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The Slipping Approach to Self-Assembling [ n ]Rotaxanes

1997; American Chemical Society; Volume: 119; Issue: 2 Linguagem: Inglês

10.1021/ja961817o

1943-2984

Masumi Asakawa, Peter R. Ashton, Roberto Ballardini, Vincenzo Balzani, Martin Bělohradský, Maria Teresa Gandolfi, Oldřich Kocián, Luca Prodi, Françisco M. Raymo, J. Fraser Stoddart, Margherita Venturi,

Molecular Sensors and Ion Detection

A synthetic approachnamely slippageto self-assembling [n]rotaxanes incorporating π-electron deficient bipyridinium-based dumbbell-shaped components and π-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 1H-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.