2 : 1 Co-crystals of p-nitrophenylacetic acid with three isomeric n-pyridinealdazines, n = 2, 3 and 4, featuring the {… HOCO … N(py)} heterosynthon

Abstract

Abstract Crystal and molecular structures of 2 : 1 co-crystals formed between p-nitrophenylacetic acid and three isomeric n-pyridinealdazines, n = 2(1), 3(2) and 4(3), are described in which the carboxylic acid is always in a general position and the respective n-pyridinealdazine is located about a centre of inversion. A common feature of the supramolecular aggregation is the formation of three-molecule aggregates sustained by the {… HOCO … N(py)} heterosynthon, further vindicating this as a most reliable synthon for co-crystal design. Molecules are assembled into three-dimensional architectures by C–H … O interactions coupled with C–H … π (1) or π … π (2 and 3) contacts.