Muchová Eva, Spirko Vladimir, Hobza Pavel, Nachtigallová Dana
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nam. 2, 166 10, Prague 6.
Phys Chem Chem Phys. 2006 Nov 14;8(42):4866-73. doi: 10.1039/b610001e. Epub 2006 Sep 26.
The character of the hydrogen bonding and the excited state proton transfer (ESPT) in the model system HCN...H(2)O is investigated. The PES of the two lowest excited states of the H(2)O...HCN complex was calculated using the CASPT2 method. The nonadiabatic coupling of the two states of the (pi-->pi*) and (pi-->sigma*) character is responsible for the excited state proton/hydrogen transfer. Compared to the ground state, the barrier for this process is significantly smaller. An increased number of water molecules in the complex with cyclic hydrogen-bonded network causes a large blue shift of the state of the (pi-->sigma*) character. The question of the dissociation of the complex in its excited state is also addressed.
研究了模型系统HCN...H₂O中的氢键特征和激发态质子转移（ESPT）。使用CASPT2方法计算了H₂O...HCN复合物两个最低激发态的势能面。（π→π*）和（π→σ*）特征的两个态的非绝热耦合导致了激发态质子/氢转移。与基态相比，该过程的势垒显著更小。具有环状氢键网络的复合物中水分子数量的增加会导致（π→σ*）特征态发生较大的蓝移。还讨论了复合物在其激发态下的解离问题。
