Construction of Three-Dimensional Metal−Organic Frameworks with Helical Character through Coordinative and Supramolecular Interactions

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• 作者：Jian-Qiao Chen^&#8224 ; ; Yue-Peng Cai*^&#8224 ; ; Hua-Cai Fang^&#8224 ; ; Zheng-Yuan Zhou^&#8224 ; ; Xu-Lin Zhan^&#8224 ; ; Gang Zhao^‡ ; ; Zhong Z
• 刊名：Crystal Growth & Design
• 出版年：2009
• 出版时间：March 4, 2009
• 年：2009
• 卷：9
• 期：3
• 页码：1605-1613
• 全文大小：464K
• 年卷期：v.9,no.3(March 4, 2009)
• ISSN：1528-7505

文摘

Self-assemblies of the semirigid dipolar ligand 1,4-bis(benzimidazol-1-ylmethyl)benzene (L) with zinc and cobalt salts have led to six new complexes, namely, {[M(L)(DMF)₂(H₂O)₂]·2(NO₃)}_n [M = Zn (1) and Co (2)], {[M(L)₂Cl₂]·DMF·S}_n [M = Zn(3), S = C₂H₅OH; Co(4), S = CH₃OH + H₂O], [Zn(L)₂]·(ClO₄)₂·4DMF·3H₂O]_n (5), and {[Co(L)₂(DMF)₂](ClO₄)₂}_n (6), respectively. Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. Compounds 1 and 2 are isomorphous and present one-dimensional chain-like structures. It is interesting that three-dimensional (3D) organic−inorganic hybrid frameworks containing meso-helical chains (P + M) have been observed in the solid-state of 1 and 2, in which meso-helical chains are alternately trapped by the cooperative association of coordination interactions as well as hydrogen bonds. With the replacement of Zn^II/Co^II nitrate salts with ZnCl₂ or CoCl₂ in the above reactions, the resulting complexes 3 and 4 contain P-helical and M-helical chains with 2₁ screw axis but crystallize as a racemate. Through π···π stacking interactions between two well-overlapping benzimidazoleyl rings from two adjacent chains, the 3D racemic supramolecular network is further assembled. However, reaction of M(ClO₄)₂ (M = Zn(5), Co(6)) and L yields two high dimensional compounds 5 and 6 with helical character, in which compound 5 has a two-dimensional (2D) (4,4) wave-like layer constructed by vertical crossing of the left-(M) and right-(P)-handed helical chains with the central Zn^II ions as the hinge nodes, and similarly, the final 3D supramolecular structure is assembled via weak π···π interactions between two central benzene rings from two adjacent ligands L of two neighboring 2D layers. Compound 6 presents a four-connected 3-fold interpenetrated 3D diamondoid network containing meso-helical chains along two mutually perpendicular directions, respectively. Furthermore, the photoluminescent properties of compounds 1, 3, and 5 were studied.