DONALD J. CRAM

Professor Emeritus; BS, Rollins College; MS, University of Nebraska; Research Chemist, Merck & Co.; PhD, Harvard University; National Academy of Sciences; ACS Award for Creative Work in Synthetic Organic Chemistry; American Academy of Arts and Sciences; ACS Cope Award for Distinguished Achievement in Organic Chemistry; California Scientist of the Year Award; Honorary Doctor of Science degrees from Uppsala University, Sweden, the University of Southern California, Rollins College, the University of Nebraska, the University of Western Ontario, Canada, and the University of Sheffield, England; Southern California ACS R.C. Tolman Award; Chicago Section ACS Gibbs Medal; first holder of Saul Winstein Chair in Organic Chemistry; ACS Roger Adams Award; Nobel Prize; University Professor; Glenn T. Seaborg Award; National Academy of Sciences Award in Chemical Sciences; President, National Medical Sciences.

Research Description

Inspired by the model of evolutionary biological systems, the Cram research group is engaged in investigating host-guest complexation chemistry. Host multiheteromacrocycles with convergent binding sites embedded in concave surfaces converge on the binding sites of complementary guest compounds with divergent binding sites composing or attached to convex surfaces. Binding forces are the sum of many host-guest contacts involving van der Waals attractions, hydrogen bonding, dipole-dipole attractions, ion-pairing, ligand to metal ion attractions, and solvophobic interactions. Structural recognition (including chiral recognition) in binding is applied to separations of enantiomers, to analyzing for Li[+], Na[+], and K[+] in serum, and to separation science and catalysis. Highly preorganized hosts (spherands, cavitands, and carcerands) are designed and synthesized. Correlations between structure and binding, structure and physical properties, structure and catalytic properties, and structure and separation are sought. Crystal structures are correlated with solutions structures using NMR spectra. Elaborate syntheses (up to 30 steps) are conducted, followed by physical-organic measurements.

The reactions of guest molecules imprisoned in the interior of rigidly hollow spherical host molecules (carceplexes) are being actively pursued. Potential uses of carceplexes include drug and radiation delivery systems, light switches, or molecular information storage and retrieval display systems (MISARDS). Guests, such as cyclobutadiene which ordinarily self-destructs, are stable when contained inside the shell of a carcerand. Benzyne has been synthesized and studied in the inner phase of a carcerand.

Key words:

Biomimetic Chemistry: structurally preorganized host compounds are designed and synthesized to bind guest compounds with high chiral and structural recognition for study of complexes, catalysts, ionophores, and molecular sensors.

Representative Publications:

1. "Container Molecules and Their Guests," by D.J. Cram and J.M. Cram, Monographs in Supramolecular Chemistry, J. Fraser Stoddart, Ed., The Royal Society of Chemistry, Cambridge, 1994.

2. "Spherands: Hosts Preorganized for Binding Cations," by E. Maverick and D.J. Cram, in "Comprehensive Supramolecular Chemistry," Vol. 1, J.-M. Lehn, Ed., Elsevier Science Ltd., 1996.

3. "Carcerands and Hemicarcerands: Hosts that Imprison Molecular Guests," by E. Maverick and D.J. Cram, in "Comprehensive Supramolecular Chemistry," Vol. 2, J.-M. Lehn, Ed., Elsevier Science Ltd., 1996.

4. Hemicarcerands with Interiors Potentially Capable of Binding Large Guests, J. Chem. Soc., Chem. Commun., 1995, 1085-1087, by C.v.d. Bussche-Hunnefeld, D. Buhring, C.B. Knobler and D.J. Cram.

5. Comparisons of Activation Energies for Dimethyl Sulfoxide Rotations in the Inner Phase of Seven Carcerands, J. Chem. Soc., Chem. Commun. 1995, 1259-1260, by S.K. Kurdistani, T.A. Robbins and D.J. Cram.

6. Comparisons of Activation Energies for Guest Escapes from the Inner Phases of Hemicarcerands with Varying Numbers of Bowl-linking Groups, J. Chem. Soc., Chem. Commun. 1995, 1515-1516, by T.A. Robbins and D.J. Cram.

7. Binding Properties and Crystal Structure of a Hemicarcerand Containing Four Diethylene Glycol Units Connecting Two Bowls, J. Chem. Soc., Chem. Commun., 1995, 1825-1827, by Y.-S. Byun, O. Vadhat, M.T. Blanda, C.B. Knobler and D.J. Cram.

8. Stepwise Shell Closures Provide Hosts That Expose or Protect Guests from Outer-Phase Reactants, J. Am. Chem. Soc., 1995, 117, 1659-1660, by S.K. Kurdistani, R.C. Helgeson and D.J. Cram.

9. Synthesis, Binding Properties and Crystal Structure of a Hemicarcerand Containing Four Pentamethylenedioxy Groups Spanning Two Bowls, J. Chem. Soc., Chem. Commun., 1995, 1947-1948, by Y.-S. Byun, T.A. Robbins, C.B. Knobler and D.J. Cram.

10. Guest-Assisted and Guest-Inhibited Shell Closures Provide Differently Shaped Carceplexes and Hemicarceplexes, J. Am. Chem. Soc., 1996, 118, 5590-5604, by R.C. Helgeson, K. Paek, C.B. Knobler, E.F. Maverick and D.J. Cram.

11. Synthesis, Binding Properties, and Structures of Seven New Hemicarcerands Each Composed of Two Bowls Bridged by Three Tetrameythlenedioxy Gruops and a Fourth Unique Linkage, J. Org. Chem., 1996, 61, 9323-9339, by J. Yoon, C. Sheu, K.N. Houk, C.B. Knobler and D.J. Cram.

12. The First Water-Soluble Hemicarceplexes, J. Chem. Soc., Chem. Commun., 1997, 497-498, by J. Yoon and D.J. Cram.

13. Correlations of Structure with Binding Ability Involving Nine Hemicarcerand Hosts and Twenty-Four Guests, J. Am. Chem. Soc., 1997, 119, 3229-3244, by R.C. Helgeson, C.B. Knobler and D.J. Cram.