Laurence K. Thompson

Memorial University of Newfoundland, Saint John's, Newfoundland and Labrador, Canada

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Publications (222)878.4 Total impact

  • Subrata K. Dey · Madhumita Hazra · Laurence K. Thompson · Animesh Patra
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    ABSTRACT: The manganese(II) coordination polymer, {[Mn(L)(pyz)]ClO4.2(H2O)}n. (1) has been synthesized from a mixture of Mn(ClO4)2.6H2O, Schiff base HL (derived from the condensation of 4-aminoantipyrine and salicylaldehyde) and pyrazine (pyz). Its molecular structure was determined by single crystal X-ray diffraction, which reveals that the polymeric structure consists of simultaneous Mn-Pyz-Mn and Mn-O(phenoate)-Mn bridges between the metal centers. Variable temperature magnetic studies give g = 2.037(4), J = -1.90(4) cm-1, ϑ = 0.5 K values, using a simple dinuclear Mn-Mn model, and indicates that the major exchange pathway is via the two phenoxide bridges and the pyrazine has little influence. The coordination polymer also shows enhanced antibacterial activity compared with the standard antibiotic levofloxacin.
    No preview · Article · Jan 2016
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    ABSTRACT: Reactions between 2,6-diformyl-4-alkyl(R)-phenol and 1,3-diamino-2-hydroxypropane in the presence of copper(II) salts (Cu(BF4)2·6H2O, Cu(ClO4)2·6H2O/H3BO3/Ar) and triethylamine in a single pot self-assemble generating antiferromagnetically coupled dimeric dodecacopper supramolecular architectures of hexatopic macrocyclic ligands with unprecedented structures having the BO33− anion as the central species bonded to all six copper centers in a symmetrical fashion (μ6-BO33−). A central BO33− moiety is produced in a single synthetic step by the Cu6-macrocycle complex catalyzed hydrolysis of BF4− ion.
    Full-text · Article · Jun 2015 · Inorganic Chemistry
  • Victoria A. Milway · Louise N. Dawe · Laurence K. Thompson
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    ABSTRACT: A square [3×3] Mn(II)9 supramolecular grid complex with appended ligand SEt groups provides a focus for extended molecular organization through outer-sphere interactions with soft metal ions. Reactions with Ag(I) and Au(III) led to extended 3D arrays in complexes [Mn9(SEt2poap)6]Ag5.75(CF3SO3)2(NO3)9.75(H2O)18 (4), [Mn9(SEt2poap)6][Ag(CN)2]2 [Ag3(CN)5](OH)2(H2O)18 (5), and [Mn9(SEt2poap-3H)4(SEt2poap-2H)2(AuCl3)4] (AuCl4)3.25Cl1.75(H2O)14 (6), involving Mn9 [3×3] square grids with external Ag–S contacts, but with Au(III) extended organization resulting through Au–N ligand contacts only. Structural and magnetic properties are discussed. In the gold complex, magnetic and structural data revealed that Au(III) behaves as an oxidant, leading to oxidation of some corner Mn(II) sites in the grid to Mn(III). Intra-grid magnetic exchange is antiferromagnetic in all cases (J =−4.4 cm−1 (4), J = −5.0 cm−1 (5)), leading to noncompensation of spins because of the odd number of metal ions and low-spin ground states.
    No preview · Article · Oct 2014 · Canadian Journal of Chemistry
  • Laurence K. Thompson · Louise N. Dawe
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    ABSTRACT: A survey of transition metal and lanthanide clusters involving polytopic hydrazone ligands in the range M3, M4, M6, M9, M12, and M16 will be discussed, with examples of chains, triangles and square [nxn] grids. Magnetic properties are interpreted using fully isotropic models in some cases, and approximations where spin state calculations exceed the computer's capacity to handle the enormous matrices involved. In the case of some Dyn complexes SMM (single molecule magnet) behavior is observed, with relaxation properties interpreted using field and temperature dependent AC measurements.
