2-[(E)-(3-Carboxy-4-hydroxyphenyl)iminiomethyl]-4-chlorophenolate

Abstract

Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.002 Å; R factor = 0.038; wR factor = 0.111; data-to-parameter ratio = 18.8.The title Schiff base compound, C 14 H 10 ClNO 4 , has been synthesized by the reaction of 5-amino-2-hydroxybenzoic acid and 5-chloro-2-hydroxybenzaldehyde. The molecule is a zwitterion in the crystal, with the phenolic hydroxy group deprotonated and the imine N atom protonated. It adopts an E configuration about the central C N double bond. The dihedral angle between the two benzene rings is 3.83 (7) . Intramolecular N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonding generates S(6) ring motifs. In the crystal, molecules are connected by intermolecular O-HÁ Á ÁO and C-HÁ Á ÁCl hydrogen bonds, forming a supramolecular chain. Related literature

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

“…Hence, a zwitterionic structure may appear, which is rarely seen for hydroxy derivatives. The characteristic property of this form is the presence of ionic N + -H⋯Ohydrogen bond [4], [5].…”

The zwitterionic structure of 2-hydroxy-4-[(2-hydroxybenzylidene)amino]benzoic acid

“…Using graph-set notation (Etter, 1990), the hydrogen-bonding system can be described as N1 = C(12)S(6)R 2 2 (14) and N2 = R 6 6 (46). These two intramolecular interactions and the abovementioned intermolecular O3-H3OÁ Á ÁO1 i interaction have the same dimensions and behaviour as those in 2-[(E)-(3-carboxy-4-hydroxyphenyl)iminiomethyl]-4-chlorophenolate (Farag et al, 2010). The only difference between these two structures is the presence of one chlorine substituent in the compound described in the literature.…”