title: Synthesis, X-ray structure, spectroscopic properties and DFT studies of a novel Schiff base.
abstract: A series of Schiff bases, salicylideneaniline derivatives 1-4, was synthesized under mild conditions and characterized by 1H NMR, HRMS, UV-Vis and fluorescence spectra, and single-crystal X-ray diffraction. In solid and aprotic solvents 1-4 exist mainly as E conformers that possess an intramolecular six-membered-ring hydrogen bond. A weak intramolecular C-H···F hydrogen bond is also observed in fluoro-functionalized Schiff base 4, which generates another S(6) ring motif. The C-H···F hydrogen bond further stabilizes its structure and leads it to form a planar configuration. Compounds 1-3 exhibit solely a long-wavelength proton-transfer tautomer emission, while dipole-functionalized Schiff base 4 shows remarkable dual emission originated from the excited-state intramolecular charge transfer (ESICT) and excited-state intramolecular proton transfer (ESIPT) states. Furthermore, the geometric structures, frontier molecular orbitals (MOs) and the potential energy curves for 1-4 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT) and time-dependent DFT calculations.
authors.affiliation: Department of Chemical Engineering, Feng Chia University, Taichung 40724, Taiwan. kyuchen@fcu.edu.tw.
authors.forename: Kew-Yu
authors.initials: KY
authors.lastname: Chen
authors.affiliation: Department of Chemical Engineering, Feng Chia University, Taichung 40724, Taiwan. p0156676@fcu.edu.tw.
authors.forename: Hsing-Yang
authors.initials: HY
authors.lastname: Tsai
mesh_terms: D000814:Aniline Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011789:Quantum Theory; D012545:Schiff Bases / Q000138:chemical synthesis / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000814:Aniline Compounds; D012545:Schiff Bases; C510217:salicylideneaniline