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The effects of hydrogen bonding between solvents (ethanol, ethanol–acetone and ethanol–ethyl acetate) and ammonium dinitramide (ADN) crystal faces on the morphology of ADN are studied experimentally and by molecular dynamics (MD) simulation. Scanning electron microscopy shows that ADN recrystallized from ethanol, ethanol–acetone and ethanol–ethyl acetate takes the form of a slice, a sheet aggregate and a sphere, respectively. The MD results show that the order of the standard deviation (E dev) of the hydrogen-bonding energy (E b) in the three solvent systems is as follows: ethanol > ethanol–acetone > ethanol–ethyl acetate. The larger the E dev, the larger the difference of each crystal plane size. The radial distribution function reveals that the carbonyl group of ethyl acetate promotes hydrogen-bond formation between O atoms in the nitro groups of ADN and H atoms in ethanol; meanwhile the O atom in the C—O bond of ethyl acetate forms a hydrogen bond with an H atom in ADN. Therefore, the E dev of each crystal face is further lowered, and finally a spherical ADN is obtained.

The synthesis, structural, and magnetic characterization of [FeIII4LnIII4(teaH)8(N3)8(H2O)] (Ln = Gd and Y) and the previously reported isostructural Dy analogue are discussed. The commonly held belief that both FeIII and GdIII can be regarded as isotropic ions is shown to be an oversimplification. This conclusion is derived from the magnetic data for the YIII analogue in terms of the zero-field splitting seen for FeIII and from the fact that the magnetic data for the new GdIII analogue can only be fit employing an additional anisotropy term for the GdIII ions. Furthermore, the Fe4Gd4 ring shows slow relaxation of magnetization. Our analysis of the experimental magnetic data employs both density functional theory as well as the finite-temperature Lanczos method which finally enables us to provide an almost perfect fit of magnetocaloric properties.

An imbalance in bone homeostasis results in bone loss and poor healing in bone diseases and trauma. Osteoimmune interactions, as a key contributor to bone homeostasis, depend on the crosstalk between mesenchymal stem cell-osteoblast (MSC-OB) and monocyte-macrophage (MC-Mφ) lineages. Currently, extracellular vesicles (EVs) are considered to be involved in cell-to-cell communication and represent a novel avenue to enhance our understanding of bone homeostasis and to develop novel diagnostic and therapeutic options. In this comprehensive review, we aim to present recent advances in the study of the effect of MC-Mφ-derived EVs on osteogenesis and the regulatory effects of MSC-OB-derived EVs on the differentiation, recruitment and efferocytosis of Mφ. Furthermore, we discuss the role of EVs as crucial mediators of the communication between these cell lineages involved in the development of common bone diseases, with a focus on osteoporosis, osteoarthritis, bone fracture, and periodontal disease. Together, this review focuses on the apparent discrepancies in current research findings and future directions for translating fundamental insights into clinically relevant EV-based therapies for improving bone health.

The pyrolysis and combustion mechanism of the hydrocarbon fuel has important scientific and practical significance. However, it is difficult to detect the whole intermediates and products using traditional methods, which brings trouble to the analysis of the reaction process. In this paper, the microscopic reaction mechanism and the main products of n-eicosane (C20H42) were simulated based on the reactive force field molecular dynamics (ReaxFF-MD). The effects of temperature (2000–3500 K) and oxygen on the initial decomposition, the distribution of main products, and the reactive pathways of C20H42 fuel were studied to determine its reaction mechanism. The initial decomposition of C20H42 was mainly initiated by small alkyl radicals in pyrolysis, and by the oxygen-containing radicals in combustion. The participation of oxygen had a greater effect on accelerating the decomposition reaction. The reactions involving oxygen of C20H42 initial decomposition accounted for 87.5% of the total reactions at 2000 K. Moreover, the detailed distribution and formation pathways of the main products of H2, C2H4, CH4, H2O, CO, and CO2 were depicted to construct the overall reaction mechanism of C20H42. •H radical formed from the composition of C2H4 was exactly consistent with the •H radical consumed by the generation of CH4 and H2 in the pyrolysis stage. The feasibility of the simulation method was verified by the result of thermal analysis. The results are helpful for further research on the reaction mechanism of hydrocarbon fuels.

