A study of the effects of the polarity of the solvents acetone and cyclohexane on the luminescent properties of tryptophan.

The luminescent properties of tryptophan in solvents less polar than water, such as acetone, and non-polar ones, such as cyclohexane, are experimentally studied and compared with theoretical calculations using time-dependent density functional theory (TD-DFT) methods. Since tryptophan may present different configurations and charge distributions, the most stable conformer is analyzed for both solvents, including its neutral and zwitterionic forms. To perform the simulation two clusters are proposed with the Zpt conformer in acetone: [Formula: see text] and [Formula: see text] , and four clusters with the Nag conformer in cyclohexane: (Trp)-(CH), (Trp)-(CH), (Trp)-(CH) and (Trp)-(CH), in order to conveniently emulate the concentration in each solvent by reducing the distance between adjacent tryptophan molecules as the concentration increases, since there is no control over the volume parameter.