A theoretical exploration and regulating about the excited state process for 2‐(4‐(diphenylamino)phenyl)‐3‐hydroxy‐4H‐chromen‐4‐one system

Abstract

In the present work, density functional theory (DFT) and time‐dependent density functional theory (TDDFT) methods have been performed to explore the ground‐state and excited‐state intramolecular hydrogen bonding interactions for 2‐(4‐(diphenylamino)phenyl)‐3‐hydroxy‐4H‐chromen‐4‐one (2‐DHC) system. We demonstrate that the intramolecular hydrogen bond formed in the ground state should be strengthened in the first single excited state by comparing the bond parameters and infrared (IR) vibrational spectra, which provides the possibility for excited‐state intramolecular proton transfer (ESIPT) reaction. The calculations about hydrogen bonding energy further confirm the strengthening hydrogen bond. The intramolecular charge transfer (ICT) around hydrogen bonding moieties upon photoexcitation promotes the ability to attract hydrogen proton, which reveals the ESIPT tendency. In view of four different polarities solvents, we construct the potential energy curves along with ESIPT path and search the transition state (TS) structure for ESIPT reaction. We clarify the ESIPT mechanism for 2‐DHC molecule, based on which we also present the ESIPT reaction could be regulated and controlled by solvent polarity.

Revelation of ESIPT mechanism for the novel fluorescent system HNIBT in toluene and methanol solvents: A TDDFT study

“…In other words, via an experimental manner, most of the excited state behaviors are inferred without the most correct explanations. [38][39][40][41][42][43][44][45][46][47][48][49][50] In fact, if the novel functions of the HNIBT molecule are to be developed and applied reasonably in the future, the correct and reasonable explanations of excited-state processes and dynamics should be essential. Therefore, in this work, we intent to elaborate the elementary aspects for the HNIBT system theoretically (i.e., based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods).…”