A 1:2 co-crystal of isonicotinamide and propionic acid

Abstract

Isonicotinamide has been shown to form many 1:1 co-crystals with monofunctional carboxylic acids, but with propionic acid it forms a co-crystal containing two acid molecules and one isonicotinamide molecule per formula unit, C6H6N2O-2C3H6O 2. The crystal structure consists of 'supermolecules' made up of of one isonicotinamide molecule and two acid molecules, and the asymmetric unit contains two of these supermolecules. One of the acid molecules is hydrogen bonded to the pyridine function, and the other to the amide function of the isonicotinamide. Further N - H⋯O hydrogen bonds connect these supermolecules into chains which run along the [100] direction. The chains are linked into layers perpendicular to (010) by C - H⋯O and π-stacking interactions. The layers are then linked together by further C -H⋯O interactions. © 2004 International Union of Crystallography Printed in Great Britain - all rights reserved.