Double-stranded monohelical complexes from an unsymmetrical chiral Schiff-base ligand.
A new Schiff-base ligand is prepared by a two-step reaction of 3-formylsalicylic acid and (1R, 2R)-diaminocyclohexane in alcoholic solvents. The 1:1 condensation product exists as a zwitterion in the solid state and forms pleated hydrogen-bonded sheets. Metalation of the ligand with divalent iron, nickel, cobalt, and zinc resulted in the formation of double-stranded monohelices with exclusively M-helicity. Each complex has two tridentate ligands, with the carboxylic acid groups remaining uncoordinated. In the crystal lattice, these complexes form extended M-helical strands through intermolecular hydrogen bonding interactions. Metalation of the ligand with copper salts resulted in a distinctly different type of complex, in which the ligand has transformed into a symmetric tetradentate salen ligand with uncoordinated carboxylic acid groups.
Lalehzari
Azadeh
A
Department of Chemistry, Kansas State University, 111 Willard Hall, Manhattan, Kansas 66506, USA.
Desper
John
J
Levy
Christopher J
CJ
D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D012545:Schiff Bases; D013237:Stereoisomerism
D008024:Ligands; D012545:Schiff Bases