Martin T. Lemaire

Associate Professor, Chemistry

Office: Cairns 508
Lab: Cairns 542
905 688 5550 x6432
mlemaire@brocku.ca

Research efforts in the Lemaire group are very multi-faceted. In general terms, we are interested in the preparation and properties of new hybrid inorganic/organic materials. This work encompasses basic and advanced organic synthetic techniques, in particular, for the preparation of new ligands, as well as coordination and polymer chemistry.

Students in my lab obtain a plethora of new skills and are exposed to a number of exotic techniques to probe electronic and magnetic properties. We have our own inert-atmosphere facilities to carefully prepare sensitive materials (Innovative Technologies glove box and Schlenk lines), as well as an in-house UV-VIS-NIR spectrophotomer (Shimadzu 3600), FTIR spectrometer (Shimadzu IRAffinity), and electrochemistry equipment (Bioanalytical Systems Inc.). Our spectrophotometer is equipped with a Specac low temperature cell with temperature controller so that we can study the variable temperature optical properties of our materials.

We have also established very fruitful collaborations with crystallographers and physicists and have the ability to investigate the structural, magnetic and Mössbauer properties of our systems.

Current research plans fall within two general themes, which are considered to be the most active areas of research in the field. These include synthetic efforts toward new multifunctional materials we are also exploring new avenues toward the synthesis of high-spin molecules as new families of single molecule magnets.

Multifunctional materials: Spin-crossover, valence tautomerism, and conductivity

One of the most exciting developments in the field of molecular materials is a new focus toward the preparation of materials that exhibit combinations of unusual and generally disparate properties, known in the literature as “multifunctional materials”. The motivation for this work is generally two-fold: Primarily, this is basic exploratory research because combining properties that typically do not exist together in nature within a single material should lead to the discovery of new and unusual properties. On the other hand, there are other interesting applied considerations, for example, using one property in the material to control the other, which has implications for sensory materials, molecular electronics or information storage. We are interested in the preparation of systems that exhibit bistable magnetic or optical properties and at the same time are electrically conducting. Our approach is to combine these properties in an intramolecular fashion by preparing conducting metallopolymers (Wolf class I, II, or III) containing spin-crossover or valence tautomeric substituents. Our intramolecular approach should lead to stronger property-property interactions and, therefore, make these materials potentially much more useful.

New synthetic pathways toward high-spin molecules

High-spin molecules are defined as molecular species containing at least two unpaired electrons, and in which the local magnetic interactions between these electrons result in, at a minimum, an S = 1 ground state. Generally, the local spin-spin interaction in high-spin molecules is ferromagnetic (magnetic dipoles align parallel to one another); however, antiferromagnetic interactions can result in high-spin ground states when the aligning spin vectors are unequal (ferrimagnetism). A challenge in materials chemistry is to design molecules containing many unpaired electrons, but doing this in a rational manner so that the magnetic interactions are ferromagnetic: This is a rather difficult challenge, but the potential benefits are enormous! Under particular conditions, high-spin molecules can exhibit single molecule magnetism, which basically means that a single molecule can exhibit magnetic properties (such as thermal hysteresis and remnance) that are analogous that of a bulk magnet! If data storage using the magnetic dipole of a single molecule as a “bit” is achievable, we have the opportunity to dramatically increase magnetic storage capacities, or computer “speeds”.

Most high-spin molecules are prepared serendipitously by coordination of paramagnetic transition metal ions with bridging ligands. Some excellent examples of high-spin molecular species have been reported, but magnetic interactions between metal ions through diamagnetic bridging ligands tend to be extremely weak. One of the major synthetic challenges is to design molecular systems with high-spin ground states that are well isolated, energetically speaking, from other spin excited states. We propose to do this using paramagnetic bridging ligands designed from known or newly developed families of stable free radicals. In this manner, the local magnetic interactions are direct, between metal and coordinated ligand. Interactions of this type are known to be very strong.

43. Taylor, R.; Lough, A.J.; Seda, T.; Lemaire, M.T. Structure and unusual magnetic properties of an iron complex containing a redox arylazo ligand. Manuscript in preparation, 2015.

