scholarly journals Magnetic Behaviour of Mn12-Stearate Single-Molecule Magnets Immobilized on the Surface of 300 nm Spherical Silica Nanoparticles

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2624 ◽  
Author(s):  
Magdalena Laskowska ◽  
Oleksandr Pastukh ◽  
Piotr Konieczny ◽  
Mateusz Dulski ◽  
Marcin Zalsiński ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Single Molecule ◽  
Silica Surface ◽  
Magnetic Measurements ◽  
Magnetic Behaviour ◽  
Silica Spheres ◽  
Squid Magnetometry ◽  
Single Molecule Magnets ◽  
Transmission Electron ◽  
Spherical Silica

The magnetic behaviour of Mn 12 -stearate single-molecule magnets (SMMs) ([ Mn 12 O 12 ( CH 3 ( CH 2 ) 16 CO 2 ) 16 ] · 2 CH 3 COOH · 4 H 2 O ) on the surface of 300 nm spherical silica nanoparticles were investigated. The SMMs were bonded at the silica surface with the assumed number of anchoring points, which influenced on their degree of freedom and distribution. In order to check the properties of Mn 12 -stearate molecules separated on the silica surface, and check their interactions, the samples containing four different concentration of spacers per single anchoring unit and variously bonded Mn 12 -stearate particles were prepared. The materials have been examined using Raman spectroscopy, transmission electron microscopy, and SQUID magnetometry. The results of magnetic measurements showed a correlation between the way of single-molecule magnets immobilization onto the silica spheres and the magnetic properties of the obtained hybrid materials.

scholarly journals How to Control the Distribution of Anchored, Mn12–Stearate, Single-Molecule Magnets

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1730 ◽  
Author(s):  
Magdalena Laskowska ◽  
Oleksandr Pastukh ◽  
Dominika Kuźma ◽  
Łukasz Laskowski
Keyword(s):  
Electron Microscopy ◽  
Single Molecule ◽  
Magnetic Particles ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Single Molecule Magnets ◽  
Transmission Electron ◽  
Spherical Silica ◽  
Anodic Stripping

Controlling the distribution of the Mn12–stearate, single-molecule magnets (SMMs) anchored on a select surface is expected to be a new method for tuning its interactions, and an investigation on the magnetic properties of separated magnetic molecules is also lacking. The anchoring of the SMMs at the surface with an assumed statistic distance between each other is not an easy task; nevertheless, in this work, we show a synthesis which allows for this in detail. The immobilization of the Mn12–stearate was demonstrated with the use of FTO glasses and spherical silica as substrates. Based on differential pulse anodic stripping voltammetry (DPASV) and transmission electron microscopy (TEM) observations, we proved the efficiency of the method proposed. We observed continuous decreasing the number of bonds, and afterward, decreasing in the number of immobilized molecules with an increasing the number of spacer units used for separation of the magnetic particles.

scholarly journals AC Susceptibility Studies of Magnetic Relaxation in Mn12-Stearate SMMs on the Spherical Silica Surface

2021 ◽  
Vol 7 (9) ◽  
pp. 122
Author(s):  
Oleksandr Pastukh ◽  
Piotr Konieczny ◽  
Magdalena Laskowska ◽  
Łukasz Laskowski
Keyword(s):  
Single Molecule ◽  
Silica Surface ◽  
Ac Susceptibility ◽  
Relaxation Times ◽  
Single Molecule Magnets ◽  
Relaxation Parameters ◽  
Spherical Silica ◽  
Measuring Techniques ◽  
Different Temperatures ◽  
Nanostructured Silica

The study of magnetic relaxations in Mn12-stearate single-molecule magnets deposited on the surface of spherical silica nanoparticles was performed. For such a purpose, the investigation of AC magnetic susceptibility dependence on the frequency and temperature was performed. Based on the Argand plots obtained for different temperatures and temperature dependencies of susceptibility, obtained for different frequencies of AC field, the corresponding relaxation times were derived. Fitting to the Arrhenius law revealed the values of an effective energy barrier and a mean relaxation time, which were consistent for both measuring techniques (Ueff/kB∼ 50 K and τ0∼ 10−7 s) and similar to the corresponding values for the analogous bulk compounds. Additionally, the obtained relaxation parameters for the Mn12-stearate molecules on the spherical silica surface were compared with corresponding values for the Mn12-based single-molecule magnets deposited upon other types of nanostructured silica surface.

