Synthesis, structure and fluorescence properties of a novel 3D Sr(II) coordination polymer

Solvothermal reaction of 2,2′-bipyridine-5,5′-dicarboxylic acid (H2bpdc) and SrCl2 affords a novel coordination polymer [Sr(Hbpdc)2]n 1. X-ray structure determination shows that 1 exhibits a novel three-dimensional network. The unique Sr II cation sits on a two-fold axis and coordinated by four O-atom donors from four Hbptc− ligands and four N-atom donors from two Hbptc− ligands in distorted dodecahedral geometry. In 1 each Sr II cation connects to six different Hbptc− ligands and each Hbptc− ligand bridges three different Sr II cations which results in the formation of a three-dimensional polymeric structure. Corresponding to the free ligand, the fluorescent emission of complex 1 display remarkable “Einstain” shifts, which may be attributed to the coordination interaction of Sr atoms, thus reduce the rigidity of pyridyl rings.