Related Experiment Video
Updated: Jul 16, 2026
Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR
Published on: December 16, 2013
Crystallographic Characterization of Stepwise Changes in Ligand Conformations as Their Internal Topology Changes and
Timothy J. Hubin1, James M. McCormick, Nathaniel W. Alcock
1Chemistry Departments, The University of Kansas, Lawrence, Kansas 66045, and University of Warwick, Coventry CV4 7AL, England.
Abstract:
The parallel syntheses of two new cross-bridged tetraazamacrocyclic complexes whose ligands are derived from 1,4,8,11-tetraazacyclotetradecane (cyclam = 14N4) and rac-1,4,8,11-tetraaza-5,5,7,12,12,14-hexamethylcyclotetradecane (tetB = 14N4Me(6)) have been characterized through the crystal structure determination of every stepwise intermediate ligand in the multistep ligand syntheses. These structures show that although the final ligand skeletons are nearly identical, the immediate precursors differ greatly because of the six additional methyl groups of the 14N4Me(6) macrocycle. The inversion from one diastereomer to another of the tetracycle derived from rac-14N4Me(6) has been chemically induced through the successive addition of methyl groups to the reactive tertiary nitrogens, and the novel heterocycles produced have been crystallographically characterized with one showing a conformation not previously known for these systems. The structures of the two copper(II) complexes have significant geometrical differences, and accordingly, their electrochemical and spectroscopic properties are compared. The complexes exhibit remarkable kinetic stability under harsh conditions.
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