42. Bonnano, N.M.; Walsby, C.; Prosser, K.; Lough, A.J.; Lemaire, M.T. Synthesis, structure and electronic properties of an open-shell stable ditopic redox-active ligands. Manuscript submitted to Dalton Transactions (in revision), 2015.

41. Taylor, R.; Williams, H.; Cibian, M.; Hannon, G.; Lemaire, M.T. Ln(Papl)3 complexes (Ln = Gd, Dy, Tb): Synthesis, magnetism and emission behavior. Manuscript in preparation, 2015.

40. Taylor, R.; Lough, A.J.; Lemaire, M.T.. Spin-crossover in a homoleptic cobalt(II) complex containing a redox-active NNO ligand. Manuscript submitted to Journal of Materials Chemistry C (in revision), 2015.

39. Taylor, R.; Lough, A.J.; Lemaire, M.T Structural features and electronic properties of a cupric complex with redox active 1-(2-pyridylazo)-9-phenanthrol (papl). Manuscript in press, Polyhedron, 2015.

38. Bonanno, N.M.; Van Damme N.; Lough, A.J.; Lemaire, M.T. Transition metal complexes containing a ditopic redox active ligand featuring very intense visible absorption bands. Dyes Pigm. 2015, 123, 212-217.

37. Sheepwash, M.A.L.; Lough, A.J.; Poggini, L.; Poneti, G.; Lemaire, M.T. Structure, magnetic properties and electronic structure of a nickel(II) complex with redox-active 6-(8-quinolylamino)-2,4-bis(tert-butyl)phenol.
Polyhedron 2015, http://dx.doi.org/10.1016/j.poly.2015.06.010.

36. Dinsdale, D.R.; Lough, A.J.; Lemaire, M.T. Structure and magnetic properties of an unusual homoleptic iron(III) thiocyanate dimer. Dalton Trans. 2015, 44, 11077-11082.

35. Dowling, C.; Dinsdale, D.R.; Lemaire, M.T. Preparation, electrochemical behavior and variable temperature magnetic properties of Co(3,5-DBSQ)2 complexes of imidazole- or pyrazole-substituted ligands. Can. J. Chem. 2015, 93, 769-774.

34. Van Damme, N.; Zaliskyy, V.; Lough, A.J.; Lemaire, M.T. Structure and magnetic properties of a cobalt(III) complex with redox active 1-(2-pyridylazo)-2-phenanthrol (papl). Polyhedron 2015, 89, 155-159.

33. Dowling, M.; Lemaire, M.T. Preparation, electrochemical behavior and variable temperature magnetic properties of transition metal complexes containing 2-phenyl-4,5-di-(2-pyridyl)imidazole. Transit. Metal Chem. 2014, 39, 843-848.

32. Wilson, D.; Djukic, B.; Lemaire, M.T. Synthesis of bromine- or aryl-substituted ditopic Schiff base ligands and their bimetallic iron(II) complexes: Electronic and magnetic properties. Transit. Metal Chem. 2014, 39, 17-24.

31. Van Damme, N.; Lough, A.J.; Gorelsky, S.I.; Lemaire, M.T. Molecular and electronic structures of complexes containing 1-(2-pyridylazo)-2-phenanthrol (PAPL): Revisiting a redox-active ligand. Inorg. Chem. 2013, 52, 13021-13028.

30. Djukic, B.; Jenkins, H.A.; Seda, T.; Lemaire, M.T. Structural and magnetic properties of homoleptic iron(III) complexes containing N-(8-quinolyl)-salicylaldimine [Fe(Qsal)2]+X- {X = I or (Qsal)FeCl3}. Transit. Metal Chem. 2013, 38, 207-212.

29. Revunova, K.; Gorelsky, S.I.; Lemaire, M. T. Synthesis and coordination chemistry of a ditopic precursor to a triarylamminium radical cation ligand. Polyhedron 2013, 52, 1118-1125.

28. Djukic, B.; Lough, A. J.; Seda, T.; Gorelsky, S. I.; Lemaire, M.T. Pi-extended and six-coordinate iron(II) complexes: Structures, magnetic properties, and the electrochemical synthesis of a conducting iron(II) metallopolymer. Inorg. Chem. 2011, 50, 7334-7343.

