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WRG Research lab

The Program

Our group utilizes a variety of electrochemical and photochemical experimental techniques in our general efforts aimed at delineating the factors that control the mechanisms and dynamics of organic reactions occurring in homogeneous solution and in heterogeneous, ordered environments.

Our main research interest is directed towards addressing fundamental aspects of interfacial organic reactions and utilize the knowledge gained to design and synthesize new materials and to demonstrate potential applications. Reactions of molecules in solution are supported by a well developed intuition and set of methods from physical organic chemistry, but the reactions of molecules at the solid-liquid or solid-solid interface are not as well understood because they often behave in ways that are very different from those in solution. To investigate these differences, we design and synthesize photochemically, electrochemically and thermally responsive organic molecular systems to act as probes of the interactions in the interfacial environment of a variety of monolayer surfaces and to provide new platforms for selective surface modifications to build new architectures.  A cornerstone of our efforts focuses on metal surfaces including self-assembled 2D monolayers and monolayer protected gold nanoparticles, but we comtinue to expnad the scope to investigate reactivity on other metallic nanoparticles and other relevant material solid surfaces.

The importance and motivation behind these studies lies in the recognition of the utility of organic thin films on functional materials in the development of molecular and biomolecular electronics, sensors, catalysis and other applications.  Currently, progress towards application is not always based on clear understanding of the fundamental factors that control surface reactivity and molecular interactions in these unique assemblies.  We are addressing these issues by examining photoinduced, redox activated and thermal reactivity in terms of chemical properties (structure-reactivity relationships, conformational and orientation mobility) and physical properties (structure, order-disorder phenomena, reaction conditions).  In many cases the photoactive or electroactive moiety also serves as an analytical sensor/reporter of the chemistry.  A complete understanding of these factors is essential for the rationale design and control of any modified surface for a particular application.   Our current studies have revealed several mechanistic factors that are important and unique to interfacial reactions that have no counterpart in solution reactions and will continue to do so with novel reactive systems and the proposal expands the scope of our studies to other types of surfaces, including other noble metal and magnetic nanoparticles, carbon nanotubes, graphene, micro-diamond, fabrics and glass.  Our next challenges are to utilize our probes to better control the reactivity and structure of these metal surfaces and nanoparticles, to develop new reactive probes activate photo- or electrochemically, and to use the reactions we developing for the controlled chemical modification of the suite of functional materials. 

Personnel working on these projects gain expertise and broad training in organic synthetic methods and analysis, inorganic and organic materials chemistry and the specialized techniques for their characterization, in addition to advanced skills in electrochemistry and photochemistry. Graduate students, undergraduate researchers and research associates involved in HQP leaving my group have had a 100% professional placement over the last 10 years.

Come Join the Group!

Selected Highlights of Scientific Achievements

The group’s expertise spans the areas of photochemistry, electrochemistry, radical ion chemistry and materials science.  This diversity places us among only a handful of researchers world wide with this "toolbox" and rather unique within the context of the Canadian science.  These tools have allowed us to make significant research contributions that have greatly influenced the understanding of the mode of action of biologically relevant molecules and in materials science.

•We were the first to introduce the idea of non-adiabatic dissociative electron transfer to endoperoxides and test it experimentally while providing a theoretical framework to test the theories of dissociative ET.  Our work lays the foundation for a new avenue of chemistry that we continue to build on.  

•Our work has established our experimental methodology and provides the first accurate values of the dissociative reduction potential of the O-O bond and other thermochemical values in a class of molecules that are key to chemists and biochemists interested in the mode of action of the prostaglandin endoperoxide and endoperoxides used as anti-malarial agents.

•Established methodology to study the reaction dynamics of distonic radical ions.

•Established a program aimed at using photochemical reactions to probe interfacial reactivity of organic substrates self-assembled on metal surfaces.  The work is providing valuable information on understanding the interactions of molecules on metal surfaces.  We are now demonstrating the generality of the photoprocesses for derivatization with important fundamental and practical applications for material manufacturing.

•Extended the methodology of the photochemistry of long chain self-assembled monolayers to small molecules on metal surfaces.  Showed that reactive intermediates can be generated (and are stable) and studied on these surfaces.  Our approach provides information on the organization in these environments and knowledge of the reactivity of these intermediates at the interface, which allow for their exploitation for functionalization.  

  Discovered and developed the use of hyperbaric conditions for the efficient modification of monolayer protected metal nanoparticles.  

  Developed a novel method involving photoinitiated carbene chemistry for the preparation of gold-nanoparticle hybrid material composites and the modification of electrodes.

  Introduced the concept of bioorthogonal reactions on modified AuNP. Working twoards using these for biological and functional material modifications.

  Contributing to the physical characterization of charged Au25 nanoclusters.

 

 
 

Contact

Mark S. Workentin, Ph.D.

Professor of Chemistry
Department of Chemistry and Centre for Advanced Materials and Biomaterials Research (CAMBR)

Western University
London, ON N6A 5B7
519-661-2111 Ext 86319

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