Photoluminescence of silver(I) and gold(I) cyanide 1D coordination polymers

Silver(I) and gold(I) cyanides exist as 1D coordination polymers and are photoluminescent on the edge of the UV–Vis region. Time-dependent density-functional theory (TD-DFT) calculations on truncated models of AgCN and AuCN show that the excitation spectra of these materials can be attributed to Laporte-allowed transitions between π-type MOs consistent with previous studies of CuCN. The longest wavelength excitation is due to excitation from the highest occupied π-type MO (HOπMO) to the lowest unoccupied π-type MO (LUπMO). The emission spectrum of the bulk materials is consistent with the DFT singlet–triplet gap calculated for the model chains. Trends in the molecular properties of MCN, to include bond distances, vibrational frequencies and electronic transition energies, are attributed to relativistic effects on Au.