A. Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland.
Spectrochim Acta A Mol Biomol Spectrosc. 2013 Mar;104:315-27. doi: 10.1016/j.saa.2012.11.072. Epub 2012 Dec 5.
Spectral characteristics study of meso-tetraphenylporphyrin derivatives (TPP1 and TPP2) used as photosensitizers for utilization in photodynamic therapy (PDT) has been performed by density functional theory (DFT) and time dependent DFT (TD-DFT) calculations at B3LYP/6-31 G(d) level of theory using PCM solvation model. The geometrical parameters of porphyrins have been studied for ground and excited-state geometry to deduce the influence of various substituents as well as solvent effect on the deformation of porphyrin ring. Two theoretical approaches - linear response (LR) and external iteration (EI) - have been performed to replicate absorption and fluorescence emission spectra. Experimental and theoretical investigations have shown that EI method reproduces the absorption energies very well for both singlet-singlet and triplet-triplet transitions, whereas the LR approach is more coherent with experimental fluorescence emission spectra. Spectral features and HOMO-LUMO band gap analysis have shown that TPP1 can be more useful in PDT. Calculations have revealed that two the highest occupied and two the lowest unoccupied molecular orbitals are responsible for the Q-band absorption and are located mainly on the porphyrin ring. In order to verify the substituent effect on the activity of tested compounds in their ground and excited states, the molecular electrostatic potential surfaces have been analyzed.
通过使用 PCM 溶剂化模型，在 B3LYP/6-31 G(d)理论水平上，使用密度泛函理论（DFT）和时间相关密度泛函理论（TD-DFT）计算，对用作光动力疗法（PDT）光敏剂的中四苯基卟啉衍生物（TPP1 和 TPP2）的光谱特性进行了研究。对基态和激发态几何形状进行了卟啉的几何参数研究，以推断各种取代基以及溶剂效应对卟啉环变形的影响。进行了两种理论方法 - 线性响应（LR）和外部迭代（EI） - 来复制吸收和荧光发射光谱。实验和理论研究表明，EI 方法非常好地再现了单重态-单重态和三重态-三重态跃迁的吸收能量，而 LR 方法与实验荧光发射光谱更一致。光谱特征和 HOMO-LUMO 能带隙分析表明，TPP1 可在 PDT 中更有用。计算表明，两个最高占据和两个最低未占据分子轨道负责 Q 带吸收，并且主要位于卟啉环上。为了验证取代基对测试化合物在基态和激发态下活性的影响，分析了分子静电势表面。
