scholarly journals Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

Crystals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 9 ◽  
Author(s):  
Magdalena Fitta ◽  
Robert Pełka ◽  
Piotr Konieczny ◽  
Maria Bałanda
Keyword(s):  
Magnetocaloric Effect ◽  
Metal Ion ◽  
Chemical Properties ◽  
Magnetic Ordering ◽  
Entropy Change ◽  
Building Blocks ◽  
Molecular Magnets ◽  
Characteristic Index ◽  
A New Technique ◽  
Physical And Chemical

Octacyanometallate-based compounds displaying a rich pallet of interesting physical and chemical properties, are key materials in the field of molecular magnetism. The [M(CN)8]n− complexes, (M = WV, MoV, NbIV), are universal building blocks as they lead to various spatial structures, depending on the surrounding ligands and the choice of the metal ion. One of the functionalities of the octacyanometallate-based coordination polymers or clusters is the magnetocaloric effect (MCE), consisting in a change of the material temperature upon the application of a magnetic field. In this review, we focus on different approaches to MCE investigation. We present examples of magnetic entropy change ΔSm and adiabatic temperature change ΔTad, determined using calorimetric measurements supplemented with the algebraic extrapolation of the data down to 0 K. At the field change of 5T, the compound built of high spin clusters Ni9[W(CN)8]6 showed a maximum value of −ΔSm equal to 18.38 J·K−1 mol−1 at 4.3 K, while the corresponding maximum ΔTad = 4.6 K was attained at 2.2 K. These values revealed that this molecular material may be treated as a possible candidate for cryogenic magnetic cooling. Values obtained for ferrimagnetic polymers at temperatures close to their magnetic ordering temperatures, Tc, were lower, i.e., −ΔSm = 6.83 J·K−1 mol−1 (ΔTad = 1.42 K) and −ΔSm = 4.9 J·K−1 mol−1 (ΔTad = 2 K) for {[MnII(pyrazole)4]2[NbIV(CN)8]·4H2O}n and{[FeII(pyrazole)4]2[NbIV(CN)8]·4H2O}n, respectively. MCE results have been obtained also for other -[Nb(CN)8]-based manganese polymers, showing significant Tc dependence on pressure or the remarkable magnetic sponge behaviour. Using the data obtained for compounds with different Tc, due to dissimilar ligands or other phase of the material, the ΔSm ~ Tc−2/3 relation stemming from the molecular field theory was confirmed. The characteristic index n in the ΔSm ~ ΔHn dependence, and the critical exponents, related to n, were determined, pointing to the 3D Heisenberg model as the most adequate for the description of these particular compounds. At last, results of the rotating magnetocaloric effect (RMCE), which is a new technique efficient in the case of layered magnetic systems, are presented. Data have been obtained and discussed for single crystals of two 2D molecular magnets: ferrimagnetic {MnII(R-mpm)2]2[NbIV(CN)8]}∙4H2O (mpm = α-methyl-2-pyridinemethanol) and a strongly anisotropic (tetren)Cu4[W(CN)8]4 bilayered magnet showing the topological Berezinskii-Kosterlitz-Thouless transition.

scholarly journals Recent Progress in the Synthesis and Characterization of Diarylethene-based MOFs

2014 ◽  
Vol 70 (a1) ◽  
pp. C1223-C1223
Author(s):  
Jason Benedict ◽  
Ian Walton ◽  
Dan Patel ◽  
Jordan Cox
Keyword(s):  
Chemical Properties ◽  
Building Blocks ◽  
Synthesis And Characterization ◽  
Next Generation ◽  
Design Synthesis ◽  
Thermally Induced ◽  
Potential Applications ◽  
External Stimuli ◽  
Physical And Chemical

Metal-organic Frameworks (MOFs) remain an extremely active area of research given the wide variety of potential applications and the enormous diversity of structures that can be created from their constituent building blocks. While MOFs are typically employed as passive materials, next-generation materials will exhibit structural and/or electronic changes in response to applied external stimuli including light, charge, and pH. Herein we present recent results in which advanced photochromic diarylethenes are combined with MOFs through covalent and non-covalent methods to create photo-responsive permanently porous crystalline materials. This presentation will describe the design, synthesis, and characterization of next-generation photo-switchable diarylethene based ligands which are subsequently used to photo-responsive MOFs. These UBMOF crystals are, by design, isostructural with previously reported non-photoresponsive frameworks which enables a systematic comparison of their physical and chemical properties. While the photoswitching of the isolated ligand in solution is fully reversible, the cycloreversion reaction is suppressed in the UBMOF single crystalline phase. Spectroscopic evidence for thermally induced cycloreversion will be presented, as well as a detailed analysis addressing the limits of X-ray diffraction techniques applied to these systems.

