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

作者：Junior Anderson A B C; De Carvalho Gustavo S G; Marques Lippy F; Correa Charlane C; Da Silva Adilson D; Machado Flavia C^*

来源：Acta Crystallographica Section C-Crystal Structure Communications, 2013, 69(8): 934-936.

DOI：10.1107/S0108270113018143

• crystal structure
• carboxylic acids
• zwitterionic structures
• Schiff bases

The title compound, C14H11NO4, exists in the solid phase in the zwitterionic form, 2-{[(4-carboxy-3-hydroxyphenyl)iminiumyl]methyl}phenolate, with the H atom from the phenol group on the 2-hydroxybenzylidene ring transferred to the imine N atom, resulting in a strong intramolecular N-H center dot center dot center dot O hydrogen bond between the iminium H atom and the phenolate O atom, forming a six-membered hydrogen-bonded ring. In addition, there is an intramolecular O-H center dot center dot center dot O hydrogen bond between the carboxylic acid group and the adjacent hydroxy group of the other ring, and an intermolecular C-H center dot center dot center dot O contact involving the phenol group and the C-H group adjacent to the imine bond, connecting the molecules into a two-dimensional network in the (10 (3) over bar) plane. pi-pi stacking interactions result in a three-dimensional network. This study is important because it provides crystallographic evidence, supported by IR data, for the iminium zwitterionic form of Schiff bases.

• 出版日期2013-8