Donor-Acceptor Diethynylsilane Oligomers: A Second-Order Nonlinear Optical Material

The interest in the study of oligomers has been motivated mainly because of their solubility in common solvents and also their capacity to be crystallized, which allowed for chemical processing leading to important applications in the area of material sciences. In this work, we carried out an investigation of polydiethynylsilane (PDES) decamers substituted with electron donor (D) and acceptor (A) groups, which is certainly of relevance, once PDES itself is known to display large third-order optical susceptibility. Therefore, density functional theory calculations of static first hyperpolarizability (beta) were performed using various functionals with the 6-31G(d) basis set along with correlated MP2 calculation used as reference for comparison. The influence of A and D substituents on the magnitude of beta was investigated by matching the acceptor (dicyanovinyl, nitrobenzene) and donor (propyl, propoxy, and phenylamine) groups attached at both ends of the oligomer. The largest beta value was predicted for the derivative having the phenylamine and dicyanovinyl groups, which is around 30 times the relative value for the nonsubstituted decamer, what is a very impressive enhancement reported for the first time in the literature, strongly suggesting that disubstituted diethynylsilane decamers are potential building blocks for molecular-based materials with second-order nonlinear responses. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1410-1419, 2011