Large quadratic nonlinear optical efficiencies in pseudosymmetric streptocyanine dyes

Valérie Guieu (1) , Corinne Payrastre (1) , Yves Madaule (1) , Sonia Garcia-Alonso (2) , Pascal G. Lacroix (3) , Keitaro Nakatani (4, 5)

1 SPCMIB - Synthèse et Physico-Chimie de Molécules d'Intérêt Biologique
2 LHFA - Laboratoire Hétérochimie Fondamentale et Appliquée
3 LCC - Laboratoire de chimie de coordination
4 PPSM - Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires
5 IDA - Institut d'Alembert

The quadratic (proportional to E-2) nonlinear optical (NLO) properties of pseudosymmetric organic cations are investigated. These chromophores belong to a family of highly polarizable streptocyanine dyes built in two steps by amination of their related carboxonium salts. They exhibit a nearly perfect optical transparency in the 200-1100 nm range, except around 700 nm, where a single but narrow band is present. Some of these dyes crystallize in noncentrosymmetric space groups, which, despite a symmetrical pi-electronic structure, leads to symmetry lowering and restores a push-pull character to the optical transition and hence a sizable molecular hyperpolarizability. One of these molecules is optimized for a solid-state NLO effect and exhibits an efficiency 120 times that of urea in second harmonic generation at 1.907 mu m.

Mots clés: transition-metal complexes; differential-overlap; intermediate neglect; molecular-crystals; chromophores

Domaines: Chimie théorique et/ou physique

Valérie Guieu, Corinne Payrastre, Yves Madaule, Sonia Garcia-Alonso, Pascal G. Lacroix, et al.. Large quadratic nonlinear optical efficiencies in pseudosymmetric streptocyanine dyes. Chemistry of Materials, 2006, 18 (16), pp.3674-3681. ⟨10.1021/cm060584p⟩. ⟨hal-00172470⟩