The S2 emission characteristics of several organic sulfur compounds obtained by molecular emission cavity analysis and pyrolysis

Emission profiles of several organic sulfur compounds are investigated by modified molecular emission cavity analysis (MECA). Thiourea, 1,3-diethylthiourea, S-methyl- cysteine and taurine are pyrolyzed in a hydrogen stream and the pyrolytic products are determined by gas chromatography. The S₂ emission mechanism is discussed on the basis of emission profiles and the composition of the pyrolytic products. Although some compounds give multipeaked responses, the splitting disappears when a worn surface cavity is used or oxalic acid is added to the sulfur compound in the cavity. When the emission profile from thiourea is compared with that from 1,3-diethylthiourea, it is clear that the multipeaked response is due to quenching by degradation products of the latter compound. The main product of pyrolysis is hydrogen sulfide. The emission intensity is related to the yield of hydrogen sulfide in pyrolysis. As methylmercaptan was not detected in the pyrolysis products, it is suggested that the quenching by the organic fragments results from their hydrogen consumption rather than their reaction with sulfur species. The S₂ emission from sulfur-containing compounds is rapidly complete in the presence of oxalic acid, and it is suggested that such compounds are subject to reductive breakdown in the cavity.     

The Thin-Layer Chromatographic Separation of Halogenated Fumigants as Ammonium Halides and Their Subsequent Determination by Meca

Abstract

A method is described for the determination of several pesticides containing bromine and chlorine by molecular emission cavity analysis (MECA). The pesticides were decomposed in an oxygen flask and the combustion products dissolved in aqueous ammonia. The ammonium halides were separated by TLC using microcrystalline cellulose adsorbent. After scraping from the TLC plates and dissolving in water the separated components were quantitated by MECA using either the InBr (Λ_max = 376 nm) or the InCl (Λ_max = 360 nm) emission bands. Recoveries of over 96% were obtained. Soils fortified with l, 2-dibromo-3-chloropropane at levels of 5–25 ppm were extracted using shaking and distillation procedures. Subsequent analysis showed that the shaking extraction gave a recovery of 92% compared to 85% from acid refluxing.     

Molecular emission cavity analysis : Part XI. The determination of carbonyl compounds

Formaldehyde (2–750 μg), acetaldehyde (0.05–1.0 μg) and acetone (0.4–3.5 smg) can be determined in aqueous solution (? 17.5 ml) by MECA. Sodium sulphite solution (5 ml, 500 p.p.m. S) and 1.5 ml of l M phosphoric acid are added and the delayed S₂ emission from the sulphite addition compound in 5 ml of the solution is measured in a MECA cavity; a hydrogen-nitrogen flame is used. Mixtures of formaldehyde and acetone can be determined simultaneously on the basis of the resolved MECA peaks of their sulphite addition compounds, after evaporation of the excess of sulphite from the cavity.     

Molecular emission cavity analysis : Part VII. The determination of cadmium

Cadmium salts give an intense cadmium atomic emission in the MECA cavity in a hydrogen-nitrogen-air flame. When a carbon or stainless steel cavity is used, 10–120 ng of cadmium in 5-μl samples can be determined. In the presence of sulphuric acid, anionic interferences are removed. Of the cations, only Fe(III), Cr(III), Mg and Sn(II) interfere seriously.     

The magnetic polaron modulated luminescence bands of organic-inorganic hybrid ferroelectric anti-perovskite (C3H9N)3Cd2Cl7 doped with Mn2+

Recently, the excellent optical properties of organic-inorganic hybrid metal halides have attracted much attention in the optoelectronic field. However, their complicated preparation processes seriously influence their properties and applications. In this work, we developed a series of organic-inorganic hybrid metal halides (C₃H₉N)₃Cd₂Cl₇:x%Mn²⁺ with an antiperovskite structure with ferroelectrics in an early report, giving tunable emissions contemporarily with different manganese (Mn)²⁺ concentrations via a simple mechanochemical method. Meanwhile, their single crystals were also grown by a slow thermal evaporation method. The as-grown products with Mn dopants exhibited diluted magnetic semiconductor behavior and varied emission profiles by different excitation wavelengths, which could be modified by the heat treatment. All the emission bands come from the different magnetic polarons with enhanced electron-phonon coupling or self-trapped exciton formation. Ferromagnetic coupling Mn–Mn pairs or clusters in the doped lattice favor the magnetic polaron and red emission at room temperature and even give much stronger emission above room temperature. The excitonic magnetic polaron and local excitonic magnetic polaron were detected at about 309 nm and 398 nm, respectively, with Mn doping. Without Mn²⁺ dopant, the weak emission band at about 398 nm can also be detected from an intrinsically bound exciton or confined exciton from the amine incorporated metal chlorides. This Mn-doped anti-perovskite Cd halides may find applications in the solid display and lighting, as well as the magneto-optical devices.     

