Anion-Mediated Architecture and Photochromism of Rigid Bipyridinium-Based Coordination Polymers

Four metal organic coordination compounds Zn-2(bcbp)Cl-4 (1), Zn(bcbp)(PO3F) (2), [CdCl(Hbcbp)-(bcbp)]center dot(ClO4)(2) (3), and [Cd-2(bcbp)(4)]center dot(ClO4)center dot F-3 (4) (H(2)bcbp center dot 2PF(6) = 1,1'-bis (4-carboxyphenyl)-(4,4'-bipyridinium) hexafluorophosphate) have been synthesized via solvothermal method and structurally characterized. Compound 1 is a 1D coordination polymer, while compound 2 shows a 2D + 2D -> 3D inclined polycatenation structure. In the case,of compound 3, due to the capped chlorine atoms and uncoordinated carboxyl of bcbp ligand, it exhibits a 1D T-shaped coordination configuration. Compound 4 is an unprecedented 13-fold interpenetrating structure with huge diamondoid frameworks. Because of the presence of electron deficient bipyridinium moieties, the photochromic behaviors of these compounds have also been studied. Interestingly, compounds 1-3 exhibit color changes under light irradiation. The impact of these anions on the photochromic process is discussed.