Organic and Organometallic Compounds

Organic and organometallic stilbazolium cations can be crystallized with various counterions; some of the resulting salts exhibit large SHG powder efficiencies. Approximately linear stilbazolium cations have a greater tendency to crystallize in noncentrosymmetric space groups than do cations with substantial geometric asymmetry. The nonresonant quadratic molecular hyperpolarizabilities of several ferrocene and ruthenocene derivatives were studied by DC electric-field-induced second-harmonic generation (EFISH) experiments using fundamental radiation at 1.91 µm. Hyperpolarizabilities approaching that of 4-dimethylamino 4'-nitro-stilbene (DANS) were observed indicating that the ferrocene moiety can act as an effective donor. EFISH measurements indicate that indoaniline dyes with very polarizable π systems have large molecular hyperpolarizabilities (β), in one case approaching three times that of DANS.