基于ICT原理氮杂冠醚光化学传感器的理论研究(英文)

A Computational Study on Coumarin Aza-crown Ether Photochemical Sensors for Ca^(2+) Based on ICT

采用DFT方法,对两个基于ICT原理的氮杂18-冠-6光化学传感器及其与Na^+、K^+、Mg^(2+)、Ca^(2+)的配合物进行了理论研究.并在B3LYP/6-31+G(d,p)理论水平上对所有分子进行了几何构型优化,优化构型及部分参数表明配合物中冠醚环上氮原子与香豆素基团平面化程度显著增加,尤其是两配体与Ca^(2+)的配合物.另外,据NBO分析结果可知,冠醚环上的氮原子不同程度地参与了与金属离子的配位.以上两种现象均会对分子内电荷转移产生影响.为了说明两现象相互作用使配体对金属离子产生的选择性,本文还利用TD-DFT方法,对配体及配合物的紫外吸收进行了计算和分析,结果显示两个配体均对Ca^(2+)有较高选择性.

Two new intramolecular charge transfer（ICT）probes,aza-18-crown-6with a coumarin group（L）,and their complexes with metal cations,L/M^（n＋）（M^（n＋）=Na~＋,K~＋,Mg^（2＋）,Ca^（2＋））were studied using density functional theory（DFT）in gas phase.All optimized structures have been proved to be stable by real frequencies obtained at B3LYP/6-31＋G（d,p）level.Their structures and relevant parameters show the planarization between N in the crown ether ring and coumarin group fromLto L/M^（n＋）,which enhances the conjugation.The binding energies,enthalpies and Gibbs free energies of the complexes L/M^（n＋）have been calculated.Besides,natural bond orbitals（NBO）analysis indicates interaction between N and M^（n＋）.Then time-dependent density functional theory（TD-DFT）calculations achieved the absorption spectra and partial excitation data,illustrating high selectivity for Ca^（2＋）.In all,comparing the two ICT probe systems,a conclusion will be made that the modification of coumarin and the structure of the molecule can make great effect on ICT process.