Spectroscopic behavior of alloxazine-based dyes with extended aromaticity: Theory vs Experiment

The chemical and electronic structure of parent (iso)alloxazine and their eight aromatic derivatives as possible candidates for dyes usage were systematically investigated by the Density Functional Theory. The effect of condensation by various (mostly benzene-like) aromatic moieties to the initial benzo[g]pteridine moiety on the energies of frontier molecular orbitals and spectroscopic properties - absorption, and emission characterization, was discussed. The spectroscopic behavior experimentally measured in alkaline dimethylsulfoxide for parent alloxazine, and its four available derivatives were compared with the theoretical predictions. In this context, the optical properties of iso-tautomers and deprotonated species were also theoretically quantified. Impact of chain modification relating to several linear and two-dimensional structure variations on electron structure and optical properties was analyzed. The correlations between theoretical estimation and experiment were proposed and could be helpful for future synthesis of novel molecules in optoelectronics or biosensing technology.