Electrochemical switching of bistable liquid crystalline [2]rotaxanes

ORGN 187

Karla K Coti, coti@chem.ucla.edu, Ivan Aprahamian, Taichi Ikeda, ikeda@chem.ucla.edu, William R. Dichtel, wdichtel@chem.ucla.edu, Sourav Saha, and J. Fraser Stoddart, stoddart@chem.ucla.edu. California NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, CA 90095-1569
Liquid crystals are ordered condensed states of molecules that can be used as dynamic functional materials which have significant roles to play in information transport, sensing and catalysis, as well as in electro-optical displays.1 Despite the potentially useful characteristics of light and heat-responsive systems, redox-responsive bistable liquid crystals are relatively unexplored materials.2 It was for this reason that that we decided to try and align electrochemically switchable, bistable [2]rotaxanes within liquid crystalline (LC) phases.

Recently, we demonstrated that the incorporation of cyclohexylbiphenyl-based mesogenic stoppers (BOX – purple) at the ends of the rod section of the dumbbell component of a switchable donor-acceptor [2]rotaxane, induces the formation of a Smectic A LC phase over a wide range of temperatures.3 According to small-angle X-ray scattering measurements, the bistable [2]rotaxane (BOX), which encompasses a tetracationic cyclophane (blue) a tetrathiafulvalene unit (green) and a 1,5-dioxynaphthalene unit (red), self-assembles into an LC phase with a layer spacing of about 8 nm.

Here, we present the electrochemical switching of the recently reported LC bistable [2]rotaxanes in both the liquid and LC phases. The electrochemical switching in the LC phase is studied in two-electrode sandwich devices in both the neat phase and in a polymer matrix and the LC properties of the systems are simultaneously monitored.

1. (a) Thermotropic Liquid Crystals (Ed.: G. W. Gray), Wiley, Chichester, 1987; (b) T. Kato, Science , 2002, 295, 2414–2418. 2. M. Sawamura, K. Kawai, Y. Matsuo, K. Kanie, T. Kato, E. Nakamura, Nature, 2002, 419, 702–705. 3. I. Aprahamian, T. Yasuda; T. Ikeda; S. Saha; W. R. Dichtel, K. Isoda, T. Kato, J. F. Stoddart, Angew. Chem. Int. Ed. In press.

 

Total Synthesis, Materials, Devices and Switches, Molecular Recognition and Self-Assembly, Biologically-Related Molecules and Processes
8:00 PM-10:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Organic Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007