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Following chemical intuition, one would expect that all closed‐shell molecules are diamagnetic. However, it is known that this is not the case for some second‐row hydrides with low‐lying unoccupied π orbitals due to an unquenching of the total angular momentum in the presence of an external magnetic field. In this article, the transition‐metal hydrides ScH and YH are investigated, assuming a similar unquenching effect involving low‐lying unoccupied π and δ orbitals formed from the metal d orbitals rather than the p orbitals. We are comparing results obtained with various quantum‐chemical methods (HF, CCSD, CCSD(T), CCSDT) and basis sets. The obtained positive values for the magnetizabilities clearly indicate paramagnetic behavior. Vibrational effects on the magnetizability tensor are also considered, but these effects are small and do not change the overall conclusion that both ScH and YH are further examples for closed‐shell paramagnetism. [ABSTRACT FROM AUTHOR]

New metastable SmSi3−x (x=0–0.05) is obtained by high‐pressure high‐temperature synthesis (9.5 GPa, 870–1270 K). Powder diffraction data refinements reveal that the crystal structure of SmSi3 is isotypic to that of YbSi3 (space group I4/mmm, a=7.23634(5) Å, c=11.0854(1) Å). In the crystal structure, two types of Si2 dumbbells agglomerate into layers, which embed the samarium atoms. At ambient pressure, SmSi3 decomposes exothermally upon heating into Si and SmSi2−x. Single‐crystal structure refinements of a specimen SmSi3−x (x=0.05) reveal considerable electron density, which is not accounted for by the YbSi3‐type model. The additional maxima can be assigned to disorder which affects the samarium positions and induces silicon vacancies. Scanning transmission electron microscopy experiments evidence that the disorder can be attributed to extended defects. Magnetic measurements on SmSi3−x reveal van Vleck paramagnetic behavior and antiferromagnetic ordering at low temperatures. Computations within the local spin density approximation (LSDA and LSDA+U) on the crystal structure of SmSi3 reproduce the antiferromagnetic coupling as the favored long‐range order. Quantum chemical analysis of the chemical bonding in SmSi3 reveals two‐center two‐electron bonds within the Si2 dumbbells plus a total of a little less than four electrons in lone pairs at each silicon atom. [ABSTRACT FROM AUTHOR]

The spin degree of freedom of charge carriers in halide‐perovskite semiconductors can be highly useful for information photonics applications. The Faraday effect is known to be the best indicator of paramagnetism of the material and of the spin‐light interaction. In this work, the Faraday effect is demonstrated, for the first time, in a hybrid organic–inorganic halide perovskite MAPbI3 (MA+ = CH3NH3+$_3^+$). The Faraday rotation and birefringence are measured across the tetragonal‐cubic phase transition at 327 K. The Faraday rotation is strongly suppressed below the phase transition temperature due to anisotropy (linear birefringence) of the tetragonal crystal phase. The situation changes drastically above the phase transition temperature, when the crystal becomes optically isotropic. The emerging Faraday rotation obeys the Curie law, demonstrating its population‐related paramagnetic nature. This observation opens new prospects for application of these systems and for their investigations using methods of the polarization noise spectroscopy applicable to optically anisotropic materials. [ABSTRACT FROM AUTHOR]

Herein, the synthesis of Co2Si5N8 nitridosilicate from α‐Ca2Si5N8 by ion exchange is described. The monoclinic Co2Si5N8$\left(\text{Co}\right)_{2} \left(\text{Si}\right)_{5} \left(\text{N}\right)_{8}$ structure (space group Cc) is compared with those of the related nitridosilicates Ca2Si5N8 and Fe2Si5N8 its magnetic properties are profoundly investigated. Most interestingly, polycrystalline Co2Si5N8 exhibits a quasi‐temperature‐independent paramagnetic susceptibility of about 6×10−3 cm3 mol−1$>$$ 6\times {10}^{-3} {\text{cm}}^{3} {\text{mol}}^{-1}$$ over a wide temperature range from 100 to 600 K. Two different magnetic models based on a phenomenological Hamiltonian that takes into account magnetic exchange coupling, crystal‐field interactions, and Zeeman effects within the framework of an angular momentum basis set are refined to the experimental susceptibility datasets. The results of the refinements point to the realization of a pseudo temperature independent paramagnetism for Co2Si5N8 that results from a near‐perfect cancellation of temperature‐dependent contributions to the susceptibility depending delicately on the mixing of ion levels in the electronic states, their relative energies, and the magnetic coupling between them. Additionally, performed direct current field scan, alternating current susceptibility, and heat capacity measurements complete the magnetic characterization and facilitate the identification of impurity phase contributions. [ABSTRACT FROM AUTHOR]

Superparamagnetic iron oxide nanoparticles (SPIONs) are nanoparticles used in a lot of applications such as batteries, and biomedical, … To obtain these nanoparticles, several techniques exist such as coprecipitation, thermal decomposition, sol–gel process but they have some advantages (synthesis in a water media, high crystallinity, high monodispersity) and disadvantages (using an organic solvent, large distribution of size, poor crystallinity). The goal of this work is to synthesize SPIONs for biomedical applications (for example as a contrast agent for the MRI): SPIONs should be stable in an aqueous media, monodisperse, and have good crystallinity and magnetic properties. To achieve this result, a microwave process is carried out. However, any study describes the microwave parameter on the synthesis of the nanoparticles. This work offers to determine the best conditions of the microwave to obtain ideal SPIONs for MRI. For this, an experimental design is carried out to determine these parameters thanks to different techniques of characterization (Transmission Electronic Microscopy, Dynamic Light Scattering, X‐ray diffraction, Thermogravimetric Analysis, magnetic characterizations). With the different results of these characterizations, the best conditions of the microwave are determined, and a simulation of all experiments is realized with a surface response. [ABSTRACT FROM AUTHOR]

This study presents the effect of chitosan on the properties of zinc ferrite nanoparticles suitable for potential biomedical applications. The co‐precipitation method is employed to fabricate these bio‐composites that exhibit excellent microstructural properties. The X‐ray diffractometer (XRD) analysis confirms the presence of a cubic spinel structure in the zinc ferrite‐chitosan bio‐composites, indicative of their crystalline nature. Scanning electron microscope (SEM) imaging revealed spherical particles with a size distribution below 100 nm, demonstrating the successful synthesis of homogenous nanosized particles. Fourier transform infrared spectroscopy (FTIR) spectroscopy analysis identifies the active functional groups within the bio‐composites, providing valuable insights into the molecular structure and interactions present in the synthesized materials. The presence of chitosan is confirmed, highlighting its role in modifying the chemical composition and enhancing the biocompatibility of the samples. UV–vis absorption spectra analysis reveals that the samples exhibits absorbance within the visible range. Vibrating sample magnetometer (VSM) analysis demonstrates the superparamagnetic behavior of the samples. Remarkably, these formulated samples exhibit superparamagnetism with zero coercivity and a magnetization of ≈0.0125 emu g−1 at 5 kOe when doped with chitosan. These properties are crucial for potential biomedical applications making it a promising candidate for various biomedical applications. [ABSTRACT FROM AUTHOR]

