups, thus the sixteen-membered ring can be split into two fifteenmembered ring with (3, 4) net topology. The distance ˚ . Except the two between two diagonal Co (II) is 5.356 A O atoms that connect the two diagonal Co (II), another two O atoms of the same succinic dianions penetrate the sixteen-membered ring and are coordinated to two Co (II) of the two neighboring rings. The approximately perpendicular Co–O–C bond angle [105.05(19)°] makes the self-penetration of each (4, 4) topological net possible. Thus, an orderly self-penetrated array like fourfold entangled catenane is observed in compound 1. The flexibility of succinic dianions make it is possible that succinic dianions rotate its carbon chain for suitable position and angle (\C1B–C2B–C2J = \C2B–C2J–C1J = 112.3°) to fit the space between two Co (II) (Figs. 1 and 2).
Fig. 1. ORTEP drawing of compound 1 with thermal ellipsoids at 50% probability (H atoms omitted for clarity). Atoms with additional labels A, B, D, G and J are related to each other by symmetry operations: A: x + 9/4, y 1/4, z 1/4; B: x + 1/4, y + 1/4, z + 1/4; D: x 1/4, y + 1/4, z 1/4; G: x + 8/4, y, z; J x + 3/4, y 1/4, z + 1/4.
Fig. 2. The structure of compound 1 viewed down c-axis (H atoms omitted for clarity).
However, the carbon chain backbone of each succinic dianion is not on the plane of fourfold entangled catenane shown in Scheme 1, it is away from the plane for achievement of penetration. Thus, the construction of entangled catenane in compound 1 is not by supramolecular force, but via covalent bond, which is different from the construction of the usual catenane. Another interesting feature of compound 1 is the presence of zigzag chains running through the structure. View down vertically in Fig. 2, zigzag chains are constructed by carboxylato-bridged CoN2O2 tetrahedra. Each CoN2O2 tetrahedron can be bridged by imidazole to form alternating left-handed and right-handed chains. Such alternating chiral chains are different from those in previous work [15], they interweave and run through different directions (Fig. 3). The two N atoms of imidazole are equivalent in compound 1 after the deprotonation. The Co–N bond ˚ ] and lengths are almost equal [1.992(2) and 1.994(3) A the difference of Co–N–C bond angles is little [125.3(2)°– 129.6(2)°]. Imidazole plays an important role in the construction of the novel fourfold entangled catenane. If imidazole was replaced by 1,10-phenanthroline under the same reaction conditions, a two-dimensional structure has been formed in compound 2 [16]. Compound 2 exhibits two
Fig. 3. Alternating left-handed and right-handed chains running along b- and c-axis in compound 1 (H atoms and succinic dianion omitted for clarity).
Y. Gong et al. / Inorganic Chemistry Communications 9 (2006) 273–276
crystallographically unique Co (II), two unique phen and four unique half succinic dianion, in which succinic dianions exhibit two coordination modes: bidentate or chelate (Fig. 4). Each Co (II) is six coordinated by four O atoms and two N atoms. Two of the O atoms are chelate-coordinated and another two are bidentate-coordinated O atoms from different succinic anions (Fig. 5). The phen ligands block the 3D direction. Its p p stacking interactions induce the two coordination modes of flexible succinic acid in compound 2. Two types of rings are observed in compound 2. The smaller ring is eightmembered ring, which is constructed by two Co (II) and two bridging carboxylato groups. Another one is twenty-eight-membered ring, which is constructed by four Co (II), two bidentate-coordinated succinic anions and two chelate-coordinated succinic anions (Figs. 4 and 5). In the twenty-eight-membered ring, the Co1 Co1A ˚ . Co1A and Co2C are bridged by one chedistance is 7.934 A ˚ late-coordinated succinic anions with a distance of 8.728 A (Fig. 5). The space of twenty-eight-membered ring is divided into three parts by two parallel phen molecules. As shown in Fig. 5, each phen group is almost planar, planes 1–5 are composed of C atoms from C21C to C30C, C9D to C20D, C9A to C20A, C21 to C30, C9 to C20, respectively. The interplanar angles of two crystallographically unique phen molecules 4 and 5 is 2.2°. The centroid–centroid distances between planes 1 and 2, 2 and 3, 3 and 4, 4 and 5 are ˚ , respectively, whereas 11.631, 3.022, 11.631 and 3.865 A their perpendicular distances are 8.086, 3.022, 7.924 and ˚ , respectively, which indicates there is p p stack3.521 A ing interactions between planes 2 and 3, 4 and 5 [17]. The emission spectra of compounds 1 and 2 are investigated on a Spex FL-2T2 spectrofluorometer equipped with
275
Fig. 5. The structure of compound 2 viewed down b-axis (H atoms omitted for clarity).
