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.