Large first hyperpolarizabilities of substituted aniline oligomers

Abstract

Substituted and nonsubstituted aniline oligomers were theoretically investigated. Aniline oligomers with a dicyanoethenyl acceptor group attached at a terminal site of each known structure (emeraldine, pernigraniline, and leucoemeraldine forms), contributing to obtain large first hyperpolarizabilities. The effect of oligomer size on the nonlinear responses was also investigated by considering oligomers with different chain length (tetramers and octamers). The magnitudes of ␤ calculated for the functionalized and nonfunctionalized octamers were larger than for the tetramers and their substituted oligomers. The substituted pernigraniline octamer presented the largest ␤ value among the investigated aniline oligomers. The results of the AM1/TDHF calculations suggest that these aniline-based materials can be good candidates for second-order nonlinear optical materials.

Donor–acceptor diethynylsilane oligomers: A second‐order nonlinear optical material

“…Several systems characterized in the literature having the strong acceptor dicyanovinyl display very low energy transitions for the charge transfer processes, which contribute to the increase in the nonlinear coefficients 94, 95. In addition, theoretical studies revealed large nonlinear responses for various polyenic and aniline derivatives with the acceptor dicyanovinyl group 2, 25, 87, 88, 96, 97. Several experimental and theoretical studies have shown that the magnitude of the first hyperpolarizability of organic molecules is associated with lower values of the HOMO–LUMO gap 2, 3, 24, 56, 57, 96–99.…”

“…Oligomers have been studied because of their solubility in common solvents and their ability to be crystallized. These properties are different from the polymers themselves, and therefore, allow for their chemical processing 22–25. These features are essential for the construction of devices from mono‐ and multilayer films, single crystals, and other forms.…”

“…These features are essential for the construction of devices from mono‐ and multilayer films, single crystals, and other forms. In addition, polymers and their oligomers have been experimentally and theoretically characterized as prominent candidates as nonlinear materials 1–4, 7, 10, 12, 24, 25. In particular, the model trimers of aniline simulate the observed experimental trends for the second hyperpolarizabilties at the Austin Model 1 (AM1) level, using the time‐dependent Hartree‐Fock approach (TDHF), namely AM1/TDHF 26.…”

“…A survey of theoretical reports shows that molecular‐based materials have potential applications as second‐ and third‐nonlinear materials, as the transition metal complexes,31 porphyrins 25, 32, 33. phtalocyanines,34 among others 35–43.…”

“…A survey of theoretical reports shows that molecular-based materials have potential applications as second-and thirdnonlinear materials, as the transition metal complexes, 31 porphyrins. 25,32,33 phtalocyanines, 34 among others. [35][36][37][38][39][40][41][42][43] Novel materials with large nonlinear coefficients are needed for advanced technologies, as well as the implementation of photonics.…”