基于ESIPT机理检测Al3+荧光探针分子结构和电子光谱的理论研究

本文应用密度泛函理论（DFT）和含时密度泛函理论（TD-DFT）方法，研究了具有激发态分子内质子转移（ESIPT）特性的3-羟基黄酮（3HF）及其两种氰基和氨基取代衍生物（3HF-CY和3HF-AM）作为水溶液中Al3+离子检测的荧光探针分子结构和电子光谱性质. 计算得到了与ESIPT过程相关的键长、键角以及势能曲线，模拟计算了单独分子和分子@Al3+复合物的吸收和荧光光谱. 结果表明，氰基或氨基的引入均会抑制3HF的质子在基态（S0）或激发态（S1）的转移. 而从得到的吸收光谱可以看出，在3HF中引入吸电子基团氰基可以引起其吸收光谱的红移，而给电子基团氨基的引入则出现相反现象. 此外，与3HF-AM的荧光光谱相比，3HF-AM@Al3+复合物发生了75.88 nm的蓝移，由此推测3HF-AM与水中的Al3+反应后，在光激发下溶液荧光会由绿色转变为紫色，表明3HF-AM分子可以作为有效检测水中Al3+的荧光探针.

Theoretical study on the molecular structures and electronic spectra of Al3+ detection fluorescent probes with the ESIPT mechanism

Based on the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods, the molecular structures and electronic spectra properties of 3-hydroxyflavone (3HF) and its two cyano- and amino- substituted derivatives (3HF-CY and 3HF-AM) with the excited state intramolecular proton transfer (ESIPT) characteristic, as fluorescence probe molecules for the detection of Al3+ ions in the aqueous solution, were studied. The bond lengths, bond angles and potential energy curves related to the ESIPT process were calculated, and the absorption and fluorescence spectra of isolated molecules and toward Al3+ complexes were simulated. The results show that the introduction of cyano- or amino- group can inhibit the proton transfer of 3HF in the ground- (S0) or excited- state (S1). It can be seen from the obtained absorption spectra that introducing the cyano- group into 3HF can cause the red shift of absorption spectrum, while the introduction of amino- group results in the opposite phenomenon. In addition, compared with that of 3HF-AM, the fluorescence spectrum 3HF-AM@Al3+ complex exhibits a blue shift of 75.88 nm, so it was speculated that the fluorescence of 3HF-AM would change from the green to the purple after it reacts with Al3+ ions in the aqueous solution, which indicates that 3HF-AM could be used as an effective fluorescence probe to detect the Al3+ ions in the aqueous solution.