Our interests focus on coordination chemistry and understanding the synergistic relationships between metals and ligands in biomolecules and materials, including coordination polymers. While the coordination of small molecules to metal centers is relatively well understood, the effect of complex ligand environments is still an area of intense investigation. Our research examines metal ions in complex coordination environments, such as macrocycles, proteins and advanced materials.
Metalloporphyrins have been studied for more than a century and many researchers have probed the relationship between macrocycle structure and the metal center. However, the metal complexes of porphyrin isomers (such as porphycene or N-confused porphyrin), porphyrin analogs (such as corrole and isocorrole) and other pyrrolic macrocycles have not been as extensively studied. Not only are porphyrin isomers and analogs excellent potential ligands for transition metals, but these compounds also can be used to examine the effects of aromaticity and central pore size on metal structure and reactivity. Our research examines the metal complexes of novel polypyrrolic ligands, in part as an attempt to determine the reasons behind the natural selection of porphyrin as the tetrapyrrole of choice. In addition, we have begun to explore a family of phthalocyanine analogs known as the hemiporphyrazines. As in N-confused porphyrin, the hemiporphyrazines can bind metal ions in unusual geometries. We can also use synthetic methodologies with the reagent diiminoisoindoline to fabricate new and unusual phthalocyanine variants.
We have also begun to explore the chemistry of organometallic complexes in aqueous systems. Normally, organometallic bonds are highly sensitive to both dioxygen and water. However, certain metal ions, especially those with d6 electron counts, can form complexes that are stable in aerobic aqueous conditions. In particular, we are currently exploring the chemistry of compounds containing the Re(CO)3+ moiety. This unit can be used to model the chemistry of next generation technetium drugs based on the Tc(CO)3+ group; technetium is the most commonly used radionuclide in the clinic and there is a continuing need for new imaging agents based on this element.
1) Costa, R.; Geier, G.R.; Ziegler, C.J. (2011) "Structure and spectroscopic characterization of free base and metal complexes of 5,5-dimethyl-10,15-bis(pentafluorophenyl)isocorrole" Dalton Transactions, 40(17), 4384-4386.
2) Costa, R.; Ziegler, C.J. (2011) "Cyclohexylcyanine: a new aliphatic phthalocyanine analogue" Chemical Communications, 47 (3), 982-984.
3) Fields, K.B.; Engle, J.T.; Sripothongnak, S.; Kim, C.; Zhang, X.P.; Ziegler, C.J. (2011) "Cobalt carbaporphyrin-catalyzed cyclopropanation" Chemical Communications, 47 (2), 749-751.
4) Sripothongnak S.; Ziegler, C.J. (2010) "Lithium complexes of N-confused porphyrin" Inorganic Chemistry, 49(13), 5789-5791.
5) Herrick, R.S.; Ziegler, C.J.; Gambella, A. (2010) "Reactions of [Re(CO)3]+ with histidylhistidine and modified histidines" European Journal of Inorganic Chemistry, (25), 3905–3908.
6) Binkley, S.L.; Barone, N.V.; Underwood, A.C; Milted, A.; Franklin, B.R.; Herrick, R.S.; Ziegler, C.J. (2010) "The synthesis and toxicity of tripodal tricarbonyl rhenium complexes as radiopharmaceutical models" Journal of Inorganic Biochemistry, 104(6), 632-638.
7) Bonner, E.S.; Engle, J.T.; Sripothongnak, S.; Ziegler C.J. " Zinc complexes of the carbahemiporphyrazines" Dalton Transactions, 2010, (8), 1932-1934.
8) Binkley, S.L.; Ziegler, C.J.; Herrick, R.S.; Rowlett, R.S. " Specific derivatization of lysozyme in aqueous solution with Re(CO)3(H2O)3+" Chemical Communications, 2010, (8), 1203-1205.
9) Sripothongnak, S.; Pischera, A.M.; Espe, M.P.; Durfee, W.S.; Ziegler, C.J. "Synthesis and characterization of lithium hemiporphyrazines" Inorganic Chemistry, 2009, 48(4), 1293-1300.
10) Durfee, W.S.; Ziegler, C.J. "The metal chemistry of the carbahemiporphyrazines" Journal of Porphyrins and Phthalocyanines, 2009, 13(3), 304-311.
11) Sripothongnak, S.; Barone, N.V.; Ziegler, C.J. "C-H bond activation and ring oxidation in nickel carbahemiporphyrazines" Chemical Communications, 2009 (30) 4584-4586.
12) Franklin, B.R.; Herrick, R.S.; Ziegler, C.J.; Çetin, A.; Barone, N.; Condon, L.R. “Reactions of the Re(CO)3(H2O)3+synthon with monodentate ligands under aqueous conditions” Inorganic Chemistry, 2008, 47(13), 5902-5909.