Nonlinear Optical Properties of Organosilicons: Intramolecular Charge Transfer in Pyridyldisilanes with a Donor-Acceptor Linker

As a novel kind of organosilicon complex, dipyridyldisilane and 1-phenyl-2-pyridyl-disilane with a donor-acceptor link by the sigma-pi interaction and intramolecular charge transfer, has been investigated by the density functional theory. It is found that the phenyl replaced by the pyridy in diphenyldisilane can significantly narrow the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap, and enhance the electronic polarization, thus make the electronic distribution more diffuse. As a result, the static first hyperpolarizability (beta(0)) of dipyridyldisilane is enhanced to the range of 10.365 x 10(-30) esu approximate to 26.385 x 10(-30) esu. And in order to know the effect of the number of pyridyl ring and the position of pyridyl ring on NLO responses, we calculated the beta(0) values for 1-phenyl-2-pyridyl-disilane, they are in the range of 6.475 x 10(-30) esu similar to 1482.613 x 10(-30) esu. The smaller HOMO-LUMO gap and the smaller transition energy make the larger value of beta(0). This kind of organosilicon complex is one of the potentially versatile and fascinating nonlinear optical materials.