Supramolecular rectangles and ladders constructed from Ni(II), Cu(II) and Zn(II) mononuclear complexes with bicompartmental ligands and 4-aminopyridine as tectons

Article abstract of DOI:10.1016/j.ica.2017.06.058

By reacting [M^II(valpn)] or [M^II(valdmpn)] mononuclear complexes with 4-aminopyridine in different molar ratios, five [M^II(valXpn)(4-NH₂-py)] and one [Ni^II(valdmpn)(4-NH₂-py)₂] complexes were obtained and structurally characterized (M^II = Ni^II, Cu^II, Zn^II; valpnH₂ and valdmpnH₂ are the Schiff bases resulted from the condensation of o-vanillin with 1,3-propylenediamine and 2,2-dimethyl-1,3-propylenediamine respectively). In the [Cu(valpn)(4-NH₂-py)], [Ni(valpn)(4-NH₂-py)], [Zn(valpn)(4-NH₂-py)] and [Ni(valdmpn)(4-NH₂-py)] complexes the metal ions are pentacoordinated with a square pyramidal geometry. The specific hydrogen bond interactions of the amino group belonging to the 4-aminopyridine with the free O₂O′₂ compartment of the Schiff base ligands led to various supramolecular architectures: rectangles, chains, and ladders. The spectroscopic properties of the compounds were also investigated.