MULTIPLE REHM-WELLER PLOTS IN THE ELECTRON-TRANSFER QUENCHING OF SINGLET EXCITED 9,10-DICYANOANTHRACENE

The rate constants of the quenching of the fluorescence of the title compound (DCA) have been measured in hexane solution with a variety of aromatic and aliphatic electron donors. The plots of the logarithm of the rate constants vs. the donors' ionization potentials show two distinct Rehm-Weller type functions, one for the 'pi' donors and another for the 'n' donors. The difference in quenching efficiency of these two groups is tentatively explained according to the different electrostatic interaction terms, that for the 'n' donors being more favourable.