    No preview · Article · Sep 2014 · Coordination Chemistry Reviews
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    ABSTRACT: Tri-topic pyridine bis-hydrazone ligands produce polynuclear complexes with Fe(II) and Fe(III) salts with varying nuclearity and metal ion oxidation states. Mononuclear, tetranuclear, hexanuclear, and nonanuclear examples are discussed using structural, magnetic and Mössbauer data. In one case, although X-ray data suggest a [3 × 3] Fe9 grid (space group P42/n), careful examination of the structure, in conjunction with magnetic and Mössbauer data, indicates an unusual situation where the corner and center sites are present at unit occupancy, whereas side site occupancy is ∼0.6.
    Full-text · Article · Apr 2014 · Inorganic Chemistry
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    ABSTRACT: Rational combination of pyridazine, hydroxo and carboxylate bridging ligands led to the assembly of three types of mixed-ligand polynuclear Cu(ii) clusters (A: [Cu2(μ-OH)(μ-pdz)(μ-COO)]; B: [Cu4(μ3-OH)2(μ-pdz)2]; C: [Cu5(μ-OH)2(μ-pdz)4(μ-COO)2(μ-H2O)2]) and their integration into 3D framework structures. Mixed-ligand complexes [Cu2(μ-OH){TMA}(L)(H2O)] (), [Cu4(μ3-OH)2{ATC}2(L)2(H2O)2]·H2O () [Cu4(μ3-OH)2{TDC}3(L)2(H2O)2]·7H2O () (L = 1,3-bis(pyridazin-4-yl)adamantane; TMA(3-) = benzene-1,3,5-tricarboxylate, ATC(3-) = adamantane-1,3,5-tricarboxylate, TDC(2-) = 2,5-thiophenedicarboxylate) and [Cu5(μ-OH)2{X}4(L)2(H2O)2]·nH2O (X = benzene-1,3-dicarboxylate, BDC(2-), n = 5 () and 5-hydroxybenzene-1,3-dicarboxylate, HO-BDC(2-), n = 6 ()) are prepared under hydrothermal conditions. Trigonal bridges TMA(3-) and ATC(3-) generate planar Cu(ii)/carboxylate subtopologies further pillared into 3D frameworks (: binodal 3,5-coordinated, doubly interpenetrated tcj-3,5-Ccc2; : binodal 3,8-coordinated tfz-d) by bitopic pyridazine ligands. Unprecedented triple bridges in (cluster of type A) support short CuCu separations of 3.0746(6) Å. The framework in is a primitive cubic net (pcu) with multiple bis-pyridazine and TDC(2-) links between the tetranuclear nodes of type . Compounds and adopt uninodal ten-coordinated framework topologies (bct) embedding unprecedented centrosymmetric open-chain pentanuclear clusters of type with two kinds of multiple bridges, Cu(μ-OH)(μ-pdz)2Cu and Cu(μ-COO)(μ-H2O)Cu (CuCu distances are 3.175 and 3.324 Å, respectively). Magnetic coupling phenomena were detected for every type of cluster by susceptibility measurements of , and . For binuclear clusters A in , the intracluster antiferromagnetic exchange interactions lead to a diamagnetic ground state (J = -17.5 cm(-1); g = 2.1). Strong antiferromagnetic coupling is relevant also for type , which consequently results in a diamagnetic ground state (J1 = -110 cm(-1); J2 = -228 cm(-1), g = 2.07). For pentanuclear clusters of type in , the exchange model is based on a strongly antiferromagnetically coupled central linear trinuclear Cu3 group (J1 = -125 cm(-1)) and two outer Cu centers weakly antiferromagnetically coupled to the terminal Cu ions of the triad (J2 = -12.5 cm(-1)).
    No preview · Article · Apr 2014 · Dalton Transactions
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    ABSTRACT: Tetranuclear, dinuclear and chain complexes involving some polyfunctional hydrazone and thio-carbohydrazone-based ligands are discussed. Ni(II) and Mn(II) [2 × 2] grids form with μ2-S and μ2-O bridges respectively, and are antiferromagnetically coupled (J = −167(5), −3.59(2) cm−1 respectively). With the Fe(II) based system oxidation to Fe(III) occurs, and a μ2-Ohydrazone bridged dimer results, with antiferromagnetic exchange between the S = 5/2 spin centers (J = −22.5(2) cm−1). In the case of Cu(II) the diazine group acts as a μ2-N–N bridge between Cu(II) centers in two cases involving a tetranuclear and a chain complex. Non-orthogonal bridging through N–N and carboxylate bridges leads to antiferromagnetic exchange in the tetranuclear case (J = −32.7(7), −16.1(7) cm−1 respectively) and ferromagnetic exchange in the chain complex due to orthogonal N–N bridging (J = 3.3(1) cm−1).