Molecular emission cavity analysis : Part 12. Evaluation for gas chromatographic detection

Molecular emission cavity analysis (MECA) is shown to be useful for selective detection of sulphur or phosphorus compounds at the nanogram level in g.l.c. effluents. Introduction of a small oxygen flow into the cavity allows many other elements (e.g. Si, As, Sb, N, C) to be detected. The detection of microgram amounts of silylated amino acids is possible by measuring their SiO emission in the cavity at 580 nm.     

The Determination of Organochlorine Pesticides in Sediment by Molecular Emission Cavity Analysis

Abstract

A rapid and convenient method is described for measuring the total organic chlorine content of sedimentary material fortified with organochlorine pesticides. The pesticides are extracted from the sediment, chlorine is then liberated as hydrogen chloride in a Schöniger flask, and the resulting aqueous solution is injected into an indium-lined MECA (Molecular Emission Cavity Analyzer) cavity. The MECA response to the InCl emission is used to determine the amount of halogen present. The study has included sediment samples spiked with between 5 and 25 ppm of p,p′-DDT, γ-BHC, and heptachlor, when the percentage recovery in each case is estimated to be greater than 95% with a similar value recorded for a mixture of all three insecticides.     

Doped Zero-Dimensional Cesium Zinc Halides for High-Efficiency Blue Light Emission

All-inorganic zero-dimensional (0D) metal halides have recently received increasing attention due to their excellent photoluminescence (PL) performance and high stability. Herein, we present the successful doping of copper(I) into 0D Cs₂ZnBr₄. The incorporating of Cu⁺ cations enables the originally weakly luminescent Cs₂ZnBr₄ to exhibit an efficient blue emission centered at around 465 nm, with a high photoluminescence quantum yield (PLQY) of 65.3 %. Detailed spectral characterizations, including ultrafast transient absorption (TA) techniques, were carried out to investigate the effect of Cu⁺ dopants and the origin of blue emission in Cs₂ZnBr₄:Cu. To further study the role of the A-site cation and halogen, A₂ZnCl₄:Cu (A=Cs, Rb) were also synthesized and found to generate intense sky-blue emission (PLQY≈73.1 %). This work represents an effective strategy for the development of environmentally friendly, low-cost and high-efficiency blue-emitting 0D all-inorganic metal halides.     

0D Pyramid-intercalated 2D Bimetallic Halides with Tunable Electronic Structures and Enhanced Emission under Pressure

Hybrid metal halides are emerging semiconductors as promising candidates for optoelectronics. The pursuit of hybridizing various dimensions of metal halides remains a desirable yet highly complex endeavor. By utilizing dimension engineering, a diverse array of new materials with intrinsically different electronic and optical properties has been developed. Here, we report a new family of 2D-0D hybrid bimetallic halides, (C₆N₂H₁₄)₂SbCdCl₉ ⋅ 2H₂O ( SbCd ) and (C₆N₂H₁₄)₂SbCuCl₉ ⋅ 2H₂O ( SbCu ). These compounds adopt a new layered structure, consisting of alternating 0D square pyramidal [SbCl₅] and 2D inorganic layers sandwiched by organic layers. SbCd and SbCu have optical band gaps of 3.3 and 2.3 eV, respectively. These compounds exhibit weak photoluminescence (PL) at room temperature, and the PL gradually enhances with decreasing temperature. Density functional theory (DFT) calculations reveal that SbCd and SbCu are direct gap semiconductors, where first-principles band gaps follow the experimental trend. Moreover, given the different pressure responses of 0D and 2D components, these materials exhibit highly tunable electronic structures during compression, where a remarkable 11 times enhancement in PL emission is observed for SbCd at 19 GPa. This work opens new avenues for designing new layered bimetallic halides and further manipulating their structures and optoelectronic properties via pressure.     