The Application Research of Single-Molecule Magnets and Molecular Spin Electronics Materials

2012 ◽  
Vol 485 ◽  
pp. 522-525
Author(s):  
Hai Mei Xiao ◽  
Li Chun Shi
Keyword(s):  
Single Molecule ◽  
Degrees Of Freedom ◽  
Organic Ligand ◽  
Chemical Properties ◽  
Molecular Magnets ◽  
Single Molecule Magnets ◽  
Spin Electronics ◽  
Molecular Spin ◽  
Basic And Applied Research ◽  
Physical And Chemical

In the basic and applied research, the electronics and spin degrees of freedom is a very promising field of research and development over the past decade, spintronics from fundamental physics to technical devices already have a great deal of progress. This study made an overview of the synthesis, structure and properties of single molecular magnets and their applications in molecular spin combined with the latest research on this study sphere. Single molecular magnets are made of inner magnetic nuclei and peripheral organic molecule lamella, which can improve physical and chemical properties by means of adorn radical of organic ligand and exchange internal magnetic ions. And this paper also analyzes the molecular spin of the electron spin and charge electronic devices at the molecular level.

Removal of Mn(II) from Aqueous Solution Using Saponified Garlic Peel

2014 ◽  
Vol 694 ◽  
pp. 382-386 ◽  
Author(s):  
Bo Liang ◽  
Wan He Zhao ◽  
Kai Huang ◽  
Hong Min Zhu
Keyword(s):  
Metal Ion ◽  
Chemical Properties ◽  
Correlation Coefficients ◽  
Ion Concentration ◽  
Batch Adsorption ◽  
Maximum Adsorption Capacity ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Physical And Chemical ◽  
Garlic Peel

The removal of Mn (II) ion by saponified garlic peel (S-GP) was investigated using batch adsorption. SEM and FT-IR were employed to investigate the physical and chemical properties of S-GP. The adsorption was evaluated as a function of initial metal ion concentration, contact time and temperature. The maximum adsorption capacity for Mn (II) was 0.51 mol/kg, and the adsorption process followed the Langmuir model. Pseudo-second-order models fitted the experimental data well and kinetic parameters, rate constants, equilibrium sorption capacity and related correlation coefficients at various temperatures were calculated and discussed. A possible adsorption mechanism based on a cation exchange was proposed for the adsorption of Mn (II).

scholarly journals Magnetic field–driven assembly and reconfiguration of multicomponent supraparticles

2020 ◽  
Vol 6 (19) ◽  
pp. eaba5337 ◽  
Author(s):  
A. Al Harraq ◽  
J. G. Lee ◽  
B. Bharti
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Building Blocks ◽  
Precise Control ◽  
Patchy Particles ◽  
Local Arrangement ◽  
Response To Change ◽  
Biological Complexes ◽  
Physical And Chemical

Suprastructures at the colloidal scale must be assembled with precise control over local interactions to accurately mimic biological complexes. The toughest design requirements include breaking the symmetry of assembly in a simple and reversible fashion to unlock functions and properties so far limited to living matter. We demonstrate a simple experimental technique to program magnetic field–induced interactions between metallodielectric patchy particles and isotropic, nonmagnetic “satellite” particles. By controlling the connectivity, composition, and distribution of building blocks, we show the assembly of three-dimensional, multicomponent supraparticles that can dynamically reconfigure in response to change in external field strength. The local arrangement of building blocks and their reconfigurability are governed by a balance of attraction and repulsion between oppositely polarized domains, which we illustrate theoretically and tune experimentally. Tunable, bulk assembly of colloidal matter with predefined symmetry provides a platform to design functional microstructured materials with preprogrammable physical and chemical properties.

