H-1 and C-13 NMR investigations of N,N'-bis(2- and 3-pyridinyl)-2,6-pyridine dicarboxamides

H-1 NMR spectra of N,N'-bis(2-pyridinyl)-2,6-pyridinedicarboxamides (1 to 3) and N,N'-bis(3-pyridinyl)-2,6-pyridinedicarboxamide (4) have been analysed using the COSY spectra. Accurate H-1 chemical shifts and coupling constants have been obtained from the simulation of the resolution enhanced spectra. UC NMR spectra were analysed with the help of HETCORR and proton coupled C-13 spectra. The C-13-H-1 coupling constants were obtained by the simulation of the proton coupled C-13 NMR spectra. From H-1 NMR spectra and NOE enhancements, it is inferred that the two 2-pyridyl rings of 1 to 3 are coplanar with the amide plane, while the 3-pyridyl ring of 4 is out of the amide plane.