Crystal structure and photoluminescent properties of a Ag(I)-carboxylate coordination compound: Luminescence modulation by a π-conjugated ancillary ligand

Reaction of the 2-D MOF [AgL]n·nH2O (1; L = 4-cyanobenzoate) with pyrazine (L′) in water yielded [Ag2L2L′]n·2nH2O (2) with a chain-like structure. Compound 1 features tunable yellow-to-white photoluminescence when its wavelength of excitation light varies. The photoluminescence of 2 obviously differs from that of 1: the former displays intense yellowish green phosphorescence with a shorter lifetime of ~ 3.58 μs and an unresolved peak shape, and does not exhibit tunable photoluminescence upon irradiation of 280–380 nm UV light. Electron transition from the [Ag2(COO)2] cluster to pyrazine is probably responsible for the phosphorescence of 2 based on the experimental and theoretical results.