Molecular structure of (Z)-6-[(5-chloro-2-hydroxyphenylamino) methylene]-3-(diethylamino)cyclohexa-2,4-dienone: A combined experimental and theoretical study

Synthesis, characterization, crystal structure and HSA binding of two new N,O,O-donor Schiff-base ligands derived from dihydroxybenzaldehyde and tert-butylamine

“…As a result, the observed bands at 210, 231, 288 and 381 nm for L 1 and three bands at 221, 299 and 371 nm for L 2 can be due to benzene π → π* and azomethine π → π* and n → π* transitions. These values are similar to those found in related compound [55], [56].…”

Aromaticity from the Viewpoint of Molecular Geometry: Application to Planar Systems

“…The theoretical study of the tautomeric equilibria and proton transfer process in Schiff bases was supplemented by experimental investigations (X-ray diffraction, UV−vis, FT-IR, and NMR spectroscopy). 297,300,303,304 Moreover, for (E)-2ethoxy-6-[(2-methoxyphenylimino)methyl] phenol, the influence of temperature on the proton transfer phenomenon was studied. 300 The crystal and molecular structures were determined at 296 and 100 K (X-ray measurements); the results obtained confirmed the coexistence of OH and NH tautomers at 296 K, whereas the OH form dominated at 100 K (DFT calculations in the gas phase predict this form as more stable than the NH one).…”

“…Among systems with heteronuclear RAHB alkyl and aryl, ,− Schiff bases were the most frequently studied. In their quasi -aromatic rings, a proton transfer from the hydroxyl group to the imine group, through the O–H···N and O···H–N hydrogen bonds, takes place (Figure ).…”

Investigation of the Electronic and pH-Sensing properties of Hydroxyl-Functionalized Imine-Linked Polymers via the UV-vis Absorption Spectra and the Density Functional Theory (DFT) Calculations

“…This attraction is less favored when compared to the quasi-six-membered ring and has a moderate stability [21]. In the same manner, it has been reported by others that the ortho-OH play a role of electron-donation group and create a resonance (electron-delocalization) [30] on the structure, which also shift the band to a higher wavelength. Consequently, the UV-vis absorption, which is assigned below 400 nm can be attributed to the presence of enol-imine tautomer only and the absorption shoulder-band above 400 nm in the polymer P(PIOH-IPI) is due to the substituent effect rather than the possibility of keto-amine tautomer formation.…”

“…Consequently, the UV-vis absorption, which is assigned below 400 nm can be attributed to the presence of enol-imine tautomer only and the absorption shoulder-band above 400 nm in the polymer P(PIOH-IPI) is due to the substituent effect rather than the possibility of keto-amine tautomer formation. This kind of reported results have encouraged us to expect that the notable red-shift above 400 nm is assigned to the presence of OH group as donating group rather than the keto-amine tautomer formation and the band below 400 nm is attributed to the enol-imine tautomer form of the polymer and the formation of a polyaromatic conjugated system in the backbone [21,30,31]. Furthermore, the observed significant blue-shift in the acidic medium can be resulted from the protonation of the imine-nitrogen atom, while, in the basic medium, the role of oxygen as proton donor become crucial and cause the de-protonation and therefore stabilized by the resonance effect of the electron-donating OH-group.…”