ON THE NECESSITY OF DISTINGUISHING N-QUENCHERS FROM PI-QUENCHERS IN ELECTRON-TRANSFER STUDIES

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