Cocrystallization: A Solution Chemistry Perspective and the Case of Benzophenone and Diphenylamine

The design and preparation of two component crystalline solids, cocrystals, for potential pharmaceutical applications has been a significant activity in the field of crystal engineering over the past five years. In this contribution, we explore the solution chemistry of one particular system, diphenylamine−benzophenone. In particular, we elucidate the relationships between crystal chemistry, solution chemistry, and phase behavior in both binary and ternary systems. The combined use of FTIR spectroscopy and proton NMR reveals the molecular basis of negative and positive deviations from ideality and provides important insights into the crystal nucleation processes.