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Recently, wide bandgap compound semiconductor materials have attracted much research interest owing to their great application potential. As most emerging oxide semiconductors are intrinsic n-type, it has become difficult to achieve p-type ones, limiting the development of pn junction-based devices. Copper bromide (CuBr) is a natural p-type semiconductor with a wide bandgap of approximately 3.0 eV and abundant reserves on the earth. In this work, we developed a vacuum thermal evaporation method to obtain high quality CuBr thin films. A self-powered p-CuBr/n-Si heterojunction photodetector that is highly sensitive to blue-violet wavelengths was constructed by preferential growth of CuBr thin films on n-Si substrates. The device has a significant response to 420 nm light, with a peak responsivity of 21.6 mA W−1 at 0 V (up to 271.5 mA W−1 at −0.5 V). Moreover, the photodetector exhibits excellent imaging ability under violet (420 nm) light. This work provides an effective approach to obtain high-quality wide bandgap CuBr films and self-powered heterojunction photodetectors. [ABSTRACT FROM AUTHOR]

The p-CuI/n-SrTiO3 heterojunction photodetector (PD) is constructed based on a SrTiO3 wafer, which is covered with a CuI film via the vacuum thermal evaporation method. Compared with the SrTiO3 (STO) device, the CuI/STO PD exhibits significantly enhanced photocurrent. Furthermore, the CuI/STO PD presents excellent self-powered characteristics, including high on/off ratio (7 × 103) and fast response speed (0.6/3.3 ms) under 400 nm light irradiation. In particular, the CuI/STO PD shows a great narrowband photoresponse (FWHM ∼ 27 nm) at zero bias because of the proper and compatible bandgap of CuI and STO. More importantly, the CuI/STO device demonstrates a transparency of 70% over the entire visible light region and blocks 99.9% UV light (200–385 nm). This work provides an effective strategy to realize power-free, filter-free and UV-free PDs for many special applications. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) metal–organic framework containing Li-oxygen clusters, namely {[Li2(IPA)]·DMF}n (1) (H2IPA = isophthalic acid), has been constructed under solvothermal conditions. The Li-based MOF can be applied to lithium energy storage. For example, it shows good compatibility with a PEO (LiTFSI) solid-state polymer electrolyte (SSPE). The PEO (LiTFSI) with the MOF additive shows an ionic conductivity of 1.1 × 10−5 S cm−1 at room temperature. The 1D rhombic channels should facilitate lithium ion transportation and provide fast lithium ion pathway. Having assembled the PEO-MOF SSPE in a Li/Li symmetric cell and cycled at a current density of 0.1 mA cm−2, the polarization voltage was below 0.1 V during a 100 h test. The PEO-MOF SSPE was also used in a LiFePO4-Li full cell and a high specific capacity of 144 mA h g−1 was achieved. [ABSTRACT FROM AUTHOR]

We present X-ray-excitable organic ultralong room temperature phosphorescence (X-OURTP) for afterglow scintillators through implanting lone-pair electron involved n–π* transitions and efficient charge transfer characters into H-aggregations of organic crystals. The thus designed X-OURTP molecule exhibits ultralong lifetimes up to 790 ms, high phosphorescence quantum yields of ∼8%, and excellent scintillation stability. These findings will pave the way to the design of organic afterglow scintillators, simulating extensive investigations on the extraordinary X-OURTP. [ABSTRACT FROM AUTHOR]

