Novel Twisted Intramolecular Charge Transfer (TICT) Extended Fluorescent Styryl Derivatives Containing Quinoline Electron Releasing Moiety

Abstract

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 (β 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.

Spectroscopic Studies of Fluorescence Effects in Bioactive 4-(5-Heptyl-1,3,4-Thiadiazol-2-yl)Benzene-1,3-Diol and 4-(5-Methyl-1,3,4-Thiadiazol-2-yl)Benzene-1,3-Diol Molecules Induced by pH Changes in Aqueous Solutions

“…The dual fluorescence effects can be induced in different molecules by changes in medium polarity, pH of the solution, temperature, or the concentration of the sample [29–33]. According to theories attempting at elucidation of the observed fluorescence effects, they can be related to appearance of intramolecular CT states [34] and the so-called TICT states (Twisted Intramolecular Charge Transfer) [35, 36]. Another explanation of the analysed phenomena is the process of Excited-State Intramolecular Proton Transfer ESIPT [37–42].…”

Electronic and Vibrational Hyperpolarizabilities of Lithium Substituted (Aza)benzenes and (Aza)naphthalenes

“…Hyperpolarizabilities of molecules containing benzene, naphthalene, and their aza analogues (pyridine, pyrazine, quinoline, quinoxaline, etc.) have been experimentally and theoretically studied. − Heteroaromatic molecules containing two nitrogen atoms, as pyrazine and quinoxaline, can play the electron acceptor role as a result of the electron withdrawing effectiveness of the two unsaturated nitrogens. − Coordination compounds obtained from combinations of organic molecules with metal complexes have been studied as a promising class of materials with nonlinear optical properties to be explored. , …”