Faculty of Chemistry, University of Plovdiv, Tzar Assen 24 Str, Plovdiv, Bulgaria.
Inst. Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria.
J Mol Model. 2022 Sep 9;28(10):306. doi: 10.1007/s00894-022-05313-6.
The vertical excitation and emission energies of the cytosine oxo-amino form were calculated at the TD DFT level of theory with several functionals, basis sets, and solvents with different polarity (PCM). They were compared with the experimental UV absorption and fluorescence maxima, revealing that the minimal deviation of the vertical excitation energies from the of UV absorption maxima can be achieved when the hybrid functional B3LYP is applied within the calculations. Regular correlations like curves with saturation between the vertical excitation/emission energies and the dielectric constants were registered. The relaxation of the ππ excited state through an ethylene-like conical intersection S/S should occur through decrease of the decay rate (commented qualitatively here) with the rise of the solvent polarity.
胸腺嘧啶酮亚氨基形式的垂直激发和发射能量是在 TD DFT 理论水平上，用几种功能、基组和具有不同极性的溶剂（PCM）计算的。它们与实验的紫外吸收和荧光最大值进行了比较，结果表明，当在计算中应用混合函数 B3LYP 时，可以使垂直激发能量与紫外吸收最大值的最小偏差。记录了垂直激发/发射能量与介电常数之间的类似曲线的饱和等正则相关性。ππ激发态应该通过类似于乙烯的锥形交叉 S/S 来松弛，S/S 应该通过降低衰减速率（这里定性地评论）来随着溶剂极性的升高而发生。