27. Lemaire, M.T. Progress and design challenges for high-spin molecules. Pure and Appl. Chem., 2011, 83, 141-149.

26. Adugna, S.; Revunova, K.; Djukic, B.; Gorelsky, S.I.; Jenkins, H.A.; Lemaire, M.T. Persistent metal bis(hexafluoroacetylacetonato) complexes featuring a 2,2-bipyridine substituted triarylamminium radical cation. Inorg. Chem. 2010, 49, 10183-10190.

25. Cheng, H.; Djukic, B.; Jenkins, H.A.; Gorelsky, S.I.; Lemaire, M.T. Iron(II) complexes containing thiophene-substituted “bispicen” ligands: Spin-crossover, ligand rearrangements, and ferromagnetic interactions. Can. J. Chem. 2010, 88, 954-963.

24. Djukic, B; Singh, M.A.; Lemaire, M.T. Formation of Spin-Crossover Polymer Microspheres. Syn. Metals 2010, 160, 825-828.

23. Djukic, B.; Lemaire, M.T. A Hybrid Spin-Crossover Conductor Exhibiting Unusual Variable Temperature Electrical Conductivity. Inorg. Chem. 2009, 48, 10489-10491.

22. Djukic, B.; Poddutoori, P.K.; Dube, P.A.; Seda, T.; Jenkins, H.A.; Lemaire, M.T. Bimetallic iron(3+) spin-crossover complexes containing a 2,2’-bithienyl bridging bis-QsalH ligand. Inorg. Chem. 2009, 48, 6109-6166.

21. O’Sullivan, T.J.; Djukic, B.; Dube, P.A.; Lemaire, M.T. Preparation and properties of thienyl and 2,2’-bithienyl substituted cobalt-bis(semiquinone) valence tautomers. Can. J. Chem. 2009, 87, 533-538.

20. O’Sullivan, T.J.; Djukic, B.; Dube, P.A.; Lemaire, M.T. A Conducting Metallopolymer Featuring Valence Tautomerism. Chem. Commun. 2009, 1903-1905.

19. Djukic, B.; Dube, P.A.; Razavi, F.; Seda, T.; Jenkins, H.A.; Britten, J. F.; Lemaire, M.T. Preparation and magnetic properties of iron(3+) spin-crossover complexes bearing a thiophene substituent: Toward multifunctional metallopolymers. Inorg. Chem. 2009, 48, 699-707.

18. Cheng, H.; Djukic, B.; Harrington, L.E.; Britten, J.F.; Lemaire, M.T. N’-(3-Thienylmethylene)pyridine-2-carbohydrazide. Acta Cryst. E. 2008, E64, o719.

17. Djukic, B.; Harrington, L.E.; Britten, J.F.; Lemaire, M.T. 5,7-Di-2-pyridyl-2,3-dihydrothieno[3,4-b][1,4]dioxine. Acta Cryst. E. 2008, E64, o463. Harrington and

16. Lemaire, M.T. Recent developments in the coordination chemistry of stable free radicals. Pure Appl. Chem. 2004, 76, 277–293.

15. Gilroy, J.B.; Lemaire, M.T.; Patrick, B.O.; Hicks, R.G. Structure and magnetism of a verdazyl radical clathrate hydrate. Strong intermolecular magnetic interactions derived from -stacking within ice-like channels. CrystEngComm. 2009, 11, 2180-2184.

14. Lemaire, M.T.; Barclay, T.M.; Thompson, L.K.; Hicks, R.G. Synthesis, structure, and magnetism of a binuclear cobalt(II) complex of a potentially bis-tridentate verdazyl radical ligand. Inorg. Chim. Acta. 2006, 359, 2616 – 2621.

13. Koivisto, B.D.; Ichimura, A.S.; McDonald, R.; Lemaire, M.T.; Thompson, L.K.; Hicks, R. G. Intramolecular -Dimerization in a 1,1′-Bis(verdazyl)ferrocene Diradical. J. Am. Chem. Soc. 2006, 128, 690 – 691.

12. Shuaev, K.V.; Rawson, J.M.; Passmore, J.; Cameron, T. S.; Thompson, L.K.; Lemaire, M.T. Preparation and Solid State Characterization of the Novel Mixed Biradical NSNSC-CNSSN. Inorg. Chem. 2005, 44, 2576.

