Supramolecular Influence on Keto-Enol Tautomerism and Thermochromic Properties of o-Hydroxy Schiff Bases
نویسندگان
چکیده
This work presents a study on thermo-optical properties of three Schiff bases (imines) in the solid state. The Schiff bases were obtained by means of mechanochemical synthesis using monosubstituted o-hydroxy aromatic aldehydes and monosubstituted aromatic amines. The keto-enol tautomerism and proton transfer via intramolecular O∙∙∙N hydrogen bond of the reported compounds was found to be influenced more by supramolecular interactions than by a temperature change. All products were characterised by powder X-ray diffraction (PXRD), FT-IR spectroscopy, thermogravimetric (TG) analysis and differential scanning calorimetry (DSC). Molecular and crystal structures of compounds 1, 2 and 3 were determined by single crystal X-ray diffraction (SCXRD). The molecules of 1 appear to be present as the enol-imine, the molecules of 2 as the keto-amine tautomer and the molecules of 3 exhibit keto-enol tautomeric equilibrium in the solid state. An analysis of Cambridge structural database (CSD) data on similar imines has been used for structural comparison.
منابع مشابه
Thermodynamic Study and Total Energy Calculation for three systems of Enol↔Keto Tautomerism
Using Hartree–Fock (HF) and ِِDensity Functional Theory (DFT) calculations the thermodynamic properties such as thermal energy , , thermal enthalpy , , thermal entropy , , thermal Gibbs free energy , , heat capacity ,Cv, and molecular structures of several species involving in keto↔enol tautomerism related to acetaldehyde (A), 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and acetylacetone (AA) h...
متن کاملSynthesis of some new anils: part 1. Reaction of 2-hydroxy-benzaldehyde and 2-hydroxynaphthaldehyde with 2-aminopyridene and 2-aminopyrazine.
New Schiff bases derived from 2-aminopyridene and 2-aminopyrazine have been synthesized. The UV-Visible spectra of the compounds have been investigated in acetonitrile and toluene. The compounds were in tautomeric equilibrium (enol-imine O- H...N, keto-amine O...H-N forms) in polar and nonpolar solvents. For some derivatives the keto-amine form was observed in both toluene and acetonitrile. 1H-...
متن کاملA photochromic-acidochromic HCl fluorescent probe. An unexpected chloride-directed recognition.
Non-classical protomerism of Schiff bases offers several advantages; for example, specific interactions in the -C[double bond, length as m-dash]N- linkage can be controlled and differentiated because the interactions are not governed by keto-enol tautomerism. Herein, the pH sensing properties of a new protomeric Schiff base probe () are reported. In particular, among several acids, the probe di...
متن کاملEvidence of aggregation induced emission enhancement and keto-enol-tautomerism in a gallic acid derived salicylideneaniline gel.
A novel salicylideneaniline type fluorescent organogelator based on a 3,4,5-(tri-dodecyloxy)benzoyl group immobilizes aromatic solvents. The resulting gels show enhancement in emission and thermochromic/non-photochromic behaviour during sol-to-gel transition.
متن کاملNovel Schiff Bases of Pyrrole: Synthesis, Experimental and Theoretical Characterizations, Fluorescent Properties and Molecular Docking
Some new Schiff-base compounds based on pyrrole were synthesized by the reaction of 2-amino-1-methyl-4,5-diphenyl-1H-pyrrole-3-carbonitrile (1)with aromatic aldehydes (2a-2e) in ethanol/acetic acid at room temperature. The structures of the Schiff bases were characterized by full spectral data. The fluorescence emission intensity of the Schiff bases has bee...
متن کامل