AIM To investigate the potential role of Kruppel-like factor 6 (KLF6) in the odontoblastic differentiation of immortalized dental papilla mesenchymal cells (iMDP-3) cells. METHODOLOGY Alizarin Red S (ARS) and Alkaline phosphatase (ALP) staining was used to examine the mineralization effect of iMDP-3 cells after odontoblastic induction. Real-time PCR and Western blotting were employed to analyse dentine sialophosphoprotein (DSPP), dentine matrix protein 1 (DMP1), RUNX family transcription factor 2 (RUNX2), ALP and KLF6 expression during this process. Co-expression of the KLF6 with DMP1, DSPP and RUNX2 was detected by double immunofluorescence staining to explore their local relationship in the cell. To further investigate KLF6 functions, Klf6 gain- and loss-of-function assays followed by ARS and ALP stainings, real-time PCR and Western blotting were performed using Klf6-overexpression plasmids and Klf6 siRNA to investigate whether changes in Klf6 expression affect the odontoblastic differentiation of iMDP-3 cells. Dual-luciferase reporter assays were used to elucidate the mechanistic regulation of Dspp and Dmp1 expression by Klf6. Means were compared using the unpaired t-test and Kruskal-Wallis one-way anova with P

An unsaturated ladder phenyl/vinyl polysilsesquioxane (PhVPOSS) was synthesized and applied to vinyl ester resin (VER) thermosets. The compatibility, mechanical properties, thermal properties, and combustion behavior of the VER-PhVPOSS composites were further investigated. As a result, the PhVPOSS and VER had a good compatibility and interaction based on the solubility parameters and Flory–Huggins parameters. PhVPOSS provided the VER with a significantly enhanced bending strength, thermal stability, and smoke-suppression effect. When 20 wt% PhVPOSS was added, the bending strength, flexural modulus, and breaking force increased by195.6%, 260.6%, and 196.6% compared with pure VER. The peak heat release rate, total smoke release, and specific optical density decreased by 52.2%, 20.7%, and 15.7%, respectively. These favorable characteristics indicated that PhVPOSS had a good application prospect in unsaturated polyester resin.

This study aims to study the accuracy of cone beam computed tomography (CBCT) for measuring peri-implant bone thickness in living patients via a novel visualization method (NVM).The validity of the NVM was verified ex vivo by measuring the same peri-implant bone thicknesses in bovine ribs by using raw postoperative CBCT (clinical measurement, CM), the visualized fused images obtained using the NVM (visualized fused measurement, VF), and hard tissue sections (gold standard measurement, GS). The NVM was applied by deconstructing the postoperative CBCT model into the ModelEx vivo, the VF was similar to GS, while CM usually underestimated the peri-implant bone thickness, especially at the implant shoulder (P 0.01). In vivo, on CBCT, areas with a peri-implant bone thickness of 0-0.50 mm were not visible, while those with a thickness of 0.50-1.00 mm were occasionally visible. There was less underestimation of bone along the implant long axis.Thin peri-implant bones could be completely underestimated on CBCT. CBCT scans alone are insufficient to warrant surgical intervention. Our NVM facilitates the accurate visual assessment of implant dimensions.The thickness of peri-implant bone could be completely underestimated when thinner than 1.0 mm in living patients. Familiarity with these confusing CBCT results may help clinicians and patients avoid further unnecessary evaluation, misdiagnosis, and invasive treatment.

