Liquid-liquid extraction separation of uranium(VI) from associated elements using dibenzo-24-crown-8 from hydrobromic acid medium

Liquid-liquid extraction of uranium (VI) from hydrobromic acid solutions with dibenzo-24-crown-8 in nitrobenzene have been investigated. Uranium(VI) was quantitatively extracted from 6.0–8.0M hydrobromic acid with 0.001–0.01M dibenzo-24-crown-8 and was quantitatively stripped from the organic phase with 0.1–1.0M hydrochloric acid, 0.5–10M nitric acid, 2–10M perchloric acid, 3.0–10M sulfuric acid or 3.0–10M acetic acid. It was possible to separate uranium(VI) from a number of elements in binary mixtures. Most of the elements showed very high tolerance limit Uranium(VI) was also separated from a number of associated elements in multicomponent mixtures. The method is very simple, selective, rapid and highly reproducible (approximately±2%) and was applied to the analysis of uranium in geological samples.     

ZnO-beta zeolite:As an effective and eco-friendly heterogeneous catalyst for the synthesis of benzothiazole derivatives

<正>A cheap and recyclable ZnO-beta zeolite was used as catalyst for the synthesis of benzothiazole derivatives.This method provides several advantages such as environmental friendliness,short reaction times,high yields,simple work-up procedure and catalyst was successfully reused for four cycles without significant loss of activity.     

Long periodic ripple in a 2D hybrid halide perovskite structure using branched organic spacers

Two-dimensional (2D) halide perovskites have great promise in optoelectronic devices because of their stability and optical tunability, but the subtle effects on the inorganic layer when modifying the organic spacer remain unclear. Here, we introduce two homologous series of Ruddlesden–Popper (RP) structures using the branched isobutylammonium (IBA) and isoamylammonium (IAA) cations with the general formula (RA)₂(MA)_n−1Pb_nI_3n+1 (RA = IBA, IAA; MA = methylammonium n = 1–4). Surprisingly, the IAA n = 2 member results in the first modulated 2D perovskite structure with a ripple with a periodicity of 50.6 Å occurring in the inorganic slab diagonally to the [101] direction of the basic unit cell. This leads to an increase of Pb–I–Pb angles along the direction of the wave. Generally, both series show larger in-plane bond angles resulting from the additional bulkiness of the spacers compensating for the MA''s small size. Larger bond angles have been shown to decrease the bandgap which is seen here with the bulkier IBA leading to both larger in-plane angles and lower bandgaps except for n = 2, in which the modulated structure has a lower bandgap because of its larger Pb–I–Pb angles. Photo-response was tested for the n = 4 compounds and confirmed, signaling their potential use in solar cell devices. We made films using an MACl additive which showed good crystallinity and preferred orientation according to grazing-incidence wide-angle scattering (GIWAXS). As exemplar, the two n = 4 samples were employed in devices with champion efficiencies of 8.22% and 7.32% for IBA and IAA, respectively.

Using branched spacer cations results in a modulated rippled 2D perovskite structure and materials for solar cells.     

Heavy Metal Stress and Its Consequences on Exopolysaccharide (EPS)-Producing <Emphasis Type="Italic">Pantoea agglomerans</Emphasis>

Currently, the heavy metal pollution is of grave concern, and the part of microorganism for metal bioremediation should take into account as an efficient and economic strategy. On this framework, the heavy metal stress consequences on exopolysaccharide (EPS)-producing agricultural isolate, Pantoea agglomerans, were studied. The EPS production is a protective response to stress to survive and grow in the metal-contaminated environment. P. agglomerans show tolerance and mucoid growth in the presence of heavy metals, i.e., mercury, copper, silver, arsenic, lead, chromium, and cadmium. EDX first confirmed the metal accumulation and further, FTIR determined the functional groups involved in metal binding. The ICP-AES identified the location of cell-bound and intracellular metal accumulation. Metal deposition on cell surface has released more Ca²⁺. The effect on bacterial morphology investigated with SEM and TEM revealed the sites of metal accumulation, as well as possible structural changes. Each heavy metal caused distinct change and accumulated on cell-bound EPS with some intracellular deposits. The metal stress caused a decrease in total protein content and increased in total carbohydrate with a boost in EPS. Thus, the performance of P. agglomerans under metal stress indicated a potential candidate for metal bioremediation.

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Synthesis and characterization of silicon-containing phenylated soluble aramids

New high molecular weight (inherent viscosities, 1.21–0.50 dL/g) aramids having silicon and pendant phenyl groups were synthesized by low temperature interfacial polycondensation technique involving the reaction of acid chlorides: bis(4-chlorocarbonylphenyl)dimethylsilane and bis(3-chlorocarbonylphenyl)dimethylsilane with diamines: 2,5-bis(4-aminophenyl)-3,4-diphenyl-thiophene and bis(4-aminophenyl)ether. Copolyamides were obtained by using different proportions of these diamines. All the polymers were completely soluble in organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and N,N-dimethylformamide. Thermal properties were evaluated by thermogravimetry which showed no weight loss below 325°C in both air and nitrogen atmospheres.     

Synthesis and Transition Metal Complexes of ((Phenylphosphanediyl) bis(ethyne-2,1-diyl))bis(diphenyl-phosphane), [PhP{C≡CPPh2}2]

This paper describes the synthesis of a new acetylene-bridged triphosphine, ((phenylphosphanediyl)bis-(ethyne-2,1-diyl))bis(diphenylphosphane) [PhP{C≡CPPh₂}₂] ( 2 ) and its coordination complexes of Ru^II, Rh^III, Cu^I, Pd^II and Pt^II. The reaction of diethynylphenylphosphine [PhP{C≡CH}₂] ( 1 ) with two equivalents of LiHMDS followed by the addition of PPh₂Cl resulted in 2 . Treatment of 2 with [Ru(η⁶-p-cymene)Cl₂]₂ and [RhCp*Cl₂]₂ in 1 : 1.5 molar ratios produced trinuclear complexes [{Ru(η⁶-p-cymene)Cl₂}₃{μ₃-PPh(C≡CPPh₂)₂}] ( 3 ) and [(RhCp*Cl₂)₃{μ₃-PPh(C≡CPPh₂)₂}] ( 4 ). The molecular structure of 3 was confirmed by single crystal X-ray analysis. Treatment of 2 with M(COD)Cl₂ (M=Pd, Pt) in 2 : 3 ratio afforded open book type complexes [(MCl₂)₃{μ₃-PPh(C≡CPPh₂)}₂] ( 5 M=Pd, 6 M=Pt). The reaction of 2 with CuI in 1 : 2 ratio afforded 1-D coordination polymer [{Cu₂(μ₂-I)₂(CH₃CN)}{PPh(C≡CPPh₂)₂}₃{CuI}₂] ( 7 ) containing [(CuI)₂{μ₂-(P−C≡C−P)₃}] cylindrical units.