Serrano-Pérez Juan José, Serrano-Andrés Luis, Merchán Manuela
Instituto de Ciencia Molecular, Universitat de València, Doctor Moliner 50, Burjassot, ES-46100 Valencia, Spain.
J Chem Phys. 2006 Mar 28;124(12):124502. doi: 10.1063/1.2178794.
Psoralen photophysics has been studied on quantum chemistry grounds using the multiconfigurational second-order perturbation method CASPT2. Absorption and emission spectra of the system have been rationalized by computing the energies and properties of the low-lying singlet and triplet excited states. The S1 pipi* state has been determined to be responsible of the lowest absorption and fluorescence bands and to initially carry the population in the photophysical processes related to the phototherapeutic properties of psoralen derivatives. The low-lying T1 pipi* state is, on the other hand, protagonist of the phosphorescence, and its prevalent role in the reactivity of psoralen is suggested to be related to the elongation of the pyrone ring C3-C4 bond, where the spin density is distributed on both carbon atoms. Analysis of energy gaps and spin-orbit coupling elements indicates that the efficient photophysical process leading to the population of the lowest triplet state does not take place at the Franck-Condon region but along the S1 relaxation path.
已基于量子化学原理，使用多组态二阶微扰方法CASPT2对补骨脂素的光物理性质进行了研究。通过计算低激发单重态和三重态的能量及性质，对该体系的吸收光谱和发射光谱进行了合理解释。已确定S1 ππ态是最低吸收带和荧光带的成因，并且在与补骨脂素衍生物光疗性质相关的光物理过程中，最初承载着激发态的粒子数。另一方面，低激发T1 ππ态是磷光的主角，并且其在补骨脂素反应性中的主要作用被认为与吡喃酮环C3-C4键的伸长有关，自旋密度分布在两个碳原子上。对能隙和自旋-轨道耦合元素的分析表明，导致最低三重态粒子数增加的有效光物理过程并非发生在弗兰克-康登区域，而是沿着S1弛豫路径发生。