    Full-text · Article · Jan 2014 · Polyhedron
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    ABSTRACT: Reactions of the copper(II)-gadolinium(III) 15-metallacrown-5 complex [GdCu5(Glyha)5(NO3)2(H2O)6](NO3) (Glyha(2-) = dianion of glycinehydroxamic acid) with different di/tricarboxylates (1,3-phthalate, 1,4-phthalate, biphenyl-4,4'-dicarboxylate, citrate) resulted in formation of different types of products: {[(GdCu5(Glyha)5(H2O)2)(GdCu5(Glyha)5(H2O)3)(1,3-bdc)3]·16H2O}n (1), {[(GdCu5(Glyha)5(H2O)3)2(1,4-bdc)2](1,4-bdc)·8H2O}n (2), {[(GdCu5(Glyha)5(H2O)4)2(1,4-bdc)3]·8H2O}n (3), [GdCu5(Glyha)5(Citr)(H2O)4]·7H2O (4), {[GdCu5(Glyha)5(H2O)5](μ2-CO3)[Cu(Fgg)]}·7H2O (5) and [Cu(Gly)2(H2O)]n (6) (where bdc(2-) is the corresponding phthalate (benzenedicarboxylate), Citr(3-) is citrate, Fgg(3-) is the trianion of [(N-formylaminoacetyl)amino]acetic acid and Gly(-) is glycinate). Complexes 1-5 contain the [GdCu5(Glyha)5](3+) cation. Complexes 2 and 3 possess the same composition but differ by the mode of p-phthalate coordination to the [GdCu5(Glyha)5](3+) unit. In compounds 1-3, metallacrown cations are linked by the corresponding phthalates in 1D, 1D and 2D polymers, respectively, whereas 4 and 5 are discrete molecules. Compound 5 is the product of a multistep reaction, which finally involves atmospheric CO2 capture. Hydrolysis of hydroxamate in this reaction is confirmed by isolation of a mononuclear copper glycine complex 6. The χMT vs T data for 1 were fitted using a model based on the Hamiltonian Ĥ (GdCu5) = -2J1(S1 × SGd + S2 × SGd + S3 × SGd + S4 × SGd + S5 × SGd) - 2J2(S1 × S2 + S2 × S3 + S3 × S4 + S4 × S1 + S5 × S1. The best fit corresponded to J1 = +0.60(2) cm(-1), J2 = -61.0(5) cm(-1) and zJ' = -0.035(4) cm(-1). Complex 1 is the first example of a 15-metallacrown-5 system, for which numerical values of exchange parameters have been reported. The isotherm for methanol absorption by compound 1 at 293 K was typical for microporous sorbents, whereas ethanol sorption was negligibly small.
    No preview · Article · Jan 2014 · Inorganic Chemistry
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    ABSTRACT: Self-assembly of the Ln(III) ions (Ln = Eu, Gd, Dy, Ho, Yb) into square [2 × 2] grid-like arrays has been readily effected using simple, symmetric ditopic ligands based on a carbohydrazone core. The metal ions are connected via single atom bridges (e.g., μ2-Ohydrazone, μ2-OH, μ2-OMe, μ2-1,1-N3(-), μ4-O), depending on reaction conditions. The Gd(III)4 examples exhibit intramolecular antiferromagnetic exchange (-J < 0.11 cm(-1)), and in one Dy(III)4 example, with a combination of μ2-1,1-N3(-), and μ4-O bridges linking adjacent metal ions, SMM behavior is observed. One thermally driven relaxation process is observed in the temperature range 10-25 K (τ0 = 6.5(1) × 10(-7) s, Ueff = 110(1) K) in the presence of an 1800 Oe external field, employed to suppress a second quantum based relaxation process. The extended group of Ln(III) ions which submit to this controlled self-assembly, typical of the transition metal ions, indicates the general applicability of this approach to the lanthanides. This occurs despite the anticipated limitations based on larger ionic radii and coordination numbers, and is an encouraging sign for extension to larger grids with appropriately chosen polytopic ligands.
