Uncovering the Solvent-Mediated Transformation Mechanism of 7-ADCA Crystal Habit at the Surface–Solvent Interface

The crystal habit is a vital property indicator of crystal products. The solvent-mediated crystal habit transformation is basic and efficient. However, the effect of the solvent on the crystal habit transformation mechanism at the crystal face–solvent interface has been limited. In this study, the solvent-mediated crystal habit transformation mechanism of 7-aminodeacetoxycephalosporanic acid (7-ADCA) is explored from the perspectives of the inherent 7-ADCA crystal structure and the solvent effect at the crystal surface–solvent interface. The crystal structure of 7-ADCA is governed by weak contacts according to the Hirshfeld surface and the Independent Gradient Model based on Hirshfeld partition, revealing that its crystal growth is easily affected by solvent molecules. According to electrostatic potential, mean square displacement, diffusion coefficient, radial distribution function, interaction energy, and adsorption energy, amino of the outermost layers of molecules in binary solvent systems have difficulty diffusing from the bulk solution and adsorbing onto the (1 1 1̅) face, as predicted by the modified attachment energy model. This leads to the disappearance of this surface and the formation of rectangular crystals in the binary solvent systems. Besides, the selective diffusion and adsorption strength of solvent molecules on the radial crystal face of (0 1 1) and the axial crystal face of (1 1̅ 0) determine the formation of rectangular crystals with different aspect ratios.