| Abstract
| - We report on the synthesis via a Knoevenagel condensation reaction of a new family ofpush−pull molecules based on 6,6‘-distyryl-3,3‘-bipyridine. These chromophores werecharacterized by spectroscopic methods (NMR, UV−vis, photoluminescence), their mesogenicbehavior was investigated by DSC and optical microscopy, and their second-order NLOproperties were evaluated by the electric field second harmonic (EFISH) technique. All thecompounds are transparent at the second harmonic wavelength of typical laser sources (1.32and 1.55 μm), and some of them exhibit a strong emission. By lateral substitutions of theπ-conjugated bridge and by varying the nature of the acceptor/donor pair, we were able totune both the mesogenic and NLO properties of the chromophores. For the mesogenicchromophores, first hyperpolarizabilities extrapolated to infinite wavelength, β0, between16 × 10-30 and 85 × 10-30 esu were measured. These compounds exhibit enhancedhyperpolarizabilities compared to typical NLO liquid crystal chromophores reported in theliterature.
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