摘要:
The copper(II)-assisted condensation of 2,3,2-tet (3,7-diazanonane-1,9-diamine) with formaldehyde and cyclopentanone yields the mono- and bis-macrocyclic Mannich condensation products L-1 and L-2, as well as the Schiff-base product L-3, all with cyclam-type tetraaza macrocycles, coordinated to copper(II). The combination of molecular mechanics and EPR spectroscopy (MM-EPR) reveals that all three isomers of [Cu-2(L-2)(OH2)(n)](2) (n = 0-4), with the expected trans-III (R,R,S,S) configuration of the 14-membered tetraaza macrocycles, are of similar stability, and that the isomer whose structure is solved by X-ray crystallography has a different structure in solution.