Acta Cryst. (2014). C70, 323-325 [ doi:10.1107/S2053229614002447 ]
Abstract: The crystal structure of a polymorph of 4-aminobenzoic acid (PABA), C7H7NO2, at 100 K is noncentrosymmetric, as opposed to centrosymmetric in the structures of the other known polymorphs. The two crystallographically independent PABA molecules form pseudocentrosymmetric O-HO hydrogen-bonded dimers that are further linked by N-HO hydrogen bonds into a three-dimensional network. The benzene rings stack in the b direction. The CO2 moieties are bent out slightly from the benzene ring plane.
CCDC reference: 984821
Keywords: crystal structure; 4-aminobenzoic acid; PABA; polymorphism; noncentrosymmetric polymorph; hydrogen bonding; pharmaceuticals.
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