A combined experiment and computation study of the fused polycyclic benzimidazole derivatives.

Novel fused polycyclic benzimidazole derivatives were synthesized from dimethyl 4,5-diaminophthalate/dimethyl 3,4-diaminophthalate with aromatic anhydride (a-b) by condensation. The UV-Visible absorption and fluorescence emission spectra of the dyes were studied in solvents of differing polarity. The dyes were characterized by the spectral analysis. Density Functional Theory computations have been used to derive more understanding of structural, molecular, electronic and photophysical parameters of the push-pull dyes. The computed absorption wavelength values were observed to be in good agreement with the experimental results. The second order hyperpolarizability (ß(o)) values were computed by Density Functional Theory and found to be in the range of 67.16 × 10(-31) to 107.76 × 10(-31) e.s.u.

Novel twisted intramolecular charge transfer (TICT) extended fluorescent styryl derivatives containing quinoline electron releasing moiety.

Novel extended fluorescent styryl derivatives were synthesized from (E)-3-(2-cyclopropyl-4-(4-fluorophenyl)quinolin-3-yl)acrylaldehyde containing quinoline ring with 4-fluorophenyl ring at the 4-position as an electron donor and different active methylene compounds as electron acceptors by conventional Knoevenagel condensation reaction. The UV-Visible absorption and fluorescence emission spectra of the dyes were studied in solvents of differing polarity and the compounds showed polarity sensitive emission properties. The dyes were characterized by the spectral analysis. Thermogravimetric analysis showed these dyes are thermally stable up to 250 °C. Density Functional Theory computations have been used to derive more understanding of structural, molecular, electronic and photophysical parameters of the push-pull dyes. The computed absorption wavelength values are found to be in good agreement with the experimental results. The second order hyperpolarizability (ß o) values were computed by Density Functional Theory and found to be in the range of 116.61 × 10(-31) to 898.48 × 10(-31) e.s.u.

Synthesis of novel carbazole based styryl: rational approach for photophysical properties and TD-DFT.

The synthesis and solvatochromic behavior of four novel carbazole based fluorescent styryl dyes were explained. In chlorinated solvents such as DCM and chloroform, these dyes show bathochromic shift in their absorption as well as emission. The styryl dyes 6b and 6c show solid state yellow fluorescence. DFT and TD-DFT computations were performed to study structural, molecular, electronic and photophysical properties of these dyes. The computed absorption and emission wavelength values are found to be in good agreement with the experimental results. The photophysical properties of these 1-styryl carbazole dyes are also compared with the recently reported 3-styrl carbazole dyes. The unique behavior of dye 6d is well explained by its optimized geometry found in the excited state. Ratio of ground to excited state dipole moment of the synthesized novel styryl compounds were calculated by Bakhshiev and Bilot-Kawski correlations.

Photophysical properties of ESIPT inspired fluorescent 2-(2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione and its derivative: experimental and DFT based approach.

The excited-state intramolecular proton transfer chromophores 2-(2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione and 2-(4-(diethylamino)-2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione are synthesized from 4,5-diamino-N-methylphthalimide. The photophysical behavior of the synthesized chromophores was studied using UV-visible and fluorescence spectroscopy in the polar and non-polar solvents. The synthesized o-hydroxyphenyl benzimidazole derivatives are fluorescent and very sensitive to the solvent polarity. These dyes are thermally stable up to 317 °C. Density Functional Theory computations have been used to understand the structural, molecular, electronic and photophysical properties of the chromophores. The experimental absorption and emission wavelengths are in good agreement with the computed vertical excitation and theoretical emission obtained by Density Functional Theory and Time Dependant Density Functional Theory.