Address:
Room: 410
Email address: L.Lindoy@chem.usyd.edu.au
Home Page: http://www.chem.usyd.edu.au/~lindoy
Telephone: +61-2-9351-4400
Faxsimile: +61-2-9351-3329
Research Associate, Ohio State University; Visiting Professor, ETH Zurich, Florida State University, Cambridge University (Bye Fellow Robinson College) and the University of Cincinnatti. Awarded Olle Prize of the Royal Australian Chemical Institute (1988), the Burrows Inorganic Award (1991), the Smith Medal, (1995) and AINSE Gold Medal for Excellence in Research (1995). Elected a Fellow of the Australian Academy of Science (1993).
Currently a consultant to several U.K., U.S.A. and Australian companies.
Metal-ion recognition by organic substrates is a topic of fundamental relevance to considerable areas of both chemistry and biochemistry. More recently, the major research area has been the design and synthesis of macrocyclic systems for the recognition of heavy metal ions and their application to a number of areas such as metal-ion transport through liquid membranes and macrocyclic immobilisation on solid substrates.
Although the use of polyether and related macrocycles to discriminate between ions such as the alkali and alkaline earths has been well investigated by other workers, much less attention has been given to the use of cyclic systems for related discrimination studies involving transition and post transition metals such as Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II) and Ag(I). Collectively, the investigations appear to be the most comprehensive series of studies of this latter type yet published.
As part of the investigations, original and deliberate strategies for obtaining heavy metal-ion recognition have been developed. Thus, a major aim of the project has been to produce ligands which are specific for particular heavy metal ions and to understand the reasons for such specificity when it does occur. Such studies are of considerable fundamental importance since the entire area of metal-ion recognition by organic substrates is quite poorly understood - even though it is central to the role of metal ions in a wide range of chemical and biochemical systems.
An aspect of the work has been to use macrocyclic ligand hole size as one means of "tuning" a cyclic ligand system for a particular metal ion. Two mechanisms for achieving ring-size discrimination have been investigated. One of these, "dislocation discrimination", was first recognised and systematically investigated my group. The studies have led to the observation of a variety of discrimination phenomena within the respective (industrially important) series Co(II)/Ni(II)/Cu(II), Zn(II)/Cd(II) and Pb(II)/Ag(I) with, in some instances, spectacular discrimination having been achieved. Apart from the production of reagents of potential practical utility, collectively the work represents a substantial contribution towards the general understanding of heavy metal-ion recognition by organic substrates.
As an extension of the studies just outlined, much current research activity is concerned with the application of selective reagents to systems for the practical separation and/or sensing of particular metal ions. New developments include extensive studies of the use of such reagents immobilised on solid supports (such as silica gel). An extensive series of studies involving heavy metal ion discrimination via solvent extraction and transport across hydrophobic membranes has been performed. Similarly, new metal ion sensors based on the above systems have been developed.
Over the past several years, molecular mechanics and molecular orbital calculations on macrocyclic complexes have been carried out jointly with Dr. K. R. Adam (James Cook University). The aim of this project has been the application of these techniques to the design of new macrocyclic ligands for metal ion and small molecule discrimination.
Supramolecular host-guest formation involving metal complex guests: A project involving the study of supramolecular host-guest formation between metal complexes (as the guests) and cyclic systems (as the hosts) is underway. The first example of the transport of a discrete metal complex intact across an artificial liquid membrane (incorporating the antibiotic lasalocid) has been reported. This has been the forerunner for a range of related studies.
The results represent a novel extension within the currently popular area of host guest chemistry and have pointed the way for the use of the technique for the separation of isomers. As part of these studies, the first example of such transport experiments being used to obtain chiral discrimination between the optical isomers of a metal complex has been obtained. The study demonstrated that the general procedure had special promise for the (partial) resolution of suitable optically active metal complexes. A range of such resolutions has now been performed. The latter remains a classical requirement in coordination chemistry that is not always readily met by conventional methods. In further studies the first example of cis-trans isomer discrimination in metal complex transport across a liquid membrane (using lasalocid as ionophore) has been achieved.
Bioinorganic and biomimetic investigations: A range of studies have been performed including the design and synthesis of technetium-containing reagents for radioimaging as well as the study of a number of simple models which successfully mimic aspects of the behaviour and reactivity of particular enzymes.
Reagents for solvent extraction and membrane transport: Associated with the above areas of study, for the past seven years our group has had a wide interest in the development of immobilized ligand systems for heavy metal removal from waste streams as well as the development and use of solvent extractants for heavy metal recovery. All of this work has been carried out in collaboration with overseas companies. The research and development of new silica gel immobilized ligand systems, at present marketed by Metre-General Inc. (Colorado), was carried out by our group. Commercialisation of further products from our research is planned by Metre General in the near future.