Carbon cage isomers and magnetic Dy amp; 8943;Dy interactions in Dy2O C88 and Dy2C2 C88 metallofullerenes

Three isomers of Dy2O C88 and two isomers of Dy2C2 C88 were synthesized and structurally characterized by single crystal X ray diffraction, vibrational spectroscopy, and DFT calculations. Both types of clusterfullerenes feature 4 fold electron transfer to the carbon cage, thus resulting in the same carbon cage isomers identified as C1 26 , Cs 32 , and D2 35 . The studies of Dy amp; 8943;Dy superexchange interactions in Dy2O and Dy2C2 clusters revealed that the O2 amp; 8722; bridge favors antiferromagnetic coupling whereas the acetylide group C22 amp; 8722; supports ferromagnetic coupling of Dy magnetic moments. The strength of the coupling showed a considerable variability in different cage isomers. All metallofullerenes exhibited slow relaxation of magnetization and magnetic hysteresis. In Dy2O C88 isomers the hysteresis remained open up to 7 9 K, while in Dy2C2 C88 the hysteresis loops were closed already at 2.5 K. This study demonstrated that both the endohedral bridge between metal atoms and the fullerene cage play an important role in magnetic interactions and relaxation of magnetizatio

'Detection of pemphigus desmoglein 1 and 3 autoantibodies and pemphigoid BP180 autoantibodies in saliva and comparison to serum values'

Although there is much literature on the detection of pemphigus and pemphigoid autoantibodies by enzyme-linked immunosorbent assay (ELISA) in serum, nothing is known about their presence in saliva. The aim of this study was to evaluate the salivary levels of these autoantibodies in pemphigus and pemphigoid patients. Autoantibodies against desmoglein3, desmoglein1, and BP180 were assayed, by ELISA, in serum and saliva samples of patients and healthy controls. The titres of autoantibodies against Dsg1/3 found in both serum and saliva of pemphigus patients showed a statistically significant correlation, suggesting that saliva may be a useful biological material for diagnostic purposes, in monitoring disease activity, as well as for the early detection of relapses. By contrast, the titres of autoantibodies against BP180 in the serum and saliva of bullous pemphigoid patients were not statistically related, and further study of the usefulness of the BP180 ELISA for saliva in this disease is needed. In addition, based on our results, the BP180 ELISA with a recombinant NC16a epitope failed to detect the autoantibodies against BP180 in the serum and saliva of mucous membrane pemphigoid patients

Using internal strain and mass to modulate Dy amp; 8943;Dy coupling and relaxation of magnetization in heterobimetallic metallofullerenes DyM2N C80 and Dy2MN C80 M Sc, Y, La, Lu

Endohedral clusters inside metallofullerenes experience considerable inner strain when the size of the hosting cage is comparably small. This strain can be tuned in mixed metal metallofullerenes by combining metals of different sizes. Here we demonstrate that the internal strain and mass can be used as variables to control Dy amp; 8943;Dy coupling and relaxation of magnetization in Dy metallofullerenes. Mixed metal nitride clusterfullerenes DyxY3 amp; 8722;xN Ih C80 x 0 3 and Dy2LaN Ih C80 combining Dy with diamagnetic rare earth elements, Y and La, were synthesized and characterized by single crystal X ray diffraction, SQUID magnetometry, ab initio calculations, and spectroscopic techniques. DyxY3 amp; 8722;xN clusters showed a planar structure, but the slightly larger size of Dy3 in comparison with that of Y3 resulted in increased elongation of the nitrogen thermal ellipsoid, showing enhancement of the out of plane vibrational amplitude. When Dy was combined with larger La, the Dy2LaN cluster appeared strongly pyramidal with the distance between two nitrogen sites of 1.15 1 , whereas DyLa2N C80 could not be obtained in a separable yield. Magnetic studies revealed that the relaxation of magnetization and blocking temperature of magnetization in the DyM2N C80 series M Sc, Y, Lu correlated with the mass of M, with DySc2N C80 showing the fastest and DyLu2N C80 the slowest relaxation. Ab initio calculations predicted very similar g tensors for Dy3 ground state pseudospin in all studied DyM2N C80 molecules, suggesting that the variation in relaxation is caused by different vibrational spectra of these compounds. In the Dy2MN C80 series M Sc, Y, La, Lu , the magnetic and hysteretic behavior was found to correlate with Dy amp; 8943;Dy coupling, which in turn appears to depend on the size of M3 . Across the Dy2MN C80 series, the energy difference between ferromagnetic and antiferromagnetic states changes from 5.6 cm amp; 8722;1 in Dy2ScN C80 to 3.0 cm amp; 8722;1 in Dy2LuN C80, 1.0 cm amp; 8722;1 in Dy2YN C80, and amp; 8722;0.8 cm amp; 8722;1 in Dy2LaN C80. The coupling of Dy ions suppresses the zero field quantum tunnelling of magnetization but opens new relaxation channels, making the relaxation rate dependent on the coupling strengths. DyY2N C80 and Dy2YN C80 were found to be non luminescent, while the luminescence reported for DyY2N C80 was caused by traces of Y3N C80 and Y2ScN C8

Shape-adaptive single-molecule magnetism and hysteresis up to 14 K in oxide clusterfullerenes Dy2O@C72 and Dy2O@C74 with fused pentagon pairs and flexible Dy-(μ2-O)-Dy angle

