Nevertheless strongly dipolar chromophore units relax back to more favorable centrosymmetric alignment even below the glass transition temperature (T g) of the material, thus reducing the second order NLO effect significantly. Non-centrosymmetric arrangement is forced upon molecules by external electric field poling in many cases. The final material must contain non-centrosymmetrically aligned chromophores to be able to demonstrate a second order NLO effect, ,, ]. Structure of the organic molecular glasses can be modified to meet five main requirements at device application conditions: large NLO coefficients, high refractive indices, good optical transparency, excellent temporal stability of non-centrosymmetrically aligned dipoles, and excellent photochemical stability, , ,6,, ].Īn organic NLO active chromophore is usually strongly polar “acceptor – conjugated π bridge – donor” (D-π-A) type compound, which molecules are ordered with antiparallel dipoles in crystals and thin amorphous films because electrostatic repulsion prohibits parallel or non-centrosymmetric arrangement. More efficient materials could be composed of a single component, a NLO active organic molecular glass. Hosting polymer or crosslinking monomers may also be present in the NLO material and responsible for the bulk physical properties, but the active chromophore becomes diluted reducing overall NLO response. Organic NLO materials consist of a chromophore denoting the NLO effect of the material. Organic nonlinear optical (NLO) materials are studied and developed to perform better than inorganic materials in applications for high speed and effective data transmission, high speed electro-optical modulators, ultrafast optical switches, signal processing, and optical data storage, ,, ,, ,, ]. NLO coefficient d 33 values were 14–73 pm⋅V −1. Glass transition temperatures of all synthesized molecular glasses were 63–83 ☌, and thermal destruction temperatures of all synthesized compounds were at least 250 ☌. Full set of trityl end groups resulted in decreased NLO parameters and stability of poled order. Thermal, optical, and NLO properties were compared to previously reported results of dendrimer samples containing both hydroxyl and trityl groups. New convergent method was used to synthesize azobenzene core dendrimer fully functionalized with trityl end groups. ![]() Effect of one or two pentafluorophenyl groups was investigated and about three times better NLO parameters were obtained when using one pentafluorophenyl group, as it has greater possibility of NLO properties enchanting Ar-Ar F interactions with neighboring molecules. The configuration, where pentafluorophenyl groups containing dendronizing fragment was attached to donor part of azochromophore, was very promising in our recent research, therefore trityl groups containing dendron was added to acceptor part to rise the glass transition temperature of amorphous compound. New NLO active organic molecular glasses were synthesized based on push-pull azobenzene, which was dendronized with 3,5-bisbenzoic acid and pentafluorophenyl groups were added to enchance thermal and NLO properties via Ar-Ar F interactions.
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