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

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 L^2´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).