Co (II), Ni(II) and Cu(II) complexes with a new pendant armed macrocyclic ligand showing several π,π-interactions

A new ligand, L, bearing four cyanoethyl pendant groups has been synthesized by reaction of the precursor ligand L1 with acrylonitrile. The X-ray crystal structure of ligand L reveals the presence of a nanotubular structure in the solid state connected by intermolecular π,π-stacking interactions between adjacent pyridine rings. The coordination capability towards transition metal ions [Co(II), Ni(II) and Cu(II)] has been investigated starting from the hydrated nitrate and perchlorate salts of the metals. The new ligand L and the metal complexes obtained were characterized by elemental analysis, FAB MS, conductivity measurements, magnetic studies, IR and UV–vis spectroscopy. Furthermore, the crystal structure of ligand L and of the complexes [CoL][Co(NO3)4] · CH3CN (1), [NiL](NO3)2 (3), [NiL](ClO4)2 · CH3CN · 3H2O (4), [CuL][Cu(NO3)3(H2O)2](NO3) · H2O (5) and [CuL](ClO4)2 · 2CH3CN (6) were determined. The nitrate ions in the complexes are located near the pyridine rings and π,π-stacking interactions between pyridine rings, nitrate ions and nitrile groups have been found.