    Full-text · Article · May 2013 · Inorganic Chemistry
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    ABSTRACT: The lanthanide coordination chemistry of a tri-functional vanillin-hydrazone-oxime ligand reveals a variety of different products, depending on reaction conditions, with mono-nuclear (Dy), dinuclear (Yb, Tm), tetranuclear (Gd) and hexanuclear (Gd, Tb, Dy) examples. The Ln6 (Ln = Gd, Dy, Tb) complexes form in the presence of both triethylamine and acetic acid, and have unique, flat hexanuclear structures built on a μ3-O bridged triangular core, with the six lanthanide ions bridged further through μ-acetate and μ-Ohydrazone connections in an expanded fused triangular array. Similar reaction conditions with Yb(iii) and Tm(iii) lead preferentially to dinuclear systems, while in the presence of a competitive benzoate ligand a rectangular Gd4 complex results. Variable temperature DC magnetic data for the Gd(iii) complexes reveal weak antiferromagnetic exchange. AC magnetic data on the other polynuclear complexes down to 2 K, both in the absence and presence of external bias fields, revealed no significant out of phase signals normally indicative of SMM behavior. However, the mononuclear Dy(iii) complex shows frequency dependent AC signals and maxima in the temperature range 2-20 K in the presence of an external bias field, indicative of SMM behaviour, with Ueff = 36(1) K, and τ0 = 4.4(2) × 10(-6) s.
    No preview · Article · Apr 2013 · Dalton Transactions
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    Nicholas M Randell · Laurence K Thompson · Louise N Dawe
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    ABSTRACT: The title compound, C16H16N2O4·2CH3OH, is a hydrazone in an E geometric arrangement, with an inversion centre at the mid-point of the N—N bond. A symmetry-related pair of six-membered hydrogen-bonded rings [graph-set motif S 1 1(6)] are present for the terminal vanillin–imine moieties. Two lattice methanol solvent mol­ecules are present per formula unit (Z′ = 1/2), which form hydrogen-bonded chains along [010] with two orientations due to disorder of the methanol H-atom.
    Preview · Article · Sep 2012 · Acta Crystallographica Section E Structure Reports Online
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    Muhammad U Anwar · Louise N Dawe · Mohammad S Alam · Laurence K Thompson
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    ABSTRACT: High nuclearity [Mn(10)M(2)] clusters have been achieved through a self-assembly approach where multiple coordinating functional groups are incorporated into one ligand. When the hydrazone group appended with an oxime function as a reactive intermediate is used, the attachment of a vanillin subunit creates a ligand (L4) with three coordinating groups, which in their own right lead to cluster assemblies. The trifunctional ligand L4 produces a series of self-assembled, mixed oxidation state (Mn(II)/Mn(III)) Mn(10)M(2) based clusters with an overall linear structure comprising two connected pentanuclear Mn(5) halves, which bind alkali metal cations (M = Li, Na, K, Rb, Cs) and H(3)O(+) in the vanillin (O(6)) end pockets, created by the assembly of three ligands around each Mn(5) subunit. Antiferromagnetic exchange dominates the spin coupling in the Mn(10) complexes, and surface studies on highly oriented pyrolytic graphite (HOPG) clearly show the arrangement of metal ions (Mn, Cs) in the Mn(10)Cs(2) linear cluster assembly.
    Full-text · Article · Mar 2012 · Inorganic Chemistry
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    Santokh S Tandon · Scott D Bunge · Joaquin Sanchiz · Laurence K Thompson
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    ABSTRACT: Reactions between 2,6-diformyl-4-methylphenol (DFMF) and tris(hydroxymethyl) aminomethane (THMAM) in the presence of copper(II)/nickel(II) salts and NaN3 in one pot self-assemble producing an antiferromagnetically coupled polymeric Cu(II) complex {[Cu2(H5L2−)(μ-N3)]2[Cu(N3)4]·2CH3OH}n (1) and ferromagnetically coupled hexanuclear Ni(II) clusters [Ni6(H3L1−)2(HL22−)2(μ-N3)4(CH3CO2)2]·6C3H7NO·C2H5OH (2) and [Ni6(H3L1−)2(HL22−)2(μ-N3)4(C6H5CO2)2]·3C3H7NO·3H2O·CH3OH (3), respectively. Intramolecular and intermolecular H-bonding interactions in all three compounds 1−3 produce 3D structures involving intradimer and interdimer azido bridges.
