RESEARCH PROJECTS
Observations described above and literature information suggest that substituted ferrocene species may show surprising photochemical activity. The attachment of a cationic pyridyl species such as a pyridinium or a metal-coordinated pyridyl species to the ferrocene seems to activate the ferrocene toward photochemical or oxidative decomposition.
Complexes Containing Sulfur Donor Ligands
A related area of study involves the investigation of polypyridyl ruthenium complexes with sulfur donor ligands. We have prepared complexes with 2-thiolatopyridyl(II), 2-(methylthio)pyridyl (III), dithizone (IV), and tetrazolium (V) ligands attached to the ruthenium center and are studying the redox and photochemical properties of these species. (Many important biological systems, such as photosynthesis and respiration, contain metal-sulfur complexes which are active in the redox system.)
(II) (III) (IV) (V)
Thiolate species undergo oxidation to form disulfide bridged oxidation products (Eq. 1).
2 R-SH R-S-S-R + 2H + (1)
Dithizone undergoes two oxidative processes: disulfide bridge formation as in Eq. 1 and formation of a tetrazolium species. (V)
In these studies we are investigating the influence of the sulfur donor ligand on the photochemical properties of the polypyridyl system and the influence of coordination on the sulfur-centered redox chemistry of the sulfur donor ligand.
Overall the research involves synthesis of ligands, synthesis of metal coordination complexes, characterization of the species formed, investigation of spectral and photochemical properties of the coordination complexes, and electrochemical characterization of proposed species.
CHEMICAL EDUCATION
Work in this area involves development of general chemistry laboratory experiments, supporting materials for laboratory, and professional development programs for teachers. A current project is a collaboration with the School of Education in presenting the NCQuest project “Teachers Teaching Teachers". This project establishes learning communities in high school that foster high quality science education. Another current project, "POST" (Preparing Outstanding Science Teachers) supports professional development for middle school teachers and promotes the inquiry approach to science teaching.
REPRESENTATIVE PUBLICATIONS
C. Yato, J. L. Walsh* “Decomposition of Ferrocenium Ion Promoted Through Remote Site Oxidation”, manuscript in preparation.
Seamans, G., Walsh, J. L., Krawiec, M., Pennington, B. “A Ruthenium Complex with 1,5-Diphenyl-3-thiocarbazone (Dithizone) Anion as Monodentate Ligands: Bis(2,2'-bipyridyl)bis(dithizonate)ruthenium(II)”, Acta Cryst. C59, 268 (2003).
M.G. Seamans, J. L. Walsh “Ligand Redox Chemistry in Dithizone and Tetrazolium of Ruthenium”, manuscript in preparation.
“Coordination Chemistry” chapter for “Chemistry: The Practical Science” by Paul Kelter, Michael Mosher, Andrew Scott Houghton-Mifflin Publishing Company, 2006.
Paul Kelter, Jerry Walsh, C. W. McLaughlin “Operation Chemistry-Where Clocks Run By Orange Juice and T-Shirts Are Never Bare” National Science Teacher Association Exemplary Science Monograph, 2005.