Metal Nuclearity Modulated Four-, Six-, and Eight-Connected Entangled Frameworks Based on Mono-, Bi-, and Trimetallic Cores as Nodes

• Published in: Chemistry : a European journal 2006-03, Vol.12 (10), p.2680-2691
• Main Authors: Wang, Xin-Long, Qin, Chao, Wang, En-Bo, Su, Zhong-Min
• Format: Article
• Language: English
• Subjects: coordination modes; coordination polymers; entangled networks; self-assembly; supramolecular chemistry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200501242

To investigate the relationship between network connectivity and metal nuclearity, we designed and synthesized a series of three‐dimensional (3D) entangled coordination frameworks based on different metal cores, namely [Zn2(bdc)2(L)2]⋅2H2O (1), [Zn(bdc)(L)0.5] (2), [Zn(oba)(L)0.5] (3) and [Cd3(bdc)3(L)2(H2O)2] (4) by self‐assembly of d10 metal salts with the flexible long‐chain ligand 1,4‐bis(1,2,4‐triazol‐1‐yl)butane (L), and with the rigid and nonrigid aromatic dicarboxylate ligands 1,4‐benzenedicarboxylate (bdc) and 4,4′‐oxybis(benzoate) (oba). Compound 1 exhibits a threefold interpenetrated diamondoid array typically based on a tetrahedral second building unit (SBU) at a single Zn center. Compound 2 adopts a threefold interpenetrated α‐polonium‐type network that is built from bimetallic cores as six‐connected vertices. The structure of 3 also consists of dinuclear units; it comprises a novel (3,4)‐connected threefold interpenetrated net with complex (4⋅6⋅10)(4⋅62⋅103) topology when single zinc centers act as four‐connected nodes (or the α‐Po topology if dinuclear units are considered as six‐connected nodes). Compound 4, derived from a crosslinked fivefold interpenetrated diamond‐like substructure, is an unusual example of a self‐penetrating coordination framework displaying an unprecedented eight‐connected 42068 topology with trinuclear cadmium clusters as eight‐connected nodes which, to our knowledge, not only defines a new topology for eight‐connected coordination networks, but also represents the highest connected topology presently known for self‐penetrating systems. Detailed structural comparison of these complexes indicates that the increase in metal nuclearity induces the progressive increase in the connectivities of the ultimate nets: that is, the metal nuclearity plays a significant role in tuning the connectivity of a specific network. The thermal and luminescent properties of these compounds are discussed. Entangled frameworks: Self‐assembly of d10 metal salts with aromatic dicarboxylate (1,4‐benzenedicarboxylate or 4,4′‐oxybis(benzoate)) and the flexible long‐chain ligand 1,4‐bis(1,2,4‐triazol‐1‐yl)butane has led to four entangled nets of different connnectivities tuned by metal nuclearity. An exceptional self‐penetrating species with Schläfli symbol 42068 defines a new topology for eight‐connected coordination networks, and represents the highest connected topology known at present for self‐penetrating systems (see picture).