    Full-text · Article · Mar 2012 · Inorganic Chemistry
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    ABSTRACT: Tritopic pyridinebis(hydrazone)-based ligands typically produce square M(9) [3 × 3] grid complexes with first-row transition-metal ions (e.g., M = Mn, Fe, Co, Cu, Zn), but with larger lanthanide ions, such coordination motifs are not produced, and instead linear trinuclear complexes appear to be a preferred option. The reaction of 2pomp [derived from pyridine-2,6-bis(hydrazone) and 2-acetylpyridine] with La(III), Gd(III), and Dy(III) salts produces helical linear trinuclear [Ln(3)(2pomp)(2)]-based complexes, where each metal ion occupies one of the three tridentate ligand pockets. Two ligands encompass the three metal ions, and internal connections between metal ions occur through μ-O(hydrazone) bridges. Coligands include benzoate, nitrate, and N,N-dimethylformamide. The linear Dy(III)(3) complex exhibits single-molecule magnet behavior, demonstrated through alternating-current susceptibility measurements. Slow thermal magnetic relaxation was detected in an external field of 1800 Oe, where quantum-tunneling effects were suppressed (U(eff) = 14 K).
    Full-text · Article · Dec 2011 · Inorganic Chemistry
  • Muhammad U Anwar · Konstantin V Shuvaev · Louise N Dawe · Laurence K Thompson
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    ABSTRACT: The iron coordination chemistry of some polytopic hydrazone based ligands is examined. The complexes derive from a general self-assembly strategy, where ligand design can be used to devise specific polymetallic [n × n] grid architectures. However, as part of any complex equilibrium process, oligomeric entities can also occur, particularly when ligand tautomeric flexibility is considered, and examples of mononuclear, dinuclear, tetranuclear, and pentanuclear complexes have been observed within a related class of ligands. In addition, ligand site donor composition can lead to coordination spheres that stabilize both high spin Fe(II) and Fe(III) sites, with evidence for Fe(II) spin crossover. Structural and magnetic properties are examined, which reveal the presence of antiferromagnetic exchange in the polynuclear systems.
    No preview · Article · Dec 2011 · Inorganic Chemistry
  • Peter J. Bettle · Louise N. Dawe · Muhammad U. Anwar · Laurence K. Thompson
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    ABSTRACT: The coordination chemistry of a group of hydrazone-based ligands, modified with carboxylate and heterocyclic terminal donor groups, with MnII and CoII has been investigated. The multifunctional nature of the ligands allows coordinative flexibility based on the hydrazone core, which is well established to lead to spin-coupled polymetallic assemblies through μ-Ohydrazone bridging. Examples of dinuclear, tetranuclear and chain complexes are reported with hydrazone, carboxylate and triazole bridging. Spin exchange through the μ-O and μ-N,N bridging connections leads to antiferromagnetic exchange in most cases, except for the central subunit in the MnII4 chain complex, where small (< 90°) bridge angles result in contributing ferromagnetic interactions.
