Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Jun 5;254:119685. doi: 10.1016/j.saa.2021.119685. Epub 2021 Mar 10.
A novel and efficient chemosensor 1 for detecting Cu has recently been developed. However, the photophysical properties of chemosensor 1 and its response mechanism to Cu are still unclear. Herein, the density functional theory and the time-dependent density functional theory approaches are implemented to investigate the excited state behavior of chemosensor 1 and its sensing mechanism for Cu is revealed. Through constructing the potential energy curve with the dihedral angle of hydroxide radical as a variable, the irreversibility of the adjustment of the hydrogen proton direction is determined. This feature provides a favorable geometric configuration condition for the formation of intramolecular hydrogen bond. Moreover, the reduced density gradient analysis and topological analysis are performed to visualize the hydrogen bond strength, it is found that the hydrogen bond is enhanced in first singlet excited state (S) compared with that in ground state (S). The chemosensor 1 has only a low potential barrier in the S state, indicating that it could undergo an ultra-fast excited state intramolecular proton transfer (ESIPT) process. Furthermore, the reaction sites of chemosensor 1 and Cu is theoretically predicted by the electrostatic potential analysis and the coordination mode of 1 + Cu-H is confirmed. Thus, we verify that the deprotonation inhibits the ESIPT behavior and leads to fluorescence quenching to achieve the recognition of chemosensor 1 to Cu. In addition, the binding energy of Cu with chemosensor 1 is greater than that of Mg and Zn, the high selectivity of chemosensor 1 to Cu is illustrated. Our investigation clarifies the sensing mechanism of chemosensor 1 to Cu based on inhibiting ultra-fast ESIPT process, which provides a theoretical basis for the development of new metal ion sensors.
最近，一种用于检测 Cu 的新型高效化学传感器 1 已被开发出来。然而，化学传感器 1 的光物理性质及其对 Cu 的响应机制仍不清楚。在此，我们采用密度泛函理论和含时密度泛函理论方法，研究了化学传感器 1 的激发态行为及其对 Cu 的传感机制。通过构建以氢氧根离子二面角为变量的势能曲线，确定了质子方向调整的不可逆性。这一特性为形成分子内氢键提供了有利的几何构型条件。此外，还进行了电子密度梯度分析和拓扑分析，以可视化氢键强度，发现与基态（S）相比，第一单重激发态（S）中的氢键增强。化学传感器 1 在 S 态下只有一个低势垒，表明它可以经历超快的分子内质子转移（ESIPT）过程。此外，通过静电势能分析和 1 + Cu-H 的配位模式对化学传感器 1 和 Cu 的反应位点进行了理论预测。因此，我们验证了去质子化抑制 ESIPT 行为并导致荧光猝灭，从而实现化学传感器 1 对 Cu 的识别。此外，Cu 与化学传感器 1 的结合能大于 Mg 和 Zn，说明了化学传感器 1 对 Cu 的高选择性。我们的研究阐明了化学传感器 1 对 Cu 的传感机制，基于抑制超快 ESIPT 过程，为开发新型金属离子传感器提供了理论依据。
