Qu Peng, Tian Dongxu
State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2014;120:529-33. doi: 10.1016/j.saa.2013.11.112. Epub 2013 Dec 9.
The equilibrium geometries, IR-spectra and transition mechanism of intramolecular hydrogen-bonded methyl salicylate in excited state were studied using DFT and TDDFT with 6-31++G (d, p) basis set. The length of hydrogen bond OH⋯OC is decreased from 1.73 Å in the ground state to 1.41 and 1.69 Å in the excited S1 and S3 states. The increase of bond length for HO and CO group also indicates that in excited state the hydrogen bond OH⋯OC is strengthened. IR spectra show HO and CO stretching bands are strongly redshifted by 1387 and 67 cm(-1) in the excited S1 and S3 states comparing to the ground state. The excitation energy and the absorption spectrum show the S3 state is the main excited state of the low-lying excited states. By analyzing the frontier molecular orbitals, the transition from the ground state to the excited S1 and S3 states was predicted to be the π→π∗ mode.
采用密度泛函理论（DFT）和含时密度泛函理论（TDDFT）以及6-31++G(d, p)基组，研究了激发态分子内氢键结合的水杨酸甲酯的平衡几何结构、红外光谱和跃迁机理。氢键OH⋯OC的长度从基态的1.73 Å减小到激发态S1和S3态的1.41 Å和1.69 Å。HO和CO基团键长的增加也表明在激发态氢键OH⋯OC得到了加强。红外光谱显示，与基态相比，在激发态S1和S3态中，HO和CO伸缩带分别强烈红移了1387和67 cm(-1)。激发能和吸收光谱表明，S3态是低激发态中的主要激发态。通过分析前线分子轨道，预测从基态到激发态S1和S3态的跃迁为π→π∗模式。
