The Slipping Approach to Self-Assembling [n]Rotaxanes
摘要:
A synthetic approach-namely slippage-to self-assembling [n]rotaxanes incorporating pi-electron deficient bipyridinium-based dumbbell-shaped components and pi-electron-rich hydroquinone- and/or dioxynaphthalene-based macrocyclic polyether components has been developed. The kinetics of rotaxane formation by the slipping procedure were investigated by absorption UV-visible and H-1-NMR spectroscopies in a range of temperatures and solvents, varying systematically the size of both the stoppers and the macrocyclic components. As expected, the rate constants for these processes are affected by the size complementarity between macrocycles and stoppers. Furthermore, the enthalpic and entropic contributions to the free energies of activation associated with the slippage and the effect of solvent polarity upon the outcome of these processes have been evaluated. In addition, the spectroscopic and electrochemical properties of some of the rotaxanes are presented and discussed with reference to the properties of their chromophoric and electroactive units.
The multicomponent reaction of 1,2-di(4-pyridyl)ethylene, catechol, 3,5-bis(trifluoromethyl)phenylboronic acid and 1,5-dinaphtho-38-crown-10 or bis-para-phenylene-34-crown-10, respectively, resulted in the formation of rotaxanes, which were characterized by X-ray crystallography.
The dynamic and electrochemical properties of two new [2]catenanes, in which bisparaphenylene-34-crown-10 is encircled by a cyclophane incorporating either (i) one bipyridinium and one bis(pyridinium)ethylene unit or (ii) two bis(pyridinium)ethylene units, are investigated in solution.
Controlling Catenations, Properties and Relative Ring-Component Movements in Catenanes with Aromatic Fluorine Substituents
作者:Roberto Ballardini、Vincenzo Balzani、Alberto Credi、Christopher L. Brown、Richard E. Gillard、Marco Montalti、Douglas Philp、J. Fraser Stoddart、Margherita Venturi、Andrew J. P. White、Brian J. Williams、David J. Williams
DOI:10.1021/ja970640a
日期:1997.12.1
of the hydroquinone rings in bis-p-phenylene-34-crown-10 had only a small effect on the percentage yields, whereas employing bis-p-phenylene-34-crown-10 derivatives, in which both hydroquinone rings have been at least partially fluorinated, resulted in a dramatic decrease in catenation yields. In [2]catenanes incorporating macrocyclic polyethers containing one hydroquinone and one fluorinated hydroquinone
Templated Synthesis of Desymmetrized [2]Catenanes with Excellent Translational Selectivity
作者:Yi Liu、Liana M. Klivansky、Saeed I. Khan、Xiyun Zhang
DOI:10.1021/ol070970s
日期:2007.6.1
Desymmetrized [2]catenanes were synthesized and shown to exhibit excellent translational selectivity. The templated synthesis takes effect from the formation of pseudorotaxanes between pi-rich crownethers and a pi-deficient pyromellitic (PmI) unit, followed by macrocyclization around the crownethers with the creation of a bipyridinium (BPy) unit. The crownethers preferably encircle the BPy unit
Regioselective Catenation of Dinuclear Palladium and Platinum Metallocycles Promoted by π···π Interactions
作者:Víctor Blanco、Dolores Abella、Elena Pía、Carlos Platas-Iglesias、Carlos Peinador、José M. Quintela
DOI:10.1021/ic8022425
日期:2009.5.4
4′-bipyridine and palladium or platinumsquare-planar cis complexes. The palladium (4a,b) or platinum (5a,b) square metallocycles were obtained as 1:1 regioisomeric mixtures depending on which pair of coordinative nitrogen atoms binds to the metal center. The squares display a π-deficient cavity suitable to incorporate two π-donor aromatic systems. Therefore, the reaction with macrocyclic polyethers (BPP34C10