Synthesis and photophysical characterization of push-pull azobenzene derivatives featuring different π-bridges for photoresponsive applications

Abstract

This study presents the synthesis, development, and comprehensive evaluation of a series of novel azobenzene derivatives – DMAC, DMAF, and DMAT – engineered with push-pull configuration by varying π-bridge substituents (benzene, furan, and thiophene, respectively). The research employs a combination of computational and experimental methods, including density functional theory (DFT) and time-resolved UV–Vis absorption spectroscopy, to explore the impact of these π-bridge modifications on the electronic, photophysical, and isomerization properties of the derivatives. Interestingly, the findings suggest that the π-bridge structure significantly influences the charge transfer characteristics, with DMAC exhibiting the most effective charge transfer and the highest photoisomerization efficiency. Time-resolved UV–Vis absorption spectroscopy demonstrates that all derivatives exhibit rapid initial E-to-Z isomerization upon light irradiation, followed by a slower approach to the photostationary state (PSS). Thermal Z-to-E isomerization kinetics are consistent with the activation energy barriers predicted by potential energy surface (PES) scans, with DMAC showing the slowest reversion due to its highest activation energy. This study contributes valuable insights into the structural influences on the photochemical dynamics of azobenzene derivatives, with implications for their applications in photoresponsive technologies.