Search

Sm2Fe17N3 powders have drawn much attention in both fundamental research and industrial applications due to their excellent magnetic properties. The magnetic properties of Sm2Fe17N3 powders mainly depend on the composition and microstructure. Herein, the intrinsic and extrinsic magnetic properties of Sm2Fe17N3 powders are introduced, where the correlation between the composition, microstructure, and magnetic properties is discussed. Based on the correlation, we provide a detailed description of the synthesis methods and regulation strategies for Sm2Fe17N3 powders, aiming to promote the design and preparation of Sm2Fe17N3 powders with better magnetic properties. [ABSTRACT FROM AUTHOR]

While controlling the wheel shuttling of prototype [2]rotaxanes has been readily achieved, which promotes the development of intelligent supramolecular systems and materials, it remains a grand challenge to access higher ordered rotaxane systems with precisely controllable relative motion between component parts. Herein, a unique tristable [3]rotaxane was synthesized by threading two cyclobis(paraquat-p-phenylene) (CBPQT4+) macrocycles with a dumbbell component, which contained three recognition sites, including a photoactive azobenzene (AB) unit and a redox active tetrathiofulvalene (TTF) unit separated by a dioxynaphthalene (DNP) unit. Upon UV (365 nm)/yellow (> 525 nm) light irradiation, the Z/E photoisomerization of the AB unit could be triggered to drive the CBPQT4+ wheel (A) to shuttle between the AB and DNP units, with the CBPQT4+ wheel (B) maintained on the TTF unit. Furthermore, regulating the redox states of the TTF unit without light irradiation can induce the CBPQT4+ wheel (B) to shuttle between the TTF and DNP units. The construction of this unique orthogonal photo and redox stimuli-responsive [3]rotaxane is conducive to the development of higher ordered rotaxane-based molecular systems with controllable sophisticated properties and functions. [ABSTRACT FROM AUTHOR]

Ferromagnetic order in two-dimensional (2D) van der Waals crystals has been attracting much attention recently. Remarkably, room temperature metallic ferromagnetism is realized in 2D Fe3GeTe2. Here we design a monolayer (ML) Fe3GeTe2 spin-valve device by attaching two ends to ferromagnetic electrodes and applying a magnetic field to these ferromagnetic electrodes. We investigate the spin-involved transport characteristics of such a spin valve by using ab initio quantum transport simulation. A high magnetoresistance of ∼390% is obtained and significantly increased to 450–510% after the gates are introduced. The magnetoresistance of the ML Fe3GeTe2 spin valve is insensitive to the strain modulation. Our study provides a potential option for magnetic storage applications and will motivate further studies in spintronics based on this class of materials. [ABSTRACT FROM AUTHOR]

Photochromic [2]rotaxanes with bidirectional photoswitchability were fabricated, whose colored states exhibit remarkable visible-light and thermal stabilities as revealed by systematically spectroscopic investigations. [ABSTRACT FROM AUTHOR]

We herein report the construction of a new heteropore COF which consists of two different kinds of micropores with unprecedented shapes. It exists as hollow microspheres and exhibits an extremely high volatile iodine uptake (up to 481 wt%) by encapsulating iodine in the inner cavities and porous shells of the microspheres. [ABSTRACT FROM AUTHOR]

A model system has been established to construct two-dimensional (2D) covalent organic frameworks (COFs) by taking advantage of the variable orientation of imine bonds. During the assembly process, the imine bonds adopt an unprecedented heterodromous orientation to facilitate the formation of the COFs. [ABSTRACT FROM AUTHOR]

Light-triggered photoisomerization of the azobenzene (AB) unit in bistable [2]rotaxanes can cause the shuttling of the macrocycle on the dumbbell, resulting in distinctive dual spectral variation characteristics: (1) the spectral change of the photochromic unit and (2) the variation of the charge-transfer band. By employing the CT bond region as an output signal, non-destructive readout of optical information could be achieved. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) supramolecular organic framework (SOF) has been constructed through the co-assembly of a triphenylamine-based building block and cucurbit[8]uril (CB[8]). Fluorescence turn-on of the non-emissive building block was observed upon the formation of the 2D SOF, which displayed highly selective and sensitive recognition of picric acid over a variety of nitroaromatics. [ABSTRACT FROM AUTHOR]

Two new types of supramolecular polymers have been constructed via the self-assembly of rigid rod-like monomers and cucurbit[8]uril (CB[8]) in water. These supramolecular polymers possessed rigid backbones and further aggregated into stick-like bunched fibres. [ABSTRACT FROM AUTHOR]

A series of oligo(quinoxalineethylene)s which exhibit n-type semi-conducting features were synthesized, and adding Ag+to their solutions induced the backbones to adopt coplanar conformations due to Ag+–N coordination. [ABSTRACT FROM AUTHOR]

