Classifying the polarity of organic solvent mixtures by using Hostalene Red adsorbed on nanosized zeolite as a fluorescent probe

A method is described for the determination of the polarity of mixed organic solvents by using the fluorescent probe Hostasol Red (HR) desposited on the outer surface of nanosized zeolite L. Organic solvents and their mixtures can be roughly classified according to their polarity with bare eyes and fluorometrically. Emission peaks range from 520 to 640 nm. Some solvents act as quenchers. The method is studied with series of protic and nonprotic solvents, and with selected mixtures of organic solvents.

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Graphical abstract The dye Hostalene Red adsorbed on nanosized zeolite shows strong fluorescence solvatochromism. This can be exploited to quickly assess the polarity of solvents and solvent mixtures.