Structure-Carcinogenicity Studies for Benz[a]Anthracenes by ¹³C NMR Spectroscopy and Molecular Orbital Calculation

Abstract

Structure-carcinogenicity studies of polycyclic aromatic hydrocarbons (PAHs) were performed on the basis of average ¹³C nuclear magnetic resonance (NMR) chemical shifts (δ_avs). The δ_av values of carcinogenic compounds were found to concentrate in a certain range. To clarify the chemical significance of the correlation, we investigated the relationship of the individual ¹³C NMR chemical shifts (δs) and carcinogenicity for three benz[a]anthracenes whose carcinogenicities vary largely. The δ values at the C1, C2, and C6 positions differ significantly between the carcinogenic and noncarcinogenic compounds. Molecular orbital calculations revealed that the carcinogens have higher electron densities at C1 and C6 positions than dose the noncarcinogen.

Key Words:

• polycyclic aromatic hydrocarbons
• benz[a]anthracenes
• ¹³C NMR
• chemical shift
• carcinogenicity
• electron density