Multiple signaling pathways are involved in the regulation of cell proliferation and differentiation in odontogenesis and dental tissue renewal, but the details of these mechanisms remain unknown. Here, we investigated the expression patterns of a transcription factor, Krüppel-like factor 6 (KLF6), during the development of murine tooth germ and its function in odontoblastic differentiation. KLF6 was almost ubiquitously expressed in odontoblasts at various stages, and it was co-expressed with P21 (to varying degrees) in mouse dental germ. To determine the function of Klf6, overexpression and knockdown experiments were performed in a mouse dental papilla cell line (iMDP-3). Klf6 functioned as a promoter of odontoblastic differentiation and inhibited the proliferation and cell cycle progression of iMDP-3 through p21 upregulation. Dual-luciferase reporter assay and chromatin immunoprecipitation showed that Klf6 directly activates p21 transcription. Additionally, the in vivo study showed that KLF6 and P21 were also co-expressed in odontoblasts around the reparative dentin. In conclusion, Klf6 regulates the transcriptional activity of p21, thus promoting the cell proliferation to odontoblastic differentiation transition in vitro. This study provides a theoretical basis for odontoblast differentiation and the formation of reparative dentine regeneration.

Successful osseointegration involves the biological behavior of bone marrow stem cells (BMSCs) on an implant surface; however, the role of BMSC-derived extracellular vesicles (EVs)/exosomes in osseointegration is little known. This study aimed to: (i) explore the interaction force between exosomes (Exo) and cells on a titanium surface; (ii) discuss whether the morphology and biological behavior of BMSCs are affected by exosomes; and (iii) preliminarily investigate the mechanism by which exosomes regulate cells on Ti surface. Exosomes secreted by rat BMSCs were collected by ultracentrifugation and analyzed using transmission electron microscopy and nanoparticle tracking analysis. Confocal fluorescence microscopy, scanning electron microscopy, Cell Counting Kit-8 (CCK-8), quantitative real-time polymerase chain reaction techniques, and alkaline phosphatase bioactivity, Alizarin Red staining, and quantification were used to investigate the exosomes that adhere to the Ti plates under different treatments as well as the morphological change, adhesion, spread, and differentiation of BMSCs. We found that exosomes were efficiently internalized and could regulate cell morphology and promoted the adhesion, spreading, and osteogenic differentiation of BMSCs. These were achieved partly by activating the RhoA/ROCK signaling pathway. Our discovery presents a new insight into the positive regulatory effect of exosomes on the biological behaviors of BMSCs on Ti surface and provides a novel route to modify the surface of a Ti implant.

A series of seven isostructural homometallic dinuclear lanthanide metal complexes having the general formula [Ln2(L)2(NO3)4]·2CH3 OH, where L = 6-methoxy-2-(2-pyridylmethyliminomethyl) phenol Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5), Yb (6), and Lu (7), are described. Compounds 1–7 were obtained from the reactions of Schiff base ligand (L) with the respective metal nitrates in the presence of triethylamine in MeOH. The structure of 2 was determined by single-crystal X-ray diffraction and the remaining compounds were characterized from X-ray powder diffraction patterns and found to be isostructural. The magnetic properties of 1–7 have been investigated using dc and ac susceptibility measurements. All these compounds show antiferromagnetic behavior between adjacent paramagnetic centers. Out of these seven compounds, only 2 displays an out-of-phase ac susceptibility signal which is attributed to the presence of the anisotropic DyIII ions.

Successful osseointegration in dental implants depends on balanced activation of osteoclasts and osteoblasts. Osteoporosis up-regulates osteoclast activity, so it is desirable to find effective interventions to inhibit osteoclastogenesis and enhance the osseointegration of implants under these conditions. It has been reported that the NF-κB essential modulator (NEMO)-binding domain (NBD) peptide can prevent osteoclast formation and bone resorption. In this study, we conjugated NBD peptide onto the surface of rough pure titanium (Ti) using the layer by layer technique. We analyzed the surface characteristics and determined the successful NBD integration by the presence of trivial granular structures, increased S elements and hydrophilia. Importantly, we first reported that Ti surface-conjugated NBD peptide retained its inhibitory effects on osteoclastogenesis by reducing osteoclast sealing zone formation and function. These effects were mediated by a reduction in NFATc1 expression, which in turn regulated integrin ανβ3 and MMP9 by targeting the P65 signaling pathway. In vivo TRAP staining suggested NBD-coating decreased osteoclast formation with less pseudopodia. Micro-CT and histomorphometric analysis demonstrated that NBD-coating enhanced pronounced osseointegration in vivo in ovariectomized rats. This study holds great promise for in vivo use of immobilized NBD peptide and offers an effective therapeutic approach to select more suitable Ti-implant surface modifications for improving implant osseointegration in osteoporotic patients.

