Professor Penelope Jane Brothers
BSc, MSc, PhD
- 1978 BSc University of Auckland
- 1979 MSc University of Auckland
- 1985 PhD Stanford University, California, USA
Research | Current
Inorganic and Organometallic Chemistry
My primary research activities involve the syntheses of new coordination and organometallic complexes, and determining their structure and chemical properties. The focus of much of this work is on understanding new coordination and bonding modes for main group and transition metals. As well as advances in fundamental knowledge, there are potential applications in new materials and drug discovery.
Porphyrin and Corrole Complexes: Designing New Materials and New Catalysts
Metalloporphyrin complexes occur naturally in hemoglobin, myoglobin and cytochromes. Synthetic porphyrin complexes are used widely as catalysts, in new materials, and as potential therapeutic agents. These applications are possible because the porphyrin ligand imparts interesting and unusual properties to the chemistry of the central atom. Corroles are relatives of porphyrins but have a slightly different framework, closely related to naturally occurring vitamin B12. Our research group is the first in the world to prepare complexes containing boron coordinated to the porphyrin ligand. They are very unusual in that they contain two boron atoms coordinated in the porphyrin cavity, in contrast to almost every other porphyrin complex which contains only one coordinated atom. We have achieved similar results with diboron corroles. The boron porphyrin and corrole complexes show unexpected types of chemical reactivity resulting from the proximity of two boron atoms within a tight cavity. We plan to investigate this further, looking at a spontaneous chemical reduction reaction which forms a B-B bond without any added reductant. This could be useful in preparing reagents for Suzuki coupling, and in hydrogen storage applications. Other potential applications of boron porphyrins and corroles are as sugar sensors and as fluorescence sensors, which will involve studying the photophysical properties of the boron porphyrins and corroles. This project will involve both fundamental studies directed at learning more about boron porphyrin complexes, and also specific experiments designed to test their feasibility for potential applications.
Metal Complexes as Potential Anti-Cancer Drugs
Inorganic medicinal chemistry is a rapidly developing field, spurred largely by the tremendous success of the Pt-based anti-cancer drugs like Cisplatin. The unique complexing and redox properties of metal centres can be exploited in the rational design and synthesis of new metal-based anti-cancer drugs. Hypoxia selective and radiation activated anti-cancer drugs, in which the drug is activated either in the oxygen-deficient, chemically reducing environment of solid tumour cells, or during radiation therapy, are a particular target in this project. The synthesis and chemistry of new complexes of cobalt and other transition metals containing small bioactive organic groups as ligands will be explored. Examples of these are hydroxamates and hydroximates which are known to inhibit matrix metalloproteinases, enzymes which are expressed on the surface of solid tumours and which promote metastasis. A further example synthesised in our group is the complex shown below in which the large organic ligand is a potent anticancer drug.
New Materials: Molecular Penrose Tiling
Like a bathroom wall, a tiled plane is covered with no gaps or overlaps. This is easy to achieve using regular tiles like triangles, squares or hexagons but impossible using only shapes with 5-fold symmetry. In the 1960s Roger Penrose approached this intriguing mathematical problem by using tiles of more than one shape, either rhombic or pentagonal, and the resulting patterns are called Penrose tilings. Similar tilings have been observed in ancient Islamic architecture. Penrose tiling on a surface has never been achieved using molecules and we are interested in pursuing this goal using 5-fold symmetric molecules as the pentagonal tiles and either metal coordination or supramolecular chemistry to control the interactions between the edges of the tiles. A range of possible “molecular tiles” have been identified based on cyclopentadienyl, expanded porphyrin, calixarene and curcurbituril motifs. This project involves synthesis of the molecular tiles and their deposition on a surface in a controlled fashion so as to design molecular materials with particular properties such as the Penrose tiling pattern.
New types of gas sensor based on semiconducting oxides
We are exploring the interaction between suitably formulated metal complexes and semiconducting oxides. The aim is to create states on the surface of the oxide whose interaction with a gas can be detected though a change in electrical conductivity of the oxide.
Fulbright Scholar Award, 2006
Areas of expertise
- Inorganic Chemistry
Associate Editor, Chemical Communications (Royal Society of Chemistry)
Selected publications and creative works (Research Outputs)
- Yun, L., Vazquez-Lima, H., Fang, H., Yao, Z., Geisberger, G., Dietl, C., ... Fu, X. (2014). Synthesis and reactivity studies of a tin(II) corrole complex. Inorganic Chemistry, 53 (13), 7047-7054. 10.1021/ic501103c
- Albrett, A. M., Thomas, K. E., Maslek, S., Młodzianowska A, Conradie, J., Beavers, C. M., ... Brothers, P. J. (2014). Mono- and diboron corroles: factors controlling stoichiometry and hydrolytic reactivity. Inorg Chem, 53 (11), 5486-5493. 10.1021/ic500114k
- Fang, H., Ling, Z., Lang, K., Brothers, P. J., De Bruin, B., & Fu, X. (2014). Germanium(iii) corrole complex: Reactivity and mechanistic studies of visible-light promoted N-H bond activations. Chemical Science, 5 (3), 916-921. 10.1039/c3sc52326h
- Buckley, H. L., Chomitz, W. A., Koszarna, B., Tasior, M., Gryko, D. T., Brothers, P. J., & Arnold, J. (2012). Synthesis of lithium corrole and its use as a reagent for the preparation of cyclopentadienyl zirconium and titanium corrole complexes. Chemical Communications, 48 (87), 10766-10768. 10.1039/c2cc35984g
- Brothers, P. J. (2011). Boron Complexes of Pyrrolyl Ligands. Inorganic Chemistry, 50 (24), 12374-12386. 10.1021/ic2011919
- Lu, G. L., Stevenson, R. J., Chang, J. Y. C., Brothers, P. J., Ware, D. C., Wilson, W. R., ... Tercel, M. (2011). N-alkylated cyclen cobalt(III) complexes of 1-(chloromethyl)-3-(5,6,7-trimethoxyindol-2-ylcarbonyl)-2,3-dihydro-1H-pyrrolo[3,2-f]quinolin-5-ol DNA alkylating agent as hypoxia-activated prodrugs. Bioorganic & Medicinal Chemistry, 19 (16), 4861-4867. 10.1016/j.bmc.2011.06.076
Other University of Auckland co-authors: William Wilson, Moana Tercel, Leon Lu, David Ware, Bill Denny, Ralph Stevenson
- Fang, H., Ling, Z., Brothers, P. J., & Fu, X. (2011). Reactivity studies of a corrole germanium hydride complex with aldehydes, olefins and alkyl halides. CHEMICAL COMMUNICATIONS, 47 (42), 11677-11679. 10.1039/c1cc15076f
- Lemon, C. M., Brothers, P. J., & Boitrel, B. (2011). Porphyrin complexes of the period 6 main group and late transition metals. Dalton Transactions, 40 (25), 6591-6609. 10.1039/c0dt01711f