a 450 W xenon lamp as the excitation source. In the blue region (kex = 380 nm) at room temperature, compounds 1 and 2 in the solid state exhibit an intense emission at 416 and 438 nm, respectively (see Fig. S1 in the supplementary materials). To understand the nature of the emission band, we analyzed the photoluminescence properties of succinic acid, imidazole and phen ligands and found that the strongest emission peaks for them were at about 398, 389 and 472 nm, respectively, which is attributable to the p* ! n transition [18]. Thus, the emission bands observed in compounds 1 and 2, which are different from those of the individual organic ligands, might be the ligand-to-metal charge transfer (LMCT) [19]. Their different photoluminescence is due to their different coordination environments and structures caused by different organic N-donors in compounds 1 and 2 [20]. As well known, Co is not an excellent metal source for photoluminescence, whereas compounds 1 and 2 exhibit relatively strong emission spectra, which indicates that their photoluminescence properties are closely related with their characteristic structures. It is presumed that the fourfold entanglement via covalent bond in compound 1 and the p p stacking interactions in compound 2 can promote the charge transfer and delocalization within the whole structure, and thus enhance the photoluminescence. In summary, using succinic acid and two different organic N donors, imidazole and phen, we have synthesized two novel coordination polymers 1 and 2. Compounds 1 and 2 are free of coordinated or dissociated solvent molecules. In compound 1, Co (II) exhibits a tetrahedral geometry, imidazole acts as bridging ligands and a novel molecular tectonics is constructed like fourfold entangled catenane via covalent bond. In compound 2, Co (II) exhibits a octahedral geometry, phen induces succinic dianions exhibit two different coordination modes and a two-dimensional structure is obtained. Acknowledgements
Fig. 4. ORTEP drawing of compound 2 with thermal ellipsoids at 50% probability (C atoms of phen and H atoms omitted for clarity). Atoms with additional labels A, C and D are related to each other by symmetry operations: A: x + 1, y + 1, z + 1; C: x, y + 1, z + 1/2; D: x, y + 1, z 1/2.
This work was supported by the National Natural Science Foundation of China (Nos. 20271007, 20331010 and 90406002), and Specialized Research Fund for the
276
Y. Gong et al. / Inorganic Chemistry Communications 9 (2006) 273–276
Doctoral Program of Higher Education of China (No. 20030007014). Appendix A. Supplementary data X-ray crystallographic information files (CIF) and tables with X-ray structural information for 1–3 and other supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2005. 11.018. References [1] (a) M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, O.M. Yaghi, Science 295 (2002) 469; (b) Y. Cui, S.J. Lee, W.B. Lin, J. Am. Chem. Soc. 125 (2003) 6014; (c) C. Janiak, J. Chem. Soc., Dalton Trans. (2003) 2781; (d) S.L. James, Chem. Soc. Rev. 32 (2003) 276; (e) L. Carlucci, G. Ciani, D. Proserpio, Coordin. Chem. Rev. 246 (2003) 247. [2] (a) A. Galet, M.C. Munoz, J.A. Real, J. Am. Chem. Soc. 125 (2003) 14224; (b) S. Kitagawa, R. Kitaura, S.I. Noro, Angew. Chem., Int. Ed. 116 (2004) 2388; (c) D. Maspoch, D. Ruiz-Molina, J. Veciana, J. Mater. Chem. 14 (2004) 2713; (d) S.R. Batten, K.S. Murray, Coordin. Chem. Rev. 246 (2003) 103. [3] (a) A.F. Wells, Three-dimensional Nets and Polyhedra, WileyInterscience, New York, 1977; (b) A.F. Wells, Further Studies of Three-dimensional Nets, ACA Monograph 8, American Crystallographic Association, 1979. [4] S.R. Batten, Cryst. Eng. Commun. 