On the necessity of distinguishing “n” from “π” quenchers in electron transfer studies

Abstract From the example of 1DCA* (where DCA is 9,10-dicyanoanthracene) fluorescence quenching by electron donors which exhibits different “π” and “n” Rehm-Weller plots for select compounds (pure “π” or “n” donors) it is shown that the quenching data of non-select compounds (donors exhibiting both “π” and “n” properties) need careful examination. Vertical ionization potentials rip for characterizing the donor ability reveal themselves to be more useful in the understanding of quenching rates than adiabatic potentials vIP or the redox potential E1/2.