Polymorphs of trimesic acid controlled by solvent polarity and concentration of solute at solid-liquid interface

Concentration of solute and polarity of solvent are vital parameters in controlling self-assembled structure formation of molecules at solid-liquid interfaces. Here we compare polymorphs of trimesic acid (TMA) obtained from different solvents as well as different concentrations at liquid-graphite interfaces. Solvents with different polarity like phenyloctane, fatty acids and fatty alcohols are used to dissolve TMA. From solvents with non-polar groups (as phenyloctane) TMA forms only a high-density structure; however, from solvents with moderate polar functional groups (as octanoic acid) there appear concentration-induced polymorphs. From solvents containing strong polar groups (as undecanol) there appears a mixed structure consisting of TMA and solvent molecules coadsorbed due to strong inter-molecular interaction. The concentration of all solutions is controlled by the time of sonication of the solute-solvent mixture.

► Solvent polarity dependant polymorphism. ► Self-assembled patterns of trimesic acid are controlled by concentration. ► Comparison of TMA structures in different solvents allow the understanding of formation mechanism of polymorphs.