By replacing Lewis acids with Brønsted acids as catalysts, continuous flow synthesis of hypercrosslinked polymers is achieved within 10% of the time required for a typical batch reaction. Compared with batch-synthesised polymers, the flow-produced materials take up 24% more CO2, precluding the need for lengthy reaction protocols to yield high-performance hypercrosslinked polymers for carbon capture. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate the characteristic blue luminescence of carbon quantum dots embedded in the Ca19Mg2(PO4)14 nanocrystalline phosphor and carbon quantum dot-sensitized luminescence of Ca19Mg2(PO4)14:Ln3+ (Ln3+ = Eu3+ and/or Tb3+) nanocrystalline phosphors with abundant colors. A series of Ca19Mg2(PO4)14 and Ca19Mg2(PO4)14:Ln3+ (Ln3+ = Eu3+ and/or Tb3+) nanocrystalline phosphors was prepared via a Pechini-type sol–gel process. With UV light excitation, the prepared Ca19Mg2(PO4)14 nanocrystalline phosphors exhibited novel blue luminescence with a broad band from 374 to 600 nm peaking at 439 nm, which is ascribed to the embedded carbon quantum dots. Also, the obtained Ca19Mg2(PO4)14:Ln3+ (Ln3+ = Eu3+ and/or Tb3+) nanocrystalline phosphors not only exhibited the characteristic broad band emission of the carbon quantum dots, but also the characteristic narrow line emission of the doped rare earth ions, i.e., the characteristic red emission of Eu3+ (5DJ→7FJ′ transitions, J, J′ = 0, 1, 2, 3) and the characteristic green emission of Tb3+ (5D4→7FJ transitions, J = 3, 4, 5, 6). Thus, energy transfer occurred from the carbon quantum dots to the doped Eu3+ and/or Tb3+ ions in the Ca19Mg2(PO4)14:Ln3+ (Ln3+ = Eu3+ and/or Tb3+) nanocrystalline phosphors. The luminescence color of the Ca19Mg2(PO4)14:Ln3+ (Ln3+ = Eu3+ and/or Tb3+) nanocrystalline phosphors could be tuned from blue to blue-green, green, white, pink, orange, red, etc. by changing the doping rare-earth ion concentration, species, and relative ratio of Eu3+ to Tb3+ ions. Furthermore, single-phase white-light luminescence was demonstrated in the Eu3+/Tb3+ codoped Ca19Mg2(PO4)14:Ln3+ nanocrystalline phosphors. Finally, the luminescence properties and mechanisms of the Ca19Mg2(PO4)14 and Ca19Mg2(PO4)14:Ln3+ (Ln3+ = Eu3+ and/or Tb3+) nanocrystalline phosphors were discussed. [ABSTRACT FROM AUTHOR]

A series of lanthanide-based metal–organic frameworks (Ln-MOFs) with significantly improved and tunable upconversion emissions were prepared. Y-MOFs co-doped with Yb3+/Er3+ ions have exhibited characteristic upconversion emissions at 520, 545, and 658 nm under 980 nm laser excitation, the intensities of which vary with Yb3+/Er3+ concentrations. In addition, experimental results have indicated that an excited state absorption mechanism is responsible for the upconversion process of Y-MOF:Yb/Er materials. This study has provided a novel design principle and experimental basis for the preparation of luminescent Ln-MOF materials. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) with thin film composite (TFC) membranes containing a thin selective layer on top of a porous substrate is key to lowering the energy costs of high-speed chemical separations. Conventional TFC membranes were often built on phase inversion induced asymmetrical substrates with high tortuosity that impedes rapid solvent transport. Nanofibers as ultrapermeable substrates have enhanced water transport in forward osmosis, nanofiltration and other aqueous separations. However, problems of solvent stability under harsh operating conditions prevent their exploitation in non-aqueous molecular separations. Here we show that by combining a simple solution-phase cross-linking process and electrospinning, the instability of nanofibrous polyacrylonitrile (PAN) in industrially important polar solvents can be overcome and harnessed to benefit the purification of polar solvents containing low molecular weight solutes. The low tortuosity of electrospun PAN nanofibrous substrates is key to uniform cross-linking, and hence they are more stable and mechanically stronger than cross-linked PAN asymmetrical substrates fabricated by the traditional approach of phase inversion. The low resistance offered by cross-linked nanofibrous substrates increased solvent permeation without sacrificing selectivity, for example, to 99.5% rejection of negatively charged Sudan 4 (MW: 380 Da) dye with a methanol permeance of 9.87 L m−2 h−1 bar−1 and water permeance of 22.40 L m−2 h−1 bar−1. The enhanced stability of TFC membranes in polar aprotic solvents such as dimethylsulfoxide highlights their potential application for molecular separations in pharmaceutical and chemical industries. [ABSTRACT FROM AUTHOR]

