Geoffrey Davies - US grants

This award from the Inorganic, Bioinorganic and Organometallic Chemistry Program is in the area of transition metal chemistry. The project is concerned with reactions in which atoms of two different metals are exchanged between carrier molecules to which they are attached, so-called transmetalation reactions. Of particular interest are reactions involving polymetallic species, species which contain several metal atoms within one molecule. One aim of the project is to use transmetalation reactions to synthesize polymetallic species containing atoms of two or more different metals within one molecule. Such mixed-metal polymetallic species are expected to have interesting catalytic properties and also are models of important enzymes, such as the respiratory enzyme cytochrome oxidase. It may be possible also to decompose the mixed-metal species to yield alloys of types which cannot be made directly from the constituent metals. The focus of the project will be the newly discovered phenomenon of transmetalation which leads to quantitative, stepwise replacement of metal centers in polymetallic targets by other metals from simple molecular transmetalators. The reactions proceed under mild conditions and the products are easily separated. The major components of the research will be: 1) isolation, structural characterization and electrochemical studies of cationic targets and transmetalation products; 2) investigation of earlier and heavier element transmetalation systems; 3) development and use of more economical transmetalators; 4) identification of reactions of linkage transmetalators which give large polymetallic molecules; 5) description of the selective ligand chemistry of heteropolymetallic molecules; 6) use of transmetalation to generate new bulk alloys and supported metal catalysts; and 7) development of heteropolyorganometallic chemistry.

Title: Transmetalation Reactions Research Collaboration in U.S. and Egypt ABSTRACT NARRATIVE: Description: This proposal is a request for a second award as a follow-on to a two-year research effort funded by NSF award INT-8512210. The research team from Northeastern University headed by Dr. Geoffrey intends to continue the collaboration with the University of Alexandria, Egypt team lead by Drs. Mohamed A. El-Sayed and Ahmed El-Touky. This collaborative effort has broadened the chemistry discovery relating to the metal exchange in polynuclear materials. The proposed new work will build on the past effort in six important areas including the building of larger and more diverse multi-metal molecules at lower cost; the use of these molecules as sources of new metal alloys and chemical catalysts to be used in still newer systems. Development of the transmetalation phenomenon will lead to the establishment of new areas of study in organic and organometallic chemistry. The purpose of the Science in Developing Countries Program is to advance the exchange of international scientific knowledge and to contribute to the scientific infrastructure of developing countries. This proposal meets those criteria. Scope: These international collaborators are in the process of developing new approaches to handling metals that can very possibly lead to new and unexpected products of unique and useful characteristics for use in both the laboratory and in the public sector. An additional pay-off of this research is the provision of a wealth of learning opportunities for students pursuing degrees in organic chemistry. A final value of this research is the advance of the scientific and technical knowledge of the research teams and their impact within their separate universities. The collaborative work of these scientists from Northeastern and Alexandria universities has resulted already in significant scientific advances and a number of joint publications in major refereed journals.

ABSTRACT NARRATIVE Description: This proposal proposes the continued support of the collaboration of the research groups of Dr. Geoffrey Davies of Northeastern University and Drs. Mohamed A. El- Sayed and Ahmed El-Toukhy of the University of Alexandria, Alexandria Egypt. These research groups have discovered and developed a new field of polymetallic transmetalation chemistry. Transmetalation is the replacement of metallic elements in a target material with other metallic elements received from chemical reagents. Research to date has been substantial resulting in nine published research papers with eight additional papers submitted for publication or in the advanced stage of preparation. This original research has revealed six new areas of importance that are considered worthy of further research and exploration. The new research is expected to have a large impact on chemical, materials and catalytic science. Further, it will provide numerous learning opportunities for students in modern inorganic and physical chemistry. Scope: The proposed research is programmed for two years with the principal investigators working in their counterpart's laboratories. The two Egyptian scientists will spend a total of 12 months at Northeastern University. Dr. Davies will work at Alexandria University for three months. This work division will advantage both researh groups in exposing one and another to the research facilities of each university, while giving the graduate students of each chemistry department opportunities to become acquainted with the scientific thinking, techniques and problem solving approaches employed by successful scientists from the cooperating foreign university. The six areas of proposed new research are: o Crystallization and Electrochemical Studies o Mechanisms of Phenolic Oxidative Coupling o Catalytic Effects of Transmetalation o Transmetalation Rate Laws and Mechanisms o Low Temperature Dimeric Copper(I)-Dioxygen Systems o Oxidation of Polynuclear Copper(I)-Dioxygen Complexes with Quinones This proposal meets the objectives of the Science in Developing Countries Program of advancing the international exchange of scientific knowledge and does contribute to the enhancement of science in a developing country.

The problem of stirring of chemical tracers in the mantle will be addressed by developing three-dimensional computer models of flow and tracer advection. Some comparable and complementary laboratory studies of stirring will be undertaken in Australia. Since parallel computers hold the greatest promise of providing the large improvements in computer performance that will be required for detailed three-dimensional modelling, the models will developed for a parallel computer. The Connection Machine is the favored computer.

Description: This proposal supports the collaboration of Dr. Geoffrey Davies, Northeastern University, and Professor Adnan Ali, Abu-Dis College of Science and Technology, Jerusalem, West Bank. This collaborative effort relates to the metal exchange of polynuclear materials. The proposed new work will build on the past efforts of both investigators including the creation of larger and more diverse multi-metal molecules at lower cost, and the use of these molecules as sources of new metal alloys and chemical catalysts to be used in still newer systems. Development of the transmetalation phenomenon will lead to the establishment of new areas of study in organic and organometallic chemistry. The purpose of the Science in Developing Countries Program is to advance the exchange of international scientific knowledge and to contribute to the scientific infrastructure of developing countries. This proposal meets those criteria. Scope: These international collaborators are in the process of developing new approaches to handling metals that can very possibly lead to new and unexpected products of unique character for use in both the laboratory and the public sector. An additional benefit of this research is the provision of a wealth of learning opportunities for students pursuing degrees in organic chemistry. Another value of this research is in the advancement of the scientific and technical knowledge of the research teams and their impact within their respective institutions.

Technical Narrative: This U.S.-Egypt collaborative research project involving Northeastern University and Alexandria University is in the general area of polymetallic chemistry. This collaborative effort relates to the metal exchange of polynuclear materials. Project funding will enable Drs. Mohamed A. El-Sayad and Ahmed El-Toukhy from Alexandria University, Egypt, to spend approximately three months in the laboratory of Dr. Geoffrey Davies at Northeastern University. Dr. Davies will visit and work at Alexandria University for a three month period as well. The proposed new work will build on the past efforts of the investigators including the creation of larger and more diverse multi-metal molecules at lower cost, and the use of these molecules as sources of new metal alloys and chemical catalysts to be used in still newer systems. Development of the transmetalation phenomenon will lead to the establishment of new areas of study in organic and organometallic chemistry. This project in polymetallic chemistry fulfills the program objective of advancing scientific knowledge by enabling leading experts in the United States and Egypt to combine complementary talents and pool research resources in areas of strong mutual interest and competence.

technology /technique development; plants; environmental health; biomedical resource; bioengineering /biomedical engineering; biomaterials; biological products;