L-Proline 2,5-Dihydroxybenzoic Acid (1/1): A Zwitterion Co-crystal.

Abstract

The crystal structure of L-proline 2,5-dihydroxybenzoic acid (1/1) (as determined by single-crystal X-ray diffraction), a rare example of a hydrogen-bonded, zwitterion co-crystal with non-linear optical properties, is reported. The colourless crystals are orthorhombic with a = 5.896(2), b = 11.486(1), c = 18.016(3) Angstrom, Z = 4, space group P2(1)2(1)2(1). The complex hydrogen-bond network within the structure is discussed in detail, and the possibilities of using such a material as a model system for theoretical and experimental investigations of hydrogen bonding are addressed