3 (2001) 67. [5] X.H. Bu, M.L. Tong, H.C. Chang, S. Kitagawa, S.R. Batten, Angew. Chem., Int. Ed. 43 (2004) 192. [6] L. Pan, H.M. Liu, S.P. Kelly, X.Y. Huang, J. Li, Chem. Commun. (2003) 854. [7] S.R. Batten, B.F. Hoskins, R. Robson, New J. Chem. 22 (1998) 173. [8] (a) D.F. Sun, R. Cao, Y.Q. Sun, W.H. Bi, D.Q. Yuan, Q. Shi, X. Li, Chem. Commun. (2003) 1528; (b) T.J. Prior, D. Bradshaw, S.J. Teat, M.J. Rosseinsky, Chem. Commun. (2003) 500; (c) S.A. Bourne, J.J. Lu, A. Mondal, B. Moulton, M.J. Zaworotko, Angew. Chem., Int. Ed. 40 (2001) 2111; (d) X.M. Zhang, X.M. Chen, Eur. J. Inorg. Chem. (2003) 413; (e) S.T. Wang, Y. Hou, E.B. Wang, Y.G. Li, L. Xu, J. Peng, S.X. Liu, C.W. Hu, New J. Chem. (2003) 1144. [9] (a) X.C. Huang, J.P. Zhang, Y.Y. Lin, X.M. Chen, Chem. Commun. (2004) 1100; (b) Y.Q. Tian, H.J. Xu, L.H. Weng, Z.X. Chen, D.Y. Zhao, X.Z. You, Eur. J. Inorg. Chem. (2004) 1813; (c) Y.Q. Tian, C.X. Cai, Y. Ji, X.Z. You, S.M. Peng, G.H. Lee, Angew. Chem. 114 (2002) 8; (d) Y.Q. Tian, C.X. Cai, X.M. Ren, C.Y. Duan, Y. Xu, S. Gao, X.Z. You, Chem. Eur. J. 9 (2003) 5673; (e) N. Masciocchi, F. Castelli, P.M. Forster, M.M. Tafoya, A.K. Cheetham, Inorg. Chem. 42 (2003) 6147.
[10] (a) J. Sanchiz, Y.R. Martı´n, C.R. Pe´rez, A. Mederos, F. Lloret, M. Julve, New J. Chem. (2002) 1624; (b) B.H. Ye, T. Mak, I.D. Williams, X.Y. Li, J. Chem. Soc., Dalton Trans. (1998) 1935; (c) E.B. Ying, Y.Q. Zheng, H.J. Zhang, J. Mol. Struct. 693 (2004) 73; (d) E. Suresh, M.M. Bhadbhade, K. Venkatasubramanian, Polyhedron 18 (1999) 657; (e) R. Carballo, A.C. Neiras, B. Covelo, E.G. Martı´nez, J. Niclos, E.M. Lopez, Polyhedron 23 (2004) 1505. [11] Synthesis of [Co(suc)(im)]n (1): A mixture of CoCl2 Æ 6H2O (0.5 mmol, 0.119 g), succinic acid (1 mmol, 0.118 g), imidazole (0.6 mmol, 0.041 g), NaOH (0.5 mmol, 0.020 g) and C2H5OH (10 mL) was heated at 120 °C in Teflon-lined autoclave for 3 days, followed by slow cooling to room temperature. The resulting blue column crystals were filtered off (yield: ca. 70% based on Co). Elemental Anal.: found: C, 32.70%; H, 2.66%; N, 1.48%. Calcd. for C5N2H5CoO2: C, 32.61%; H, 2.72%; N, 1.52%. IR (cm1): 1639(s), 1338(s), 1234(w), 1166(w), 1084(m), 949(w), 908(w), 839(w), 784(m), 662(m). [12] The preparation of compound 2 were similar to that of compound 1 except using phen instead of imidazole. The resulting red column crystals were filtered off (yield: ca. 70% based on Co). Elemental Anal.: found: C, 54.11%; H, 3.35%; N, 7.91%. Calcd. for C32N4H24Co2O8: C, 54.08%; H, 3.38%; N, 7.89%. IR (cm1): 1635(s), 1536 (m), 1424 (m), 1321(s), 1211(w), 1156(w), 933 (w), 854(m), 775 (s), 732 (m), 675 (m), 530 (m). [13] (a) Y.Q. Zheng, W.H. Liu, J.L. Lin, Z. Anorg. Allg. Chem. 626 (2002) 620; (b) D. Ghoshal, T.K. Maji, G. Mostafa, S. Sain, T.H. Lu, J. Ribas, E. Zangrando, N.R. Chaudhuri, J. Chem. Soc., Dalton Trans. (2004) 1687; (c) M. Devereux, M. McCann, J.F. Cronin, G. Ferguson, V. McKee, Polyhedron 18 (1999) 2141; (d) J.L. Lin, Y.Q. Zheng, Z.P. Kong, H.L. Zhang, Z. Anorg. Allg. Chem. 627 (2001) 1066; (e) Y.Q. Zheng, J.L. Lin, J. Sun, Z. Anorg. Allg. Chem. 627 (2001) 1059. [14] Crystal data for compound 1: C5N2H5CoO2, M = 184.04, orthorhombic, ˚ , b = 