Molecular pendulum

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Example of a molecular pendulum in which a macro cycle (green) moves between two stations (yellow).

In supramolecular chemistry, a molecular pendulum is a special type of molecular machine that is able to transport molecules or ions from one place to another. This research area is relevant to nanotechnology in the development of electronic connections on the nanoscale and also to biology , where biochemical functions are based on molecular pendulums. There is an academic interest in the synthesis of such compounds, the first prototype of which was described in 1991 and is based on rotaxanes .

This device is based on a connection consisting of an ethylene glycol chain bounded by two benzene rings , the so-called stations. The endpoints or stoppers of this cable are bulky triisopropylsilyl groups . The pearl on the string is a quadruple positively charged cyclophane , consisting of two bipyridine groups and two phenyl groups . The bead is attracted to one of the stations by π-π interactions, but since the activation energy for movement from one station to the other is only 54 kJ / mol, the bead shuttles between the two. The stoppers prevent the pearl from falling. The chemical synthesis of this device is based on molecular self-organization from a chain and two pearl fragments. The yield of the reaction is 32%.

Educts for a molecular pendulum
Molecular Pendulum

Many a molecular switch also has two unequal stations.

literature

  • J.-M. Lehn: Supramolecular Chemistry: Concepts and Perspectives. VCH, Weinheim 2015, ISBN 978-3-527-29312-4 .
  • F. Vögtle: Supramolecular Chemistry . Teubner, Stuttgart 1992, ISBN 3-519-13502-7 .
  • Sundus Erbas-Cakmak, David A. Leigh, Charlie T. McTernan, Alina L. Nussbaumer: Artificial Molecular Machines . In: Chemical Reviews . tape 115 , no. 18 , 23 September 2015, p. 10081-10206 , doi : 10.1021 / acs.chemrev.5b00146 .
  • Richard A. Bissell, Emilio Córdova, Angel E. Kaifer, J. Fraser Stoddart: A chemically and electrochemically switchable molecular shuttle . In: Nature . tape 369 , no. 6476 , May 12, 1994, pp. 133-137 , doi : 10.1038 / 369133a0 .
  • A. Credi: Molecular Machines and Motors A2 . In: David L. Andrews, Gregory D. Scholes, Gary P. Wiederrecht (Eds.): Comprehensive Nanoscience and Technology . Vol. 4. Academic Press, Amsterdam 2011, ISBN 978-0-12-374396-1 , 4.12, pp. 339-382 , doi : 10.1016 / B978-0-12-374396-1.00133-1 .
  • Marcos Gómez-López, J. Fraser Stoddart: Molecular and supramolecular nanomachines A2 . In: Hari Singh Nalwa (Ed.): Handbook of Nanostructured Materials and Nanotechnology . Academic Press, Burlington 2000, ISBN 978-0-12-513760-7 , Chapter 3, pp. 225-275 , doi : 10.1016 / B978-012513760-7 / 50055-1 .

Individual evidence

  1. ^ Pier Lucio Anelli, Neil Spencer, J. Fraser Stoddart : A molecular shuttle . In: Journal of the American Chemical Society . tape 113 , no. 13 , June 1, 1991, pp. 5131-5133 , doi : 10.1021 / ja00013a096 .