REMINDER: CrystEngComm - Invitation to submit an article Enhancement of the Microwave Absorption Properties by Adjusting the Sintering Conditions and Canbon Shell Thickness of Ni@C Submicrospheres

The combination of traditional magnetic metal materials and dielectric carbon materials to improve microwave absorption properties has aroused great interest. In this article, the Ni@C submicrospheres have been successfully synthesized...

Immobilization of D-allulose 3-Epimerase Into Magnetic Metal-Organic Framework Nanoparticles For Efficient Biocatalysis

D-allulose is a rare low-calorie sugar that has many fundamental biological functions. D-allulose 3-epimerase from Agrobacterium tumefaciens (AT-DAEase) catalyzes the conversion of D-fructose to D-allulose. The enzyme has attracted considerable attention because of its mild catalytic properties. However, the bioconversion efficiency and reusability of AT-DAEase limit its industrial application. Magnetic metal-organic frameworks (MOFs) have uniform pore sizes and large surface areas and can facilitate mass transport and enhance the capacity for enzyme immobilization. Here, we successfully encapsulated cobalt-type AT-DAEase into the cobalt-based magnetic MOF ZIF-67@Fe3O4 using a self-assembly strategy. The AT-DAEase@ZIF-67@Fe3O4 nanoparticles had higher catalytic activity (65.1 U mg-1) and bioconversion ratio (38.1%) than the free AT-DAEase. The optimal conditions for maximum enzyme activity of the AT-DAEase@ZIF-67@Fe3O4 nanoparticles were 55°C and pH 8.0, which were significantly higher than those of the free AT-DAEase (50°C and pH 7.5). The AT-DAEase@ZIF-67@Fe3O4 nanoparticles displayed significantly improved thermal stability and excellent recycling performance, with 80% retention of enzyme activity at temperature range of 45-70°C and >45% of its initial activity after eight cycles of enzyme use. The AT-DAEase@ZIF-67@Fe3O4 nanoparticles have great potential for large-scale industrial preparation of D-allulose by immobilizing cobalt-type AT-DAEase into magnetic MOF ZIF-67@Fe3O4.

Switchable Spiral Josephson junction: A superconducting spin-valve proposal

We propose a superconducting spin valve based on a Josephson junction with B20-family magnetic metal as barrier material. Our analysis shows that the states of this element can be switched by reorienting the intrinsic non-collinear magnetization of the spiral magnet. This reorientation modifies long-range spin-triplet correlations and thereby influences strongly the critical Josephson current. Compared to superconducting spin valves proposed earlier, our device has the following advantages: (i) it contains only one barrier layer, which makes it easier to fabricate and control; (ii) its ground state is stable, which prevents uncontrolled switching; (iii) it is compatible with devices of low-T Josephson electronics. This device may switch between two logical states which exhibit two different values of critical current, or its positive and negative value. I.e. 0-π switch is achievable on one simple Josephson junction.

Structural and Magnetic Studies on Nickel(II) and Cobalt(II) Complexes with Polychlorinated Diphenyl(4-pyridyl)methyl Radical Ligands

New magnetic metal complexes with organic radical ligands, [M(hfac)2(PyBTM)2] (M = NiII, CoII; hfac = hexafluoroacetylacetonato, PyBTM = (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radical), were prepared and their crystal structures, magnetic properties, and electronic structures were investigated. Metal ions in [M(hfac)2(PyBTM)2] constructed distorted octahedral coordination geometry, where the two PyBTM molecules ligated in the trans configuration. Magnetic investigation using a SQUID magnetometer revealed that χT increased with decreasing temperature from 300 K in the two complexes, indicating an efficient intramolecular ferromagnetic exchange interaction taking place between the spins on PyBTM and M with J/kB of 21.8 K and 11.8 K for [NiII(hfac)2(PyBTM)2] and [CoII(hfac)2(PyBTM)2]. The intramolecular ferromagnetic couplings in the two complexes could be explained by density functional theory calculations, and would be attributed to a nearly orthogonal relationship between the spin orbitals on PyBTM and the metal ions. These results demonstrate that pyridyl-containing triarylmethyl radicals are key building blocks for magnetic molecular materials with controllable/predictable magnetic interactions.