Molecular Assembly and Nucleation Kinetics during Nucleation of 3,5-Dinitrobenzoic Acid.

As one of the most important processes in the process of crystallization, nucleation determines the physicochemical properties of the crystal products. The mechanism of nucleation has not been sufficiently understood due to the complexity of the molecular assembly process. In this work, a rigid molecule of 3,5-dinitrobenzoic acid (DNBA) was selected as the model compound to investigate the connection between nucleation kinetics and solution chemistry and to investigate the mechanism of nucleation. The nucleation induction period was determined by the nonrandom method, and the parameters including interfacial energy γ and collision frequency were calculated. FTIR, NMR, and MS were used to analyze the existing form of DNBA molecules in solutions. It was found that the solute exists in the form of monomer, multimers, and solvates in different solvents. Besides, molecular simulation and calculation were also used to investigate the intermolecular interactions of DNBA in different solvents, and the relationship between the molecular existing form and the nucleation kinetics was revealed. Finally, a possible nucleation mechanism of DNBA molecules in solution was proposed.