SUBSTITUENT EFFECTS ON ELECTRONIC-SPECTRA OF VICINALLY SUBSTITUTED 2-AMINOPYRIDINE, 3-AMINOPYRIDINE AND 4-AMINOPYRIDINE

The electronic spectra of forty vicinally substituted 2-, 3- and 4-aminopyridines have been discussed. The low-energy transition of 17 derivatives was analyzed with the help of CNDO/S calculations. In general, the experimental band corresponds to two theoretical transitions. The dual substituent parameter approach (DSP) quite well explains the frequency of one transition in the long-wavelength region of the experimental spectrum.