Zhao Guang-Jiu, Han Ke-Li
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China.
J Chem Phys. 2007 Jul 14;127(2):024306. doi: 10.1063/1.2752808.
The intermolecular dihydrogen bonding in the electronically excited states of the dihydrogen-bonded phenol-BTMA complex in gas phase was theoretically investigated using the time-dependent density functional theory method for the first time. It was theoretically demonstrated that the S(1) state of the dihydrogen-bonded phenol-BTMA complex is a locally excited state, in which only the phenol moiety is electronically excited. The infrared spectra of the dihydrogen-bonded phenol-BTMA complex in ground state and the S(1) state were calculated at both the O-H and B-H stretching vibrational regions. A novel infrared spectrum of the dihydrogen-bonded phenol-BTMA complex in the electronically excited state was found. The stretching vibrational absorption bands of the dihydrogen-bonded O-H and B-H groups are very strong in the ground state, while they are disappeared in the S(1) state. At the same time, a new strong absorption band appears at the C[Double Bond]O stretching region. From the calculated bond lengths, it was found that both the O-H and B-H bonds in the dihydrogen bond O-H...H-B are significantly lengthened in the S(1) state of the dihydrogen-bonded phenol-BTMA complex. However, the C-O bond in the phenol moiety is markedly shortened in the excited state, and then has the characteristics of C[Double Bond]O group. Furthermore, it was demonstrated that the intermolecular dihydrogen bonds in the electronically excited state of the dihydrogen-bonded phenol-BTMA complex are strengthened, since calculated H...H distance is drastically shortened in the S(1) state.
首次采用含时密度泛函理论方法对气相中氢键连接的苯酚 - BTMA配合物电子激发态下的分子间双氢键进行了理论研究。从理论上证明了氢键连接的苯酚 - BTMA配合物的S(1)态是一个局域激发态，其中只有苯酚部分发生了电子激发。在O - H和B - H伸缩振动区域计算了氢键连接的苯酚 - BTMA配合物基态和S(1)态的红外光谱。发现了氢键连接的苯酚 - BTMA配合物电子激发态下的一种新型红外光谱。氢键连接的O - H和B - H基团的伸缩振动吸收带在基态很强，而在S(1)态消失。同时，在C = O伸缩区域出现一个新的强吸收带。从计算得到的键长发现，在氢键连接的苯酚 - BTMA配合物的S(1)态中，氢键O - H...H - B中的O - H和B - H键均显著变长。然而，苯酚部分的C - O键在激发态明显缩短，具有C = O基团的特征。此外，由于计算得到的S(1)态中H...H距离大幅缩短，证明了氢键连接的苯酚 - BTMA配合物电子激发态下的分子间双氢键得到了加强。
