H-1, C-13, N-15 NMR and X-ray diffractometry in structural studies of macrocyclic lactams containing pyridine moiety

We examined complexing sites of the Pb2+ complex of the macrocyclic lactam 1 using N-15 NMR and other spectroscopies and we have found that the amide groups undergo conformational changes to allow the complexation process to proceed via the pyridine nitrogen atom and carbonyl and ethereal oxygen ato ms. X-Ray analysis of compound 1 was carried out successfully. Space group I4(1)/a, a=28.332(4)Angstrom, b= 28.332(4)Angstrom; c=10.7379(4)Angstrom, Z =16, V=8619.3(18)Angstrom (3), D-c=1.197gcm(-3), R1=0.0479 (based on 2510 r eflections I>2 sigma (I). It shows presence of intramolecular hydrogen bond s, which are broken during the complexation. Molecules form supramolecular tetragonal assemblies in the crystal, which form channels the walls of whic h are 7.42 Angstrom apart.