How amino and nitro substituents affect the aromaticity of benzene ring

The effect of strongly electron-accepting and electron-donating substituents on the aromaticity of the benzene ring has been revealed based on experimental and computational data. It has been documented that the nitro group affects the π-electron structure of the ring in its benzene derivative ca. 2.8 times weaker than the amino group. However, their joint effects in the meta and para nitroaniline, compared to nitrobenzene, results in a decrease of the delocalization in the ring by a factor ca. 4.0 and 6.5, respectively.