RESUMO
The interactions of isonicotinamide (INA) with seven common solvents (acetic acid, acetonitrile, acetone, chloroform, ethyl acetate, and methanol) have been studied to examine solute-solvent effects on the nucleation of INA from these solvents. In a simple model of 1:1 solute-solvent interactions, the strongest INA-solvent interaction is with acetic acid (binding energy, Δ Ebind = -64.05 kJ mol-1) and the weakest is with chloroform (Δ Ebind = -24.85 kJ mol-1). This arises since acetic acid and INA form a hydrogen-bonding motif containing two moderate strength N-H···O hydrogen bonds, while chloroform and INA have a single weak C-H···O hydrogen bond. Taking acetic acid, chloroform, and methanol, the solvents with the strongest, the weakest, and an intermediate strength INA-solvent binding energy, the solvation of INA was studied to compare it with the 1:1 model. Acetic acid has the strongest binding energy (-872.24 kJ mol-1) and solvation energy (-341.20 kJ mol-1) with chloroform binding energy (-517.72 kJ mol-1) and solvation energy (-199.05 kJ mol-1). Methanol has intermediate binding energy (-814.19 kJ mol-1) and solvation energies (-320.81 kJ mol-1). These results further confirm the recent the findings which indicate that the key trends in solvent-solute interactions can be determined from a simple and efficient 1:1 dimer model and can be used to predict ease of nucleation with stronger binding energies correlating to slower, more difficult nucleation. A limit of this model is revealed by considering alcohol and acid solvents with longer alkyl chains.