Strong enhancement of nonlinear optical properties through supramolecular chirality.

Verbiest, T; Elshocht, SV; Kauranen, M; Hellemans, L; Snauwaert, J; Nuckolls, C; Katz, TJ; Persoons, A · Science · 1998

basic_science · Level V

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Abstract

A new approach to second-order nonlinear optical (NLO) materials is reported, in which chirality and supramolecular organization play key roles. Langmuir-Blodgett films of a chiral helicene are composed of supramolecular arrays of the molecules. The chiral supramolecular organization makes the second-order NLO susceptibility about 30 times larger for the nonracemic material than for the racemic material with the same chemical structure. The susceptibility of the nonracemic films is a respectable 50 picometers per volt, even though the helicene structure lacks features commonly associated with high nonlinearity. Susceptibility components that are allowed only by chirality dominate the second-order NLO response.