3-nitro-7H-benzo[de]anthracene-7-oneなどのニトロベンズアントロン(NBA)は、排気ガスとして大気中に放出され、しかも強い変異原性を示すために最近注目を集めている。分光学的な方法によりNBAを同定することを目標として、1-,2-,3-,9-,10-NBAを合成し、吸収スペクトルおよび蛍光・燐光スペクトルを測定した。吸収スペクトルは、基本的にベンズアントロンに似ているが、3-NBAと10-NBAの第一吸収帯のモル吸光係数はかなり小さくなった。一方、蛍光スペクトルはニトロ基の導入により大きく変化した。3-NBAのバンドピークはBAに比べて約80nmレッドシフトし、2-NBAの蛍光量子収率はBAの約1/10であった。燐光は、77Kでは1-NBAを除いて全てのNBAで観測された。これらの結果は、スペクトルデータを基にした、NBAの同定が有望であることを示唆している。

Nitrobenzoanthrones (NBAs) such as 3-nitro-7H-benzo[de]anthracene-7-one (3-NBA) have received a considerable amount of attention because of their mutagenic activity and occurrence in the air. To identify NBAs by spectroscopic methods, we have synthesized 1-, 2-, 3-, 9-, and 10-NBAs and measured their absorption and emission spectra. The features of the first absorption band of the NBAs were practically similar to those of 7H-benzo[de]anthracene-7-one (BA); the bands are broad with peaks at about 400nm and molar absorptivities (e) of about 850M^-1cm^-1. The substituion of a nitro group, however, caused a considerable increase in e for 3-NBA and a significant decrease for 10-NBA. Fluorescence spectra were more largely affected by the substitution than absorption spectra; the specral shape and intensity of the compounds varied individually. The band peak of 3-NBA was red-shifted by more than 80nm from that of BA; the quantum yield of fluorescence for 2-NBA was reduced to about one-tenth of that of BA. and had a peak at 540nm longer than BA. Phosphorescence was observed at 77K for all compounds except 1-NBA. These results give the promise of characterizing individual isomers of NBAs on the basis of their spectroscopic data.