Adopting a mixed ligand strategy, a novel fluorescent chain-based 3D metal–organic framework, [Zn(BPTC)0.5(Tz)]·DMF·CH3OH (1), has been synthesized by the solvothermal method. The obtained hybrid has two kinds of 1D channel, one of which is surrounded by the uncoordinated nitrogens of Tz ligands. Owing to the well-isolated feature of tetrazole moieties within the framework, compound 1 is greatly armed with accessible recognition sites, which exhibits a turn-off luminescence sensing for Cu2+ ions. Besides, thanks to the mono-dentate oxygen atom of the carboxylic group, compound 1 could absorb a similar number of Ln3+ ions and manifests selective sensitization of different Ln3+ ions. [ABSTRACT FROM AUTHOR]

A new family of BODIPY dyes (PPB1–4) based on the pyridine–pyrimidine hybrid structure has been synthesized. These dyes show high cyan fluorescence in hexane with quantum yields (Φf) ranging from 0.33 to 0.90. Interestingly, moderate fluorescence of PPB1–4 is observed in the solid state (Φf, 0.11–0.26). X-ray structure analysis demonstrates that H-aggregation should be responsible for the red-shifted and quenched emission in the solid state. Moreover, PPB1–4 show high contrast and reversible mechanochromic fluorescence based on the proposed mechanism of mechanical stimuli triggered dimer dissolution and formation. In addition, rewritable mechanochromic fluorescence recording media fabricated with PPB4 have been successfully achieved. [ABSTRACT FROM AUTHOR]

By means of a mixed-ligand strategy, a novel bi-functional metal–organic framework, [H2N(CH3)2]·Zn(NDC)(atz)·H2O (NDC = 2,6-naphthalenedicarboxylic acid, Hatz = 1H-tetrazol-5-amine), was synthesized, which displays a three-dimensional two-fold interpenetrated framework. Owing to the introduction of two different functional organic ligands, this complex exhibits bi-functional properties, i.e., selective gas adsorption of CO2 over CH4 and fluorescence sensing response for nitrobenzene. [ABSTRACT FROM AUTHOR]

In this paper, we propose and demonstrate a study of Fe plasma using collinear dual-wavelength femtosecond double-pulse laser-induced breakdown spectroscopy (LIBS) with a fundamental wavelength (800 nm) and a second harmonic wavelength (400 nm) from Ti:sapphire laser. By varying the time separation of the dual-wavelength femtosecond double-pulse, the experimental results clearly show the signal enhancement up to a factor of 10 and more than 10 times, in comparison with it at 0 ps time separation. The electron temperature and electron density are analyzed as the basic parameters of plasma properties, and they are respectively based on the theory of Boltzmann plot and Stark broadening. It proves that dual-wavelength femtosecond double-pulse LIBS is excellent for enhancing the emission intensity of the signal. [ABSTRACT FROM AUTHOR]

A new luminescent lanthanide metal–organic framework was synthesized under hydrothermal conditions by introducing the tetracarboxylic acid ligand (H4bptc) as a chromophore to sensitize the luminescence of the Tb3+ ion. Interestingly, despite the achiral nature of H4bptc, the resulting framework exhibited rare chiral helical channels. The luminescence studies revealed that this material showed a highly selective fluorescence quenching response to Fe3+ ions in liquid suspension, which can be conveniently observed by the naked eye under UV light. Thus, this material can be potentially used as a chemosensor for sensing Fe3+ ions and its selective luminescence quenching response can be explained in terms of the competitive absorption mechanism. [ABSTRACT FROM AUTHOR]

A 3D metal–organic framework, [NH2(CH3)2]2[Cd17(L)12(μ3-H2O)4(DMF)2(H2O)2]·solvent (1), has been constructed with a π-electron rich aromatic ligand 2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene (H3L) and d10 configuration metal ion Cd2+ under solvothermal conditions. The crystal structure reveals that complex 1 consists of hexanuclear and trinuclear cadmium building units, which are further bridged by the multicarboxylate ligands to give a (3, 6, 12)-connected topological net. This complex exhibits strong ligand originated photoluminescence emission, which is selectively sensitive to electron-deficient nitroaromatic explosives (nitrobenzene, 4-nitrotoluene, 1,4-dinitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene). This property makes complex 1 a potential fluorescence sensor for these chemicals. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) heterometallic metal–organic framework containing cubic-like cages, namely {[Co3Na6(TzDC)4(H2O)6]·7H2O}n (1) (H3TzDC = 1,2,3-triazole-4,5-dicarboxylate), has been synthesized by the edge-directed self-assembly of TzDC3−, Co2+ and Na+ ions. Crystal data reveals that one hydrous Co2+ cation is embedded in the central cavity of a cubic-like cage [Co8(TzDC)12]20− with eight Co2+ cations as the corners and twelve TzDC3− ligands as the edges. The cages are further bridged by Na+ ions to result in a 3D framework with pcu topology. Magnetic investigation indicates that besides the spin–orbit coupling of Co2+ ions, an antiferromagnetic exchange interaction was found to exist between the Co2+ ions in the Co9 cluster of 1. [ABSTRACT FROM AUTHOR]

