Cobalt-catalyzed Pauson–Khand synthesis of π-extended tetrahydrocyclopentaquinolinones: photophysical properties and DFT analysis

Abstract

A series of π-extended tetrahydrocyclopentaquinolinones were effectively prepared using a Co-catalyzed Pauson–Khand reaction, and their photophysical properties were examined. This protocol creates complex quinolinone scaffolds by leveraging the versatility and utility of transition metal catalysis. The compounds displayed strong fluorescence quantum yield, and a comprehensive analysis of their molecular structures, including rigidity, coplanarity, and substituent effects, revealed their impact on fluorescence efficiency. Density functional theory (DFT) calculations confirmed that extended π-conjugation and structural rigidity enhance radiative decay pathways. These insights into the relationship between molecular structure and photophysical behavior suggest future applications in material science, bioimaging, and photonic technology.