Two new coordination polymers constructed by angular tripyridyl ligand: syntheses, structures, and properties.

U-shaped tripyridyl ligand 2,6-bis(pyridine-4-carboxamido)pyridine (L) was synthesized and used to assemble metal complexes. The resulting new complexes [Mn(L)3(SCN)2]n (1) and [Co(L)3(SCN)2]n (2) are isostructural, crystallizing in the monoclinic C2/c space group. In compounds 1 and 2, each metal is in a slightly distorted octahedron ligated by six nitrogens from four L and two SCN-. Complexes 1 and 2 possess infinite 1-D zigzag polymeric chain structures where L adopts bridge and terminal coordination. These 1-D coordination polymers assemble into 3-D supermolecules of compounds 1 and 2 through hydrogen bonds. Fluorescence measurements and thermal analysis show that 1 emits strong fluorescence with a single broad band centered at 410 nm upon excitation at 357 nm and the polymeric chain structure is stable up to 340°C. [ABSTRACT FROM AUTHOR]