18.373(4) A ˚ , c = 10.515(2) A ˚ , V = 2583.7(10) A ˚ 3, a = 13.373(3) A T = 298(2) K, space group Fdd2, Z = 16, l = 2.585 mm1, 3239 reflections measured, 1057 unique (Rint = 0.0198) which were used in all calculations. R1 = 0.0189 and wR2 = 0.0465 for I < 2r(I). CCDC 258679. [15] (a) Y.J. Qi, Y.H. Wang, C.W. Hu, M.H. Cao, L. Mao, E.B. Wang, Inorg. Chem. 42 (2003) 8519; (b) H.X. Zhang, J. Zhang, S.T. Zheng, Inorg. Chem. 42 (2003) 6595. [16] Crystal data for compound 2: C32N4H24Co2O8, M = 710.41, mono˚ , b = 10.1301(19) A ˚ , c = 22.663(4) A ˚, U= clinic, a = 12.330(2) A ˚ 3, T = 298(2) K, space group P2/c, Z = 4, l = 1.247 2804.0(9) A mm1, 14,310 reflections measured, 4935 unique (Rint = 0.0544) which were used in all calculations. R1 = 0.0451 and wR2 = 0.1158 for I < 2r(I). CCDC 255634. [17] C. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885. [18] W. Chen, J.Y. Wang, C. Chen, Q. Yue, H.M. Yuan, J.X. Chen, S.N. Wang, Inorg. Chem. 42 (2003) 944. [19] L.Y. Zhang, G.F. Liu, S.L. Zheng, B.H. Ye, X.M. Zhang, X.M. Chen, Eur. J. Inorg. Chem. (2003) 2965. [20] Z.Y. Fu, X.T. Wu, J.C. Dai, S.M. Hu, W.X. Du, H.H. Zhang, R.Q. Sun, Eur. J. Inorg. Chem. (2002) 2730.
Two novel coordination polymers with different molecular tectonics based on cobalt–succinate-organoamine systems Yun Gong, Changwen Hu *, Hui Li, Wang Tang Department of Chemistry, Beijing Institute of Technology, Beijing 100081,China Received 31 August 2005; accepted 15 November 2005 Available online 4 January 2006
Abstract Two novel coordination polymers with different N-donors, [Co(suc)(im)]n (1) and [Co(suc)(phen)]n (2) (suc = succinic dianion, im = imidazole, phen = 1,10-phenanthroline) were synthesized by solvothermal technique and structurally characterized by elemental analysis, IR and single crystal X-ray diffraction. Compound 1 exhibits a novel molecular tectonics like fourfold entangled catenane. Compound 2 shows a two-dimensional structure with two types of rings observed. They exhibit different photoluminescence properties. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Succinic anion; N-donor; Tectonics; Photoluminescence
The construction of coordination networks with novel topologies have been attracting considerable interest, not only because of their intriguing structural diversity but also due to their interesting properties and potential applications [1,2]. A large number of network topologies and entangled systems such as catenanes, rotaxanes, and molecular knots were elucidated by Wells, Batten and Robson in their monograph and comprehensive reviews [3–7]. Rigid ligand such as benzenecarboxylates, pyridinecarboxylates, 4,4 0 -bipyridine are usually utilized to construct network because of their symmetrical structure [8]. However, imidazole as an exo-bidentate rigid ligand is relatively rarely investigated due to its inequal electron density of two nitrogen atoms. Recently, a serial of coordination polymers based on imidazole and metal ions have been reported [9]. If dicarboxylatos such as succinic acid is introduced into such metal-imidazole systems, it is presumed novel network topologies to be built up. Succinic acid is a preference because its flexible linear ligand can make up for the rigidity of imidazole. However, it is a challenge to expect both dicarboxylatos and imidazolo act as bridging ligands *
Corresponding author. Tel./fax: +86 010 62828869. E-mail address: [email protected] (C. Hu).