This paper presents a dual gravity model for a (2+1)‐dimensional system with a limit on finite charge density and temperature, which will be used to study the properties of the holographic phase transition to paramagnetism‐ferromagnetism in the presence of Horndeski gravity terms. In our model, the non‐zero charge density is supported by a magnetic field. As a result, the radius ρ/B$\rho /B$ indicates a localized condensate, as the Horndeski gravity parameter is increased, that is represented by γ. Furthermore, such condensate shows quantum Hall‐type behavior. This radius is also inversely related to the total action coefficients of our model. It is observed that increasing the Horndeski parameter decreases the critical temperature of the holographic model and leads to the harder formation of the magnetic moment at the bottom of the black hole. However, when removing the magnetic field, the ferromagnetic material presents a disorder of its magnetic moments, which is observed through the entropy of the system. The authors also found that at low temperatures, spontaneous magnetization and ferromagnetic phase transition. [ABSTRACT FROM AUTHOR]

Highly dispersed Ni‐TiO2 catalyst has been studied in the process of preparation and under catalytic transfer hydrogenation reaction conditions in supercritical 2‐propanol (250°C, 70 bar) using electron spin resonance in situ. Electron spin resonance in situ has been used to study the process of the catalyst passivation and subsequent reduction of the oxide layer in the gas flow. Reduction of the NiO layer on the surface of passivated Ni nanoparticles has been detected in supercritical 2‐propanol, which is in agreement with kinetic modeling data. It has been found that the reduction of the nickel oxide layer in supercritical 2‐propanol occurs at a lower temperature compared with the reduction in hydrogen flow, according to in situ electron spin resonance study. [ABSTRACT FROM AUTHOR]

Dielectric constants determine the level of miniaturization in capacitive components involved in electronic devices. Cu‐Li co‐doping is attempted to introduce the multiferroic relaxor nature of dielectricity and dilute magnetism in the bulk material simultaneously as Li+ ion substitution in ZnO lattice is known to form acceptor states within the band gap of ZnO and paramagnetic Cu2+ present in ZnO lattice can introduce dilute magnetism. Phase purity and substitution of Cu2+ and Li+ ions in ZnO lattice along with oxide‐ion vacancy formation was confirmed using Powder x‐ray diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive X‐ray analysis (EDX), X‐ray Photoelectron Spectroscopy (XPS), Inductively Coupled Plasma Mass Spectrometry (ICP‐MS) and Magnetic property measurement system (MPMS) studies. The dielectric constant (ϵr′) of bulk pristine Zn0.92Cu0.05Li0.03O and Zn0.9Cu0.05Li0.05O is found to be 18000 and 20000 respectively at 1000 Hz frequency at 600 °C. Both dielectric constant and dielectric loss were decreasing with increasing frequencies. The increase in dielectric constant (ϵr′) with increasing temperatures at different frequencies for Zn0.92Cu0.05Li0.03O1‐δ and Zn0.9Cu0.05Li0.05O1‐δ is likely due to the localized nature of hopping charge carriers in addition to interfacial polarization due to space charge. Tm was found to increase with increasing frequencies suggesting the relaxor nature of dielectricity in the Zn0.9Cu0.05Li0.05O1‐δ. Bulk pristine Zn0.9Cu0.05Li0.05O1‐δ also exhibits ferroelectricity at room temperature with remnant polarization Pr and Vc equal to 4.20e–02 μC/cm2 and 4.1e+03 V/cm at (30KV, 500 Hz) respectively. Zn0.9Cu0.05Li0.05O also shows the paramagnetic behaviour. [ABSTRACT FROM AUTHOR]

The present manuscript portrays environmental benign, cost‐effective and energy efficient green route way to synthesize Mg−Zn ferrite nanoparticles [Mg0.05Zn0.05Fe2O4 NPs] using Ocimum Basilicum leaf extract [OBLE]. X‐ray diffraction (XRD) analysis revealed that Ocimum Basilicum leaf extract mediated Mg−Zn ferrite nanoparticles [OBLE@Mg−Zn NPs] exhibit face centred cubic crystallinity with space group Fd3‾m ${{\rm F}{\rm d}\bar{3}{\rm m}}$ as confirmed by Rietveld refinement studies. Microstructural analysis illustrated uniform surface morphology with well interlinked grain with an average grain size of 35.6±0.12 nm. FTIR spectra showed existence of hydroxyl −OH group at 3403 cm−1 and C=C vibration at 2345 cm−1. Magnetic hysteresis loop (M−H loop) confirmed the superparamagnetic behaviour of OBLE@Mg−Zn NPs. Cytotoxic activity of OBLE@Mg−Zn NPs was carried out against breast cancer cell line MDA‐MB‐231. Dose dependent cell viability of cancerous cells depicted cytotoxic potential of OBLE@Mg−Zn NPs. [ABSTRACT FROM AUTHOR]

Macroscopic compass‐like magnetic alignment at low magnetic fields is natural for ferromagnetic materials but is seldomly observed in paramagnetic materials. Herein, we report a "paramagnetic compass" that magnetically aligns under ∼mT fields based on the single‐crystalline framework constructed by lanthanide ions and organic ligands (Ln‐MOF). The magnetic alignment is attributed to the Ln‐MOF's strong macroscopic anisotropy, where the highly‐ordered structure allows the Ln‐ions' molecular anisotropy to be summed according to the crystal symmetry. In tetragonal Ln‐MOFs, the alignment is either parallel or perpendicular to the field depending on the easiest axis of the molecular anisotropy. Reversible switching between the two alignments is realized upon the removal and re‐adsorption of solvent molecules filled in the framework. When the crystal symmetry is lowered in monoclinic Ln‐MOFs, the alignments become even inclined (47°‐66°) to the field. These fascinating properties of Ln‐MOFs would encourage further explorations of framework materials containing paramagnetic centers. [ABSTRACT FROM AUTHOR]

Macroscopic compass‐like magnetic alignment at low magnetic fields is natural for ferromagnetic materials but is seldomly observed in paramagnetic materials. Herein, we report a "paramagnetic compass" that magnetically aligns under ~mT fields based on the single‐crystalline framework constructed by lanthanide ions and organic ligands (Ln‐MOF). The magnetic alignment is attributed to the Ln‐MOF's strong macroscopic anisotropy, where the highly‐ordered structure allows the Ln‐ions' molecular anisotropy to be summed according to the crystal symmetry. In tetragonal Ln‐MOFs, the alignment is either parallel or perpendicular to the field depending on the easiest axis of the molecular anisotropy. Reversible switching between the two alignments is realized upon the removal and re‐adsorption of solvent molecules filled in the framework. When the crystal symmetry is lowered in monoclinic Ln‐MOFs, the alignments become even inclined (47°‐66°) to the field. These fascinating properties of Ln‐MOFs would encourage further explorations of framework materials containing paramagnetic centers. [ABSTRACT FROM AUTHOR]

NdFe1−xCoxO3 samples are prepared by the sol–gel method. The X‐ray diffraction (XRD) results show that these samples conform to the orthogonal perovskite structure (Pbnm), and different doping amounts can cause the patterns to shift by XRD pattern. Through the Williamson–Hall analysis, the microstrain of the lattice between different doping amounts was obtained, and the average crystal size was calculated. The element content of each sample was obtained by scanning electron microscope and energy‐dispersive X‐ray analysis. Mössbauer spectra show that different doping levels change the surrounding environment of iron, and the magnetic properties of the samples also change. [ABSTRACT FROM AUTHOR]

