Classification of organic molecules to obtain electron affinities from half-wave reduction potentials: cytosine, uracil, thymine, guanine and adenine

A procedure for obtaining the adiabatic electron affinities (AEA) of organi c molecules from half-wave reduction potentials in aprotic solvents is pres ented. Molecules are placed into groups according to their structure. Each group has a different solution energy difference. Calculations of AEA and c harge distributions with AM1-multiconfiguration configuration interaction a re used to support the intuitive classification of the molecules. The proce dure is illustrated for Vitamins A and E, riboflavin, the azines, polyenes, hydroxy-pyrimidine, oxo-guanine, the hydrogen bonded cytosine-oxo-guanine as well as the AEA, and vertical EA (VEA) of Cytosine (C), Uracil (U), Thym ine (T), Guanine (G) and Adenine (A). The latter values are: (VEA) G, 0.10; A, -0.49; U, 0.33; T, 0.31; C, -1.48 and (AEA) G,1.51 +/- 0.05; A, 0.95 +/ - 0.05; U, 0.80 +/- 0.05; T, 0.79 +/- 0.05; C, 0.56 +/- 0.05 in eV. (C) 199 9 Elsevier Science S.A. All rights reserved.