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Roger E. Cramer, Professor Emeritus

Contact

Department of Chemistry
University of Hawai’i at Manoa
2545 McCarthy Mall
Honolulu, HI 96822-2275

Phone: (808) 956-7192
Fax: (808) 956-5908
Email: Roger Cramer
Office: Bilger 205B

Educational Background

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.

Research Interests

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.

Recent Publications

  • Ariyaratne, Kanahara A. N. S.; Cramer, Roger E.; Jameson, Geoffrey B.; Gilje, John W. Uranium-sulfilimine chemistry. Hydrolysis of Cp*2UCl2 with HNSPh2×H2O and the crystal structure of Cp*2UCL(OH)(HNSPh2), a metallocene terminal hydroxy complex of tetravalent uranium. Journal of Organometallic Chemistry 2004, 689, 2029-2032.
  • Ariyaratne, Kanahara A. N. S.; Cramer, Roger E.; Gilje, John W. Uranium-Sulfilimine Chemistry: Synthesis and Characterization of Cp*2UCl(NSPh2) and Cp*2U(NSPh2)2. Organometallics 2002, 21, 5799-5802.
  • Morales-Morales, David; Cramer, Roger E.; Jensen, Craig M. Enantioselective synthesis of platinum group metal complexes with the chiral PCP pincer ligand R,R-{C6H4-2,6-(CH2P*PhBut)2}. The crystal structure of R,R-PdCl{C6H3-2,6-(CH2P*PhBut)2}. Journal of Organometallic Chemistry 2002, 654, 44-50.