Dysprosium oxide clusterfullerenes Dy2O@Cs(10528)-C72 and Dy2O@C2(13333)-C74 are synthesized and characterized by single-crystal X-ray diffraction. Carbon cages of both molecules feature two adjacent pentagon pairs. These pentalene units determine positions of endohedral Dy ions hence the shape of the Dy2O cluster, which is bent in Dy2O@C72 but linear in Dy2O@C74. Both compounds show slow relaxation of magnetization and magnetic hysteresis. Nearly complete cancelation of ferromagnetic dipolar and antiferromagnetic exchange Dy⋯Dy interactions leads to unusual magnetic properties. Dy2O@C74 exhibits zero-field quantum tunneling of magnetization and magnetic hysteresis up to 14 K, the highest temperature among Dy-clusterfullerenes

Single Molecule Magnetism with Strong Magnetic Anisotropy and Enhanced Dy∙∙∙Dy Coupling in Three Isomers of Dy-Oxide Clusterfullerene Dy2O@C82

A new class of single-molecule magnets (SMMs) based on Dy-oxide clusterfullerenes is synthesized. Three isomers of Dy2O@C82 with Cs(6), C3v(8), and C2v(9) cage symmetries are characterized by single-crystal X-ray diffraction, which shows that the endohedral Dy−(µ2-O)−Dy cluster has bent shape with very short Dy−O bonds. Dy2O@C82 isomers show SMM behavior with broad magnetic hysteresis, but the temperature and magnetization relaxation depend strongly on the fullerene cage. The short Dy−O distances and the large negative charge of the oxide ion in Dy2O@C82 result in the very strong magnetic anisotropy of Dy ions. Their magnetic moments are aligned along the Dy−O bonds and are antiferromagnetically (AFM) coupled. At low temperatures, relaxation of magnetization in Dy2O@C82 proceeds via the ferromagnetically (FM)-coupled excited state, giving Arrhenius behavior with the effective barriers equal to the AFM-FM energy difference. The AFM-FM energy differences of 5.4–12.9 cm−1 in Dy2O@C82 are considerably larger than in SMMs with {Dy2O2} bridges, and the Dy∙∙∙Dy exchange coupling in Dy2O@C82 is the strongest among all dinuclear Dy SMMs with diamagnetic bridges. Dy-oxide clusterfullerenes provide a playground for the further tuning of molecular magnetism via variation of the size and shape of the fullerene cage

Single Molecule Magnetism with Strong Magnetic Anisotropy and Enhanced Dy∙∙∙Dy Coupling in Three Isomers of Dy‐Oxide Clusterfullerene Dy 2

A new class of single-molecule magnets (SMMs) based on Dy-oxide clusterfullerenes is synthesized. Three isomers of Dy2O@C82 with Cs(6), C3v(8), and C2v(9) cage symmetries are characterized by single-crystal X-ray diffraction, which shows that the endohedral Dy−(µ2-O)−Dy cluster has bent shape with very short Dy−O bonds. Dy2O@C82 isomers show SMM behavior with broad magnetic hysteresis, but the temperature and magnetization relaxation depend strongly on the fullerene cage. The short Dy−O distances and the large negative charge of the oxide ion in Dy2O@C82 result in the very strong magnetic anisotropy of Dy ions. Their magnetic moments are aligned along the Dy−O bonds and are antiferromagnetically (AFM) coupled. At low temperatures, relaxation of magnetization in Dy2O@C82 proceeds via the ferromagnetically (FM)-coupled excited state, giving Arrhenius behavior with the effective barriers equal to the AFM-FM energy difference. The AFM-FM energy differences of 5.4–12.9 cm−1 in Dy2O@C82 are considerably larger than in SMMs with {Dy2O2} bridges, and the Dy∙∙∙Dy exchange coupling in Dy2O@C82 is the strongest among all dinuclear Dy SMMs with diamagnetic bridges. Dy-oxide clusterfullerenes provide a playground for the further tuning of molecular magnetism via variation of the size and shape of the fullerene cage

High Blocking Temperature of Magnetization and Giant Coercivity in the Azafullerene Tb 2 @C 79 N with a Single-Electron Terbium–Terbium Bond

The azafullerene Tb 2 @C 79 N is found to be a single-molecule magnet with a high 100-s blocking temperature of magnetization of 24 K and large coercivity. Tb magnetic moments with an easy-axis single-ion magnetic anisotropy are strongly coupled by the unpaired spin of the single-electron Tb−Tb bond. Relaxation of magnetization in Tb 2 @C 79 N below 15 K proceeds via quantum tunneling of magnetization with the characteristic time τ QTM =16 462±1230 s. At higher temperature, relaxation follows the Orbach mechanism with a barrier of 757±4 K, corresponding to the excited states, in which one of the Tb spins is flipped. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA11sci

Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal–metal bond

Engineering intramolecular exchange interactions between magnetic metal atoms is a ubiquitous strategy for designing molecular magnets. For lanthanides, the localized nature of 4f electrons usually results in weak exchange coupling. Mediating magnetic interactions between lanthanide ions via radical bridges is a fruitful strategy towards stronger coupling. In this work we explore the limiting case when the role of a radical bridge is played by a single unpaired electron. We synthesize an array of air-stable Ln 2 @C 80 (CH 2 Ph) dimetallofullerenes (Ln 2 = Y 2 , Gd 2 , Tb 2 , Dy 2 , Ho 2 , Er 2 , TbY, TbGd) featuring a covalent lanthanide-lanthanide bond. The lanthanide spins are glued together by very strong exchange interactions between 4f moments and a single electron residing on the metal–metal bonding orbital. Tb 2 @C 80 (CH 2 Ph) shows a gigantic coercivity of 8.2 Tesla at 5 K and a high 100-s blocking temperature of magnetization of 25.2 K. The Ln-Ln bonding orbital in Ln 2 @C 80 (CH 2 Ph) is redox active, enabling electrochemical tuning of the magnetism