Three isostructural lanthanide series with a core of MnMnLn2 are reported. These three families have the formulae of [MnMnLn2(μ4-O)2(H2edte)2(piv)6(NO3)2] {no crystallization solvent, Ln = La, Ce, Pr, Nd, Eu (1-4, 6); solv = 3MeCN, Ln = Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y (5, 7-13)}, where H2edte = N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine and piv = pivalate; [MnMnLn2(μ4-O)2(H2edte)2(benz)6(NO3)2], where benz = benzoate, or [MnMnLn2(μ4-O)2(edteH2)2(benz)6(NO3)2]·2MeCN {Ln = Gd, Tb, Dy (14-16); and [MnMnLn2(μ4-O)2(edteH2)2(piv)8].solv {solv = 4MeCN, Ln = La (17); solv = 2MeCN·tol·H2O, Ln = Pr, Nd, Sm, Tb (18-20, 22); solv = 2MeCN·H2O, Ln = Gd (21). These compounds crystallize in two different systems, namely, monoclinic in the space groups P21/n for 1-4, 6, and 14-16 and C2/c for 5, 7-13, 18-20, and 22 and triclinic in the space group P1[combining macron] for 17 and 21. The crystal structures of these compounds display a face-fused dicubane structure connected by different types of bridged oxygen atoms. Solid-state dc magnetic susceptibility characterization was carried out for 1-22, and fitting showed that MnIIIMnIII is antiferromagnetically (AF) coupled and MnIIMnIII, MnIILn and MnIIILn are weakly ferromagnetically coupled. In addition, ac measurements were carried out and showed that only 7, 15, and 22 for Tb, 8 and 16 for Dy, and 20 for Sm exhibited slow magnetization relaxation. In the case of 15, it was possible to determine the energy barrier of the slow-relaxation behavior by fitting peak temperatures to the Arrhenius law, which gave a value of Ueff = 21.2 K and a pre-exponential factor of τ0 = 4.0 × 10-9 s.

Pyrolysis mechanisms and flame retardant properties of polycarbonate (PC) and PC/ octyphenylsiloxane (OPS) composites at different temperatures (2000–4000 K with an interval of 500 K) were studied using reactive force field (ReaxFF) molecular dynamics simulation. The initial decomposition mechanism, products distribution, and main products generation and consumption paths of PC and PC/OPS composites were analyzed. Results showed that decomposition of PC molecular chain was caused by the rupture of the C O bond, and the decomposition of OPS molecule was caused by the rupture of the C-Si bond. The breaking of partial C Si bond made OPS from cage structure into a lamellar-like or reticular structure, which has been proven this structure was a key factor to improve the flame retardance of PC by suppressing the transfer of heat, flammable volatile gaseous products. From the potential energy and decomposition time of PC and PC/OPS composites, the addition of OPS slowed down the decomposition rate of the PC molecular chain and improved the thermal stability of the composites. These have overall good agreement with the reported results. The amounts of CO2, CO, C6H5OH and their derivatives in PC/OPS composites were lower than those in PC at the later stage of reaction, which was because unsaturated Si atoms in OPS adsorbed small oxygen-containing molecules to suppress these harmful materials. Moreover, OPS promoted the combination of molecular products into carbon clusters and large thermally stable organic structures. Thus, the ReaxFF method could be effectively used to study the pyrolysis mechanism of PC/OPS composites, and provide a new method for the prediction and analysis of flame retardance.

The paper presents a new material (named PMPP) with interpenetrating polymer network (IPN) formed by rigid polysilsesquioxane and flexible poly(hexamethylene diisocyanate)/poly(ethylene glycol) (PHMDI/PEG). Based on the network, polysilsesquioxanes with different structures, such as ladder-like polysilsesquioxane (PPSQ), cage-like polysilsesquioxane (T7POSS) and reactive ladder-like polysilsesquioxane (VPOSS), were selected to further modify PMPP. All samples were subjected to mechanical analysis, thermal analysis and combustion analysis and simulated by molecular dynamics (MD) and MesoDyn simulation. The introduction of polysilsesquioxanes obviously improved the flexural strength, tensile strength, heat resistance and fire resistance due to the strong interaction between polysilsesquioxanes and PMPP network structures. The results of solubility parameters (δ), radial distribution functions (RDF), Flory-Huggins parameters (χ) and mesoscopic morphologies showed that T7POSS and VPOSS had stronger interaction, better compatibility and dispersion in PMPP, thereby providing theoretical foundation for performance improvements.

