On the origin of surfaces-dependent growth of benzoic acid crystal inferred through the droplet evaporation method

TL;DR

This study investigates how different surfaces influence the growth and morphology of benzoic acid crystals, revealing that polar surfaces significantly alter crystal faces and that quantum chemistry helps explain these effects.

Contribution

It demonstrates the impact of polar and non-polar surfaces on benzoic acid crystal morphology and uses quantum chemistry to elucidate energetic factors behind face stabilization.

Findings

Polar surfaces reduce the number of observable crystal faces.

Scraping crystals restores bulk-like morphology.

Quantum chemistry reveals energetic basis for face stability.

Abstract

Crystal growth behavior of benzoic acid crystals on different surfaces was examined. The performed experiments documented the existence of very strong influence introduced by polar surfaces as glass, gelatin, and polyvinyl alcohol (PVA) on the growth of benzoic acid crystals. These surfaces impose strong orientation effect resulting in a dramatic reduction of number of faces seen with x-ray powder diffractions (XPRD). However, scrapping the crystal off the surface leads to a morphology that is similar to the one observed for bulk crystallization. The surfaces of low wettability (paraffin) seem to be useful for preparation of amorphous powders, even for well-crystallizable compounds. The performed quantum chemistry computations characterized energetic contributions to stabilization of morphology related faces. It has been demonstrated, that the dominant face (002) of benzoic acid crystal, growing on polar surfaces, is characterized by the highest densities of intermolecular interaction energies determining the highest cohesive properties among all studied faces. Additionally, the inter-layer interactions, which stand for adhesive properties, are also the strongest in the case of this face. Thus, quantum chemistry computations providing detailed description of energetic contributions can be successfully used for clarification of adhesive and cohesive nature of benzoic acids crystal faces.