Quantifying supramolecular interactions using modern numerical techniques

ORGN 697

Travis B. Gasa, gasa@chem.ucla.edu1, Jason M. Spruell, jspruell@chem.ucla.edu1, William R. Dichtel, wdichtel@chem.ucla.edu2, Petr Kuzmic3, and J. Fraser Stoddart, stoddart@chem.ucla.edu1. (1) California NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, CA 90095-1569, (2) Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Dr. East, Los Angeles, CA 90095-1569, (3) BioKin, Ltd, Pullman, WA 99163
The design of new bistable catenanes and rotaxanes for applications in molecular electronics1 or nanoelectromechanical systems (NEMS) can be predicated on the basis of a precise understanding of the host-guest chemistry of the relevant macrocycles with appropriate guest molecules.2 In the course of developing a new class of bistable rotaxanes containing macrocyclic polyethers and dicationic viologen guests, we found that the observed association constant between dibenzo-24-crown-8 (DB24C8) and methyl viologen dihexafluorophosphate (MV) exhibits an apparent dependence on the concentration used for the binding study. Though this observation had previously been reported3 and interpreted as differences in ion-pairing between free and bound MV, we have found compelling evidence for the formation of 2:1 (DB24C8:MV) complexes in solution. Modern curve-fitting techniques4 were utilized to develop a more complete model for the binding and ion-pairing processes of the two neutral crown ethers to MV guests (Box).

(1) Flood, A. H.; Stoddart, J. F.; Steuerman, D. W.; Heath, J. R. Science 2004, 306, 2055–2056. (2) Choi, J. W.; Flood, A. H.; Steuerman, D.; Nygaard, S.; Braunschweig, A. B.; Moonen, N. N. P.; Laursen, B. W.; Luo, Y.; DeIonno, E.; Peters, A. J.; Jeppesen, J. O.; Xu, K.; Stoddart, J. F.; Heath, J. R. Chem. Eur. J. 2006, 12, 261–279. (3) Huang, F.; Jones, J. W.; Slebodnick, C.; Gibson, H. W. J. Am. Chem. Soc. 2003, 125, 14458–14464. (4) Kuzmic, P. Anal. Biochem. 1996, 237, 260–273.

 

Asymmetric Reactions, Combinatorial Chemistry, Molecular Recognition and Self-Assembly, Proteins, Peptides, Amino Acids and Enzyme Inhibitors
8:00 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster

Division of Organic Chemistry

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007