1387-7003/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2005.11.018
[10]. Our strategy to solve problem is to choose solvothermal technique and adjust the molar ratio of imidazole and succinic acid. A novel coordination polymer [Co(suc)(im)]n (1) (suc = succinic dianion, im = imidazole) was obtained successfully [11], which exhibits a novel molecular tectonics like fourfold entangled catenane (Scheme 1), in which entanglement or self-penetration is happened around anode and each (4, 4) topological net is hinged with four neighboring nets. In order to investigate the role of imidazole in the construction of the molecular tectonics [Co(suc) (phen)]n (2) (phen = 1,10-phenanthroline) was synthesized in comparison with compound 1 [12]. Coordination polymers based on metal-succinate-phen systems usually exhibit a one-dimensional chain with water or excess molar ratio of phen coordinated to metal center [13]. Compound 2 exhibits a novel two-dimensional structure, which is rarely reported in previous work. Single-crystal X-ray analysis has revealed that in compound 1, the ratio of the crystallographically unique Co (II), imidazole and succinic dianion is 1:1:0.5 [14]. Each Co (II) is four coordinated by two O atoms from different succinic dianions and two N atoms from different imidazole ligands. Each Co (II) exhibits a slightly distorted ˚ , Co–O tetrahedral geometry [Co–N 1.992(2)–1.994(3) A
274
Y. Gong et al. / Inorganic Chemistry Communications 9 (2006) 273–276
Scheme 1. Molecular tectonics like fourfold entangled catenane in compound 1.
˚ , O–Co–N 101.57(10)–117.29(11)°, 1.988(2)–2.017(2) A O–Co–O 96.97(9)°, N–Co–N 116.39(11)°]. The carboxylato groups in each succinic dianion are bidentate coordination mode linking four different Co(II). Compound 1 exhibits a uniform (4, 4) net topology, in which a sixteen-membered ring is constructed by four Co (II), two bridged imidazole molecules, two carboxylato groups from two succinic dianions (Figs. 1 and 2). A succinic dianion connects the two diagonal Co (II) of the ring with two O atoms from its two carboxylato groups, thus the sixteen-membered ring can be split into two fifteenmembered ring with (3, 4) net topology. The distance ˚ . Except the two between two diagonal Co (II) is 5.356 A O atoms that connect the two diagonal Co (II), another two O atoms of the same succinic dianions penetrate the sixteen-membered ring and are coordinated to two Co (II) of the two neighboring rings. The approximately perpendicular Co–O–C bond angle [105.05(19)°] makes the self-penetration of each (4, 4) topological net possible. Thus, an orderly self-penetrated array like fourfold entangled catenane is observed in compound 1. The flexibility of succinic dianions make it is possible that succinic dianions rotate its carbon chain for suitable position and angle (\C1B–C2B–C2J = \C2B–C2J–C1J = 112.3°) to fit the space between two Co (II) (Figs. 1 and 2).
Fig. 1. ORTEP drawing of compound 1 with thermal ellipsoids at 50% probability (H atoms omitted for clarity). Atoms with additional labels A, B, D, G and J are related to each other by symmetry operations: A: x + 9/4, y 1/4, z 1/4; B: x + 1/4, y + 1/4, z + 1/4; D: x 1/4, y + 1/4, z 1/4; G: x + 8/4, y, z; J x + 3/4, y 1/4, z + 1/4.
Fig. 2. The structure of compound 1 viewed down c-axis (H atoms omitted for clarity).
However, the carbon chain backbone of each succinic dianion is not on the plane of fourfold entangled catenane shown in Scheme 1, it is away from the plane for achievement of penetration. Thus, the construction of entangled catenane in compound 1 is not by supramolecular force, but via covalent bond, which is different from the construction of the usual catenane. Another interesting feature of compound 1 is the presence of zigzag chains running through the structure. View down vertically in Fig. 2, zigzag chains are constructed by carboxylato-bridged CoN2O2 tetrahedra. Each CoN2O2 tetrahedron can be bridged by imidazole to form alternating left-handed and right-handed chains. Such alternating chiral chains are different from those in previous work [15], they interweave and run through different directions (Fig. 3). The two N atoms of imidazole are equivalent in compound 1 after the deprotonation. The Co–N bond ˚ ] and lengths are almost equal [1.992(2) and 1.994(3) A the difference of Co–N–C bond angles is little [125.3(2)°– 129.6(2)°]. Imidazole plays an important role in the construction of the novel fourfold entangled catenane. If imidazole was replaced by 1,10-phenanthroline under the same reaction conditions, a two-dimensional structure has been formed in compound 2 [16]. Compound 2 exhibits two
Fig. 3. Alternating left-handed and right-handed chains running along b- and c-axis in compound 1 (H atoms and succinic dianion omitted for clarity).
