New unsymmetrical Schiff base Ni(ii) complexes as scaffolds for dendritic and amino acid superstructures

Abstract

An efficient stepwise template approach has been developed that leads to a novel Ni(II) complex of an unsymmetrical 1∶1∶1 Schiff base derived from o-phenylenediamine, benzoylacetone and salicylic aldehyde [abbreviated as salophbac Ni(II)]. The 3- and 5-hydroxysubstituted salicylic aldehydes lead to complexes containing reactive OH groups that were further employed as points of attachment for the ligand superstructures. A range of new O-substituted derivatives of salophbac Ni(II) complexes have been synthesized bearing N-protected (L)-amino acid moieties as well as poly(arylether) and poly(arylester) dendrons. New products have been characterized by means of ¹H and ¹³C NMR, MS and IR data. The crystal structures of the 3-Boc–(L)-phenylalanyloxy, 3-Ac–(D,L)-alanyloxy and (3′,5′-dibenzyloxy)-3-benzyloxy derivatives of salophbac Ni(II) complexes have been determined. The supramolecular C–H⋯π, π⋯π interactions and hydrogen bonds are discussed on the basis of the crystallographic data.