Revisiting Dimorphs of 4-n-octyloxybenzoic Acid: Contrasting Mechanical Property and Surface Wettability

Chem Asian J. 2024 Mar 15;19(6):e202301090. doi: 10.1002/asia.202301090. Epub 2024 Feb 28.

Abstract

4-n-octyloxy benzoic acid is known to exhibit liquid crystalline properties, and under normal pressure and temperature conditions, it exists as at least two crystalline polymorphs. We revisited the system and discovered that single crystals of one of the polymorphs display plastic deformation, whereas the other is brittle. n-octyl chains are arranged in an end-to-end fashion, forming slip planes in the plastically deformable polymorph, whereas they are interdigitated in the crystal structure of the brittle polymorph. Due to the difference in the arrangement of the -COOH group and alkyl chains, the major faces of the crystals of both polymorphs possess significant differences in the wettability towards moisture.

Keywords: Molecular Crystal; Plastic Deformation; Polymorph; Wettability.