Synthesis and crystal structure of a 3-D Ag+ coordination polymer with white-light emission

Treatment of AgNO3 with a tetrazolyl ligand H2L1 afforded a 3-D coordination polymer [Ag-2(L-1)](n) (1). The crystal structure was determined by X-ray crystallography and it shows that both Ag1 and Ag2 atoms in the asymmetric unit exhibit distorted tetrahedron geometries, which are modified by AgAg interactions. The flexible methylene -CH2- linkage between tetrazolate and phenyl ring effectively reduces the steric strain in the resultant 3D-framework. L-1 exhibits an unsual coordination mode in which all nitrogen atoms in the two tetrazolato units are coordinated to the Ag-I centers. The luminescent property of 1 was also investigated. It exhibits multiple emission bands; the high energy emission band is assigned to the ligand-centered transition, while the low energy emission bands are tentatively assigned to ligand-to-metal charge transfer (LMCT) that are modified by AgAg interaction. The independence of the chromaticity coordinates of 1 on the excitation wavelength also suggests that it is a potentially useful single-component white-light-emitting material.