State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2019 Apr 15;213:309-317. doi: 10.1016/j.saa.2019.01.077. Epub 2019 Jan 27.
For TNP chemosensor 2-(4,5-Bis(4-Chlorophenyl)-1H-Imidazol-2-yl)-4-Chlorolphenol (HPICI), previous thought with no theoretical basis was that excited-state intramolecular proton transfer (ESIPT) process and the ground-state HPICI-TNP complex are mainly responsible for its fluorescence emission and the detection of TNP. However, this interpretation has been proved to be wrong by the present theoretical DFT/TDDFT explorations. Actually, the strong fluorescence of HPICI is mainly induced by the local excitation of the enol form HPICI(E) without ESIPT, and the fluorescence quenching by TNP is due to the photo-induced electron transfer (PET) process together with the cooperative effect of hydrogen-bonding interaction and π-π stacking interaction coexisting in the HPICI-TNP complex. The strengthened excited-state hydrogen bond promotes the PET process, thus facilitates the fluorescence quenching. This mechanism is proposed on the basis of the theoretical analyses on molecule geometry, binding energy, Gibbs free energy, electronic transitions, and frontier molecular orbitals (FMOs).
对于 TNP 化学传感器 2-(4,5-双(4-氯苯基)-1H-咪唑-2-基)-4-氯苯酚（HPICI），之前认为没有理论依据的是，激发态分子内质子转移（ESIPT）过程和基态 HPICI-TNP 配合物主要负责其荧光发射和 TNP 的检测。然而，目前的理论 DFT/TDDFT 研究已经证明这种解释是错误的。实际上，HPICI 的强荧光主要是由无 ESIPT 的烯醇形式 HPICI(E)的局域激发引起的，而 TNP 的荧光猝灭是由于光诱导电子转移（PET）过程以及氢键相互作用和 π-π 堆积相互作用的协同效应共存于 HPICI-TNP 配合物中。增强的激发态氢键促进了 PET 过程，从而促进了荧光猝灭。该机制是基于对分子几何、结合能、吉布斯自由能、电子跃迁和前沿分子轨道（FMO）的理论分析提出的。
