A DFT/TDDFT Investigation on Fluorescence and Electronic Properties of Chromone Derivatives

The development of quick and precise detection technologies for active compounds in vivo is critical for disease prevention, diagnosis and pathological investigation. The fluorescence signal of the fluorophore usually defines the probe's sensitivity to the chemical being examined. Many natural compounds containing flavone and isoflavone scaffolds exhibit a certain amount fluorescence, albeit with poor fluorescence quantum yields. Therefore, we used density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations to investigate the fluorescence characteristics of chromium-derived fluorophores in more depth. Different substituents are introduced at different positions of the chromone. As weak electron donor groups, alkyl and aromatic groups were discovered to have varying quantum yields on the fluorophore scaffold, and longer alkyl chains are favorable to enhance fluorescence quantum yield. In comparison to the amino group, substituted amino group can avoid group rotation, and the introduction of cyclic amines such as pyrrolidine and heterocyclic amines can improve optical characteristics. The electron-donating methoxy group at position 6 helps to increase the fluorescence quantum yield.