Department of Chemistry and Chemical Biology, Rutgers University, Wright-Rieman Laboratories, New Brunswick, NJ 08854-8087, USA.
Photochem Photobiol Sci. 2012 Jun;11(6):931-7. doi: 10.1039/c1pp05334e. Epub 2012 Jan 5.
Radical ion pairs generated by photo-induced electron transfer from 1,2-disubstituted cyclopropanes to various acceptors undergo return electron transfer in pairs of singlet and triplet multiplicity. The pair energies relative to the reactant ground states and to accessible triplet states, respectively, determine the competition between the recombination pathways. The potential surfaces of the radical cations and triplet states of 1,2-diphenyl-, 1, and 1,2-dimethylcyclopropane, 2, have been examined by density functional theory calculations. The radical cation surfaces have minima at geometries that retain significant bonding between C-1 and C-2, preventing geometric isomerization of the radical cations. The triplet potential surfaces are dissociative with minimal rotational differentiation at long distances between C-1 and C-2.
由 1,2-二取代环丙烷光诱导电子转移生成的自由基离子对以单重态和三重态的双重态经历返电子转移。相对于反应物基态和可及三重态的对能量分别决定了重组途径的竞争。通过密度泛函理论计算研究了 1,2-二苯基-、1-和 1,2-二甲基环丙烷、2 的自由基阳离子和三重态的势能面。自由基阳离子表面在保持 C-1 和 C-2 之间显著键合的几何形状处具有最小值，防止了自由基阳离子的几何异构化。三重态势能面在 C-1 和 C-2 之间的长距离处具有最小的旋转差异，是离解的。