Two‐line ferrihydrite particles are synthesized. Structural characterization of the sample is done with an X‐ray diffractometer, transmission electron microscope, Fourier‐transform infrared spectroscope, and thermogravimetric analyzer. Average particle size is 2 nm. Temperature variation (10–300 K) of zero‐field‐cooled and field‐cooled susceptibility in 500 G applied magnetic field bifurcates at 50 K. The field‐cooled susceptibility below this temperature is almost temperature independent. Magnetization versus applied magnetic field (0–120 kG) data at 300 K are analyzed considering particle size distribution. [ABSTRACT FROM AUTHOR]

Development of targeted nanoparticles as carriers to deliver photosensitizers to cancer cells is highly beneficial for ensuring the expected therapeutic outcome of photodynamic therapy. Herein, polyacrylic acid (PAA) coated superparamagnetic iron oxide nanoparticles (SPIONs), conjugated with endothelial growth factor receptor (EGFR) targeting Cetuximab (Cet) were loaded with a BODIPY‐based (BOD‐Se‐I) photosensitizer (Cet‐PAA@SPION/BOD‐Se‐I) to achieve enhanced and selective photodynamic therapy on colon cancer cells. In vitro studies showed that Cet‐PAA@SPION/BOD‐Se‐I improved phototoxicity dramatically compared to free BOD‐Se‐I on the HT29 cell line due to high uptake of the photosensitizer via endothelial growth factor receptor. Most importantly, the developed nano‐agent completely eliminated the phototoxicity of BOD‐Se‐I on the healthy L929 cell line. [ABSTRACT FROM AUTHOR]

The behavior of the N‐heterocyclic carbene (NHC) stabilized 'parent' phosphinidene [(sIDipp)PH] (Dipp=2,6‐di‐isopropylphenyl) towards 3d‐metal(II) hexamethyldisilazanides is described. This leads to formation of the three‐coordinated phosphinidene adducts [M{PH(sIDipp)}{N(SiMe3)2}2] (M=Mn−Co), as evidenced by X‐Ray diffraction analysis. In solution, all compounds exhibit strong paramagnetism that limited NMR spectroscopic examinations to cobalt. Here it shows that the system is coordinatively highly fluxional, which is mitigtated upon cooling. At low temperatures, small amounts of free phosphinidene becomes further evident by 31P NMR spectroscopy that implicates in part ligand coordination competes with [M{N(SiMe3)2}2] dimerisation and an overall weak binding of the phosphinidene ligand. The rapid chemical exchange is evidenced in the presence of an excess of phosphinidene or a phosphine (PCy3), whereas diethyl ether proved as a stronger donor ligand. [ABSTRACT FROM AUTHOR]

Ceria (CeO2) and its solid solutions with Gd2O3 are technologically important and environmentally friendly materials with numerous interesting properties and important applications. Nevertheless, the magnetic properties of ceria are even today not fully understood, and magnetoelastic coupling in pure or doped ceria remains essentially unexplored. This has been so, in part, due to the difficulty of measuring very small magnetostrictive strains in weakly paramagnetic materials. During the last decade, however, technical advances have enabled sensitive and accurate measurements of sample deformation in high magnetic fields. Here, forced magnetostriction (MS) in Gd2O3‐CeO2 solid solution ceramics (Ce1−xGdxO2−x/2, 0 ≤x≤ 1) at room temperature is characterized. In a pulsed magnetic field μ0H≤ 60 Tesla, longitudinal MS strain is observed to depend on the square of the field amplitude and to increase linearly with Gd3+ concentration but is not sensitive to the lattice symmetry of the ceramics. The theory attributes the origin of the observed strain to the single‐ion MS response of Gd3+ to the crystal field via mixing of ground and excited electronic states and covalent hybridization with oxygen ligands. Contributions of charge‐compensating oxygen vacancies and/or Van Vleck paramagnetism to the observed magnetoelastic coupling are determined to be negligible. [ABSTRACT FROM AUTHOR]

Soy protein is one kind of environment‐friendly nonbioactive plant protein with excellent properties. Paramagnetic γ‐Fe2O3 nanoparticles with a mean particle size of 7 nm are prepared by submerged circulative impinging stream reactor (SCISR). And a series of soy protein isolate (SPI)/Fe2O3 nanocomposites with excellent magnetic performance have been successfully prepared with glycerol as plasticizer and γ‐Fe2O3 as fillers. The results show that the strong hydrogen bonds are formed between polar amino acids of SPI and the fillers. The Fe2O3 nanoparticles exhibit homogeneous dispersion in the protein matrix. The resulting SPI/Fe2O3 nanocomposites exhibit good paramagnetism and good microwave absorbing properties at 2–18 GHz. In addition, the mechanical properties and thermal stability of soy protein materials are improved with the addition of Fe2O3 nanocomposites. The interactions between the fillers and matrix as well as between the fillers would influence the reinforcing effect of Fe2O3. These natural resources based on green functional materials would exhibit wide potential applications in electromagnetic interference shielding and packaging areas. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Molecules with long preserved magnetic moments are perceived as the smallest units for storing bytes, which could bring a new revolution for information technology. However, the rational design of such molecules remains challenging. Here two rigid adamantanol ligand based dysprosium(III) complexes ([Dy(1‐AdO)2(py)5]BPh4 ‐ 1 and [Dy(2‐AdO)2(py)5]BPh4 ‐ 2) with pentagonal‐bipyramidal coordination geometry and local D5h symmetry were successfully prepared, which display excellent single‐molecule magnet (SMM) behavior (Ueff ≈ 1835 K, TBZFC ≈ 24 K, TB100s ≈ 17 K and TBH = 23 K for 1; Ueff ≈ 1756 K, TBZFC ≈ 20 K, TB100s ≈ 16 K and TBH = 23 K for 2) due to the much weakened vibration in low energy regimes. Remarkably, the large energy barriers and high blocking temperatures for these two complexes in solid states are well preserved in solution. This is never observed in previous studies of SMMs, indicating that the adamantanol is rigid and can be introduced to make the composed molecules stable enough to maintain the solid state magnetic property in solution. [ABSTRACT FROM AUTHOR]

Uniform perovskite type SmFeO3 and SmCoO3 nanofibers have been prepared by a simple electrospinning approach and calcination process. The obtained samples had orthorhombic structure and strong absorbance behaviors in UV‐vis regions. The diameters of SmFeO3 and SmCoO3 nanofibers were 220 and 300 nm, respectively. The electrochemical and magnetic properties of SmFeO3 and SmCoO3 were investigated. SmFeO3 and SmCoO3 electrodes exhibited typical pseudocapacitive behaviors owing to the redox reactions of Fe3+/Fe2+ and Co3+/Co2+. At 0.5 A g‐1, the specific capacitances of SmFeO3 and SmCoO3 nanofibers were 90.8 and 126.6 F g‐1, respectively. The high‐performance nanostructured SmFeO3 and SmCoO3 have significantly potential application in supercapacitors. SmFeO3 nanofibers exhibited weak ferromagnetic behavior. SmCoO3 nanofibers presented paramagnetism at high temperature and ferromagnetism at 5 K. [ABSTRACT FROM AUTHOR]