scholarly journals Investigation of the Reactivity of 1-Azido-3-Iodobicyclo[1.1.1]pentane under “Click” Reaction Conditions

2020 ◽  
Author(s):  
Elisabeth Sitte ◽  
Brendan Twamley ◽  
nitika grover ◽  
Mathias Senge
Keyword(s):  
Click Reaction ◽  
Chemical Properties ◽  
Building Blocks ◽  
Dipolar Cycloaddition ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
One Pot ◽  
Click Reactions ◽  
Drug Molecules ◽  
Physical And Chemical

The bicyclo[1.1.1]pentane (BCP) unit exhibits special physical and chemical properties and is under scrutiny as a bioisostere in drug molecules. We employed methodologies for the synthesis of different BCP triazole building blocks from one precursor, 1-azido-3-iodobicyclo[1.1.1]pentane, by Cu(I)-catalyzed 1,3-dipolar cycloaddition (“click”) reactions and integrated cycloaddition-Sonogashira coupling reactions. Thereby, we accessed three classes of substituted BCP derivatives: 1,4-disubstituted triazoles, 5-iodo-1,4,5-trisubstituted triazoles and 5-alkynylated 1,4,5-trisubstituted triazoles. This gives entry to the synthesis of multiply substituted BCP triazoles either on a modular or a one-pot basis. These methodologies were further utilized for appending large chromophoric porphyrin moieties onto the BCP core.

Cobalt Metal ion Doped Cerium Oxide (Co-CeO2) Nanoparticles Effect Enhanced Photocatalytic Activity

MRS Advances ◽  
2020 ◽  
pp. 1-13
Author(s):  
G. Killivalavan ◽  
B. Sathyaseelan ◽  
G. Kavitha ◽  
I. Baskarann ◽  
K. Senthilnathan ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Metal Ion ◽  
Chemical Properties ◽  
Visible Spectrum ◽  
Average Crystallite Size ◽  
Cobalt Metal ◽  
Uv Visible ◽  
Co Precipitation ◽  
Average Size ◽  
Physical And Chemical

Abstract The REE (rare-earth-elements) cerium (Ce) is the most abundant earth-crust element and their oxides have great attention in the form of nanocrystalline nature with superior physical and chemical properties. Pure and Co (1%, 3% and 5%) doped CeO2 nanoparticles (NPs) synthesized by co-precipitation technique were characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-visible spectroscopy. XRD shows face-centred-cubic (FCC) crystal symmetry with average crystallite size 6–12 nm. HRTEM exhibits almost identical cubical shaped particles with average size 4–10 nm. Tuned band-gap may be observed from UV-visible spectrum of CeO2-NPs upon Co (1%, 3% & 5%) incorporation. Enhancement of the photocatalytic activity observed for Co-doped (1%, 3% & 5%) to the degradation of methylene-blue (MB) dye under visible-light absorption.

scholarly journals A Novel 3d-4f CoII-GdIII system with 4,5-imidazoledicarboxylate and oxalate

2014 ◽  
Vol 70 (a1) ◽  
pp. C1721-C1721
Author(s):  
Andrés Vega ◽  
Carlos Cruz ◽  
Verónica Paredes-García ◽  
Evgenia Spodine ◽  
Diego Venegas-Yazigi
Keyword(s):  
Phase 1 ◽  
Chemical Properties ◽  
Structural Complexity ◽  
Building Blocks ◽  
Point Of View ◽  
Advanced Materials ◽  
Water Molecules ◽  
New Materials ◽  
Metal Centers ◽  
Physical And Chemical

