A study of substituent effect on 1H and 13C nmr spectra of N- and C-substituted carbazoles

H-1 and C-13 nmr spectra of several N- and C-substituted carbazoles (Series 1, 2, 3 and 4) were measured. Correlations between chemical shifts and substituent constants show that these parameters describe properly the substituent effect on the nmr phenomena. Atomic charge densities for carbazoles of Series 1, 2, 3 and 4 were calculated by using the semi empirical PM3 method. These values also show a linear correlation with the C-13 chemical shifts. The synthesis of several carbazole derivatives 1a - 1g, 2a - 2g, 3a - 3j and 4a - 4g have been carried out according to literature procedures. The carbazoles 3i, 3j and 4c have been synthesized and fully characterized for the first time.