The NMR study of some macrocyclic and macrobicyclic Schiff bases in solution and solid state

One macrocyclic and two macrobicyclic Schiff bases have been synthesized and investigated by 1 H, 13 C and 15 N NMR spectroscopy in solid state and CDCl3 solution at different temperatures. The results obtained have shown that all studied Schiff bases in CDCl3 solution at ambient temperature exist in a fast dynamical equilibrium that leads to the averaged symmetrical structure. The presence of flexible aliphatic chains and possibility of formation of different intramolecular hydrogen bonds in II and III leads to several different conformations in CDCl3 solution at low temperatures. An asymmetry of the Schiff bases molecules in solid state has been established. q 2002 Elsevier Science B.V. All rights reserved.