Y. Gong et al. / Inorganic Chemistry Communications 9 (2006) 273–276
crystallographically unique Co (II), two unique phen and four unique half succinic dianion, in which succinic dianions exhibit two coordination modes: bidentate or chelate (Fig. 4). Each Co (II) is six coordinated by four O atoms and two N atoms. Two of the O atoms are chelate-coordinated and another two are bidentate-coordinated O atoms from different succinic anions (Fig. 5). The phen ligands block the 3D direction. Its p p stacking interactions induce the two coordination modes of flexible succinic acid in compound 2. Two types of rings are observed in compound 2. The smaller ring is eightmembered ring, which is constructed by two Co (II) and two bridging carboxylato groups. Another one is twenty-eight-membered ring, which is constructed by four Co (II), two bidentate-coordinated succinic anions and two chelate-coordinated succinic anions (Figs. 4 and 5). In the twenty-eight-membered ring, the Co1 Co1A ˚ . Co1A and Co2C are bridged by one chedistance is 7.934 A ˚ late-coordinated succinic anions with a distance of 8.728 A (Fig. 5). The space of twenty-eight-membered ring is divided into three parts by two parallel phen molecules. As shown in Fig. 5, each phen group is almost planar, planes 1–5 are composed of C atoms from C21C to C30C, C9D to C20D, C9A to C20A, C21 to C30, C9 to C20, respectively. The interplanar angles of two crystallographically unique phen molecules 4 and 5 is 2.2°. The centroid–centroid distances between planes 1 and 2, 2 and 3, 3 and 4, 4 and 5 are ˚ , respectively, whereas 11.631, 3.022, 11.631 and 3.865 A their perpendicular distances are 8.086, 3.022, 7.924 and ˚ , respectively, which indicates there is p p stack3.521 A ing interactions between planes 2 and 3, 4 and 5 [17]. The emission spectra of compounds 1 and 2 are investigated on a Spex FL-2T2 spectrofluorometer equipped with
275
Fig. 5. The structure of compound 2 viewed down b-axis (H atoms omitted for clarity).
a 450 W xenon lamp as the excitation source. In the blue region (kex = 380 nm) at room temperature, compounds 1 and 2 in the solid state exhibit an intense emission at 416 and 438 nm, respectively (see Fig. S1 in the supplementary materials). To understand the nature of the emission band, we analyzed the photoluminescence properties of succinic acid, imidazole and phen ligands and found that the strongest emission peaks for them were at about 398, 389 and 472 nm, respectively, which is attributable to the p* ! n transition [18]. Thus, the emission bands observed in compounds 1 and 2, which are different from those of the individual organic ligands, might be the ligand-to-metal charge transfer (LMCT) [19]. Their different photoluminescence is due to their different coordination environments and structures caused by different organic N-donors in compounds 1 and 2 [20]. As well known, Co is not an excellent metal source for photoluminescence, whereas compounds 1 and 2 exhibit relatively strong emission spectra, which indicates that their photoluminescence properties are closely related with their characteristic structures. It is presumed that the fourfold entanglement via covalent bond in compound 1 and the p p stacking interactions in compound 2 can promote the charge transfer and delocalization within the whole structure, and thus enhance the photoluminescence. In summary, using succinic acid and two different organic N donors, imidazole and phen, we have synthesized two novel coordination polymers 1 and 2. Compounds 1 and 2 are free of coordinated or dissociated solvent molecules. In compound 1, Co (II) exhibits a tetrahedral geometry, imidazole acts as bridging ligands and a novel molecular tectonics is constructed like fourfold entangled catenane via covalent bond. In compound 2, Co (II) exhibits a octahedral geometry, phen induces succinic dianions exhibit two different coordination modes and a two-dimensional structure is obtained. Acknowledgements
Fig. 4. ORTEP drawing of compound 2 with thermal ellipsoids at 50% probability (C atoms of phen and H atoms omitted for clarity). Atoms with additional labels A, C and D are related to each other by symmetry operations: A: x + 1, y + 1, z + 1; C: x, y + 1, z + 1/2; D: x, y + 1, z 1/2.