Organic radical ferroics such as TEMPO have attracted widespread interest. However, the relatively low Curie temperature of 287 K and melting point of 311 K severely hinder its application potential. Despite extensive interest, high‐temperature radical ferroics have not yet been found. Here, taking advantage of chemical design and supramolecular radical chemistry, we designed two high‐temperature organic supramolecular radical ferroics [(NH3‐TEMPO)([18]crown‐6)](ReO4) (1) and [(NH3‐TEMPO)([18]crown‐6)](ClO4) (2), which can retain ferroelectricity up to 413 K and 450 K, respectively. To our knowledge, they are both the first supramolecular radical ferroics and unprecedented high‐temperature radical ferroics, where the supramolecular component is vital for the stabilization of the radical and extending the working temperature window. Both also have paramagnetism, non‐interacting spin moments, and excellent piezoelectric and electrostrictive behaviors comparable to that of LiNbO3. [ABSTRACT FROM AUTHOR]

Ternary compounds with the [M6X14]2− (M=Mo, W; X=Cl, Br, I) cluster have been established with several counter cations. Herein, we report examples of the ternary rare‐earth (RE) compounds REW6Cl15 and REW6Cl14. Preparations of the compounds GdW6Cl15, TbW6Cl15 and EuW6Cl14 are accomplished by solid‐state reactions of W6Cl12 and RECl3 (RE=Gd, Tb), or EuCl2 at 575 °C in fused silica tubing. GdW6Cl15 and TbW6Cl15 crystallize in the space group C2/c and EuW6Cl14 in Pn3‾ , isotypic to BiW6Cl15 (REW6Cl15) and PbMo6Cl15 (EuW6Cl14) according to X‐ray powder diffraction. Crystal structures are discussed in the light of related compounds, and properties such as magnetism and photoluminescence are reported. [ABSTRACT FROM AUTHOR]

In this paper, new energy functionals are described via the variational approach method. By doing this, a new class of elastic curves is described in the three‐dimensional ordinary space. An alternative method is also investigated to compute critical points of the bending energy functionals acting on a class of magnetic curves. Then, classifications of these critical curves are presented as elastic magnetic curves of the Frenet–Serret vectors family. Moreover, the dynamics of the elastic magnetic curves of ferromagnetic and superparamagnetic models are discussed with their numerical and analytical analysis. [ABSTRACT FROM AUTHOR]

Magnetic fabric analyses of rocks by anisotropy of magnetic susceptibility (AMS) are a robust petrofabric tool that has been used in varied geological environments and tectonic settings. A fundamental difficulty of this method is to define the dominant magnetic phases and their resulting geological interpretation. We study the magnetic behavior of rocks by simulating data of mixed magnetic phases (i.e., diamagnetic, paramagnetic, and ferromagnetic). We show that it is possible to recognize the dominant magnetic phases by measuring the mean susceptibility at room temperature (kmRT) and at low temperature (kmLT). Distinct regions of magnetic phase dominancy are demonstrated in kmLT/kmRT versus kmRT and kmLT versus kmRT plots. We present a comprehensive approach by coupling the magnetic phase dominancy with possible magnetic fabrics, which are obtained from AMS measured at room and low temperatures (RT‐AMS and LT‐AMS) and anisotropy of anhysteretic remanent magnetization, into a scenario table. Application of this table allows a robust procedure for determining which magnetic phases are dominant, and permits a fast and reliable geological interpretation in complex settings. Key Points: We present a robust procedure for determining the anisotropy of magnetic susceptibility (AMS) carriers (ferro, para, and diamagnetic phases)Mean susceptibility at room and low temperatures defines the respective contributions of the magnetic phases to the rock's susceptibilityA novel scenario table, coupling respective contributions and associated magnetic fabrics, allows reliable interpretation of AMS data [ABSTRACT FROM AUTHOR]

Recent proposals for molecular switches are reviewed that adopt a different spin state before and after the encounter with an analyte (metabolite) or physical stimulus (light). Spin‐state switching has significant potential to provide molecular MRI with a first line of probes operating by an off/on mode. Past efforts to design MRI sensors relied on strategies other than spin‐switching and thus mostly comprised probes only modulating the signal before and after encounter with the analyte (X%‐on/Y%‐on). The article thus essentially treats small‐molecule metal ion chelates, i.e. coordination compounds. Initially, a comprehensive treatment of design considerations for optimal spin‐state switches is furnished. The article then enters into a treatment of reported examples of spin‐state switches according to three response mechanisms: 1) changes in the redox state of the metal center; 2) changes in coordination geometry; and 3) modification of the surrounding ligand field, either by peripheral interaction with the analyte, or by replacement of a coordinating ligand by another. [ABSTRACT FROM AUTHOR]

Effective and targeted delivery of the antitumour drugs towards the specific cancer spot is the major motive of drug delivery. In this direction, suitably functionalised magnetic iron oxide nanoparticles (NPs) have been utilised as a theranostic agent for imaging, hyperthermia and drug delivery applications. Herein, the authors reported the preparation of multifunctional polyethyleneglycol‐diamine functionalised mesoporous superparamagnetic iron oxide NPs (SPION) prepared by a facile solvothermal method for biomedical applications. To endow targeting ability towards tumour site, folic acid (FA) is attached to the amine groups which are present on the NPs surface by 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide hydrochloride/N‐hydroxysuccinimide chemistry. FA attached SPION shows good colloidal stability and possesses high drug‐loading efficiency of ∼ 96% owing to its mesoporous nature and the electrostatic attachment of daunosamine (NH3+) group of doxorubicin (DOX) towards the negative surface charge of carboxyl and hydroxyl group. The NPs possess superior magnetic properties in result endowed with high hyperthermic ability under alternating magnetic field reaching the hyperthermic temperature of 43°C within 223 s at NP's concentration of 1 mg/ml. The functionalised NPs possess non‐appreciable toxicity in breast cancer cells (MCF‐7) which is triggered under DOX‐loaded SPION. [ABSTRACT FROM AUTHOR]

To improve understanding of M−L bonds in 3d transition metal complexes, analysis by energy decomposition analysis and natural orbital for chemical valence model (EDA‐NOCV) is desirable as it provides a full, quantitative and chemically intuitive ab initio description of the M−L interactions. In this study, a generally applicable fragmentation and computational protocol was established and validated by using octahedral spin crossover (SCO) complexes, as the transition temperature (T1/2) is sensitive to subtle changes in M−L bonding. Specifically, EDA‐NOCV analysis of Fe−N bonds in five [FeII(Lazine)2(NCBH3)2], in both low‐spin (LS) and paramagnetic high‐spin (HS) states led to: 1) development of a general, widely applicable, corrected M+L6 fragmentation, tested against a family of five LS [FeII(Lazine)3](BF4)2 complexes; this confirmed that three Lazine are stronger ligands (ΔEorb,σ+π=−370 kcal mol−1) than 2 Lazine+2 NCBH3 (=−335 kcal mol−1), as observed. 2) Analysis of Fe−L bonding on LS→HS, reveals more ionic (ΔEelstat) and less covalent (ΔEorb) character (ΔEelstat:ΔEorb 55:45 LS→64:36 HS), mostly due to a big drop in σ (ΔEorb,σ ↓50 %; −310→−145 kcal mol−1), and a drop in π contributions (ΔEorb,π ↓90 %; −30→−3 kcal mol−1). 3) Strong correlation of observed T1/2 and ΔEorb,σ+π, for both LS and HS families (R2=0.99 LS, R2=0.95 HS), but no correlation of T1/2 and ΔΔEorb,σ+π(LS‐HS) (R2=0.11). Overall, this study has established and validated an EDA‐NOCV protocol for M−L bonding analysis of any diamagnetic or paramagnetic, homoleptic or heteroleptic, octahedral transition metal complex. This new and widely applicable EDA‐NOCV protocol holds great promise as a predictive tool. [ABSTRACT FROM AUTHOR]

