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

• Synthesis of a new complex with 2,2′-bipyridine-5,5′-dicarboxylic acid (H2bpdc) and SrCl2 under hydrothermal condition.
• Detail study of crystal structure and their packing.
• The comparison of solid-state fluorescence spectra among title compound and free H2bpdc shows that title compound exist a large red-shifted emission compared to free ligand.
• The powder XRD shows the single phases of title compound.

Solvothermal reaction of 2,2′-bipyridine-5,5′-dicarboxylic acid (H2bpdc) and SrCl2 affords a novel coordination polymer [Sr(Hbpdc)2]n1. 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.

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