Five new metal complexes based on H4bptc: {[Cu2(bptc)(H2O)6]·11H2O}n(1), {[Ni2(bptc)(H2O)6]·11H2O}n(2), {[Co2(H2bptc)2(4,4′-bpy)2(H2O)2]·4H2O}n(3), [Ni2(bptc)(2,2′-bpy)2(H2O)6]·2H2O (4), [Zn2(bptc)(2,2′-bpy)2(H2O)6]·3H2O (5) (bptc = biphenyl-2,5,2′,5′-tetracarboxylic acid, 2,2′-bpy = 2,2′-bipyridine, 4,4′-bpy = 4,4′-bipyridine) have been synthesized and structurally characterized by elemental analysis, IR spectra, powder X-ray diffraction, thermogravimetric analysis and X-ray crystallography. Complex 1features a 2D sheet structure with (4, 4) grid units. The Cu(ii) center in 1is penta-coordinated in a square-pyramidal geometry. Complex 2is isostructural with 1excluding the metal ions. Complex 3shows a 2D layer structure with rectangular windows. There exist parallel left- and right-handed helical chains in adjacent 2D sheets in complexes 1–3. Complex 4exhibits a 3D supramolecular structure with a butterfly-shaped unit cell. Complexes 5and 4are isomers excluding the lattice water molecules. The non-covalent interactions (O–HO, C–HO, C–Hπ and ππ interactions) extend complexes 1–5into 3D supramolecular networks. In addition, the photoluminescent properties for 1–5and magnetic properties for 1, 3have been investigated, respectively. Complexes 1and 3exhibit weak antiferromagnetic behaviour. [ABSTRACT FROM AUTHOR]

A series of lanthanide-based metal-organic frameworks (Ln-MOFs) with significantly improved and tunable upconversion emissions were prepared. Y-MOFs co-doped with Yb3+/Er3+ ions have exhibited characteristic upconversion emissions at 520, 545, and 658 nm under 980 nm laser excitation, the intensities of which vary with Yb3+/Er3+ concentrations. In addition, experimental results have indicated that an excited state absorption mechanism is responsible for the upconversion process of Y-MOF:Yb/Er materials. This study has provided a novel design principle and experimental basis for the preparation of luminescent Ln-MOF materials.

A new family of BODIPY dyes (PPB1-4) based on the pyridine-pyrimidine hybrid structure has been synthesized. These dyes show high cyan fluorescence in hexane with quantum yields (Φ f ) ranging from 0.33 to 0.90. Interestingly, moderate fluorescence of PPB1-4 is observed in the solid state (Φ f , 0.11-0.26). X-ray structure analysis demonstrates that H-aggregation should be responsible for the red-shifted and quenched emission in the solid state. Moreover, PPB1-4 show high contrast and reversible mechanochromic fluorescence based on the proposed mechanism of mechanical stimuli triggered dimer dissolution and formation. In addition, rewritable mechanochromic fluorescence recording media fabricated with PPB4 have been successfully achieved.

By means of a mixed-ligand strategy, a novel bi-functional metal-organic framework, [H 2 N(CH 3 ) 2 ]·Zn(NDC)(atz)·H 2 O (NDC = 2,6-naphthalenedicarboxylic acid, Hatz = 1H-tetrazol-5-amine), was synthesized, which displays a three-dimensional two-fold interpenetrated framework. Owing to the introduction of two different functional organic ligands, this complex exhibits bi-functional properties, i.e., selective gas adsorption of CO 2 over CH 4 and fluorescence sensing response for nitrobenzene.