Recent Developments on Rotaxane-Based Shuttles: An Update to 2010

Author(s): Antonio Rescifina , Ugo Chiacchio , Antonino Corsaro , Giovanni Romeo .

Journal Name: Current Organic Chemistry

Volume 16 , Issue 2 , 2012

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Abstract:

This update reviews the major developments on rotaxane-based shuttles during the period of August 2008 to October 2010 and is organized similarly to the previous review [1].

The progress in the field of chemical controlled shuttles can be summarized as a significant increase of the shuttling rates, second-generation pH-switchable Pd(II)-complexed rotaxanes, and new synthetic approaches, especially those based on Diels-Alder cycloadditions. The new synthetic routes allow ready access to rotaxanes that feature the template site fully incorporated into the interlocked product. This template site is unusual for active-template reactions and produces shuttles that exhibit entropy-driven translational isomerism with remarkably improved positional discrimination as was shown by the incorporation of a hydrogen-bonding TEG-station into an imine-bridged rotaxane.

With respect to photochemically powered molecular switches, the most important result originated from the synthesis of a degenerate, donor-acceptor, light-gated, STOP-GO molecular shuttle. For electrochemically controllable bistable rotaxanes, the first example of a molecular shuttle with three different stations, which dramatically increase the shuttling process rate, has been reported.

Finally, the last study in this review involves redox-driven switching and electrochromic responses of LC films containing a bistable [2]rotaxane. The presence of a polymer electrolyte provides new prospects for the further development of rotaxane-based molecular materials by exploiting the dynamic, anisotropic, and coherent properties of liquid crystals.

Keywords: Mechanically interlocked molecules, Click chemistry, Molecular devices, Nanoscale machines, Rotaxane-Based, Shuttles, interlocked machines, chemically, photochemically, electrochemically, induced molecular, ring component, molecules, synthetic methodologies, kinetics

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Article Details

VOLUME: 16
ISSUE: 2
Year: 2012
Page: [127 - 160]
Pages: 34
DOI: 10.2174/138527212798993040

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