SYNTHESIS OF BENZYL-1,4,7,10-TETRAAZACYCLOTRIDECANE-11,13-DIONE AND PROPERTIES OF ITS COPPER(II) COMPLEX

Reduction of benzopyran-3-carboxylic acid 2-oxo-ethyl ester with sodiu m borohydride and then aminolysing the products with triethylenetetraa mine, without isolation, gave the ligand enzyl-1,4,7,10-tetraazacyclot ridecane-11,13-dione. The H-3L ligand can be diprotonated. [CuL]- and [Cu(HL)] complexes are formed in aqueous solution by the extrusion of two hydrogen ions from the amido groups and one from the phenol hydrox yl. The copper(II) complex is of axial symmetry; in its EPR spectra, t he g and A parameters are obviously different from those of similar co mplexes without the phenolic hydroxyl. Two redox processes appeared in the cyclic voltammogram in the range -0.1 to -0.8 V (vs S.C.E): one i s the oxidation of the phenol hydroxyl and the other is the oxidation of copper(II) to (III), the former being irreversible and the latter q uasireversible.