Self-assembly of a family of suprametallomacrocycles: revisiting an o-carborane bisterpyridyl building block

• Published in: Dalton transactions : an international journal of inorganic chemistry 2014-07, Vol.43 (25), p.9604-9611
• Main Authors: Ludlow Iii, James M, Tominaga, Masato, Chujo, Yoshiki, Schultz, Anthony, Lu, Xiaocun, Xie, Tingzheng, Guo, Kai, Moorefield, Charles N, Wesdemiotis, Chrys, Newkome, George R
• Format: Article
• Language: English
• Subjects: Boron Compounds - chemistry; Coordination Complexes - chemistry; Crystallography, X-Ray; Dimers; Dynamical systems; Dynamics; Iron - chemistry; Kinetics; Ligands; Macrocyclic Compounds - chemistry; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Structure; Monomers; Nuclear magnetic resonance; Pyridines - chemistry; Self assembly; Spectrometry, Mass, Electrospray Ionization; Temperature; Thermodynamics; Transition metals; Zinc - chemistry
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c4dt00989d

The self-assembly of the o-carborane-based, bisterpyridyl monomer, 1,2-bis[4'-(4-ethynylphenyl)-2,2':6',2''-terpyridine]-o-carborane, utilizing either Zn(II) or Fe(II) in a precise metal : ligand ratio (1 : 1), generated a family of metallomacrocycles that were studied via ESI-TWIM-MS, (1)H NMR, and 2D NMR (COSY, NOESY). Under kinetic control, via formation of Fe(II) complexes, the main cyclic product was triangular, as is typical of 60°-based bisligands. Under thermodynamic control using more labile transition metal complexes, e.g. Zn(II), the ratio of cyclic species was found to be concentration and temperature dependent, and under an adequate entropic driving force, the cyclic dimer was formed. This system was probed via variable temperature NMR to reveal dynamic equilibrium between the entropically favored dimer and enthalpically favored trimer.