A5022800410- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Magnetism in coordination complexes
- Metal complexes synthesis and properties
- Crystallography and molecular interactions
- Physics of Superconductivity and Magnetism
- Organic and Molecular Conductors Research
- Metal-Organic Frameworks: Synthesis and Applications
- Crystal structures of chemical compounds
- Lanthanide and Transition Metal Complexes
- Advanced Condensed Matter Physics
- Theoretical and Computational Physics
- Quantum and electron transport phenomena
- Synthesis and Characterization of Heterocyclic Compounds
- Magnetic properties of thin films
- Metal-Catalyzed Oxygenation Mechanisms
- Organometallic Complex Synthesis and Catalysis
- Advanced NMR Techniques and Applications
- Inorganic Fluorides and Related Compounds
- Electron Spin Resonance Studies
- Molecular spectroscopy and chirality
- Porphyrin and Phthalocyanine Chemistry
- Asymmetric Hydrogenation and Catalysis
- Fluorine in Organic Chemistry
- Solid-state spectroscopy and crystallography
Clark University
2016-2025
Northumbria University
2023
University of Worcester
2016-2021
AbbVie (United States)
2015
Universitat de Barcelona
2003-2014
University of Canterbury
1996-2011
St. Francis Xavier University
2007-2008
Imperial College London
2007
Eastern Washington University
2007
Argonne National Laboratory
2007
We present an introduction to the workings, units of measure, and general properties magnetic materials. This is intended as a "primer interpretation data" for those who are entering field, or encountering measurements in literature. expect this work will serve initial guide reader familiarize them with basics hope that working field magnetochemistry wish explore additional, more detailed literature their specific investigations demand. Topics covered include: fields (SI cgs), paramagnetism...
High-field magnetization, field-dependent specific heat measurements, and zero-field inelastic magnetic neutron scattering have been used to explore the properties of copper pyrazine dinitrate $[\mathrm{Cu}({\mathrm{C}}_{4}{\mathrm{H}}_{4}{\mathrm{N}}_{2})({\mathrm{NO}}_{3}{)}_{2}].$ The material is an ideal one-dimensional spin-1/2 Heisenberg antiferromagnet with nearest-neighbor exchange constant $J=0.90(1) \mathrm{meV}$ chains extending along orthorhombic a direction. As opposed...
Measurements are reported of the magnetic field dependence excitations in quantum critical state spin S=1/2 linear chain Heisenberg antiferromagnet copper pyrazine dinitrate (CuPzN). The complete spectrum was measured at k(B)T/J< or =0.025 for H=0 and H=8.7 T, where system is approximately 30% magnetized. At H=0, results agreement with exact calculations dynamic correlation function a two-spinon continuum. there multiple overlapping continua incommensurate soft modes. boundaries these...
The complex (2,3-dmpyH)2CuBr4 has been synthesized and its crystal packing determined by single-crystal X-ray diffraction (2,3-dmpyH = 2,3-dimethylpyridinium). compound crystallizes in the triclinic space group P̄1. is characterized formation of a ladder structure for CuBr4 anions showing short Br···Br contacts. rungs are formed via crystallographic inversion center, while rails unit cell translations. Variable temperature magnetic susceptibility measurements agree very well with model...
We study the magnetic-field-induced quantum phase transition from a gapped that has no magnetic long-range order into gapless in spin-1/2 ladder compound bis(2,3-dimethylpyridinium) tetrabromocuprate (DIMPY). At temperatures below about 1 K, specific heat attains an asymptotic linear temperature dependence, characteristic of Tomonaga-Luttinger liquid. Inelastic neutron scattering and measurements both phases are good agreement with theoretical calculations, demonstrating DIMPY is first model...
Crystal structures of six iodopyridinium tetrahalocuprate(II) salts are reported, (nIP)2CuX4, where X = Cl or Br, nIP is the n-iodopyridinium cation, and n 2, 3, 4. The supramolecular structure these developed based on N–H···X hydrogen bonding C–I···X halogen interactions. Comparing with previously published general formulas (nCP)2CuX4 (nBP)2CuX4, nCP+ nBP+ n-chloropyridinium n-bromopyridinium cations, respectively, allows us to investigate competition between Henceforth, formula (nYP)2CuX4...
Abstract The literature of low‐dimensional Cu II molecular magnetic systems in which superexchange pathways involve halide ions and/or cyclic 1,4‐diazines is reviewed. Compounds are organized by lattice type between 1D (including uniform and alternating chains, ladders) 2D square rectangular layers).
High-precision dc magnetization measurements have been made on Cu(C4H4N2) (NO3)2 in magnetic fields up to 14.7 T, slightly above the saturation field Hs=13.97 temperature range from 0.08 15 K. The curve and differential susceptibility at lowest show excellent agreement with exact theoretical results for spin-1/2 Heisenberg antiferromagnet one dimension. A broad peak is observed measured as a function of temperature, signaling crossover low-temperature Tomonaga-Luttinger-liquid regime. With...
A family of 6-X-2-hydroxyprydine/pyridone (6-X-2-HOpy/pyridone) Cu(II) compounds, [Cu(6-X-2-HOpy)2Cl2] (1 X = F; 2 Cl) and [(6-X-2-pyridone)CuCl(μ-Cl)]2 (3 Cl; 4 Br), has been prepared. Solution-based infrared spectra displayed a correlation between tautomeric state, primarily driven by halogen identity, coordination mode with neutral nitrogen favored as Br ≪ Cl < F. The state 6-Cl-2-HOpy is influenced metal ion concentration (M) lactam increasing M increases. Compound 1 F–F contacts less...