Aging effect on the magnetic properties of Mn12-stearate single-molecule magnets anchored onto the surface of spherical silica nanoparticles

2020 ◽  
Vol 261 ◽  
pp. 114670 ◽  
Author(s):  
Oleksandr Pastukh ◽  
Piotr Konieczny ◽  
Dominik Czernia ◽  
Magdalena Laskowska ◽  
Mateusz Dulski ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Silica Nanoparticles ◽  
Single Molecule ◽  
Aging Effect ◽  
Single Molecule Magnets ◽  
Spherical Silica

scholarly journals The Separation of the Mn12 Single-Molecule Magnets onto Spherical Silica Nanoparticles

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 764 ◽  
Author(s):  
Lukasz Laskowski ◽  
Iwan Kityk ◽  
Piotr Konieczny ◽  
Oleksandr Pastukh ◽  
Mateusz Schabikowski ◽  
...  
Keyword(s):  
Single Molecule ◽  
Molecular Magnets ◽  
Single Molecule Magnets ◽  
Silica Substrate ◽  
Transmission Electron ◽  
Spherical Silica ◽  
The Individual ◽  
Magnetic States ◽  
First Time ◽  
Direct Microscopic Observation

The Mn12 single-molecule magnets (SMMs) could be attached to the surface of spherical silica for the first time with a high probability. This allowed separation of the individual molecular magnets and direct microscopic observation of the SMMs. We described in detail how to fabricate such a composite material. The synthesis procedure proposed here is simple and efficient. We confirmed the efficiency of the method by transmission electron microscopy (TEM): single-molecule magnets were visible at the surface of a silica substrate. Based on TEM observation, we described how the molecules anchor to the surface of silica (the geometry of the magnetic molecule in regard to the surface of the substrate). The SQUID magnetometry showed that single-molecule magnet behaviour is kept intact after grafting. The attachment of the single-molecule magnets to the surface of silica allows to investigate their properties as separate molecules. This is particularly important in the analysis of magnetic properties such as magnetic states of the separated SMMs, their mutual interactions, and the influence of a silica support.

Cu(ii)–Dy(iii) and Co(iii)–Dy(iii) based single molecule magnets with multiple slow magnetic relaxation processes in the Cu(ii)–Dy(iii) complex

2015 ◽  
Vol 44 (29) ◽  
pp. 13242-13249 ◽  
Author(s):  
Malay Dolai ◽  
Mahammad Ali ◽  
Ján Titiš ◽  
Roman Boča
Keyword(s):  
Schiff Base ◽  
Single Molecule ◽  
Schiff Base Ligand ◽  
Magnetic Relaxation ◽  
Magnetic Behaviour ◽  
Dinuclear Complexes ◽  
Relaxation Processes ◽  
Single Molecule Magnets ◽  
Slow Magnetic Relaxation

Two CuII–DyIII and CoIII–DyIII dinuclear complexes of a Schiff base ligand (H3L) exhibit single-molecule magnetic behaviour with multiple slow magnetic relaxation processes for the former.

1,2-Diaza-4-phospholide complexes of chromium(ii): dipotassium organochromates behaving as single-molecule magnets

2020 ◽  
Vol 49 (21) ◽  
pp. 6945-6949
Author(s):  
Jing Su ◽  
Lei Yin ◽  
Zhongwen Ouyang ◽  
Zhenxing Wang ◽  
Wenjun Zheng
Keyword(s):  
Single Molecule ◽  
Magnetic Measurements ◽  
Planar Geometry ◽  
Single Molecule Magnets ◽  
Square Planar

Heterobimetallic 1,2-diaza-4-phospholide chromium(ii) complexes with a near-square planar geometry behave as field-induced single-molecule magnets, as characterized by HF-EPR and magnetic measurements.

scholarly journals Silica-Polystyrene Nanocomposite Particles Synthesized by Nitroxide-Mediated Polymerization and Their Encapsulation through Miniemulsion Polymerization

2006 ◽  
Vol 2006 ◽  
pp. 1-10 ◽  
Author(s):  
Bérangère Bailly ◽  
Anne-Carole Donnenwirth ◽  
Christèle Bartholome ◽  
Emmanuel Beyou ◽  
Elodie Bourgeat-Lami
Keyword(s):  
Silica Nanoparticles ◽  
Functional Group ◽  
Silica Surface ◽  
Miniemulsion Polymerization ◽  
Molecular Weights ◽  
Transmission Electron ◽  
Shell Particles ◽  
Terminal Functional Group ◽  
Nitroxide Mediated Polymerization

