Molecular turnstiles

Mir Wais Hosseini

Université de Strasbourg, Institut Le Bel, UMR CNRS 7140, Tectonique Moléculaire, 4, rue Blaise Pascal, 67000 Strasbourg, France, Hosseini@unistra.fr

Movement plays a fundamental role in the living world.2 Biological motors of the linear type based on myosine1

or kinesine2 have been discovered and studied. A rotary motor based on ATPase has been also described.3

Molecular translational or rotational motors are molecular architecture for which movements between a fixed and

a mobile portion may be induced by external stimuli. 4 As a first step towards molecular motors, a series of

molecular turnstiles have been designed and synthesized. The first category is based on Sn(IV)porphyrins as

stators bearing at the meso positions interactions sites and equipped with different handles as rotors. The

connection between stators and rotors is achieved through Sn-O (Fig. 1).5-10

Fig. 1: Schematic representations of the tetra substituted porphyrin (a), introduction of the hinge (b) and connection of the handle bearing a monodentate site and the locking of the rotor with an effector (green sphere)(c).

The second design principle is based on the covalent attachment of the rotor to the stator using two opposite meso

positions on the porphyrin backbone (strapped porphyrins) (Fig. 2).11,12

Fig. 2: Schematic representations of porphyrin based turnstile(closed (left) and open (right) states). The rotor bearing an interaction site is covalently connected to the stator using two opposite meso positions on the porphyrin backbone.

Finally, the tired approach is based on organometallic Pt complexes as rotors and coordinating handles as stators (Fig. 3).13

Fig. 3 Schematic representation of the molecular turnstile composed of a handle (red) bearing a central coordinating site and a rotor composed of a hinge (yellow, Pt(II)) and two interaction sites. The presence of the effector (green) induces the closing of the turnstile.

The design, synthesis and structural characterisations, both in solution by multidimensional 1H-NMR techniques and in the solid state by X-ray diffraction on single crystals, of a series of molecular gates and turnestils of both categories is presented and discussed. References 1 J. T. Finer, R. M. Simmons, J. A. Spudlich, Nature 1994, 368, 113; 2 M. Whittaker, E. M. Wilson-Kubalek, J. E. Smith, L. Faust, R. A. Milligan, H. L. Sweeney, Nature 1995, 378, 748. 2 E. P. Sabin, F. J. Kull, R. Cook, R. D. Vale, R. J. Fletterick, Nature 1996, 380, 555; E. Meuhöfer, J. Howard, Proc. Natl. Acad. Sci. U.S.A., 1995, 92, 574. 3 T. Elston, H. Wang, G. Oster, Nature 1998 391, 510; H. Noji, R. Yasuda, M. Yoshida, K. Kinosita Jr., Nature 1997, 386, 299. 4 J.-P. Sauvage, Science, 2001, 291, 2105; J. P. Sauvage, Acc. Chem. Res. 1998, 31, 611; V. Balzani, M. Gomez-Lopez, J. F. Stoddart, Acc. Chem. Res. 1998, 31, 405; W. R. Browne, B. L. Feringa, Nature Nanotechnology, 2006, 1, 25; E. R. Kay, D. A. Leigh, F. Zerbetto, Angew. Chem. Int. Ed, 2007, 46, 72. 5 A. Guenet, E. Graf, N. Kyritsakas, L. Allouche, M. W. Hosseini, Chem. Commun. 2007, 2935. 6 A. Guenet, E. Graf, N. Kyritsakas, M. W. Hosseini, Inorg Chem., 2010, 49, 1872. 7 T. Lang, A. Guenet, E. Graf, N. Kyritsakas, M. W. Hosseini, Chem. Commun., 2010, 46, 3508. 8 T. Lang, E. Graf, N. Kyritsakas and M. W. Hosseini, Dalton Trans., 2011, 40, 3517. 9 T. Lang, E. Graf, N. Kyritsakas and M. W. Hosseini, Dalton Trans., 2011, 40, 5244 10 A. Guenet, E. Graf, N. Kyritsakas and M. W. Hosseini, Chem. Eur. J., 2011, 17, 6443. 11 T. Lang, E. Graf, N. Kyritsakas and M. W. Hosseini, Chem. Eur. J., 2012, 33, 10419. 12 T. Lang, E. Graf, N. Kyritsakas and M. W. Hosseini, New J. Chem., 2013, 37, 112. 13 N. Zigon, A. Guenet, E. Graf, M. W. Hosseini, Submitted.