Severity parameters are critical for safety management and risk assessment of coal dust explosions. We evaluated explosion severity parameters using a 20-L spherical vessel and numerical simulation by the program FLUENT to reveal the explosion mechanism of coal dusts. The explosion pressure and the rate of explosion pressure increased with coal dust concentration and the ignition delay up to a concentration of 250 g/m3 coal dust and an ignition delay of 60 ms for a maximum explosion pressure of 0.67 MPa and a rate of explosion pressure rise of 68.89 MPa/s. Comparison of the numerical and experimental explosion pressure profiles showed reasonable quantitative and qualitative agreement. Additionally, the numerical simulation was used to address the technical difficulties of understanding the mechanisms of dust explosion, it suggested that the airflow of the dust explosion played a more important role in the secondary explosion of dusts in a closed chamber than in a half-closed one.

A new mixed-valent Mn–Ln complex with an Mn 9 III Mn 2 II La2 core $$ [{\text{Mn}}_{9}^{\text{III}} {\text{Mn}}_{2}^{\text{II}} {\text{La}}_{ 2} (\mu_{ 4} {-}{\text{O}})_{7} (\mu_{ 3} {-}{\text{O}})(\mu_{ 3} {-}{\text{OH}})_{ 2} ({\text{benzoate}})_{ 1 8} ({\text{NO}}_{3} )({\text{MeCN}})] $$ has been synthesized. Its magnetic characterization reveals a complex with dominating slow relaxation. In addition, alternating current (ac) susceptibility measurements reveal a frequency-dependent out-of-phase (χ′′M) signal below 4 K, suggesting the complex to be a single-molecule magnet.

Osteomyelitis, which is characterized by progressive inflammatory bone destruction and resorption, is a difficult‑to‑treat infection. Staphylococcus aureus (S. aureus) is one of the major causes of this disease. This pathogenic microorganism possesses several characteristics, which facilitate its involvement in the occurrence and progression of osteomyelitis. A cell‑permeable peptide inhibitor of the IκB kinase complex, the nuclear factor (NF)‑κB essential modulator‑binding domain (NBD) peptide, has been reported to block osteoclastogenesis and may be considered a potential strategy for preventing inflammatory bone resorption. However, it remains to be determined as to whether the NBD peptide can regulate inflammation and bone resorption in S. aureus‑induced osteomyelitis. In order to investigate the role of NBD in S. aureus‑induced osteomyelitis, the present study obtained the NBD peptide, and confirmed that it inhibited receptor activator of NF‑κB ligand‑induced osteoclastogenesis in vitro. Subsequently, a bone defect was generated and S. aureus was injected into the mandible of experimental animals, in order to establish an in vivo osteomyelitis model. The present study analyzed the following three experimental groups: Untreated, treated with debridement, and treated with debridement plus NBD peptide administration. The results revealed that treatment with the NBD peptide reduced the bone defect in a 3‑dimensional manner, and reduced bone resorption. To the best of our knowledge, the present study is the first to demonstrate that, in a model of osteomyelitis caused by S. aureus, the NBD peptide serves a role in inhibiting osteolysis and promoting bone remodeling in the direction of osteogenesis. The effects were better than those produced by debridement alone, thus suggesting that it may have promising therapeutic potential in osteomyelitis.

A unique belt-like one-dimensional Dy chain linked through hydroxyl groups was synthesized and structurally characterized. Magnetic studies showed that this Dy chain exhibited significant frequency-dependent ac behavior and clear hysteresis loop below 0.6 K.