11. Thompson, L.K.; Kelly, T.L.; Dawe, L.N.; Grove, H.; Lemaire, M.T.; Howard, J.A.K.; Spencer, E.C.; Matthews, C.J.; Onions, S.T.; Coles, S.J.; Horton, P.N.; Hursthouse, M. B.; Light, M.E. Mixed Valence Mn(II)/Mn(III) [3×3] Grid Complexes: Structural, Electrochemical, Spectroscopic, and Magnetic Properties. Inorg. Chem. 2004, 43, 7605.

10. Hicks, R.G.; Koivisto, B.D.; Lemaire, M.T. Synthesis of Multitopic Verdazyl Radical Ligands. Paramagnetic Supramolecular Synthons. Org. Lett. 2004, 6, 1887.

9. Barclay, T.M.; Hicks, R.G.; Lemaire, M.T.; Thompson, L.K. Verdazyl Radicals as Oligopyridine Mimics: Structures and Magnetic Properties of M(II) Complexes of 1,5-Dimethyl-3-(2,2´-bipyridin-6-yl)-6-oxoverdazyl (M = Mn, Ni, Cu, Zn). Inorg. Chem. 2003, 42, 2261.

8. Barclay, T.M.; Hicks, R.G.; Lemaire, M. T.; Thompson, L.K.; Xu, Z. Synthesis and Coordination Chemistry of a Water-Soluble Verdazyl Radical. Structures and Magnetic Properties of M(H2O)2(vdCO2)2·2H2O [M = Co, Ni; vdCO2 = 1,5-dimethyl-6-oxo-verdazyl-3-carboxylate]. Chem. Commun. 2002, 1688.

7. Barclay, T.M.; Hicks, R.G., Lemaire, M.T.; Thompson, L.K. Weak Magnetic Coupling of Coordinated Verdazyl Radicals Through Diamagnetic Metal Ions. Synthesis, Structure, and Magnetism of a Homoleptic Copper(I) Complex. Inorg. Chem. 2001, 40, 6521.

6. Barclay, T.M.; Hicks, R.G.; Lemaire, M.T.; Thompson, L.K. Synthesis, Structure, and Magnetism of Bimetallic Manganese or Nickel Complexes of a Bridging Verdazyl Radical. Inorg. Chem. 2001, 40, 5581.

5. Hicks, R.G.; Lemaire, M.T.; Öhrström, L.; Richardson, J.F.; Thompson, L.K.; Xu, Z. Strong Supramolecular-Based Magnetic Exchange in -Stacked Radicals: Structure and Magnetism of a Hydrogen-Bonded Verdazyl:Hydroquinone Molecular Solid. J. Am. Chem. Soc. 2001, 123, 7154.

4. Barclay, T.M.; Hicks, R.G.; Lemaire, M.T.; Thompson, L.K. Structure and Magnetic Properties of a Nickel(II) Complex of a Tridentate Verdazyl Radical: Strong Ferromagnetic Metal-Radical Exchange Coupling. Chem. Commun. 2000, 2141.

3. Hicks, R.G.; Lemaire, M.T.; Thompson, L.K.; Barclay, T.M. Strong Ferromagnetic and Antiferromagnetic Exchange Coupling Between Transition Metals and Coordinated Verdazyl Radicals. J. Am. Chem. Soc. 2000, 122, 8077.

2. Letkeman, P.; Lemaire, M.T.; Murase, I.; Motekaitis, R.J.; Martell, A.E. A Potentiometric study of metal chelates with pentaethylenehexaamineoctaacetic acid. J. Coord. Chem. 2000, 52, 33.

1. Barr, C.L.; Chase, P.A.; Hicks, R.G.; Lemaire, M.T.; Stevens, C.L. Synthesis and Characterization of Verdazyl Radicals Bearing Pyridine or Pyrimidine Substituents: A New Family of Chelating Spin-Bearing Ligands. J. Org. Chem. 1999, 64, 8893.

  • CHEM 3P31: Transition metal chemistry
  • CHEM 3P40:  Spectroscopic techniques for structure elucidation