"Coinage Metal Chalcogenide Clusters with N-Heterocyclic Carbene Ancill" by Alex Polgar
Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Chemistry

Supervisor

Corrigan, John F.

Abstract

This thesis describes the synthesis and characterization of homo- and heterometallic group 11 – group 16 clusters with N-heterocyclic carbene (NHC) ligands. The clusters were prepared from reactive group 11 trimethylsilylchalcogenolate reagents (NHC-M-ESiMe3; M = Cu, Au; E = S, Se, Te) by silane deprotection reactions with phosphine- or phosphite-solubilized group 11 acetates (R3P-M-OAc; M = Cu, Ag, Au). Clusters were characterized by combustion analysis and spectroscopic methods in solution and the solid state. The clusters were phosphorescent at low temperatures with emission energies that depend on the metal/chalcogen composition, ancillary NHC ligand, cluster geometry and nuclearity, and local environment. Lower energy photoluminescence is associated with higher atomic number chalcogenide ligands and correlates with the M→S metal-to-ligand charge transfer energy, for which M = Ag > Cu > Au. Quantum yield of emission is increased in a cluster of high nuclearity and connectivity because of increased molecular rigidity and thermally activated delayed fluorescence. Quantum chemical calculations point to a common mode of emission from all clusters, originating from a charge transfer process from metal-chalcogenide core to the NHC ancillary ligands.

Share

COinS