This study aimed to develop sorafenib loaded magnetic microspheres for the treatment of hepatocellular carcinoma. To achieve this goal, superparamagnetic iron oxide nanoparticles (SPIONs) were synthesised and encapsulated in alginate microspheres together with an antineoplastic agent, sorafenib. In the study, firstly SPIONs were synthesised and characterised by dynamic light scattering, energy‐dispersive X‐ray spectroscopy, and scanning electron microscopy. Then, alginate‐SPIONs microspheres were developed, and further characterised by electron spin resonance spectrometer and vibrating sample magnetometer. Besides the magnetic properties of SPIONs, alginate microspheres with SPIONs were also found to have magnetic properties. The potential use of microspheres in hyperthermia treatment was then investigated and an increase of about 4°C in the environment was found out. Drug release studies and cytotoxicity tests were performed after sorafenib was encapsulated into the magnetic microspheres. According to release studies, sorafenib has been released from microspheres for 8 h. Cytotoxicity tests showed that alginate‐SPION‐sorafenib microspheres were highly effective against cancerous cells and promising for cancer therapy. [ABSTRACT FROM AUTHOR]

Until now, there have been limited studies on T2 magnetic resonance imaging (MRI) contrast agents (CAs) using paramagnetic nanoparticles (NPs). In this study, ultrafine dysprosium oxide (Dy2O3) NPs were synthesized as a T2 MRI CA. To obtain high biocompatibility and colloidal stability in aqueous medium for in vivo applications, they were grafted with polyacrylic acid. They displayed paramagnetism with an appreciable magnetization value at 300 K and consequently, an appreciable transverse water proton spin relaxivity (r2) value which increased as the applied MR field increased. Their potential as a T2 MRI CA was proved by taking in vivo T2 MR images in mice. [ABSTRACT FROM AUTHOR]

FeSb2 exhibits a colossal Seebeck coefficient (S) and a record‐breaking high thermoelectric power factor. It also has an atypical shift from diamagnetism to paramagnetism with increasing temperature, and the fine details of its electron correlation effects have been widely discussed. The extraordinary physical properties must be rooted in the nature of the chemical bonding, and indeed, the chemical bonding in this archetypical marcasite structure has been heavily debated on a theoretical basis since the 1960s. The two prevalent models for describing the bonding interactions in FeSb2 are based on either ligand‐field stabilization of Fe or a network structure of Sb hosting Fe ions. However, neither model can account for the observed properties of FeSb2. Herein, an experimental electron density study is reported, which is based on analysis of synchrotron X‐ray diffraction data measured at 15 K on a minute single crystal to limit systematic errors. The analysis is supplemented with density functional theory calculations in the experimental geometry. The experimental data are at variance with both the additional single‐electron Sb−Sb bond implied by the covalent model, and the large formal charge and expected d‐orbital splitting advocated by the ionic model. The structure is best described as an extended covalent network in agreement with expectations based on electronegativity differences. [ABSTRACT FROM AUTHOR]

Superparamagnetic cobalt ferrite nanoparticles (CoFe2 O4) possess favourite advantages for theranostic applications. Most of previous studies reported that CoFe2 O4 magnetic nanoparticles (MNPs) are suitable candidates for induction of hyperthermia and transfection agents for drug delivery. The present study synthesized and investigated the potential use of CoFe2 O4 as a contrast agent in magnetic resonance imaging (MRI) by using a conventional MRI system. The CoFe2 O4 were synthesized using co‐precipitation method and characterized by TEM, XRD, FTIR, EDX and VSM techniques. Relaxivities r1 and r2 of CoFe2 O4 were then calculated using a 1.5 Tesla clinical magnetic field. The cytotoxicity of CoFe2 O4 was evaluated by the MTT assay. Finally, the optimal concentrations of MNPs for MRI uses were calculated through the analysis of T2 weighted imaging cell phantoms. The superparamagnetic CoFe2O4 NPs with an average stable size of 10.45 nm were synthesized. Relaxivity r1, 2 calculations resulted in suitable r2 and r2 / r1 with values of 58.6 and 51 that confirmed the size dependency on relaxivity values. The optimal concentration of MNPs for MR image acquisition was calculated as 0.154 mM. Conclusion: CoFe2 O4 synthesized in this study could be considered as a suitable T2 weighted contrast agent because of its high r2 /r1 value. [ABSTRACT FROM AUTHOR]

Superparamagnetic iron oxide nanoparticles (SPIONs) conjugated with anti‐epidermal growth factor receptor monoclonal antibody (anti‐EGFR‐SPIONs) were characterised, and its cytotoxicity effects, ex vivo and in vivo studies on Lewis lung carcinoma (LLC1) cells in C57BL/6 mice were investigated. The broadband at 679.96 cm−1 relates to Fe–O, which verified the formation of the anti‐EGFR‐Mab with SPIONs was obtained by the FTIR. The TEM images showed spherical shape 20 and 80 nm‐sized for nanoparticles and the anti‐EGFR‐SPIONs, respectively. Results of cell viability at 24 h after incubation with different concentrations of nanoprobe showed it has only a 20% reduction in cell viabilities. The synthesised nanoprobe administered by systemic injection into C57BL/6 mice showed good Fe tumour uptake and satisfied image signal intensity under ex vivo and in vivo conditions. A higher concentration of nanoprobe was achieved compared to non‐specific and control, indicating selective delivery of nanoprobe to the tumour. It is concluded that the anti‐EGFR‐SPIONs was found to be as an MR imaging contrast nanoagent for lung cancer (LLC1) cells detection. [ABSTRACT FROM AUTHOR]

In modern medicine, major attention has been paid to superparamagnetic iron oxide nanoparticles (SPIONs). Recent studies have shown the antibacterial properties of SPIONs against some Gram‐positive and Gram‐negative bacterial strains. These nanoparticles (NPs) can bind to bacterial membranes via hydrophobic or electrostatic interactions and pass through cell barriers. In this study, the authors evaluated the antibacterial activity of magnetic NPs in comparison with ferrous and ferric ions. The level of reactive oxygen species (ROS) in the treated Staphylococcus aureus and Escherichia coli bacteria were directly measured by fluorometric detection. The results showed that iron ions and SPIONs had significant dependent antimicrobial activities. SPIONs showed greater inhibitory effects than ferrous and ferric ions against the growth of treated bacterial strains under anaerobic conditions, while in aerobic conditions, ferrous showed the strongest antibacterial activity. In anaerobic conditions, they observed the greatest ROS formation and lowest minimum inhibitory concentration in the SPION‐treated group in comparison with the other groups. It seems that the release of iron ions from SPIONs and subsequent activation of ROS pathway are the main antibacterial mechanisms of action. Nevertheless, the greater antibacterial effect of SPIONs in anaerobic conditions represents other mechanisms involved in the antibacterial activity of these NPs [ABSTRACT FROM AUTHOR]

