VERSATILE OPTICAL-MATERIALS - FLUORESCENCE, NONLINEAR-OPTICAL AND MESOGENIC PROPERTIES OF SELECTED 2-PYRAZOLINE DERIVATIVES

A study of the structure-property relationships in a series of -(4-n-d ecyloxyphenyl)-1-(p-X-phenyl)-2-pyrazolines has been performed. By sim ply changing the substituent in the 1-phenyl ring we were able to tune the physical properties of the compounds. If this ring is non-substit uted or substituted with a 4-methoxy, 4-chloro or 4-carboxy group, the pyrazoline compounds are fluorescent. If the ring is 4-nitro- or 2,4- dinitro-substituted, the compounds have interesting second-order non-l inear optical properties. The first hyperpolarizability has been measu red using the Hyper-Rayleigh Scattering technique in solution. The 4-n itro derivative displays liquid crystalline behaviour, showing a monot ropic smectic A phase with a partial bilayer structure due to an antip arallel arrangement of molecules as confirmed by X-ray studies in the mesophase.