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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.


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.


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.


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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