Physicochemical and solvatochromic analysis of an imidazole derivative as NLO material

Bioactive imidazole derivative, 2-(2,4-difluorophenyl)-1-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline, has been synthesized and characterized by IR, UV–vis, NMR and elemental (CHN) analysis. The electric dipole moment (μ) and the hyperpolarizability (β) have been studied both experimentally and theoretically, which reveals that the synthesized imidazole derivative possesses non-linear optical (NLO) behavior. This chromophore possess more appropriate ratio of off-diagonal versus diagonal β tensorial component (r = βxyy/βxxx = −0.19) which reflects the in plane nonlinearity anisotropy. Since they have largest μβ0 value, the reported imidazole can be used as potential NLO material. Within this context, reasonable conclusions concerning the steric hindrance in the chromospheres, push–pull character, hyperpolarizability of the imidazole and their application as NLO materials will be drawn. The solvent effect on the absorption and fluorescence bands was analyzed by a multi-component linear regression in which several solvent parameters were analyzed simultaneously.

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► Catalan-Taft parameter: the coefficient shows acidity of the solvent, Cα or CSA has a negative value.
► Octupolar and dipolar components of dfppip: the steric interaction must be reduced in order to obtain larger β0 values.
► NBO analysis: elucidates the intramolecular, hybridization and delocalization within the molecule.
► Electronic properties: probable charge transfer (CD) taking place inside the chromophore.
► Bar Diagram: the charge distribution of dfppip was calculated by the NBO and Mulliken methods.