Synthesis, coordination properties and DFT studies of novel trans-disubstituted hexaaza-macrocycles containing pyridine and/or ethyldioxolane arms

Abstract

Novel trans-disubstituted hexaaza-macrocyclic ligands L1 and L2 were successfully prepared by the alkylation of the trans secondary amines presented in L with pyridine and ethyldioxolane groups, respectively. The coordination properties of compounds L1 and L2 towards different transition, post-transition and lanthanoid metal ions were explored. Colorless crystals of [NaL1]I and L2´Br2, suitable for X-ray diffraction, were obtained by slow evaporation of an acetonitrile solution of compounds L1 or L2, showing an anti conformation between the methyl groups and the pendant arms in trans positions. The [ML1]n+ (M = Ni2+, Cu2+, Zn2+) systems were investigated by DFT calculations (B3LYP model).