New exotic phenomena have recently been discovered in oxides of paramagnetic Ir4+ ions, widely known as ‘iridates'. Their remarkable properties originate from concerted effects of the crystal field, magnetic interactions and strong spin-orbit coupling, characteristic of 5d metal ions. Despite numerous experimental reports, the electronic structure of these materials is still challenging to elucidate, and not attainable in the isolated, but chemically inaccessible, [IrO6]8– species (the simplest molecular analogue of the elementary {IrO6}8− fragment present in all iridates). Here, we introduce an alternative approach to circumvent this problem by substituting the oxide ions in [IrO6]8− by isoelectronic fluorides to form the fluorido-iridate: [IrF6]2−. This molecular species has the same electronic ground state as the {IrO6}8− fragment, and thus emerges as an ideal model for iridates. These results may open perspectives for using fluorido-iridates as building-blocks for electronic and magnetic quantum materials synthesized by soft chemistry routes., Iridates are known to exhibit a range of exotic electronic and magnetic behaviours but it is difficult to prepare isolated [IrO6]8− species via soft chemical routes. Here, the authors isolate the isoelectronic [IrF6]2− complex, and assess it as a model and for iridate analogues.

A 3D metal-organic framework (MOF) having single-molecule magnet (SMM) linkers was prepared in crystalline form by using a tetrairon(III) complex functionalised with two divergent pyridyl groups, namely [Fe4 (pPy)2 (dpm)6 ] (1; H3 pPy=2-(hydroxymethyl)-2-(pyridin-4-yl)propane-1,3-diol, Hdpm=dipivaloylmethane). Reaction of 1 with silver(I) perchlorate afforded {[Fe4 (pPy)2 (dpm)6 ]2 Ag}ClO4 (2), which crystallises in a cubic face-centred lattice and exhibits two interlocked diamondoid networks. In 2, the SMMs act as linear ditopic synthons, and silver(I) ions as tetrahedral nodes coordinated by four pyridyl nitrogen atoms. The magnetic properties of 1 (S=5 and D≈-0.4 cm(-1) in the ground spin state) are largely preserved in 2, which shows slow magnetic relaxation with an anisotropy barrier of Ueff /kB =11.46(10) K in zero field and 14.25(8) K in an applied field of 1 kOe. However, crystal symmetry triggers highly noncollinear magnetic anisotropy contributions oriented at 109.47° from each other along the threefold axes of AgN4 tetrahedra, a unique scenario fully confirmed by a single-crystal cantilever torque magnetometry investigation. Magnetisation curves down to 0.03 K demonstrated the occurrence of a wide hysteresis loop when the magnetic field was swept along one of the four Ag-N bonds. By symmetry, the crystalline compound can then be persistently magnetised parallel or antiparallel to the four main diagonals of the unit cell, although the crystals have no overall second-order anisotropy.

Preparation of polystyrene nanocomposites containing flame retardants is difficult to achieve in one step by suspension polymerization. Styrene suspension polymerization was studied to determine the effects of the flame retardant on the polymerization process and properties of polystyrene beads. Triphenyl phosphate (TPP) was used in this work, which can dissolve completely in styrene monomers. The results showed that TPP were nanosized spherical particles, distributed homogenously and uniformly in a polystyrene (PS) matrix, and the formation mechanism of TPP nanoparticles was also investigated. In addition, the effects of TPP on the styrene polymerization process were investigated. With TPP amount increasing, the polymerization time increased significantly; molecular weight of PS nanocomposites also decreased and molecular weight distribution became wide; the particle size distribution (PSD) of the PS nanocomposites became wider than pure PS slightly as the particle size decreased. PS/TPP nanocomposites obtained good flame retardance because of nanodispersed TPP particles in its matrix. In a word, the suspension polymerization method provides a facile approach to prepare PS/TPP nanocomposites with better properties.