The magnetic susceptibility and magnetization of two layered $S=\frac{1}{2}$ Heisenberg antiferromagnets with moderate exchange are reported. isostructural compounds, $(2\ensuremath{-}\mathrm{amino}\ensuremath{-}5\ensuremath{-}\mathrm{chloropyridinium}{)}_{2}{\mathrm{CuBr}}_{4}$ $[(5\mathrm{C}\mathrm{A}\mathrm{P}{)}_{2}{\mathrm{CuBr}}_{4}]$ $(2\ensuremath{-}\mathrm{amino}\ensuremath{-}5\ensuremath{-}\mathrm{methylpyridinium}{)}_{2}{\mathrm{CuBr}}_{4}$...
Hydrotropes are a class of compounds that widely used in chemical, cosmetic, and pharmaceutical industries. Though amphiphilic character, they have short hydrophobic regions thus differ from classical surfactants. Yet display substantial (and often selective) ability to solubilize lipophilic water. Beyond the minimal hydrotropic concentration, molecules self-aggregate produce operating assembly. We show this paper, based on crystal structure analysis several hydrotropes, these form...
We report on the syntheses, crystal structures, and magnetic susceptibilities of a family copper pyrazine (pz)-based antiferromagnets with moderate in-plane exchange. These materials fall into two classes: monoclinic complexes [Cu(pz)2]A2 for A = ClO4 (1) or BF4 (2) tetragonal complex [Cu(pz)2(NO3)]PF6 (3). Compound 1 its deuterated version [Cu(pz-d4)2](ClO4)2 (1a) crystallize in space group C2/m at room temperature disordered perchlorate anions. For both 2, C centering Cu(II), S 1/2, site...
Hybrid organic–inorganic perovskites (HOIPs) have attracted considerable attention for their scientific and technological potential in photovoltaics optoelectronic devices.
Four new copper compounds of 2-amino-5-nitropyridine/pyridinium (5NAP/5NAPH) have been prepared and characterized: (5NAPH)2[CuBr4], 2; (d2-5NAPD)2[CuBr4], 2a; (5NAP)2CuCl2, 3; (5NAP)2CuBr2, 4. Compounds 2 2a are isomorphous crystallize in the triclinic space group P-1. Packing is stabilized by hydrogen/deuterium bonds. Short Br…Br contacts provide potential magnetic superexchange pathways, but only very weak antiferromagnetic exchange observed (J/kB∼-2 K). 3 4 also monoclinic P21/c. The...
We present experiments on the thermal transport in spin-$\frac{1}{2}$ chain compound copper pyrazine dinitrate $\mathrm{Cu}({\mathrm{C}}_{4}{\mathrm{H}}_{4}{\mathrm{N}}_{2})({\mathrm{NO}}_{3}{)}_{2}$. The heat conductivity shows a surprisingly strong dependence applied magnetic field $B$, characterized at low temperatures by two main features. first one appearing $B$ is characteristic dip located ${\ensuremath{\mu}}_{B}B\ensuremath{\sim}{k}_{B}T$, that may arise from umklapp scattering....
The crystal structure of bis(cyclopentylammonium)tetrabromocuprate(II) has been determined at room temperature and −70 °C. is orthorhombic, space group Pn21a, with a = 12.092(6) Å, b 8.134(4) c 18.698(10) Å. low also Pna21, 24.111(5) 8.089(2) 18.448(4) DSC studies reveal the presence weak endotherm −13 structures two phases are very similar, differing only in relative orientations cyclopentyl rings organic cations slight displacements anionic tetrahedra. CuBr42- anions phase arranged to...
We present an experimental study of the two-dimensional $S=\frac{1}{2}$ square-lattice antiferromagnet $\text{Cu}{(\text{pz})}_{2}{({\text{ClO}}_{4})}_{2}$ (pz denotes pyrazine-${\text{C}}_{4}{\text{H}}_{4}{\text{N}}_{2}$) using specific-heat measurements, neutron diffraction, and cold-neutron spectroscopy. The magnetic field dependence ordering temperature was determined from measurements for fields perpendicular parallel to planes, showing identical field-temperature phase diagrams. This...
Using micromechanical force magnetometry, we have measured the magnetization of strong-leg spin-1/2 ladder compound (C$_7$H$_{10}$N)$_2$CuBr$_2$ at temperatures down to 45 mK. Low-temperature magnetic susceptibility as a function field exhibits maximum near critical H_c which magnon gap vanishes, expected for gapped one-dimensional antiferromagnet. Above clear minimum appears in temperature predicted by theory. In this region, conjunction with our specific heat data yields Wilson ratio R_W....
A 1D perovskite, (C<sub>5</sub>H<sub>14</sub>N<sub>2</sub>) CuCl<sub>4</sub>, is stabilized as alternative lead-free material for more environmentally friendly solar cells. The absence of magnetic properties results from the cancelation antiferromagnetic and ferromagnetic contributions.
We have synthesized and characterized a new spin-1/2 Heisenberg antiferromagnetic ladder: bis 5-iodo-2-aminopyridinium tetrabromocuprate(II) dihydrate. X-ray diffraction studies show the structure of compound to consist well isolated stacked ladders interaction between Cu(2+) atoms be due direct Br...Br contacts. Magnetic susceptibility magnetization in strong-coupling limit, with along rungs (J' ~ 13 K) much greater than rails (J 1 K). critical fields are observed near 8.3 T 10.4 T,...