- B.Sc. - York University
- Ph.D. - University of British Columbia
COORDINATION AND ORGANOMETALLIC CHEMISTRY
As an inorganic coordination chemist, the periodic table is a fabulous playground! My group works with a wide range of metals, from lithium to uranium. Main-group alkali/alkali-earth, transition-metals, lanthanides and actinides all gain attention in the Leznoff group. My research program is focused on developing new ways to understand how to control structure, properties, and reactivity of molecular and supramolecular metal complexes, by harnessing coordination chemistry to explore a range of fundamental properties and applications of metal-organic ligand systems. We are particularly interested in the areas of coordination polymer materials and their uses, and new phthalocyanine-based compounds, with a special emphasis on emissive materials and paramagnetic organometallic complexes, as outlined below.
Coordination polymers are multi-dimensional materials that are held together with metal-ligand bonds, which can be self-assembled – like lego pieces - from judiciously chosen building blocks, and their structures and properties tuned to target a range of applications. The need to understand how to control structure, properties and reactivity of these coordination polymers via the choice of metals and the design of appropriate building blocks and ligands fundamentally lies at the heart of this research. Our group focuses in particular on cyanide-based coordination polymers, with a special interest in incorporating metals that form attractive “metallophilic” interactions, such as gold(I) and platinum(II).
Phthalocyanines (Pc) are intensely coloured, chemically inert, redox-active compounds that are ubiquitous in industry, with uses from dyes to photodynamic therapy of cancer. However, despite their useful attributes, the synthesis and reactivity of metal-phthalocyanine (PcM) complexes for many metals remains barely unexplored and their organometallic chemistry is sparse. We explore PcM complexes with non-traditional metals and ring-oxidation states, uncovering new classes of compounds with unusual properties and reactivity.
We are also active in the area of actinide chemistry, studying the unique coordination chemistry, properties and reactivity of complexes of the very large elements uranium and thorium.
Current Research Programs
• Transition-Metal and f-block Metal-Based Supramolecular Cyanometallate Coordination Polymers
Using combinations of transition metals, lanthanides, actinides and appropriate bridging ligands, we are pursuing novel coordination polymer materials. Bridging ligands include metal cyanides and thiocyanates, heterocyclic amines and sulfur-based ligands. In particular, the use of linear d10 and square-planar d8 metal cyanides such as [Au(CN)2]- and [Pt(CN)4]2- that display strongly attractive metal-metal (aurophilic, platinophilic etc.) interactions are under investigation. We are targeting emissive and vapochromic materials for toxic small-molecule sensing, highly birefringent materials, molecule-based magnetic and multifunctional materials, systems with unusual thermal-expansion properties, crystalline Non-Linear Optical (NLO) materials, supramolecular systems that emit white or other-coloured light, and coordination polymer materials with other exciting properties.
• Non-Traditional Metal Phthalocyanines (PcM)
A large majority of PcM complexes incorporate late first-row transition-metals. We focus on rare PcM complexes with early-transition and f-block metals. We probe their ability to act as redox-active ligands by isolating their ring-reduced/oxidized species, and use X-ray structures and spectroscopy to understand their properties. The overall goal is to harness these non-traditional PcM complexes for small-molecule activation, catalysis and as magnetic materials. The exploration of organometallic compounds based on PcM complexes is also of particular interest, given the minimal overlap between these two huge fields of chemistry.
• Actinide Chemistry
As an extension of our research in both supramolecular coordination chemistry and paramagnetic organometallics, the chemistry of thorium(IV) and uranium complexes from oxidation state +3 to +6, with a variety of ligand systems is explored. Actinide complexes with phthalocyanines, other chelating amido ligands and incorporation into cyanometallate coordination polymers are all being pursued. Actinides are relatively under-examined compared with their transition-metal counterparts and provide an exciting route into some unusual chemistry.
• Paramagnetic Organometallic Chemistry
Paramagnetic organometallic complexes have been much less studied relative to the vast literature on diamagnetic organometallic complexes. We are interested in the synthesis, structural chemistry, reactivity and magnetic behaviour of this underexamined class of organometallics. To what extent does the presence of unpaired electrons at the metal centre affect the stability, structure and reactivity of these compounds? Reactivity studies in particular with respect to catalysis and redox chemistry are explored. Our phthalocyanines as well as chelating diamido ligand platforms are utilized in this work.
Overall, this research will generate a fundamental understanding of structure-property relationships, which will lead to the rational design of future materials.
The Leznoff Group Experience
The Leznoff group is very multidisciplinary, and graduate students who join my group will experience a blend of synthesis, property measurement and spectroscopic studies Having a diverse research program in coordination chemistry (coordination polymer materials, phthalocyanines, organometallic and actinide chemistry) exposes students to a range of areas, fostering a cross-germination of ideas.
The determination of solid state structures by X-ray crystallography plays a crucial role in our research and my students routinely collect diffraction data and solve their own crystal structures. They will also gain experience in an unusually wide range of techniques, including FTIR and Raman spectroscopy, UV-vis absorption and emission, multinuclear NMR (and NMR of paramagnetic complexes), ESR, DFT calculations, birefringence (unique in Canada), Mossbauer, porosimetry, cyclic voltammetry and thermogravimetric analysis, as appropriate to their project, correlating design, structure and properties of materials. They will also be exposed to a variety of magnetic measurement methods, including the use of a state-of-the-art SQUID magnetometer at SFU. If appropriate, students will be trained in the synthesis and manipulation of air and moisture-sensitive compounds using vacuum-line/Schlenk techniques and a state-of-the-art glovebox system. We work with SFU physicists to measure muon-spin resonance at the TRIUMF cyclotron.
My students become immersed in a wide variety of non-laboratory experiences that will hone them into top-class scientists and prepare them for a broad range of careers: academia, industry, policy makers, educators and communicators. Thus, I impart not only high-level interdisciplinary laboratory skills and safety, but organically incorporate soft-skills, leadership and management into the life of my students so as to mold the highest quality, well-rounded, globally-minded researchers. All students present their research at conferences and have opportunities to participate in collaborations, manage infrastructure, and engage with industrial partners. My Ph.D. students are encouraged to participate in an international research experience (e.g., with colleagues/collaborators in France, Japan etc.) for several months.
Interested students are encouraged to contact me directly at email@example.com.
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