Roger E. Cramer

Professor

University of Hawaii at Manoa
Department of Chemistry
2545 The Mall, Honolulu,
HI 96822-2275

Phone: (808) 956-5163
Fax: (808) 956-5908
Email: rogerc@gold.chem.hawaii.edu

 

  

Roger Cramer received a B.S. in Chemistry from Bowling Green State University in 1965, an M.S. from the University of Illinois in 1967, and a Ph.D. from the University of Illinois in 1969. He joined the faculty of the University of Hawaii in 1969. His current interests are in molecular recognition, supramolecular chemistry and bioinorganic chemistry.

 
 

    Our research is focused on the structure and bonding of supramolecular complexes and coordination compounds via the use of multiple physical methods, but primarily through the use of x-ray crystallography. Other physical methods used include NMR spectroscopy, IR, Raman, visible, and UV spectroscopy.

    We have observed that the decomposition of thiamin mononitrate in methanol leads to a hexacationic macrocycle, [24-Pyrimidinium Crown 6]6+. Utilizing x-ray diffraction techniques, it has been shown that this cation not only associates strongly with simple nitrate ions,1 but also with the previously unknown [Hg2I7]3- ion2 and the novel [Pb(NO3)6]4- ion.3 Recent work has shown that this cationic macrocycle will also associate with [Co(NCS)4]2- and [M(C2O4)3]3- ions.

    The macrocycle possesses a flexible cavity with a diameter which ranges from 2.67 Å to 4.14 Å , depending on the species associated with it. This gives it the ability to associate with a wide variety of guest molecules. The most recent work in our group has revolved around the formation of rotaxane complexes, in which a linear molecule is threaded through the macrocycle and capped by a bulky end group to prevent dissociation of the two. To date, we have prepared and studied crystallographically three pseudorotaxane complexes in which the neutral 2-butyne-1,4-diol and 2,4-hexadiyne-1,6-diol, and the acetylenedicarboxylate anion are threaded through the center of the cation.

    The major force which acts to stabilize these complexes has been found to be unusually strong C-H X hydrogen bonds, where X = O or C (pi cloud of the triple bond). These complexes present exciting possibilities in the ever broadening field of inclusion chemistry, including our ultimate goal of a molecular electrostatically driven, optically readable switch.

 
 

Representative Publications

  1. "Crystal Structures of the Nitrate Salt of 24-Pyrimidinium Crown 6...and its Degradation Product in Water-Methanol Mixtures,"R.E. Cramer, C.A. Waddling, C.H. Fujimoto, D.W. Smith and K.E. Kim, J. Chem. Soc., Dalton Trans., 1997, 1675.
  2. R.E. Cramer and M.J. Carrie, Inorg. Chem., 1990, 29, 3902.
  3. "Crystal Structures of [Pb(NO3)6]4- and [Ba(NO3)6]4- Salts of 24-Pyrimidinium Crown 6," R.E. Cramer, K.A. Mitchell, A.Y. Hirazumi, and S.L. Smith, J. Chem. Soc.,Dalton Trans., 1994, 563.
  4. "Synthesis and Structure of the Chloride and Nitrate Inclusion Complexes of [16-Pyrimidinium Crown 4]4+," R.E. Cramer, V. Fermin, E. Kuwabara, R. Kirkup, M. Selman, K. Aoki, A. Adeyamo, and H. Yamazaki, J. Am. Chem. Soc., 1991, 113, 7033.

 
Last updated 06/04/01