Coordination assemblies of seven metal-organic frameworks based on a bent connector: structural diversity and properties

Seven new coordination polymers, namely,[Zn(L)(bdc)]center dot 2H(2)O (1), [Zn(L)(2-NH2-bdc)]center dot 2H(2)O (2), [Zn(L)(bdc)]center dot 1.75DMF center dot 0.5H(2)O (3), [Zn(L)(oba)]center dot H2O (4), [Co(L)(oba)]center dot H2O (5), [Cd-2(L)(2)(bdc)(NO3)(2)]center dot 2DMF (6) and [Cd(L)(ndc)(H2O)] (7) (L = 4-amino-3,5-bis.4-imidazol-1-ylphenyl)-1,2,4-triazole, H(2)bdc = 1,4-benzenedicarboxylic acid, 2-NH2-H(2)bdc = 2-amino-1,4-benzenedicarboxylic acid, H(2)oba = 4,4'-oxydibenzoic acid and H(2)ndc = 1,4-naphthalenedicarboxylic acid), have been synthesized. The structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR, and thermogravimetric (TG) analysis. 1 and 2 feature a similar three-fold interpenetrating network combined with interdigitation which extends the structure into a three-dimensional framework. 3 is a two-fold interpenetrating framework showing intralayer porosity and interdigitation. Compounds 1 and 3 represent a pair of supramolecular isomers where structural motifs and different interpenetration modes exist; compounds 4 and 5 are isostructural and display the same three-fold interpenetrating framework where two types of interlaced triple-stranded helices A and B can be found. The triple-stranded helices with opposite chirality for each type are distributed in adjacent layers. Compound 6 exhibiting a unique simultaneous threading fashion of adjacent polymeric motifs gives the novel (2D -> 3D) polythreaded array where coordinated NO3- anions act as the dangling ligands. Compound 7 is a 6-connected 3D self-penetrating network where right-and left-handed single-stranded helical chains (A(R) and A(L)) and interlaced triple-stranded helices (B-R and B-L) coexist. The luminescence properties of compounds 1-7 were also measured and discussed.