ISMSC 2007 - Università degli Studi di Pavia

PSA 45
A fast-moving electrochemically-driven molecular shuttle: the biisoquinoline
effect.
Fabien Durola, Jean-Pierre Sauvage
Laboratoire de Chimie Organo-Minerale, UMR 7177 du CNRS
Institut de Chimie, Université Louis Pasteur, 4 rue Blaise Pascal, 67000 Strasbourg, France
Two different copper-complexed [2]rotaxanes have been prepared and their
electrochemically triggered motions have been investigated. Both compounds contain the same
thread, which consists of a 2,9-diphenyl-1,10-phenanthroline (dpp) chelate and a 2,2',6',2''terpyridine
(terpy) unit, whereas the threaded rings are different. In the first case, it is a 30membered
ring derived from dpp. In the second compound, the ring incorporates a 8,8'diphenyl-3,3'-bi-isoquinoline
(dpbiiq) chelate, which is at the same time non sterically hindering
but endocyclic. By playing with the stereoelectronic preferences of copper (I) and copper (II),
the ring with its complexed copper atom can be translocated from one station to the other
reversibly. For the dpp-containing ring, the electrochemically-driven motion is extremely slow
(hours to days). By contrast, the dpbiiq-based system is set in motion very readily, the
translation process occuring in the milliseconds to seconds timescale, i.e. at least 4 orders of
magnitude faster than for its dpp-based homologue. [1]
[1] F. Durola, J.-P. Sauvage, Angew. Chem. Int. Ed., 2007, in press.
PSA 46
Efficient synthesis of copper(I)-rotaxane complexes via « click chemistry »
Stéphanie Durot a , Pierre Mobian a , Jean-Paul Collin a , Jean-Pierre Sauvage a
a Institut de Chimie de Strasbourg, Laboratoire de Chimie Organo-Minérale, Université Louis
Pasteur, 4 rue Blaise Pascal, F-67070 Strasbourg cedex, France
In the course of the last 15 years, the field of rotaxanes has experienced a spectacular
development, mostly in relation to molecular machines [1, 2] and new materials. Threads and
rings can be quantitatively assembled using copper(I) as a template. Pseudo-rotaxanes are
then converted to rotaxanes by a stoppering reaction, that can be the limiting step, since the
reaction conditions have to be compatible with the other functions present in the precursor. The
efficient synthesis of new rotaxanes using « click chemistry » is described here.
« Click chemistry » [3, 4] is a modular approach that relies on near perfect reactions. These
reactions must be wide in scope, give very high yields, proceed from readily available reagents,
and be easy to perform (that means ideally, be insensitive to oxygen and water). They should
also be selective chemical transformations, and the workup as well as the product isolation
should be simple. The prototype of a « click » reaction is the 1,3-dipolar cycloaddition of azides
and alkynes, and especially the copper(I)-catalyzed synthesis of 1,2,3-triazoles.
This reaction has been used for the synthesis of new copper(I)-rotaxane complexes by a double
stoppering approach. The remarkable efficiency of such a strategy has to be emphasized, with
yields ranging from 60 to 65 % (scheme 1). [5] The mild reaction conditions of the « click
chemistry » methodology are clearly very well adapted to the synthesis of copper(I)-rotaxane
complexes, especially when copper(I)-complex precursors are relatively unstable. It is expected
that such methodology will also be suitable for more elaborate rotaxanes.
N 3
N N
Cu
N N
I
N3 O
O O
O
O
O
N N
Cu
N N
I
O
O O
O
O
O
, PF 6
N3
, PF6 N3 i)
62 %
i)
65 %
O
O
N
N
N
N N
Cu
N N
I
O
O O
O
O
O
, PF 6
N N
Cu
N N
I
N N
O
O O
N
N
N
N
O
O
O
i) 3 eq. 4-[tris[(t-butyl)phenyl]methyl]phenyl propargyl ether
0.5 eq. Cu(CH 3CN) 4.PF 6, 0.4 eq. Na 2CO 3, CH 2Cl 2/CH 3CN (7/3), 20 C, 21 h
O
, PF6 N
N O
N
Scheme 1: synthesis of a Cu(I)-rotaxane complexes via « click chemistry ».
[1] V. Balzani, M. Venturi, A. Credi, Molecular Devices and Machines - A journey into the
Nanoworld, Wiley-VCH, Weinheim, 2003.
[2] B. Champin, P. Mobian, J.-P. Sauvage, Chem. Soc. Rev. 2007, 36, 358.
[3] H. C. Kolb, M. G. Finn, K. B. Sharpless, Angew. Chem. Int. Ed. 2001, 40, 2004
[4] H. C. Kolb, K. B. Sharpless, Drug Discov. Today 2003, 8, 1128.
[5] P. Mobian, J.-P. Collin, J.-P. Sauvage, Tetrahedron Lett. 2006, 47.