Kristin Bowman-James

Distinguished Professor; Director Kansas NSF EPSCoR

1251 Wescoe Hall Drive Malott Hall, Room 1017 University of Kansas Lawrence, KS 66045 Phone: (785) 864-3669 Fax: (785) 864-5396 Email: kbjames@ku.edu

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Academic Degrees

• B.S. 1968, Ph.D., 1974, Temple University
• Postdoctoral Research Fellow, The Ohio State University, 1974-1975.

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Areas of Specialization

Supramolecular and Traditional Coordination Chemistry

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Research Interests

For more information on exciting developments in Inorganic Chemistry, see Frontiers in Inorganic Chemistry Workshop report.

Research in the Bowman-James group involves the strategic design and synthesis of molecules that are capable of specific functions, such as the selective recognition or sensing of ions and molecules. The results of this research can provide insight and solutions to a variety of current issues. Included in these are environmental remediation in the sensing and extraction of deleterious species, the synthesis of biomimetic systems to allow for a better understanding of biological pathways, and the creation of new catalysts for organic transformations.

In the recent past the Bowman-James group has sought to design new, readily synthesized (by a minimal number of steps) hosts for anions. Anion coordination chemistry is becoming an increasingly popular field within the realm of supramolecular chemistry. Emphasis within our group has been on achieving selective recognition of small anions such as simple oxo anions and halides. Because anion coordination as a subfield of supramolecular chemistry is still in its infancy, it is important to establish a structural basis for anion binding by X-ray crystallography in addition to assessing anion binding affinities by methods such as NMR and/or potentiometric titrations.

Recent endeavors in the Bowman-James group have resulted in the synthesis of a series of systematically designed mixed amine/amide-based receptors of varying dimensionality, from mono- to di- to tri-cyclic, 1, 2, and 3, respectively. The goal was to utilize the same building blocks, a heterocycle/aromatic group in conjunction with chains containing amido and amino functionalities, to build increasingly complex hosts. The presence of the amines allows for quaternization, thereby introducing positive charge into the host ligands.

Examples of key crystallographic findings are: 1) the dichromate complex of H₂1²⁺, X = N (A)¹⁰; encapsulated anion complexes as shown for sulfate with H₂2²⁺, X = N (B)¹; and the first example of an encapsulated bifluoride (C) with 3.⁵

Offshoots to the anion coordination chemistry have also been forthcoming that illustrate the versatility of the new mixed amide/amine hosts or ligands. Because of the multiple hydrogen bonding groups inherent in these hosts, they can stabilize solvent structures, including hexagonal ice-like formations as shown for 3D).⁹ An unusual and possibly globally important finding has been the crystallographic location of an unexpected “lone proton” (in this example actually an encircled proton) with a very short Low-Barrier Hydrogen Bond. The proton is held between two amide carbonyl atoms in Q₂1²⁺, the quaternized version of 1, X = CH (E),¹¹ and serves to mold the conformation of the monocycle. This finding could be of major significance in many aspects of supramolecular chemistry, including protein folding, molecular self assembly, and molecular machines and motors. A third example of the versatility of these ligand systems is that they are also capable of binding metal ions, resulting in the formation of regular transition metal coordination complexes.¹⁰ In the amide-based systems, this switching of guests from anion to transition metal cation is achieved after deprotonation of the amide nitrogen atoms, as for example shown in the ditopic dinickel(II) complex of 1, X = N, obtained after deprotonation of the amide groups, H_-41^4– (F).

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Selected Publications

V. W. Day, M. A. Hossain, S. O. Kang, D. Powell, Douglas; G. Lushington, and K. Bowman-James, Encircled Proton, J. Am. Chem. Soc. 2007, 129, 8692-8693.

S. Ghosh, B. Roehm, R. A. Begum, J. Kut, M. A. Hossain, V. W. Day, and K. B. Bowman-James, Versatile Host for Metallo Anions and Cations, Inorg. Chem. 2007, 46, 9219-9521.

S. O. Kang, D. Powell, V. W. Day, and K. Bowman-James, Crystallized Water: Internal and External Ice Fragments in Polycyclic Hosts. Crys. Growth & Des. 2007, 7, 606-608. 7(4), 606-608.

R. Begum, S. O. Kang, and K. Bowman-James, Amide-Based Ligands for Anion Coordination, Angew. Chem. 2006, 45, 7882-7894.

R. A. Begum, D. Powell, and K. Bowman-James, Thioamide Pincer Ligands with Charge Versatility, Inorg. Chem. 2006, 45, 964-966.

S. O. Kang, M. A. Hossain, and K. Bowman-James, Influence of Dimensionality and Charge on Anion Binding in Amide-based Macrocyclic Receptors, Coord. Chem. Rev. 2006, 250, 3038-3052.

S. O. Kang, D. Powell, and K. Bowman-James, Trapped Bifluoride, Angew. Chem., 2006, 45, 1921-1925.

K. Bowman-James, Alfred Werner Revisited: The Coordination Chemistry of Anions, Acc. Chem. Res. 2005, 38, 671-678.

S. O. Kang, D. Powell, K. Bowman-James, Anion Binding Motifs: Topicity and Charge in Amidocryptands, J. Am. Chem. Soc. 2005, 127, 13478-13479.

M. A. Hossain, P. Morehouse, D. Powell, and K. Bowman-James, Tritopic (Cascade) and Ditopic Complexes of Halides with an Azacryptand, Inorg. Chem. 2005, 44, 2143-2149.

S. O. Kang, M. A. Hossain, D. Powell, and K. Bowman-James, Encapsulated Sulphates, Insight to Binding Propensities, Chem. Commun. 2005, 320-330.