3H-1,2-Dithiole-3-thione derivatives as nonel solvatocromic dyes

ALEJANDRO M. FRACAROLI, FERNANDO O. SILVA, ALEJANDRO M. GRANADOS, RITA H. DE ROSSI

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY

Wiley InterScience

Lugar: New York, Estados Unidos; Año: 2008 vol. 21 p. 1007 - 1013

0894-3230

The UV-Vis spectrum of 5-(1-butylthio)-3H-1,2-dithiole-3-thione (1) and that of the chromium pentacarbonyl complex of 5-methyl-3H-1,2-dithiole-3-thione (2) present significant changes with the solvent polarity. The two absorption bands shown by the compounds in the region above 300nm were identified by theoretical calculations. For Compound 1 these are n to pi* transitions and for Compound 2 the longest wavelength absorption corresponds to a charge transfer band and shows a remarkably negative solvatochromism. Not only has the wavelength of maximum absorption changed with the solvent but also the ratio of the absorbances at the two wavelengths. The effect of solvents was correlated with solvatochromic parameters such as pi* and alpha. The spectrum of 5-(1-butylthio)-3H-1,2-dithiole-3-one (3) was also measured in different solvents but in this case the changes observed are less significant than for the other two compounds. The spectra of 1 and 2 were also determined in the presence of anionic (SDS), cationic (CTAB), and neutral surfactants (Brig-35) and it is shown that these compounds can be used as probes for the polarity of the binding sites of organized assemblies.