New Luminescent Host–Guest System Based on an Iridium(III) Complex: Design, Synthesis, and Theoretical–Experimental Spectroscopic Characterization

This work presents the design, preparation, and characterization of a very efficient solid state luminescent material based on a cationic bis-cyclometalated Ir(III) complex [Ir(dfptrBn)2(dmbpy)]+ (dfptrBn = 1-benzyl-4-(2,4-difluorophenyl)-1H-1,2,3-triazole; dmbpy = 4,4′-dimethyl-2,2′-bipyridine) encapsulated in sodium aluminosilicate mesoporous sol–gel glasses via the ion exchange process. The optical properties of the Ir(III) complex were fully characterized in solution and in the mesoporous solid host. The employed approach resulted in irreversible encapsulation of the complex and superior photophysical properties, such as increased photoluminescence lifetime values. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were carried out to understand how the chemical environment around the Ir(III) complex influences its photophysical properties. In particular, we show that in low-polarity media (ε < 20) the coupling between the cationic Ir(III) complex and the counterion appreciably affects its electronic structure.