RESEARCH

​SUPRAMOLECULAR CYANOMETALLATE COORDINATION POLYMER MATERIALS

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, we often use linear d10 and square-planar d8 cyanometallates such as [Au(CN)2]- and [Pt(CN)4]2- that display strongly attractive metal-metal (aurophilic, platinophilic etc.) interactions in order to make new materials.  We are targeting emissive and vapochromic materials for toxic small-molecule gas sensing (e.g. ammonia), 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.

Representative Publications: 

• Varju, Bryton R.; Wollschlaeger, S.; Leznoff, D.B.  “Zinc(II) Tetracyanoplatinate:  A reversible luminescence-based ammonia sensor”, Chem. Eur. J., 2019, 25, 9017-9025. 
• Sergeenko, A.S.; Ovens, J.S.; Leznoff, D.B.  “Designing Anisotropic cyanometallate coordination polymers with zero thermal expansion in two dimensions”, Chem. Commun., 2018, 54, 1599-1602.
• Roberts, R.J.; Le, D. and Leznoff, D.B., “Colour-tunable and white-light luminescence in lanthanide-dicyanoaurate coordination polymers”, Inorg. Chem., 2017, 56, 7948-7959. 
• Thompson, J.R.; Katz, M.J.; Williams, V.E.; Leznoff, D.B.  "Structural design parameters for highly birefringent coordination polymers", Inorg. Chem., 2015, 54 6462-71. 
• Geisheimer, A.; Huang, W.; Pacradouni, V.; Sabok-Sayr, S.A.; Sonier, J.E.; Leznoff, D.B. " Magnetic properties of Isostructural M(OH2)4[Au(CN)4]2-based coordination polymers (M = Mn, Co, Ni, Cu, Zn) by SQUID and mSR studies ", Dalton Trans., 2011, 40, 7505-7516.

NON-TRADITIONAL METALLOPHTHALOCYANINES​

Phthalocyanines are extremely important industrial dyes that are highly chemically stable and have among the highest extinction coefficients known; they are also redox-active.  They have a wide range of applications, including their use as blue/green dyes (such as "Phthalo-blue, the background colour of this website!), optical components, read-write optical memory, solar cells, catalysis and photodynamic therapy of cancer. However, 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 goals are to harness these non-traditional PcM complexes for small-molecule activation, catalysis, as magnetic materials, and as other advanced optical materials such as Near-IR dyes that take advantage of their huge extinction coefficients. 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.

Representative Publications: 

• ​Zhou, W.; McKearney, D.; Leznoff, D.B.  “Structural diversity of F-element monophthalocyanine complexes”, Chem. Eur. J., 2020, 26, 1027-1031. 
• McKearney, D.; Zhou, W.; Williams, V.E.; Leznoff, D.B. “Facile tuning of the wavelength of strong Near-IR absorptions in manganese(III) phthalocyanines via axial ligand exchange”, Chem. Commun., 2019, 55, 6696-6699. 
• Zhou, W.; Thompson, J.R.; Leznoff, C.C.; Leznoff, D.B.  "The redox active Chromium Phthalocyanine system: Isolation of five oxidation states from Pc4-Cr(I) to Pc2-Cr(III)", Chem. Eur. J., 2017, 23, 2323-31. 

ACTINIDE COORDINATION POLYMERS AND COMPLEXES​

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.

Representative Publications: 

• Brown, M.L.; Ovens, J.S.; Leznoff, D.B.  "Dicyanoaurate-based Heterobimetallic uranyl coordination polymers”, Dalton Trans., 2017, 46, 7169-7180. 
• Hayes, C.E. and Leznoff, D.B. "Multidentate Polyamido-based actinide complexes in coordination and organometallic chemistry", Coord. Chem. Rev., 2014, 266-267, 155-170.
• ​Zhou, W.; McKearney, D.; Leznoff, D.B.  “Structural diversity of F-element monophthalocyanine complexes”, Chem. Eur. J., 2020, 26, 1027-1031.

PARAMAGNETIC ORGANOMETALLICS​

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.

Representative Publications: 

• Zhou, W.; Leznoff, D.B.  "Phthalocyanine as a redox-active platform for organometallic chemistry", Chem. Commun., 2018, 54, 1829-1832. 
• Hayes, C.E.; Leznoff, D.B. "Paramagnetic diamidodonor metal complexes"  Dalton Trans., 2012, 41, 5743-5753.
• ​Moatazedi, Z.; Katz, M.J.; Leznoff, D.B.  "Synthesis and characterization of a series of halide-bridged, multinuclear iron(II) and cobalt(II) diamido complexes and a dinuclear, high-spin cobalt(II) alkyl derivative", Dalton Trans., 2010, 39, 9889-9896.

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