An Investigation of the Hydrogen-Bond Preferences and Co-crystallization Behavior of Three Didonor Compounds.

We assess the suitability of the three didonor compounds as building blocks for ternary co-crystals of the type (didonor)(monoacceptor)2. A Cambridge Structural Database (CSD) survey was carried out to analyze the hydrogen-bond connectivity and develop a strategy for the preparation of the desired co-crystal. Six specific compounds were selected and crystals were grown from 1:1 and 1:2 solutions of didonor compounds (m-hydroxybenzoic acid, p-hydroxybenzoic acid, and racemic mandelic acid) and acceptor compounds (acridine, triphenylphosphine oxide, and nicotinamide) leading to three co-crystals (m-hydroxybenzoic acid)·(triphenylphosphine oxide)2 (1), ((RS)-mandelic acid)·(acridine) (2) and (p-hydroxybenzoic acid)·(nicotinamide) (3). Characterization by single-crystal structure determination confirms the success of this design strategy.