Hydrogen-bonded co-crystal structure of benzoic acid and zwitterionic l-proline

The title compound [systematic name: benzoic acid-pyrrolidin-1-ium-2-carboxyl-ate (1/1)], C₇H₆O₂·C₅H₉NO₂, is an example of the application of non-centrosymmetric co-crystallization for the growth of a crystal containing a typically centrosymmetric component in a chiral space group. It co-crystallizes in the space group P2₁2₁2₁ and contains benzoic acid and l-proline in equal proportions. The crystal structure exhibits chains of l-proline zwitterions capped by benzoic acid mol-ecules which form a C(5)[R₃³(11)] hydrogen-bonded network along [100]. The crystal structure is examined and compared to that of a similar co-crystal containing l-proline zwitterions and 4-amino-benzoic acid.