    No preview · Article · Nov 2011 · Berichte der deutschen chemischen Gesellschaft

    No preview · Chapter · Oct 2011
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    ABSTRACT: Two lanthanide tetrafluoro-p-phthalate (L(2-)) complexes, Ln(L)(1.5)·DMF·H(2)O (Ln = Pr(3+) (1), Nd(3+) (2)), were synthesized using pyridine as a base. The compounds were found to be isostructural, and the structure of 1 has been determined by single crystal X-ray diffraction (monoclinic, space group C2, a = 22.194(2) Å, b = 11.4347(12) Å, c = 11.7160(12) Å, β = 94.703(2)°, V = 2963.3(5) Å(3), Z = 4). The crystal structure of 1 consists of dinuclear Pr(3+) units, which are connected by tetrafluoro-p-phthalate, forming separate 2D polymeric layers. The Ln(3+) ions in the dinuclear Ln(2) units are linked by two μ-O atoms and by two bridging O-C-O groups. The structure is porous with DMF and water molecules located between layers. Non-coordinated DMF molecules occupy about 27% of the unit cell volume. A systematic analysis of reported structures of Ln(III) polymers with p-phthalate and its derivatives shows that the ca. known 60 structures can be divided into six possible structural types depending on the presence of certain structural motifs. The magnetic properties of compounds 1 and 2 were studied. The dependence of χ(M)T on T (where χ(M) is magnetic susceptibility per dinuclear lanthanide unit) for 1 and 2 was simulated using two different models, based on: (i) the Hamiltonian Ĥ = ΔĴ(z)(2)+ μ(B)g(J)HĴ, which utilises an axial splitting parameter Δ and temperature-independent paramagnetism (tip) and (ii) crystal field splitting. It was found that both models gave satisfactory fits, indicating that the Ln-Ln exchange interactions are small and the symmetry of the coordination environment is the main factor influencing the magnetic properties of these compounds.
    No preview · Article · Sep 2011 · Dalton Transactions
  • Muhammad U Anwar · Andrew S Elliott · Laurence K Thompson · Louise N Dawe
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    ABSTRACT: Hydrazone ligands modified with benzothiazole and oxime groups produce spin-coupled tetra- (Mn, Ni, Cu), penta- (Co), and hexanuclear (Cu) self-assembled clusters.
    No preview · Article · Mar 2011 · Dalton Transactions
  • Laurence K Thompson
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    ABSTRACT: Polynuclear coordination complexes result from the interplay between the arrangement of the binding sites of a ligand, and their donor content, and the coordination preferences of the metal ion involved. Rational control of the ligand properties, such as denticity, geometry, and size, can lead to large, and sometimes predictable, polynuclear assemblies. This Alcan Award Lecture highlights our "adventures" with polynucleating ligands over the last 25 years, with examples ranging from simple dinucleating to more exotic high-denticity ligands. Complexes with nuclearities ranging from 2 to 36 have been produced, many of which have novel magnetic, electrochemical, and spectroscopic properties. Self-assembly strategies using relatively simple "polytopic" ligands have been very successful in producing high-nuclearity clusters in high yield. For example, linear "tritopic" ligands produce M9 (M = Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II)) [3 × 3], flat grid-like molecules, which have quantum dot-like arrays of nine closely spaced metal centers in electronic communication. Some of these grids are discussed in terms of their novel magnetic and electrochemical properties, and also as multistable nanometer-scale platforms for potential molecular device behaviour. Bigger ligands with extended arrays of coordination pockets, and the capacity to self-assemble into much larger grids, are highlighted to illustrate our current and longer term goals of generating polymetallic molecular two-dimensional layers on surfaces.Key words: Alcan Award Lecture, transition metal, polynuclear, structure, magnetism, electrochemistry, surface studies, molecular device.
    No preview · Article · Feb 2011 · Canadian Journal of Chemistry

Publication Stats

7k Citations
878.40 Total Impact Points


  • 1981-2015
    • Memorial University of Newfoundland
      • Department of Chemistry
      Saint John's, Newfoundland and Labrador, Canada
  • 1984-2011
    • National Research Council Canada
      Ottawa, Ontario, Canada
  • 2010
    • University of Toronto
      • Department of Chemistry
      Toronto, Ontario, Canada
  • 2007
    • University of Waterloo
      • Department of Chemistry
      Waterloo, Quebec, Canada
  • 2001-2007
    • University of Victoria
      • Department of Chemistry
      Victoria, British Columbia, Canada
  • 2005
    • The University of Calgary
      • Department of Chemistry
      Calgary, Alberta, Canada
  • 1999-2001
    • Durham University
      Durham, England, United Kingdom
  • 1998
    • Universität Paderborn
      Paderborn, North Rhine-Westphalia, Germany
  • 1997
    • University of Valencia
      Valenza, Valencia, Spain
    • University of Hull
      Kingston upon Hull, England, United Kingdom