A series of 2,2’-bipyrimidine-bridged dinuclear lanthanide complexes with the general formula [Ln(tmhd)3]2bpm (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate, bpm = 2,2’-bipyrimidine, Ln = Gd(III), 1; Tb(III), 2; Dy(III), 3; Ho(III), 4 and Er(III), 5) has been synthesized and characterized. Sublimation of [Tb(tmhd)3]2bpm onto a Au(111) surface leads to the formation of a homogeneous film with hexagonal pattern, which was studied by scanning tunneling microscopy (STM). The bulk magnetic properties of all complexes have been studied comprehensively. The dynamic magnetic behavior of the Dy(III) and Er(III) compounds clearly exhibits single molecule magnet (SMM) characteristics with an energy barrier of 97 and 25 K, respectively. Moreover, micro-SQUID measurements on single crystals confirm their SMM behavior with the presence of hysteresis loops.

The synthesis and characterization of a family of compounds (pipzH2)[CrIII2LnIII4(µ4-O)2(µ3-OH)4(H2O)10(µ3-SO4)4(SO4)2]·2H2O [hereafter abbreviated as Cr2Ln4; Ln = Tb (1), Ho (2), Er (3), Yb (4), and Y (5); pipz = piperazine] are reported. The compounds were obtained from hydrothermal reactions of Ln(NO3)3·6H2O (Ln = Tb, Ho, Er, Yb, and Y), Cr(NO3)3·9H2O, Na2SO4, and pipz in a 2:1:3:4 molar ratio. Single-crystal X-ray diffraction studies revealed that 1–5 crystallize isomorphously in the space group P21/c with Z = 2. The metallic core is composed of a rare face-fused double-cubane [CrIII2LnIII4(µ4-O2–)2(µ3-OH–)4]10+ unit. The temperature dependence of bulk magnetic susceptibilities is indicative of antiferromagnetic interactions dominant in the Tb, Ho, and Er compounds. In fitting with the data of the diamagnetic YIII analogue, the interactions of Cr–Cr in this system are determined to be ferromagnetic with a coupling strength of 3.61(11) cm–1, but the type of Cr–Ln could be antiferromagnetic. The dynamic magnetic properties revealed the presence of slow magnetic relaxation in the Tb and Er analogues, which represent two rare examples of CrIII-containing clusters that exhibit single-molecule magnet (SMM) behavior.

In-depth investigations of the low energy electronic structures of mononuclear lanthanide complexes, including single molecule magnets, are challenging at the best of times. For magnetically coupled polynuclear systems, the task seems well nigh impossible. However, without detailed understanding of the electronic structure, there is no hope of understanding their static and dynamic magnetic properties in detail. We have been interested in assessing which techniques are most appropriate for studying lanthanide single-molecule magnets. Here we present a wide ranging theoretical and experimental study of the archetypal polynuclear lanthanide single-molecule magnet Dy3 and derive the simplest model to describe the results from each experimental method, including high-frequency electron paramagnetic resonance and far-infrared spectroscopies and cantilever torque magnetometry. We conclude that a combination of these methods together with ab initio calculations is required to arrive at a full understanding of the properties of this complex, and potentially of other magnetically coupled lanthanide complexes. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Liviu Ungur (ORCID) identifier: Liviu Ungur (ResearcherID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported Licence (CC BY-NC 3.0) history: Received 22 January 2016; Accepted 16 March 2016; Accepted Manuscript published 16 March 2016; Advance Article published 29 March 2016; Version of Record published 21 June 2016 ispartof: Chemical Science vol:7 issue:7 pages:4347-4354 ispartof: location:England status: published

TbPc2 single-molecule magnets adsorbed on a magnesium oxide tunnel barrier exhibit record magnetic remanence, record hysteresis opening, perfect out-of-plane alignment of the magnetic easy axes, and self-assembly into a well-ordered layer.

A new synthetic non-halogen, flame-retardant cyclotriphosphazene containing the silicon functional group (APESP) was incorporated with ammonium polyphosphate (APP) to prepare flame-retarded polypropylene (PP). APESP/APP/PP composites were prepared by melt-blending and extrusion in a twin-screw extruder with different loading levels of APESP. The combustion and thermal behaviors were investigated based on the limiting oxygen index, UL-94, and cone calorimeter test as well as thermogravimetric analysis (TGA). Then, TGA coupled with Fourier transform infrared spectroscopy was used to probe the degradation mechanism of APESP/APP/PP composites. The results indicated that a good flame-retardant performance could be achieved by incorporating APESP with APP in PP. The synergistic effect between APESP and APP was observed and is discussed here. The mechanical properties and rheological behaviors of APESP/APP/PP composites indicated that APESP significantly contributed to the dispersion and distribution of APP in t...