This work was supported by the National Natural Science Foundation of China (Nos. 20271007, 20331010 and 90406002), and Specialized Research Fund for the
276
Y. Gong et al. / Inorganic Chemistry Communications 9 (2006) 273–276
Doctoral Program of Higher Education of China (No. 20030007014). Appendix A. Supplementary data X-ray crystallographic information files (CIF) and tables with X-ray structural information for 1–3 and other supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2005. 11.018. References [1] (a) M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, O.M. Yaghi, Science 295 (2002) 469; (b) Y. Cui, S.J. Lee, W.B. Lin, J. Am. Chem. Soc. 125 (2003) 6014; (c) C. Janiak, J. Chem. Soc., Dalton Trans. (2003) 2781; (d) S.L. James, Chem. Soc. Rev. 32 (2003) 276; (e) L. Carlucci, G. Ciani, D. Proserpio, Coordin. Chem. Rev. 246 (2003) 247. [2] (a) A. Galet, M.C. Munoz, J.A. Real, J. Am. Chem. Soc. 125 (2003) 14224; (b) S. Kitagawa, R. Kitaura, S.I. Noro, Angew. Chem., Int. Ed. 116 (2004) 2388; (c) D. Maspoch, D. Ruiz-Molina, J. Veciana, J. Mater. Chem. 14 (2004) 2713; (d) S.R. Batten, K.S. Murray, Coordin. Chem. Rev. 246 (2003) 103. [3] (a) A.F. Wells, Three-dimensional Nets and Polyhedra, WileyInterscience, New York, 1977; (b) A.F. Wells, Further Studies of Three-dimensional Nets, ACA Monograph 8, American Crystallographic Association, 1979. [4] S.R. Batten, Cryst. Eng. Commun. 3 (2001) 67. [5] X.H. Bu, M.L. Tong, H.C. Chang, S. Kitagawa, S.R. Batten, Angew. Chem., Int. Ed. 43 (2004) 192. [6] L. Pan, H.M. Liu, S.P. Kelly, X.Y. Huang, J. Li, Chem. Commun. (2003) 854. [7] S.R. Batten, B.F. Hoskins, R. Robson, New J. Chem. 22 (1998) 173. [8] (a) D.F. Sun, R. Cao, Y.Q. Sun, W.H. Bi, D.Q. Yuan, Q. Shi, X. Li, Chem. Commun. (2003) 1528; (b) T.J. Prior, D. Bradshaw, S.J. Teat, M.J. Rosseinsky, Chem. Commun. (2003) 500; (c) S.A. Bourne, J.J. Lu, A. Mondal, B. Moulton, M.J. Zaworotko, Angew. Chem., Int. Ed. 40 (2001) 2111; (d) X.M. Zhang, X.M. Chen, Eur. J. Inorg. Chem. (2003) 413; (e) S.T. Wang, Y. Hou, E.B. Wang, Y.G. Li, L. Xu, J. Peng, S.X. Liu, C.W. Hu, New J. Chem. (2003) 1144. [9] (a) X.C. Huang, J.P. Zhang, Y.Y. Lin, X.M. Chen, Chem. Commun. (2004) 1100; (b) Y.Q. Tian, H.J. Xu, L.H. Weng, Z.X. Chen, D.Y. Zhao, X.Z. You, Eur. J. Inorg. Chem. (2004) 1813; (c) Y.Q. Tian, C.X. Cai, Y. Ji, X.Z. You, S.M. Peng, G.H. Lee, Angew. Chem. 114 (2002) 8; (d) Y.Q. Tian, C.X. Cai, X.M. Ren, C.Y. Duan, Y. Xu, S. Gao, X.Z. You, Chem. Eur. J. 9 (2003) 5673; (e) N. Masciocchi, F. Castelli, P.M. Forster, M.M. Tafoya, A.K. Cheetham, Inorg. Chem. 42 (2003) 6147.