Polystyrene (PS) chains with molecular weights comprised between 8000 and 64000g⋅mol-1and narrow polydispersities were grown from the surface of silica nanoparticles (Aerosil A200 fumed silica and Stöber silica, resp.) through nitroxide-mediated polymerization (NMP). Alkoxyamine initiators based on N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide (DEPN) and carrying a terminal functional group have been synthesized in situ and grafted to the silica surface. The resulting grafted alkoxyamines have been employed to initiate the growth of polystyrene chains from the inorganic surface. The maximum grafting density of the surface-tethered PS chains was estimated and seemed to be limited by initiator confinement at the interface. Then, the PS-grafted Stöber silica nanoparticles were entrapped inside latex particles via miniemulsion polymerization. Transmission electron microscopy indicated the successful formation of silica-polystyrene core-shell particles.

scholarly journals Electro-activity and magnetic switching in lanthanide-based single-molecule magnets

2019 ◽  
Vol 6 (12) ◽  
pp. 3398-3417 ◽  
Author(s):  
Olivier Cador ◽  
Boris Le Guennic ◽  
Fabrice Pointillart
Keyword(s):  
Magnetic Field ◽  
Single Molecule ◽  
Magnetic Behaviour ◽  
Light Irradiation ◽  
Redox Processes ◽  
Single Molecule Magnets ◽  
Magnetic Switching

The present work reviews switching of single-molecule magnetic behaviour achieved through various stimuli such as temperature, light irradiation, redox processes, solvation/desolvation, and magnetic field.

scholarly journals Pressure tunablity in ReX4based SMMs; A magnetostructural study

2014 ◽  
Vol 70 (a1) ◽  
pp. C903-C903
Author(s):  
Christopher Woodall ◽  
Francisco Jose Martinez Lillo ◽  
Martin Míšek ◽  
Alessandro Prescimone ◽  
Dave Allan ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Susceptibility ◽  
Hydrostatic Pressure ◽  
Single Molecule ◽  
High Hydrostatic Pressure ◽  
Magnetic Behaviour ◽  
Magnetic Interactions ◽  
Antiferromagnetic Coupling ◽  
X Ray Diffraction ◽  
Single Molecule Magnets

Since the discovery of Single-Molecule Magnets (SMMs) in 1993 there has been extensive interest in understanding, developing and tuning the nature of magnetic interactions within SMMs with the intention of gaining greater insight into the nature of these interactions.[1] Typically this is done synthetically using variations in ligand geometry and co-ordination environment to vary magnetic behaviour. More recently it has been demonstrated that high hydrostatic pressure are also an effective mechanism for "tuning" properties such as magnetic susceptibility in a variety of SMMs.[2] The number of studies utilising high hydrostatic pressure to investigate molecular magnetism is extremely limited due to their inherent difficulty however we report a new study investigating the pressure tunabilty of Re(IV) based SMMs. 4d and 5d metal ions such as Re are of interest due their enhanced magnetic exchanges relative to their 3d analogues and Re(IV) based complexes are of particular interest. Previous studies into [ReX6]2-(X = Cl, Br and I) anions demonstrate significant antiferromagnetic coupling, not transmitted through chemical interactions but rather through weak Re-X...X interactions in the solid state which may be easily perturbed at high pressure. [3] Therefore we report an investigation into the tunability of magnetic susceptibility in a variety of [ReX4] based compounds using high pressure magnetic susceptibility measurements and correlate the results with structure observations taken from high pressure single crystal X-ray diffraction experiments. The effects of the removal of solvent trapped in the lattice using temperature and vacuum and the corresponding effect on magnetic behaviour and chemical structure are also reported.

Dispersion and Lorentz Microscopy of Samarium Cobalt Nanoparticles in a Polymer Matrix

1997 ◽  
Vol 501 ◽  
Author(s):  
Yan Jin ◽  
Sara A. Majetich ◽  
Anit Giri
Keyword(s):  
Polymer Matrix ◽  
Magnetic Measurements ◽  
Exchange Interactions ◽  
Squid Magnetometry ◽  
Spherical Nanoparticles ◽  
Single Particles ◽  
Interacting Particles ◽  
Magnetic Composites ◽  
Lorentz Microscopy ◽  
Transmission Electron

A new method for dispersing magnetic nanoparticles in a polymer matrix is described. SmCo5 nanoparticle powders are first prepared by ball milling, and then embedded in thermoplastic powder by further milling. The nanoparticle-embedded thermoplastic powder was compacted to form solid magnetic composites which were characterized by transmission electron microscopy (TEM) and by SQUID magnetometry. The conventional TEM measurements on microtomed sections of the composites showed spherical nanoparticles clearly separated from their nearest neighbors, thereby eliminating exchange interactions and greatly reducing magnetostatic interactions. Lorentz microscopy illustrated the potential for imaging single particles and determining the magnetization directions of isolated and interacting particles. Magnetic measurements on dilute samples show that the processing method does not degrade the magnetic properties of the particles.

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