Augmented escape of nanostructures to the ecosystem has necessitated the comprehensive study of their impact, especially on plants. In the current study, hematite nanoparticles were prepared by employing garlic extract and checked for their cytogenetic effect on onion roots and germination characteristics of five agricultural crops (Vigna radiata, Triticum aestivum, Trigonella foenum‐graecum, Cicer arietinum and Vicia faba) in the concentration range of 20–100 mg/L. Onion roots exhibited an increased mitotic index till 60 mg/L dosage, beyond which trend decreased marginally. Percentage of aberrant chromosomes reported for 100 mg/L exposure was very low (3.358 ± 0.13%) and included common defects such as clumped/sticky metaphase, ring chromosomes, laggards, spindle abnormality, chromosome bridges etc. Moreover, comet assay, DNA laddering experiment and electron micrograph study confirmed negligible damage to onion roots. Seed germination study indicated a positive response in different agronomic traits (germination index, root length, fold change in weight and vigour index) up to 60 mg/L, beyond which either negative or neutral effect was observed. However, none of the samples showed 50% inhibition in germination index; highest being 33.33% inhibition for V. faba, compared to the control. In brief, biogenic hematite nanoparticles caused insignificant phytotoxicity and were likely assimilated as iron source at lower dosage. [ABSTRACT FROM AUTHOR]

Along with the extensive range of exotic nanoparticle (NPs) applications, investigation of magnetic NPs (MNPs) in vitro has ushered modern antibacterial studies into an increasingly attractive research area. A great number of microorganisms exist in the size scales from nanometre to micrometre regions. The enormous potential of engineered MNPs in therapeutic procedures against various drug‐resistant bacteria has declined the menace of fatal bacterial infections. Many biocompatible MNPs have been introduced that possess remarkable impacts on various bacterial strains. Conventional synthesis methods such as co‐precipitation or hydrothermal techniques have been widely adopted in the production of MNPs. The MNPs for antibacterial applications are mainly required to be superparamagnetic, recyclable and biocompatible. To implement novel strategies in developing new generation antimicrobial magnetic nanomaterials, it is essential to obtain a comprehensive preview of recent achievements in synthesis, proposed antibacterial mechanisms and characterisation techniques of these nanomaterials. This review highlights notable aspects of antibacterial activity in engineered MNPs and nanocomposites including their particle properties (size, shape and saturation magnetisation), antibacterial mechanisms, synthesis methods, testing methods, surface modifications and minimum inhibitory concentrations. [ABSTRACT FROM AUTHOR]

Ordered graphitic carbon nanosheets (GCNs) were, for the first time, synthesized by the direct condensation of multifunctional phenylacetyl building blocks (monomers) in the presence of phosphorous pentoxide. The GCNs had highly ordered structures with random hole defects and oxygenated functional groups, showing paramagnetism. The results of combined structural and magnetic analyses indicate that the hole defects and functional groups are associated with the appearance and stabilization of unpaired spins. DFT calculations further suggest that the emergence of stabilized spin moments near the edge groups necessitates the presence of functionalized carbon atoms around the hole defects. That is, both hole defects and oxygenated functional groups are essential ingredients for the generation and stabilization of spins in GCNs. [ABSTRACT FROM AUTHOR]

Ordered graphitic carbon nanosheets (GCNs) were, for the first time, synthesized by the direct condensation of multifunctional phenylacetyl building blocks (monomers) in the presence of phosphorous pentoxide. The GCNs had highly ordered structures with random hole defects and oxygenated functional groups, showing paramagnetism. The results of combined structural and magnetic analyses indicate that the hole defects and functional groups are associated with the appearance and stabilization of unpaired spins. DFT calculations further suggest that the emergence of stabilized spin moments near the edge groups necessitates the presence of functionalized carbon atoms around the hole defects. That is, both hole defects and oxygenated functional groups are essential ingredients for the generation and stabilization of spins in GCNs. [ABSTRACT FROM AUTHOR]

Spinel magnetite (Fe3O4) nanoparticles (MNPs) were successfully synthesized from the reduction of stoichiometric ratio of aqueous solutions of Fe2+ and Fe3+ with NaOH solution. Then naturally available Ipomoea aquatica leaf aqueous extract (IA extract) was used for the surface modification of MNPs where biomolecules of leaf extract were acted as stabilizer. Gas chromatography‐mass spectrometry (GC‐MS), Fourier transform infrared (FT‐IR), and energy dispersive X‐ray (EDX) analyses evidence the proper incorporation of the biomolecules of leaf extract in MNPs. X‐ray diffraction (XRD) confirms the synthesis of MNPs where the uniform size distribution with spherical shape was approved by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses. Thermal analysis was performed using differential scanning caloremetry (DSC) and thermogravimetric analysis (TGA) and a phase transition from Fe3O4 to maghemite (γ‐Fe2O3) was detected at 650 °C. The superparamagnetic nature of the studied materials at room temperature was confirmed by vibrating sample magnetometer (VSM) study and the correlation among saturation magnetization (Ms), crystallite size (D), particle size (d), dislocation density (δ), and microstrain (ϵ) were described. The antibacterial activity of the synthesized MNPs was confirmed by investigating the zones of inhibition which were 19 mm for Gram‐negative bacteria Escherichia coli and 14 mm for Gram‐positive bacteria Bacillus subtilis. [ABSTRACT FROM AUTHOR]

The aim of this study is to synthesise superparamagnetic iron oxide nanoparticles conjugated with anti‐epidermal growth factor receptor monoclonal antibody (ANTI‐EGFR‐SPION) and investigate its physicochemical characterisation and biocompatibility as a targeted magnetic resonance imaging (MRI) contrast agent for the EGFR‐specific detection in EGFR expressing tumour cells. These particles employed biocompatible polymers, poly(D,L‐lactide‐co‐glycolide) (PLGA) and polyethylene glycol aldehyde (PEG‐aldehyde), to increase the half‐life of particles in circulation and reduce their side effects. The Fe3 O4 ‐loaded PLGA‐PEG‐aldehyde nanoparticles were prepared by a modified water‐in‐oil‐in‐water double emulsion method. The EGFR antibody was conjugated to the surface of SPIONs using the aldehyde‐amine reaction. Synthesised conjugates (nanoprobes) were characterised using Fourier transform infrared spectrophotometry, dynamic light scattering, transmission electron microscopy images, and vibrating‐sample magnetometery, and the results showed that the conjugation was successful. The mean diameter of nanoprobes was about 25 nm. These nanoprobes exhibited excellent water‐solubility, stability, and biocompatibility. Meanwhile, MR susceptibility test proved that synthesised nanoprobes can be managed for negative contrast enhancement. The results of this study suggested the potential use of these nanoprobes for non‐invasive molecular MRI in EGFR detection in the future. [ABSTRACT FROM AUTHOR]

