Paying Comprehensive Attention to the ESPT Mechanism and Luminescent Property of Salicylic Acid and Its Derivatives in Various Microenvironments
Changjiao Shang, Yunjian Cao, Yajie Zhang, Min Ma, Chaofan Sun
Abstract
Abstract Investigating the effects of surrounding microenvironments and substituents on the excited‐state proton transfer (ESPT) mechanism have always been a great challenge, especially in protic solvents and solid state. In this work, a detailed theoretical study on ESPT processes of salicylic acid (SA) and its two derivatives (5ASA and 5NSA) in gas, cyclohexane, acetonitrile, ethanol (EtOH), and crystal phases is performed based on the density functional theory (DFT) and time‐dependent DFT as well as the combined quantum mechanics/molecular mechanics (QM/MM) methods. Intramolecular charge transfer‐induced aggregation‐caused quenching phenomenon of 5ASA is unveiled utilizing the hole–electron analysis. Independent gradient model analysis is implemented to reveal the spontaneous forward proton transfer (PT) behavior of 5ASA. Besides, potential energy surfaces are constructed to evaluate the dominant PT pathway in EtOH, and the related transition state structures are also obtained to accurately provide the intra‐ and inter‐PT energy barriers. Eventually, excited‐state ab initio molecular dynamics computation reaffirms that the intra‐PT reaction is predominant for SA. This theoretical work comprehensively explores the ESPT mechanism and luminescent properties of SA and its two derivatives, which provides a reference for developing efficient organic light‐emitting materials based on ESPT chromophores.