[10] (a) J. Sanchiz, Y.R. Martı´n, C.R. Pe´rez, A. Mederos, F. Lloret, M. Julve, New J. Chem. (2002) 1624; (b) B.H. Ye, T. Mak, I.D. Williams, X.Y. Li, J. Chem. Soc., Dalton Trans. (1998) 1935; (c) E.B. Ying, Y.Q. Zheng, H.J. Zhang, J. Mol. Struct. 693 (2004) 73; (d) E. Suresh, M.M. Bhadbhade, K. Venkatasubramanian, Polyhedron 18 (1999) 657; (e) R. Carballo, A.C. Neiras, B. Covelo, E.G. Martı´nez, J. Niclos, E.M. Lopez, Polyhedron 23 (2004) 1505. [11] Synthesis of [Co(suc)(im)]n (1): A mixture of CoCl2 Æ 6H2O (0.5 mmol, 0.119 g), succinic acid (1 mmol, 0.118 g), imidazole (0.6 mmol, 0.041 g), NaOH (0.5 mmol, 0.020 g) and C2H5OH (10 mL) was heated at 120 °C in Teflon-lined autoclave for 3 days, followed by slow cooling to room temperature. The resulting blue column crystals were filtered off (yield: ca. 70% based on Co). Elemental Anal.: found: C, 32.70%; H, 2.66%; N, 1.48%. Calcd. for C5N2H5CoO2: C, 32.61%; H, 2.72%; N, 1.52%. IR (cm1): 1639(s), 1338(s), 1234(w), 1166(w), 1084(m), 949(w), 908(w), 839(w), 784(m), 662(m). [12] The preparation of compound 2 were similar to that of compound 1 except using phen instead of imidazole. The resulting red column crystals were filtered off (yield: ca. 70% based on Co). Elemental Anal.: found: C, 54.11%; H, 3.35%; N, 7.91%. Calcd. for C32N4H24Co2O8: C, 54.08%; H, 3.38%; N, 7.89%. IR (cm1): 1635(s), 1536 (m), 1424 (m), 1321(s), 1211(w), 1156(w), 933 (w), 854(m), 775 (s), 732 (m), 675 (m), 530 (m). [13] (a) Y.Q. Zheng, W.H. Liu, J.L. Lin, Z. Anorg. Allg. Chem. 626 (2002) 620; (b) D. Ghoshal, T.K. Maji, G. Mostafa, S. Sain, T.H. Lu, J. Ribas, E. Zangrando, N.R. Chaudhuri, J. Chem. Soc., Dalton Trans. (2004) 1687; (c) M. Devereux, M. McCann, J.F. Cronin, G. Ferguson, V. McKee, Polyhedron 18 (1999) 2141; (d) J.L. Lin, Y.Q. Zheng, Z.P. Kong, H.L. Zhang, Z. Anorg. Allg. Chem. 627 (2001) 1066; (e) Y.Q. Zheng, J.L. Lin, J. Sun, Z. Anorg. Allg. Chem. 627 (2001) 1059. [14] Crystal data for compound 1: C5N2H5CoO2, M = 184.04, orthorhombic, ˚ , b = 18.373(4) A ˚ , c = 10.515(2) A ˚ , V = 2583.7(10) A ˚ 3, a = 13.373(3) A T = 298(2) K, space group Fdd2, Z = 16, l = 2.585 mm1, 3239 reflections measured, 1057 unique (Rint = 0.0198) which were used in all calculations. R1 = 0.0189 and wR2 = 0.0465 for I < 2r(I). CCDC 258679. [15] (a) Y.J. Qi, Y.H. Wang, C.W. Hu, M.H. Cao, L. Mao, E.B. Wang, Inorg. Chem. 42 (2003) 8519; (b) H.X. Zhang, J. Zhang, S.T. Zheng, Inorg. Chem. 42 (2003) 6595. [16] Crystal data for compound 2: C32N4H24Co2O8, M = 710.41, mono˚ , b = 10.1301(19) A ˚ , c = 22.663(4) A ˚, U= clinic, a = 12.330(2) A ˚ 3, T = 298(2) K, space group P2/c, Z = 4, l = 1.247 2804.0(9) A mm1, 14,310 reflections measured, 4935 unique (Rint = 0.0544) which were used in all calculations. R1 = 0.0451 and wR2 = 0.1158 for I < 2r(I). CCDC 255634. [17] C. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885. [18] W. Chen, J.Y. Wang, C. Chen, Q. Yue, H.M. Yuan, J.X. Chen, S.N. Wang, Inorg. Chem. 42 (2003) 944. [19] L.Y. Zhang, G.F. Liu, S.L. Zheng, B.H. Ye, X.M. Zhang, X.M. Chen, Eur. J. Inorg. Chem. (2003) 2965. [20] Z.Y. Fu, X.T. Wu, J.C. Dai, S.M. Hu, W.X. Du, H.H. Zhang, R.Q. Sun, Eur. J. Inorg. Chem. (2002) 2730.