Center for Catalysis Research and Innovation

Ottawa, Canada

Center for Catalysis Research and Innovation

Ottawa, Canada
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Cook C.,University of Ottawa | Habib F.,University of Ottawa | Aharen T.,University of Ottawa | Clerac R.,CNRS Paul Pascal Research Center | And 3 more authors.
Inorganic Chemistry | Year: 2013

A nitrogen-rich ligand bis(1H-tetrazol-5-yl)amine (H3bta) was employed to isolate a new FeIII complex, Na2NH 4[FeIII(Hbta)3]·3DMF·2H 2O (1). Single crystal X-ray diffraction revealed that complex 1 consists of FeIII ions in an octahedral environment where each metal ion is coordinated by three Hbta2- ligands forming the [Fe III(Hbta)3]3- core. Each unit is linked to two one-dimensional (1-D) Na+/solvent chains creating a two-dimensional (2-D) network. In addition, the presence of multiple hydrogen bonds in all directions between ammonium cation and ligands of different [Fe III(Hbta)3]3- units generates a three-dimensional (3-D) network. Magnetic measurements confirmed that the FeIII center undergoes a Spin Crossover (SCO) at high temperature (T1/2 = 460(10) K). © 2013 American Chemical Society.


Davis B.L.,Los Alamos National Laboratory | Rekken B.D.,Los Alamos National Laboratory | Michalczyk R.,Los Alamos National Laboratory | Garner III E.B.,University of Alabama | And 4 more authors.
Chemical Communications | Year: 2013

Lewis bases react with borazine and polyborazylene, yielding borane adducts. In the case of NH3 (l), ammonia-borane (AB) is formed and quantified using NMR spectroscopy against an internal standard. Calculations indicate that the formation of B(NH2)3 may provide the driving force of this redistribution. Given the complexity and expense of currently known spent AB regeneration pathways, it is suggested that this redistribution chemistry be used to recover AB and improve regeneration methods. © 2013 The Royal Society of Chemistry.


Salehpour S.,Center for Catalysis Research and Innovation | Zuliani C.J.,Center for Catalysis Research and Innovation | Dube M.A.,Center for Catalysis Research and Innovation
European Journal of Lipid Science and Technology | Year: 2012

Temperature and pH-responsive polyglycerol-based hydrogels were successfully synthesized and characterized. An increase in polyglycerol molecular weight was achieved by cross-linking polyglycerol using multifunctional electrophilic epoxide-containing compounds. The chemical structure of polyglycerol-based hydrogels was determined by FTIR spectroscopy. The temperature-dependent swelling behavior of the hydrogels was studied at 293, 310, 333, and 353K and a negative temperature-sensitive system was observed. The hydrogels exhibited pH sensitivity at pH 4, 7, and 10. The hydrophilicity and biocompatibility of these hydrogels make them suitable for pharmaceutical, biomedical, and biotechnological applications. They could potentially serve as a replacement for fossil-based poly(ethylene glycol) and poly(vinyl alcohol) hydrogels. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lin P.-H.,University of Ottawa | Korobkov I.,University of Ottawa | Wernsdorfer W.,CNRS Neel Institute | Ungur L.,Catholic University of Leuven | And 3 more authors.
European Journal of Inorganic Chemistry | Year: 2011

Coordination-induced chirality was achieved in a uniquetetrahedral [Dy 4(μ 4-O)(μ-OMe) 2(beh) 2(esh) 4]·3MeOH complex through a twisted diazine bridge from a Schiff base ligand. Magnetic measurements reveal weak intramolecular antiferromagnetic interactions (J = -0.3 cm -1) with single-molecule magnet behaviour (U eff = 23.42 K). Coordination-induced chirality was achieved in a unique tetrahedral [Dy 4(μ 4-O)(μ-OMe) 2(beh) 2(esh) 4]·3MeOH complex through a twisted diazine bridge from a Schiff base ligand. Magnetic measurementsreveal weak intramolecular antiferromagnetic interactions (J = -0.3 cm -1) with single-molecule magnet behaviour (U eff = 23.42 K). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA.


Long J.,University of Ottawa | Long J.,Center for Catalysis Research and Innovation | Habib F.,University of Ottawa | Habib F.,Center for Catalysis Research and Innovation | And 9 more authors.
Journal of the American Chemical Society | Year: 2011

A family of five dinuclear lanthanide complexes has been synthesized with general formula [LnIII 2(valdien)2(NO 3)2] where (H2valdien = N1,N3-bis(3- methoxysalicylidene)diethylenetriamine) and LnIII = Eu III1, GdIII2, TbIII3, DyIII4, and HoIII5. The magnetic investigations reveal that 4 exhibits single-molecule magnet (SMM) behavior with an anisotropic barrier U eff = 76 K. The step-like features in the hysteresis loops observed for 4 reveal an antiferromagnetic exchange coupling between the two dysprosium ions. Ab initio calculations confirm the weak antiferromagnetic interaction with an exchange constant JDy-Dy = -0.21 cm-1. The observed steps in the hysteresis loops correspond to a weakly coupled system similar to exchange-biased SMMs. The Dy2 complex is an ideal candidate for the elucidation of slow relaxation of the magnetization mechanism seen in lanthanide systems.(Figure Presented) © 2011 American Chemical Society.


