Tubular bimetal oxysulfide CuMgOS catalyst for rapid reduction of heavy metals and organic dyes

Tubular bimetal oxysulfide CuMgOS catalyst was prepared using a feasible method at a low process temperature of 95°C. X‐ray diffractometry, X‐ray photoelectron spectrometry, field emission‐scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence emission spectrum, and nitrogen adsorption–desorption isotherms were used for CuMgOS characterizations. The CuMgOS reduction activities were investigated through the reduction of heavy metals of Cr (VI), Pb (II) and Hg (II) solutions, and the organic dyes of rhodamine‐B (RhB), methyl orange (MO) and methylene blue (MB) solutions under dark. The results showed that the CuMgOS prepared with an appropriate N₂H₄ amount for a suitable Cu (I)/Cu (II) ratio exhibited fast reduction activity without adding any reagents, with which the 100 mL Cr (VI), Pb (II) and Hg (II) solutions of 50 ppm were 100% reduced by 20 mg CuMgOS within 4 min, 6 min and 4 min, respectively. The 100 mL RhB, MO and MB solutions of 50 ppm were 100% reduced by 10 mg CuMgOS within 4 min, 5 min and 1 min, respectively, under the existence of NaBH₄. CuMgOS displayed excellent chemical stability for the re‐use tests on heavy metal ions and organic dyes. The excellent performance is attributed to CuMgOS bimetal oxysulfide catalyst with active surface reaction centers to interact with reactants, and the carrier hopping between Cu (I) and Cu (II).     

Near-infrared broadband luminescence and energy transfer in Bi–Tm–Er co-doped lanthanum aluminosilicate glasses

The Bi–Tm–Er co-doped SiO₂–Al₂O₃–La₂O₃ (SAL) glasses, which exhibited a broadband near-infrared (NIR) emission, were investigated by the optical absorption and photoluminescence spectra. A super broadband NIR emission extending from 0.95 to 1.6 μm with a full-width at half-maximum (FWHM) of 430 nm which covered the whole O, E, S, C and L bands, was observed in Bi–Tm–Er co-doped samples under 808 nm excitation, as a result of the overlap of the Bi-related emission band (centered at 1270 nm) and the emission from Tm^{3+ 3}H₄→³F₄ transition (1450 nm) as well as Er^{3+ 4}I_13/2→⁴I_15/2 transition (1545 nm). In addition, a super broadband emission with amplitude relatively flat from 0.95 to 2.1 μm has been observed. The possible energy transfer between Bi-related centers, Tm³⁺ ions and Er³⁺ ions was proposed.     

Linear and nonlinear optical properties of a macrocyclic trichromophore bundle with parallel-aligned dipole moments

A macrocyclic trichromophore bundle 1 with parallel-aligned dipole moments has been synthesized to study the influence of aggregation and orientation of a nonlinear optical (NLO) chromophore on its optical properties. The linear and nonlinear optical properties of 1 and a single chromophore standard 2 have been studied by UV-vis absorption, fluorescence, solvatochromic spectrometry, and hyper-Rayleigh scattering (HRS). Reduced first-order hyperpolarizability beta, hypsochromic shift, enhanced solvatochromic shifts, and fluorescence quenching for individual chromophores were observed when 1 was compared with 2. Analysis of the data showed that the transition dipole moment changes only slightly when the chromophores are parallel aligned in the bundle architecture. However, the apparent hyperpolarizability of the individual chromophores decreased significantly by about 20%. The reduction in beta for the individual chromophores in 1 is largely due to the hypsochromic shift, i.e., excitation energy increase of the interband (charge-transfer) energy gap and the reduced difference between the ground-state and excited-state dipole moments. The hypsochromic shift and fluorescence quenching are consistent with exciton theory. Possible reasons for the enhanced solvatochromic shift are discussed.     