The challenges of designing and synthesizing new materials, the complexity of their structures, and their potential physical properties have continued to attract a great deal of interest. The combination of organic and inorganic components into the same molecular backbone has captivated many researchers, and as a consequence of the multiple choices of the components and also of the used synthetic strategies, a wide variety of advanced materials has been obtained. In many cases, an increase in structural complexity gives rise to new properties, which cannot be foreseen on the basis of the single constituting moieties. Therefore, the assembly of different components, or molecular fragments, may give rise to new materials that exhibit interesting and useful physical and chemical properties in the condensed phase.1 From a structural and synthetic point of view, the literature shows that a wide variety of polymetallic systems ranging from 0D to 3D structures have been rationally designed and synthesized by the appropriate selection of the metal centers and organic building blocks, as well as of the reaction pathways.2 In this work, we will inform the synthesis and structural characterization of a novel 3d-4f bimetallic system: {[Co(H2O)2(ImDC)Gd(ox)2(H2O)]·2H2O}n. (ImDC: 4,5-imidazoledicarboxylate; ox: oxalate). The structure displays CoII cations having an approximately octahedral environment completed by two N,O-ImDC ligands and two water molecules, while the GdIII cations displays nine coordination completed exclusively by oxygen atoms coming from a water molecule and oxalate and ImDC anions (Figure1, left). The structure defines a covalent tridimensional lattice where two water molecules by formula are trapped inside the cavities left by this arrangement (Figure1, right). Figure 1: Structural diagram for the basic bimetallic unit Co(H2O)2(ImDC)Gd(ox)2(H2O) (left) and the packing showing trapped water molecules {[Co(H2O)2(ImDC)Gd(ox)2(H2O)]·2H2O}n (right). Acknowledgements: The authors acknowledge financial support from FONDECYT 1130643, Financiamiento Basal, FB0807. C.C. thanks CONICYT Fellowship.

scholarly journals Ryugu: A brand-new planetary sample returned from a C-type asteroid

2021 ◽  
Author(s):  
Toru Yada ◽  
Masanao Abe ◽  
Tatsuaki Okada ◽  
Aiko Nakato ◽  
Kasumi Yogata ◽  
...  
Keyword(s):  
Solar System ◽  
Near Infrared ◽  
Chemical Properties ◽  
Building Blocks ◽  
Bulk Sample ◽  
Near Infrared Reflectance ◽  
Origin And Evolution ◽  
Thermal Measurements ◽  
Solar System Bodies ◽  
Physical And Chemical

Abstract C-type asteroids are considered to be primitive small Solar-System bodies enriched in water and organics, providing clues for understanding the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing and on-asteroid measurements with Hayabusa2, but further studies are expected by direct analyses of returned samples. Here we describe the bulk sample mainly consisting of rugged and smooth particles of millimeter to submillimeter size, preserving physical and chemical properties as they were on the asteroid. The particle size distribution is found steeper than that of surface boulders11. Estimated grain densities of the samples have a peak around 1350 kg m-3, which is lower than that of meteorites suggests a high micro-porosity down to millimeter-scale, as estimated at centimeter-scale by thermal measurements. The extremely dark optical to near-infrared reflectance and the spectral profile with weak absorptions at 2.7 and 3.4 microns implying carbonaceous composition with indigenous aqueous alteration, respectively, match the global average of Ryugu, confirming the sample’s representativeness. Together with the absence of chondrule and Ca-Al-rich inclusion of larger than sub-mm, these features indicate Ryugu is most similar to CI chondrites but with darker, more porous and fragile characteristics.

scholarly journals Investigation of the Reactivity of 1-Azido-3-Iodobicyclo[1.1.1]pentane under “Click” Reaction Conditions

2020 ◽  
Author(s):  
Elisabeth Sitte ◽  
Brendan Twamley ◽  
nitika grover ◽  
Mathias Senge
Keyword(s):  
Click Reaction ◽  
Chemical Properties ◽  
Building Blocks ◽  
Dipolar Cycloaddition ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
One Pot ◽  
Click Reactions ◽  
Drug Molecules ◽  
Physical And Chemical

The bicyclo[1.1.1]pentane (BCP) unit exhibits special physical and chemical properties and is under scrutiny as a bioisostere in drug molecules. We employed methodologies for the synthesis of different BCP triazole building blocks from one precursor, 1-azido-3-iodobicyclo[1.1.1]pentane, by Cu(I)-catalyzed 1,3-dipolar cycloaddition (“click”) reactions and integrated cycloaddition-Sonogashira coupling reactions. Thereby, we accessed three classes of substituted BCP derivatives: 1,4-disubstituted triazoles, 5-iodo-1,4,5-trisubstituted triazoles and 5-alkynylated 1,4,5-trisubstituted triazoles. This gives entry to the synthesis of multiply substituted BCP triazoles either on a modular or a one-pot basis. These methodologies were further utilized for appending large chromophoric porphyrin moieties onto the BCP core.

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