Herein we report the synthesis and characterization of a dinuclear TbIII single-molecule magnet (SMM) with two [TbPc2]0 units connected via a fused-phthalocyaninato ligand. The stable and robust complex [(obPc)Tb(Fused-Pc)Tb(obPc)] (1) was characterized by using synchrotron radiation measurements and other spectroscopic techniques (ESI-MS, FT-IR, UV). The magnetic couplings between the TbIII ions and the two π radicals present in 1 were explored by means of density functional theory (DFT). Direct and alternating current magnetic susceptibility measurements were conducted on magnetically diluted and nondiluted samples of 1, indicating this compound to be an SMM with improved properties compared to those of the well-known [TbPc2]−/0/+ and the axially symmetric dinuclear TbIII phthalocyaninato triple-decker complex (Tb2(obPc)3). Assuming that the probability of quantum tunneling of the magnetization (QTM) occurring in one TbPc2 unit is PQTM, the probability of QTM simultaneously occurring in 1 is PQTM2, mean...

A family of isostructural undecanuclear 3d–4f coordination clusters of formula [FeIII7LnIII4O4(OH)3(tea)2(Htea)3(Piv)7(H2O)2(NO3)3], where Ln = Y (1), Gd (2), Tb (3), Dy (4); PivH ≡ pivalic acid and H3tea ≡ triethanolamine, was synthesised. The central Fe7 core of the coordination cluster can be described in terms of two {Fe4O2} butterfly motifs sharing a common body Fe atom. The two Fe4 mean-planes subtend a dihedral angle of ca. 72°. The Tb (3) and Dy (4) compounds show Single Molecule Magnet (SMM) behaviour as confirmed by ac-susceptibility and μ-SQUID measurements. Furthermore, 57Fe Mossbauer spectra of 1–4 confirm the presence of high-spin FeIII sites. The spectra of all complexes in the high temperature range (30–300 K) show broad overlapping doublets which were assigned to the body and wing-tip pairs of metal ions within the Fe7 core. The low temperature Mossbauer spectra show dependence on the nature of the rare-earth metal as a result of its interaction with the iron sites. Thus, we observed a transition from fast (2), to intermediate (1) and very slow (frozen) (3, 4) spin fluctuation phenomena in these compounds.

Two new heterometallic Zn3 Ln3 (Ln3+ =Dy, Tb) complexes, with a double triangular topology of the metal ions, have been assembled from the polytopic Mannich base ligand 6,6'-{[2-(dimethylamino)ethylazanediyl]bis(methylene)}bis(2-methoxy-4-methylphenol) (H2 L) with the aid of an in situ generated carbonate ligand from atmospheric CO2 fixation. Theoretical calculations indicate axial ground states for the Ln3+ ions in these complexes, with their local magnetic moments being almost coplanar and tangential to the Ln3+ atoms that define the equilateral triangle. Therefore, they can be considered as single-molecule toroics (SMTs) with almost zero total magnetic moment. Micro-SQUID measurements on the Dy3+ counterpart show hysteresis loops below 3 K that have an S-shape, with large coercive fields opening upon cooling. This behavior is typical of a single molecule magnet (SMM) with very slow zero-field relaxation. At around ±0.35 T, the loops have a broad step, which is due to a direct relaxation process and corresponds to an acceleration of the relaxation of the magnetization, also observed at this magnetic field from ac susceptibility measurements. Simulations suggest that the broad step corresponds to two level avoidance of crossing points where the spin chiral Kramers doublet meets excited states of the coupled manifold, whose position is defined by exchange and dipole interactions. The Tb3+ counterpart does not exhibit SMM behavior, which is due to the fact that the degeneracy of the ground state of the exchange coupled system is lifted at zero field, thus favoring quantum tunneling of magnetization (QTM).