Salehpour S.,Center for Catalysis Research and Innovation | Dube M.A.,Center for Catalysis Research and Innovation
Macromolecular Chemistry and Physics | Year: 2011

The step-growth polymerization of glycerol to relatively high molecular weight polyglycerol is investigated. Glycerol is a renewable material that can be derived from the transesterification of vegetable oils to biodiesel. Several soluble catalysts and their reaction mechanisms are compared and their effect on polymer molecular weight and microstructure is measured. High-molecular-weight PG with multimodal molecular weight distributions is observed using GPC, and partial branching is identified using 13C NMR spectroscopy. Theoretical models are used to predict the gel point and to calculate monomer functionality.(Figure Presented) © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Brunet G.,University of Ottawa | Habib F.,University of Ottawa | Cook C.,University of Ottawa | Pathmalingam T.,University of Ottawa | And 7 more authors.
Chemical Communications | Year: 2012

A high-spin tridecanuclear Ni II cluster, [Ni II 13(N 3) 18(dpo) 4(Hdpo) 2(H 2hpo) 4(H 2O)(MeOH)] [Ni II 13(N 3) 18(dpo) 4(Hdpo) 2(H 2hpo) 4(H 2O) 2] (1) (Hdpo = 1-(dimethylamino)propan-2-one oxime and H 2hpo = 1-(hydroxyamino)propan-2-one oxime) with a purely azido-bridged core, is reported with dominant ferromagnetic coupling between Ni II ions. The latter molecule exhibits a unique planar core topology with the largest N 3 -:Ni II ratio reported to date. © The Royal Society of Chemistry 2012.


Habib F.,University of Ottawa | Lin P.-H.,University of Ottawa | Long J.,University of Ottawa | Korobkov I.,University of Ottawa | And 3 more authors.
Journal of the American Chemical Society | Year: 2011

The magnetic dilution method was employed in order to elucidate the origin of the slow relaxation of the magnetization in a Dy2 single-molecule magnet (SMM). The doping effect was studied using SQUID and micro-SQUID measurements on a Dy2 SMM diluted in a diamagnetic Y2 matrix. The quantum tunneling of the magnetization that can occur was suppressed by applying optimum dc fields. The dominant single-ion relaxation was found to be entangled with the neighboring DyIII ion relaxation within the molecule, greatly influencing the quantum tunneling of the magnetization in this complex. © 2011 American Chemical Society.


Habib F.,University of Ottawa | Cook C.,University of Ottawa | Korobkov I.,University of Ottawa | Murugesu M.,University of Ottawa | Murugesu M.,Center for Catalysis Research and Innovation
Inorganica Chimica Acta | Year: 2012

A novel in situ Mn n+-promoted double-aldol reaction is reported. Single crystal X-ray measurements confirm the addition of acetone to two o-vanillin molecules in an original in situ α,α double aldol reaction promoted by Mn ions in the presence of base. The newly formed ligands coordinate to four Mn III ions forming a defect-dicubane core structure (1) bridged exclusively by oxygen-based ligands. Other 3d metals were employed under the same reaction conditions, however no aldol addition occurred and tetranuclear cubane-like structures formed using Co II (2) and Ni II (3) ions. Magnetic measurements were carried out on all complexes using SQUID magnetometry. Dominant ferromagnetic interactions were observed for complexes 1 and 3 with J = 1.8 cm -1, J′ =-2.5 cm -1, g = 1.95 for 1 and J = 3.1 cm -1, g = 2.17 for 3 while complex 2 exhibited antiferromagnetic exchange interactions. Notably, complex 1 was shown to exhibit spin frustration rarely seen in {Mn III} 4 systems resulting in an intermediate spin ground state of S T = 6. © 2011 Elsevier B.V. All rights reserved.


Habib F.,University of Ottawa | Long J.,University of Ottawa | Lin P.-H.,University of Ottawa | Korobkov I.,University of Ottawa | And 5 more authors.
Chemical Science | Year: 2012

In order for molecular magnetic materials to become functional, they must retain their magnetization at reasonable temperatures implying high energy barriers for spin reversal. The field of single-molecule magnets (SMMs) has recently experienced an explosion of research targeting these high anisotropic barriers. Achieving such feats has involved increasing the spin of a complex and/or increasing the inherent magnetic anisotropy. Exerting control over the total spin of a complex has been possible contrary to controlling the global anisotropy. Herein, we report the experimental and theoretical study of local anisotropy alignment on Dy III metal centers and their orientation relative to other centers in rare, dinuclear quadruply-stranded helicate/mesocate complexes. A detailed study of these supramolecular architectures has advanced our knowledge of the origins of magnetic relaxation in SMMs which was shown to arise from minute changes in bond distances around the metal centers leading to changes in the local anisotropy and, in turn, the effective energy barriers. © 2012 The Royal Society of Chemistry.

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