NMR Spectroscopy and Molecular Orbital Calculations to Interpret the Mutagenicity of Nitrobenzanthrones

Abstract

Thorough NMR measurements were made on 3-nitro-7H-benz[d,e]anthracen-7-one (1), 1,9-dinitro-7H-benz[d,e]anthracen-7-one (2), 3,11-dinitro-7H-benz[d,e]anthracen-7-one (3), and 11-nitro-7H-benz[d,e]anthracen-7-one (4), whose mutagenic activities vary largely with the position and the number of the nitro group. Their ¹H and ¹³C chemical shifts were assigned by means of several kinds of two dimensional NMR spectroscopic techniques, and correlations were examined between the chemical shifts and mutagenicity among the compounds. The chemical shifts at the ortho carbon atoms with respect to the nitro group differ between mutagenic compounds (1) – (3) and nonmutagenic compound (4). The difference can be related to that in the reactivity toward formation of nitrenium ions by taking into account of the electron density on the ortho carbon atoms obtained by molecular orbital calculations.

Key Words:

• nitrobenzanthrones
• NMR
• molecular orbital calculations
• nitration
• mutagenicity