Santos, Fabiano S. M. H. Costa, Tania Stefani, Valter F. B. Gonçalves, Paulo Descalzo, Rodrigo R. Benvenutti, Edilson V. Rodembusch, Fabiano S. Synthesis, Characterization, and Spectroscopic Investigation of Benzoxazole Conjugated Schiff Bases Two Schiff bases were synthesized by reaction of 2-(4′-aminophenyl)benzoxazole derivatives with 4-<i>N</i>,<i>N</i>-diethylaminobenzaldehyde. UV–visible (UV–vis) and steady-state fluorescence in solution were applied in order to characterize its photophysical behavior. The Schiff bases present absorption in the UV region with fluorescence emission in the blue-green region, with a large Stokes’ shift. The UV–vis data indicates that each dye behaves as two different chromophores in solution in the ground state. The fluorescence emission spectra of the dye <b>5a</b> show that an intramolecular proton transfer (ESIPT) mechanism takes place in the excited state, whereas a twisted internal charge transfer (TICT) state is observed for the dye <b>5b</b>. Theoretical calculations were performed in order to study the conformation and polarity of the molecules at their ground and excited electronic states. Using density functional theory (DFT) methods at theoretical levels BLYP/Aug-SV(P) for geometry optimizations and B3LYP/6-311++G(2d,p) for single-point energy evaluations, the calculations indicate that the lowest energy conformations are in all cases nonplanar and that the dipole moments of the excited state relaxed structures are much larger than those of the ground state structures, which corroborates the experimental UV–vis absorption results. intramolecular proton transfer;Theoretical calculations;BLYP;charge transfer;TICT;fluorescence emission spectra;Spectroscopic Investigation;UV region;cases nonplanar;dye 5 b;dye 5;fluorescence emission;Benzoxazole Conjugated Schiff BasesTwo Schiff bases;ESIPT;Schiff bases;photophysical behavior;DFT;geometry optimizations;energy conformations;ground state structures;ground state;B 3LYP 2011-11-24
    https://acs.figshare.com/articles/journal_contribution/Synthesis_Characterization_and_Spectroscopic_Investigation_of_Benzoxazole_Conjugated_Schiff_Bases/2579911
10.1021/jp206905f.s001