PROGRESS TOWARDS A GENERALIZED SOLVENT POLARITY SCALE - THE SOLVATOCHROMISM OF 2-(DIMETHYLAMINO)-7-NITROFLUORENE AND ITS HOMOMORPH 2-FLUORO-7-NITROFLUORENE

More than 100 solvents and the gas phase were used to develop a solven t dipolarity-polarizability scale that combines the medium dipolarity and polarizability into a single parameter (SPP) calculated from the U V-visible spectra of 2-(dimethylamino)-7-nitrofluorene (DMANF) and its homomorph 2-fluoro-7-nitrofuorene (FNF). The proposed scale compares favourably for nonprotic solvents with existing solvent polarity scale s including Kosower's Z, Dimroth and Reichardt's E(T)(30), Brooker's c hi(R), Dong and Winnick's Py; Kamlet, Abboud, and Taft's pi(), and Dr ago's S' scale. When data are derived from electronic transitions, the y provide an accurate description for the solvent effect in W-Vis, IR, NMR, and fluorescence spectroscopy as well as in other chemical areas including thermodynamics and kinetics.