title: Synthesis, spectroscopy, X-ray structure and redox behaviors of 4-(N-R-salicylideneimine)-2,6-diphenylphenols.
abstract: A series of sterically hindered 4-(N-R-salicylaldimine)-2,6-diphenylphenols (X), where R=H (1), 3-CH3 (2), 5-CH3 (3), 3-OCH3 (4), 4-OCH3 (5), 5-OCH3 (6), 3-tBu (7), 5-tBu (8), 3,5-tBu2(9) and 5,6-benzo(10), were synthesized and their structure as well as redox behavior studied by analytical, spectroscopic [1H, (13C) NMR, IR, UV-vis and mass spectrometry] and cyclic voltammetric (CV) techniques. Single crystal X-ray diffraction studies of 7 evidenced its existence as non-planar enol-imine tautomer structure, in which the phenol ring of the molecule is twisted around C-N single bond by 21.5(2) degrees. The packing structure of 7 is stabilized by C-H...pi(Ph) and O...O and C...O intermolecular short contact interactions. The CV of X display rate is dependent on irreversible and quasi-reversible redox waves in the anodic and cathodic regions due to oxidation and reduction of phenolic and iminic groups, respectively. As evidenced by ESR and UV-vis study, chemical oxidation of X by PbO2 and (NH4)2Ce(NO3)6 in MeCN and CHCl3 generates stable phenoxyl radicals [(g approximately 2.005 and lambda approximately 450 nm (1600-8200 M(-1) cm(-1))].
authors.affiliation: Chemistry Department, Faculty of Arts and Sciences, HU, Sanliurfa, Turkey.
authors.forename: Veli T
authors.initials: VT
authors.lastname: Kasumov
authors.forename: Hasan
authors.initials: H
authors.lastname: Türkmen
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Uçar
authors.forename: Ahmet
authors.initials: A
authors.lastname: Bulut
authors.forename: Nurettin
authors.initials: N
authors.lastname: Yayli
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D007097:Imines / Q000138:chemical synthesis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D012459:Salicylates / Q000138:chemical synthesis* / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013057:Spectrum Analysis
chemical_list: D007097:Imines; D010636:Phenols; D012459:Salicylates