Interactions of phenylalanine, tyrosine and histidine in aqueous caffeine solutions at different temperatures

o, , # , enthalpy, H * and entropy, S * of activation of viscous flow, and molar refraction, Rm were calculated. The results are interpreted from the point of view of solute-solvent and solute-solute interactions in these systems. It has been observed that there exist strong solute-solvent and weak solute-solute interactions in these systems. Further, the solute-solvent interactions decrease, whereas solute-solute interactions increase with rise in temperature. It is observed that these amino acids act as structure-makers in aqueous-caffeine solvent. The thermodynamics of viscous flow have also been discussed.