Synthesis, structural, thermal and photo-physical properties of triazine based NLO material

Three novel triazine based organic chromophores with D-π-A (Donor-π system- Acceptor) push-pull type have been synthesized from 2, 4-diamino-6-phenyl-1,3,5-triazine as a starting material. Structures of all the three compounds have been confirmed by UV-Visible absorption, FT-IR, NMR and Mass spectral techniques. Their photo physical and thermal properties have been investigated. Among the three compounds, 6-phenyl-2,4-((4-amino-1,5-dimethyl-2-phenyl pyrazol-3-ylidene)(4-nitro benzylidene))-diamino-1, 3, 5-triazine (NDP) showed positive solvatochromism compared to the other two compounds. The absorption in the UV region of these three compounds were found to be less dependent on solvent polarities, whereas the red shifted fluorescence was strongly dependent on solvent polarities. The TGA data indicates that all the three compounds are stable up to 160 °C. Measurement of non linear optical properties showed that there is an increased second harmonic generation (SHG) efficiency with respect to urea indicating the existence of high molecular nonlinearity in NDP.