Monomethoxy-4-aminoazobenzenes: a computational study

The structural and electronic properties of the positional isomers of monomethoxy-4aminoazobenzene (n-OMe-AAB) have been investigated using density functional theory with a basis set that includes polarization functions on all the atoms. These azo dyes are of interest because their carcinogenic activities depend dramatically on the position (n) of the methoxy group, e.g. 3-OMe-AAB is a potent hepatocarcinogen in the rat, whereas 2-OMe-AAB is a noncarcinogen. While it is generally believed that the various isomers of OMe-AAB require metabolic activation via N-hydroxylation prior to reaction with cellular macromolecules, we have shown that there are structural and electronic features present in these isomers that correlate with their carcinogenic behavior.