Regioselective,Unconventional Pictet–Spengler Cyclization Strategy Toward the Synthesis of Benzimidazole‐Linked Imidazoquinoxalines on a Soluble Polymer Support

A novel strategy for an unconventional Pictet–Spengler reaction has been developed for the regioselective cyclization of the imidazole ring system at the C2 position. The developed strategy was utilized to develop a diversity‐oriented parallel synthesis for bis(heterocyclic) skeletal novel analogs of benzimidazole‐linked imidazoquinoxalines on a soluble polymer support under microwave conditions. Condensation of polymer‐immobilized o‐phenylenediamines with 4‐fluoro‐3‐nitrobenzoic acid followed by nucleophilic aromatic substitution with an imidazole motif affords bis(heterocyclic) skeletal precursors for the Pictet–Spengler reaction. The unconventional Pictet–Spengler cyclization with various aldehydes was achieved regioselectively at the C2 position of the imidazole ring to furnish rare imidazole‐fused quinoxaline skeletons. During the Pictet–Spengler cyclization, aldehydes bearing electron‐donating groups afford 4,5‐dihydro‐imidazoquinoxalines, which then auto‐aromatize into benzimidazole‐linked imidazo[1,2‐a]quinoxalines. However, interestingly, aldehydes bearing electron‐withdrawing groups directly provide aromatized imidazo[1,2‐a]quinoxalines, which unexpectedly afford novel benzimidazole‐linked 4‐methoxy‐4,5‐dihydro‐imidazo[1,2‐a]quinoxalines after polymer cleavage.     

Highly selective ion probe for Al3+ based on Au(I)···Au(I) interactions in a bis-alkynyl calix[4]arene Au(I) isocyanide scaffold

A bis-alkynyl calix[4]arene Au(I) isocyanide complex has been synthesized and demonstrated to be a selective ion probe for Al(3+) based on Au(I)Au(I) interactions.     

Intramolecular nitrile oxide-alkene cycloaddition of sugar derivatives with unmasked hydroxyl group(s)

[reaction: see text] Intramolecular nitrile oxide-alkene cycloaddition (INOC) of sugar derivatives with one to four free hydroxyl group(s) is reported. The INOC reaction, using chloramine-T, in the presence of silica gel, to generate nitrile oxides from oximes, proceeded smoothly to afford five- or six-membered carbocycles in good to excellent yields. This new methodology alleviates protection/deprotection steps and makes the synthetic route shorter and more efficient.     

Selective Monolithiation of 1,1‐Dibromoferrocene Applied to the Synthesis of New Unsymmetrical 1,1‐Disubstituted Ferrocenyl Ligands

A novel convenient method for preparing unsymmetrical 1,1′‐disubstituted ferrocenyl ligands by using the readily accessible 1,1′‐dibromoferrocene as a precursor is described. The method is of interest for modifying the chelating ferrocenyl ligands in view of the growing influence of homogeneous catalysis in organic synthesis, manipulation of materials and production of high optical yield.     

The magnetic phases of NdCu2

The magnetic phase diagram of a NdCu₂ single crystal is investigated by means of specific-heat measurements and neutron diffraction as a function of temperature and external magnetic field applied along the crystallographic b-direction. In the low temperature region we observe three commensurate phases AF1, F1, and F2. Their magnetic structures all consist of ferromagnetic (bc)-planes with different stacking sequences along the a-direction comprising 5, 3 and 8 chemical unit cells, respectively. Above 2.8 T the system is in a ferromagnetically aligned state (F3). Furthermore, there is an incommensurate phase AF3 between the low temperature commensurate phases and the paramagnetic state and, in a very narrow temperature region of only 0.2 K, an intermediate phase AF2 between AF1 and AF3. The Nd-moments are oriented along the b-direction in all phases.     

Infrared properties of the ambient pressure organic superconductor (BEDT-TTF)2I3

The infrared principal axes of superconducting β-(BEDT-TTF)₂I₃ are found to be directed along the chain axis and perpendicular to the axis in the a-b plane. At low temperatures well-defined plasma edges appear in both directions. Adopting a simplified 2-D orthorhombic band structure model, effective transfer integrals are found to be $\text{ = 0.10}\text{eV}\text{and}\text{t}{}_{\mathrm{perp;}}\text{= 0.13}\text{eV}$. A cross-over from semiconductor-like optical properties at 300 K to metallic-like optical properties at 40 K is observed in both directions. This is the first such observation in any organic conductor.