Theoretical calculation of gas-phase ionization potentials for mono- and polysubstituted benzenes

This Letter provides an accurate and efficient method to obtain gas-phase i onization potentials for monosubstituted benzene molecules, using density f unctional theory with the B3LYP functional and geometry/frequencies obtaine d by the AM1 method. The results show an excellent correlation between calc ulated and experimental IPs for 20 different monosubstituted benzene rings. The study is extended to include polymethylated benzenes, up to hexamethyl benzene, whose IPs are also shown to be in good agreement with experimental data, making this a promising approach for large, polysubstituted benzene systems. (C) 1999 Elsevier Science B.V. All rights reserved.