Novel double perovskite SrLaLiTeO 6 (abbreviated as SLLT):Mn 4+ ,Dy 3+ phosphors synthesized using a solid-state reaction strategy exhibit distinct dual-emission of Mn 4+ and Dy 3+ . High-sensitivity and wide-temperature-range dual-mode optical thermometry was exploited taking advantage of the diverse thermal quenching between Mn 4+ and Dy 3+ and the decay lifetime of Mn 4+ . The thermometric properties in the range of 298-673 K were investigated by utilizing the fluorescence intensity ratio (FIR) of Dy 3+ ( 4 F 9/2 → 6 H 13/2 )/Mn 4+ ( 2 E g → 4 A 2g ) and the Mn 4+ ( 2 E g → 4 A 2g ) lifetime under 351 nm and 453 nm excitation, respectively. The maximum relative sensitivities (S R ) of the resultant SLLT:1.2%Mn 4+ ,7%Dy 3+ phosphor under 351 nm and 453 nm excitation employing the FIR technology were determined to be 1.60% K -1 at 673 K and 1.44% K -1 at 673 K, respectively. Additionally, the maximum S R values based on the lifetime-mode were 1.59% K -1 at 673 K and 2.18% K -1 at 673 K, respectively. It is noteworthy that the S R values can be manipulated by different excitation wavelengths and multi-modal optical thermometry. These results suggest that the SLLT:Mn 4+ ,Dy 3+ phosphor has prospective potential in optical thermometry and provide conducive guidance for designing high-sensitivity multi-modal optical thermometers.

Developing new photoswitchable noncovalent interaction motifs with controllable bonding affinity is crucial for the construction of photoresponsive supramolecular systems and materials. Here we describe a unique "photolocking" strategy for realizing photoswitchable control of quadruple hydrogen-bonding interactions on the basis of modifying the ureidopyrimidinone (UPy) module with an ortho -ester substituted azobenzene unit as the "photo-lock". Upon light irradiation, the obtained Azo-UPy motif is capable of unlocking/locking the partial H-bonding sites of the UPy unit, leading to photoswitching between homo- and heteroquadruple hydrogen-bonded dimers, which has been further applied for the fabrication of novel tunable hydrogen bonded supramolecular systems. This "photolocking" strategy appears to be broadly applicable in the rational design and construction of other H-bonding motifs with sufficiently photoswitchable noncovalent interactions., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Ferromagnetic order in two-dimensional (2D) van der Waals crystals has been attracting much attention recently. Remarkably, room temperature metallic ferromagnetism is realized in 2D Fe3GeTe2. Here we design a monolayer (ML) Fe3GeTe2 spin-valve device by attaching two ends to ferromagnetic electrodes and applying a magnetic field to these ferromagnetic electrodes. We investigate the spin-involved transport characteristics of such a spin valve by using ab initio quantum transport simulation. A high magnetoresistance of ∼390% is obtained and significantly increased to 450-510% after the gates are introduced. The magnetoresistance of the ML Fe3GeTe2 spin valve is insensitive to the strain modulation. Our study provides a potential option for magnetic storage applications and will motivate further studies in spintronics based on this class of materials.

Linear tetrathiafulvalene (TTF) oligomers were synthesized, which could not only form a pleated TTF˙ + radical cation foldamer under oxidation conditions, but also interlocked with CBPQT 4+ to form folded donor-acceptor [3]pseudorotaxane in the neutral state of TTF. Moreover, switchable transformation between these two folded supramolecular structures was achieved under the alternative regulation of the redox states of TTF units.

Two new types of supramolecular polymers have been constructed via the self-assembly of rigid rod-like monomers and cucurbit[8]uril (CB[8]) in water. These supramolecular polymers possessed rigid backbones and further aggregated into stick-like bunched fibres.

A series of 1,4-disubstituted ruthenium-vinyl complexes, (E,E)-[{(PMe3)3(CO)ClRu}2(μ-HC=CH-Ar-CH=CH)], in which the 1,4-diethenylphenylene bridge bears two oligo(ethylene glycol)methyl ether side chains at different positions (2,5- and 2,3-positions), were prepared. The respective products were characterized by elemental analyses and NMR spectroscopy. The structures of complexes 1b and 1e were established by X-ray crystallography. The electronic properties of the complexes were investigated by cyclic voltammetry, and IR and UV-vis/NIR spectroscopies. Electrochemical studies showed that the 2,5-substituents better stabilized the mixed-valence states; the electrochemical behavior was greatly affected by lithium cations, especially complex 1g with 2,3-substituents, which was further supported by IR and UV-vis/NIR spectra changes. Spectroelectrochemical studies showed that the redox chemistry was dominated by the non-innocent character of the bridging fragment.

A series of oligo(quinoxalineethylene)s which exhibit n-type semi-conducting features were synthesized, and adding Ag(+) to their solutions induced the backbones to adopt coplanar conformations due to Ag(+)-N coordination.