In the first section of this research, superparamagnetic nanoparticles (NPs) (Fe3 O4) modified with hydroxyapatite (HAP) and zirconium oxide (ZrO2) and thereby Fe3 O4 /HAP and Fe3 O4 /ZrO2 NPs were synthesised through co‐precipitation method. Then Fe3 O4 /HAP and Fe3 O4 /ZrO2 NPs characterised with various techniques such as X‐ray photoelectron spectroscopy, X‐ray diffraction, scanning electron microscopy, energy dispersive X‐ray analysis, Brunauer–Emmett–Teller, Fourier transform infrared, and vibrating sample magnetometer. Observed results confirmed the successful synthesis of desired NPs. In the second section, the antibacterial activity of synthesised magnetic NPs (MNPs) was investigated. This investigation performed with multiple microbial cultivations on the two bacteria; Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Obtained results proved that although both MNPs have good antibacterial properties, however, Fe3 O4 /HAP NP has greater antibacterial performance than the other. Based on minimum inhibitory concentration and minimum bactericidal concentration evaluations, S. aureus bacteria are more sensitive to both NPs. These nanocomposites combine the advantages of MNP and antibacterial effects, with distinctive merits including easy preparation, high inactivation capacity, and easy isolation from sample solutions by the application of an external magnetic field. [ABSTRACT FROM AUTHOR]

The magnetization of hematite‐bearing sedimentary rocks provides critical records of geomagnetic reversals and paleogeography. However, the timing of hematite remanent magnetization acquisition is typically difficult to constrain. While detrital hematite in sediment can lead to a primary depositional remanent magnetization, alteration of minerals through interaction with oxygen can lead to the postdepositional formation of hematite. In this study, we use exceptionally preserved fluvial sediments within the 1.1‐billion‐year‐old Freda Formation to gain insight into the timing of hematite remanence acquisition and its magnetic properties. This deposit contains siltstone intraclasts that were eroded from a coexisting lithofacies and redeposited within channel sandstone. Thermal demagnetization, petrography, and rock magnetic experiments on these clasts reveal two generations of hematite. One population of hematite demagnetized at the highest unblocking temperatures and records directions that rotated along with the clasts. This component is a primary detrital remanent magnetization. The other component is removed at lower unblocking temperatures and has a consistent direction throughout the intraclasts. This component is held by finer‐grained hematite that grew and acquired a chemical remanent magnetization following deposition resulting in a population that includes superparamagnetic nanoparticles in addition to remanence‐carrying grains. The data support the interpretation that magnetizations of hematite‐bearing sedimentary rocks held by >400‐nm grains that unblock close to the Néel temperature are more likely to record magnetization from the time of deposition. This primary magnetization can be successfully isolated from cooccurring authigenic hematite through high‐resolution thermal demagnetization. Key Points: Red siltstone intraclasts reveal two ancient magnetizations held by hematite—one acquired before redeposition and the other after burialFine‐grained hematite spans from superparamagnetic to single domain leading to a wide range of unblocking temperatures and coercivitiesDetrital hematite thermally unblocks in a narrow high‐temperature range that can be isolated through high‐resolution thermal demagnetization [ABSTRACT FROM AUTHOR]

Azo dyes are widely used in industries and their release in the environment contributes to the pollution of effluents. The authors aim to develop a new eco‐friendly water treatment method for the degradation of azo dyes based on in situ magnetic separation and immobilisation of bacterial cells. The immobilisation was achieved using superparamagnetic Fe3 O4 nanoparticles and offers the possibility of reusing bacteria by magnetic separation for several degradation cycles. The iron– oxide nanoparticles were synthesised by reverse co‐precipitation. The Gram‐positive bacteria Bacillus subtilis were immobilised using iron–oxide nanoparticles by adsorption and then separated with an external magnetic field. Transmission electron microscopy observation showed that the particles' diameter was ∼20 nm with a narrow size distribution. Moreover, the iron–oxide nanoparticles were adsorbed onto the surface in order to coat the cells. B. subtilis has proved its ability to decolorise and degrade several azo dyes at different values of pH, with the highest decolorisation rate for Congo red. Furthermore, immobilised cells have a degradation activity similar to that of free cells. The system provided a degradation rate up to 80% and could be reused for seven batch cycles. [ABSTRACT FROM AUTHOR]

In this contribution, we for the first time propose the targeted synthesis of Co‐metalated salen‐based crystalline polymer, starting from corner and square building units in the presence of cobalt metal ions. On the basis of structural characterizations, this kind of salen‐based crystalline polymer is proved to be the long hollow tube. Due to its covalent connected unique structure, the obtained Co‐salen polymer possesses high crystallinity and excellent stability. The experimental and theoretical studies show that this kind of material holds paramagnetism, unique electronic structure, and remarkable catalytic activity with high selectivity for the coupling of CO2 and epoxides to form cyclic carbonates. And specifically, it shows favorable recyclability with only a slight drop in yield after six catalytic cycles. We hope that the results reported here will greatly inspire the design and synthesis of different metalated salen‐based polymer and enlarge their interesting applications in the future. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 641–647 This article introduces the synthesis of Co salen‐based crystalline polymers; most of the atoms in this polymer are linked by covalent bonds. The formation mechanism of this polymer is displayed. The SEM and TEM characterizations match well with the formation mechanism, confirming that this polymer is self‐assembled by more little nanotubes. Due to the covalent connection and the introduction of Co species, this polymer has high crystallinity according to powder X‐ray diffraction analysis. [ABSTRACT FROM AUTHOR]

To investigate how ligninolytic peroxidases acquired the uniquely high redox potential they show today, their ancestors were resurrected and characterized. Unfortunately, the transient Compounds I (CI) and II (CII) from peroxide activation of the enzyme resting state (RS) are unstable. Therefore, the reduction potentials (E°′) of the three redox couples (CI/RS, CI/CII and CII/RS) were estimated (for the first time in a ligninolytic peroxidase) from equilibrium concentrations analyzed by stopped‐flow UV/Vis spectroscopy. Interestingly, the E°′ of rate‐limiting CII reduction to RS increased 70 mV from the common peroxidase ancestor to extant lignin peroxidase (LiP), and the same boost was observed for CI/RS and CI/CII, albeit with higher E°′ values. A straightforward correlation was found between the E°′ value and the progressive displacement of the proximal histidine Hϵ1 chemical shift in the NMR spectra, due to the higher paramagnetic effect of the heme Fe3+. More interestingly, the E°′ and NMR data also correlated with the evolutionary time, revealing that ancestral peroxidases increased their reduction potential in the evolution to LiP thanks to molecular rearrangements in their heme pocket during the last 400 million years. E°′ in evolution: Natural evolution leading to high redox potential lignin peroxidases shows a progressive movement of the proximal histidine relative to heme cofactor. This structural change correlated with the increase of redox potential that could be estimated, for the first time, from stopped‐flow equilibrium after enzyme resurrection. [ABSTRACT FROM AUTHOR]

