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Solvent Dependent Prototropic Tautomerism in a Schiff Base Derived from o ‐Vanillin and 2‐Aminobenzylalcohol
Author(s) -
Plyuta Nataliya,
Kokozay Vladimir,
Cauchy Thomas,
Avarvari Narcis,
Goreshnik Evgeny,
Petrusenko Svitlana
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201902118
Subject(s) - tautomer , chemistry , schiff base , enol , acetonitrile , solvent , keto–enol tautomerism , crystallization , crystal structure , vanillin , crystallography , condensation reaction , medicinal chemistry , organic chemistry , catalysis
The Schiff base H 2 L, namely 2‐(3‐methoxysalicylidene‐amino)‐benzyl‐alcohol, 1 and its two pseudo‐polymorphs H 2 L⋅CH 3 OH 2 and H 2 L⋅H 2 O 3 , have been synthesized by the condensation reaction of 2‐aminobenzyl alcohol and o ‐vanillin in different solvents. X‐ray crystallographic analysis revealed that the keto‐enol tautomerism of H 2 L in solid state exists as a complex system of three different enol, keto and zwitterionic forms in equilibrium, dependent on crystal packing forces and the crystallization solvent. The enol, keto and mixed enol‐zwitterionic (roughly 1:1) forms were observed in the crystal structures of 1 , 2 and 3 , respectively. The crystallographic results are supported by FTIR and DFT calculations. Photophysical properties were determined in acetonitrile solution and solid state and were supported by TD‐DFT studies.