Influence of halide anions on the construction of coordination complexes with mercury(II) center: Syntheses, structures and photoluminescent properties

Abstract

Three coordination complexes, namely, {[Hg(bppdca)Cl 2]·DMF} n ( 1), Hg 2(bppdca) 2Br 4 ( 2) and {[Hg(bppdca)I 2]·MeOH} n ( 3) were synthesized by reactions of HgX 2 (X = Cl, Br and I) with ligand N, N′-bis(pyridine-3-yl)pyridine-3,5-dicarboxamide (bppdca). The structures of the complexes were determined by single-crystal X-ray diffraction analyses, and the results reveal that 1 exhibits a two-dimensional (2D) network structure. While 2 is a M 2L 2 dinuclear metallamacrocycle in which two mercury(II) cations are bridged by two bppdca ligands. In complex 3, bppdca acts as a bidentate ligand to link two mercury(II) atoms to form a one-dimensional (1D) zigzag chain structure. The significant differences in these complexes indicate that anions have a great influence on the formation and structures of complexes. Furthermore, the solid-state fluorescent analyses reveal that complexes 1 and 2 exhibit a broad emission band at 449 and 441 nm, respectively, while complex 3 shows weak emission centered at 438 nm at room temperature.