Open‐shell transition metal oxides are capable of developing a rich diversity of electronic phases. The specific features evolving crucially depend on an intricate interplay of various local and long‐range electronic interactions. Recently, the 5d transition elements have come into sharp focus because for these elements spin‐orbit coupling (SOC) and onsite Coulomb repulsion (U) are on a comparable energy scale. For Ir4+ the t2g level associated to an octahedral crystal field (CF) is split by SOC, giving rise to a Jeff=1/2 spin state and rendering respective oxides like Sr2IrO4 as Mott insulators. Transferring this scenario to iridium(V) oxides would lead to a diamagnetic ground state, Jeff=0. However, reported experimental results do not lend unambiguous support for such an electronic state. Theoretical explanations for the breakdown of the J=0 magnetic state suffer from conspicuous discrepancies. In an attempt to empirically contribute to resolving the puzzle, Bi2NaIrO6 was synthesized in high purity by precipitation from homogeneous solution; it represents an iridium(V) oxide where long range band structure effects and magnetic superexchange are minimized, and the t2g degeneracy is lifted geometrically. We managed to reduce the strength of paramagnetic response, lending support to a Jeff=0 ground state of Bi2NaIrO6, exhibiting van Vleck type behavior. Common ground: A new iridate(V), Bi2NaIrO6, is synthesized under hydrothermal conditions. The expected diamagnetic Jeff=0 ground state is almost realized; the residual weak paramagnetism is suggested to result from intrinsic non‐stoichiometry, from the presence of traces of Ir4+. [ABSTRACT FROM AUTHOR]

Easily available chromium(II) acetate was used for an entry into chromium chemistry: sodium tetraisopropylcyclopentadienide (Na4Cp), sodium 1,2,4‐tri(tert‐butyl)cyclopentadienide (NaCp′′′), or lithium pentaisopropylcyclopentadienide (Li5Cp) convert the acetate to the acetate‐bridged dimers [4CpCr(µ‐OOCCH3)]2 (1a), [Cp′′′Cr(µ‐OOCCH3)]2 (1b), or [5CpCr(µ‐OOCCH3)]2 (1c) in yields well above 70 %. These acetates could be converted into the halide‐bridged dimers [4CpCr(µ‐Cl)]2 (2a), [4CpCr(µ‐Br)]2 (3a), [Cp′′′Cr(µ‐Br)]2 (3b), or [5CpCr(µ‐Br)]2 (3c), [4CpCr(µ‐I)]2 (4a), or [Cp′′′Cr(µ‐I)]2 (4b) with the corresponding trimethylsilyl halides in nearly quantitative yield. With bis(trimethylsilyl)sulfate the acetate 1a gave crude bis(tetraisopropylcyclopentadienylchromium)sulfate (5a). From the bromide 3b and sodium bis(trimethylsilyl)amide the mononuclear chromium(II) silylamide [Cp′′′CrN(SiMe3)2(THF)] (7b) was obtained as a tetrahydrofuran adduct. Upon reaction with sodium azide, the iodide 4a afforded the tetranuclear chromium(IV) nitride cubane [(4CpCr)3(µ3‐N)4CrOH] (8a) after extraction with heptane containing traces of water. The analogous chromium nitride derivative [(Cp′′′Cr)3(µ3‐N)4CrBr] (9b) was obtained from the bromide 3b and sodium azide. A facile entry into reactive alkylcyclopentadienylchromium(II) starting compounds afforded the chromium(IV) nitride cubane shown above from chromium(II) acetate in three steps using sodium tri(tert‐butyl)cyclopentadienide, trimethylsilylbromide, and sodium azide via the chromium(II) bromide intermediate [Cp′′′Cr(µ‐Br)]2. Three tert‐butyl groups per ring ligand have been omitted for clarity. [ABSTRACT FROM AUTHOR]

Abstract: Characterization of the conformational ensemble of disordered proteins is highly important for understanding protein folding and aggregation mechanisms, but remains a computational and experimental challenge owing to the dynamic nature of these proteins. New observables that can provide unique insights into transient residual structures in disordered proteins are needed. Here using denatured ubiquitin as a model system, NMR solvent paramagnetic relaxation enhancement (sPRE) measurements provide an accurate and highly sensitive probe for detecting low populations of residual structure in a disordered protein. Furthermore, a new ensemble calculation approach based on sPRE restraints in conjunction with residual dipolar couplings (RDCs) and small‐angle X‐ray scattering (SAXS) is used to define the conformational ensemble of disordered proteins at atomic resolution. The approach presented should be applicable to a wide range of dynamic macromolecules. [ABSTRACT FROM AUTHOR]

Abstract: A reactive radical species, nitric oxide (NO), was encapsulated in a unimolecular form inside an open‐cage fullerene derivative under high‐pressure conditions in the solid state. Surprisingly, the molecular complex showed sharp 1H NMR signals despite the existence of the paramagnetic species inside the carbon cage. Owing to the paramagnetic shifts, the escape rate of the NO was determined experimentally. After constructing a stopper on the rim of the opening, the NO was found to stay inside the cage even at 50 °C. The ESR measurements of the powdery sample showed paramagnetic properties at low temperature. The single‐crystal X‐ray structure analysis clearly demonstrated the existence of the encapsulated NO molecule, suggesting rapid rotation inside the cage. The 1H NMR chemical shifts displayed a large temperature dependence owing to the paramagnetic effects. [ABSTRACT FROM AUTHOR]

Abstract: The [(iPr3P)Ni]5H6 cluster (1) and H2C=CHOtBu react at room temperature to form the new pentanuclear NiH carbide [(iPr3P)Ni]5H4(C)(CO) (3), along with an equivalent of isobutylene. This transformation requires the activation of multiple unreactive bonds, including C−H, C−C, and C(sp3)−O bond cleavage. Analysis of the reaction mixture by 1H NMR revealed the production of two additional paramagnetic species, assigned as [(iPr3P)Ni]4H4(C‐CH3)NiOtBu (4 a) and [(iPr3P)Ni]4H4(C‐CH2OtBu)NiOtBu (5 a), which arise from C(sp2)−O bond cleavage and CH bond rearrangements. The reaction of 1 with H2C=CHOSiMe2CH2Ph produced the isolable 4 a analogue [(iPr3P)4Ni5]H4(CCH3)(OSiMe2CH2Ph) (4 c). An isolable analogue of 5 a was obtained from the reaction of 1 with H2C=CHOAd (Ad=1‐admantyl), which produced [(iPr3P)4Ni5]H4(CCH2OAd)(OAd) (5 d). The utilization of both cluster faces and vertices for bonding substrate fragments in these transformations demonstrates the remarkable flexibility of the robust Ni5H4 core in the cooperative activation of multiple C−O, C−C and C−H bonds. [ABSTRACT FROM AUTHOR]

Abstract: Making cells magnetic is a long‐standing goal of chemical biology, aiming to enable the separation of cells from complex biological samples and their visualization in vivo using magnetic resonance imaging (MRI). Previous efforts towards this goal, focused on engineering cells to biomineralize superparamagnetic or ferromagnetic iron oxides, have been largely unsuccessful due to the stringent required chemical conditions. Here, we introduce an alternative approach to making cells magnetic, focused on biochemically maximizing cellular paramagnetism. We show that a novel genetic construct combining the functions of ferroxidation and iron chelation enables engineered bacterial cells to accumulate iron in “ultraparamagnetic” macromolecular complexes, allowing these cells to be trapped with magnetic fields and imaged with MRI in vitro and in vivo. We characterize the properties of these cells and complexes using magnetometry, nuclear magnetic resonance, biochemical assays, and computational modeling to elucidate the unique mechanisms and capabilities of this paramagnetic concept. [ABSTRACT FROM AUTHOR]