Catalytic Carbonylation and Carboxylation of Organosulfur Compounds via C−S Cleavage

Transition‐metal‐catalyzed carbonylation with CO gas occupies a privileged position in organic synthesis for the synthesis of carbonyl compounds. Although this attractive and useful chemistry has led many researchers to investigate carbonylative transformations of various organic (pseudo)halides, C?S‐cleaving carbonylation of organosulfur compounds has been fairly limited. Recently, a broad spectrum of C?S‐cleaving transformations has been emerging in the field of cross‐coupling. In light of the importance of carbonyl compounds as well as considerable advancement for employing organosulfur compounds as competent surrogates of (pseudo)halides, carbonylative transformations of C?S bonds should be of high value. This Minireview focuses on catalytic C?S carbonylation of organosulfur compounds with CO or its equivalents. In addition, reductive carboxylation of C?S bonds with CO₂ is described.     

Anomalous Charge Transfer from Organic Ligands to Metal Halides in Zero-Dimensional [(C6H5)4P]2SbCl5 Enabled by Pressure-Induced Lone Pair-π Interaction

Low-dimensional (low-D) organic metal halide hybrids (OMHHs) have emerged as fascinating candidates for optoelectronics due to their integrated properties from both organic and inorganic components. However, for most of low-D OMHHs, especially the zero-D (0D) compounds, the inferior electronic coupling between organic ligands and inorganic metal halides prevents efficient charge transfer at the hybrid interfaces and thus limits their further tunability of optical and electronic properties. Here, using pressure to regulate the interfacial interactions, efficient charge transfer from organic ligands to metal halides is achieved, which leads to a near-unity photoluminescence quantum yield (PLQY) at around 6.0 GPa in a 0D OMHH, [(C₆H₅)₄P]₂SbCl₅. In situ experimental characterizations and theoretical simulations reveal that the pressure-induced electronic coupling between the lone-pair electrons of Sb³⁺ and the π electrons of benzene ring (lp-π interaction) serves as an unexpected “bridge” for the charge transfer. Our work opens a versatile strategy for the new materials design by manipulating the lp-π interactions in organic–inorganic hybrid systems.     

(CH3NH3)AuX4⋅H2O (X=Cl,Br) and (CH3NH3)AuCl4: Low-Band Gap Lead-Free Layered Gold Halide Perovskite Materials

Perovskite solar cells have recently enabled power conversion efficiency comparable to established technologies such as silicon and cadmium telluride. Ongoing efforts to improve the stability of halide perovskites in ambient air has yielded promising results. However, the presence of toxic heavy element lead (Pb) remains a major concern requiring further attention. Herein, we report three new Pb-free hybrid organic–inorganic perovskite-type halides based on gold (Au), (CH₃NH₃)AuBr₄⋅H₂O ( 1 ), (CH₃NH₃)AuCl₄⋅H₂O ( 2 ), and (CH₃NH₃)AuCl₄ ( 3 ). Hydrated compounds 1 and 2 crystallize in a brand-new structure type featuring perovskite-derived 2D layers and 1D chains based on pseudo-octahedral AuX₆ building blocks. In contrast, the novel crystal structure of the solvent-free compound 3 shows an exotic non-perovskite quasi-2D layered structure containing edge- and corner-shared AuCl₆ octahedra. The use of Au metal instead of Pb results in unprecedented low band gaps below 2.5 eV for single-layered metal chlorides and bromides. Moreover, at room temperature the three compounds show a weak blue emission due to the electronic transition between Au-6s and Au-5d, in agreement with the density function theory (DFT) calculation results. These findings are discussed in the context of viability of Au-based halides as alternatives for Pb-based halides for optoelectronic applications.     

Multicomponent Organic Metal Halide Hybrid with White Emissions

Zero‐dimensional (0D) organic metal halide hybrids, in which organic and metal halide ions cocrystallize to form neutral species, are a promising platform for the development of multifunctional crystalline materials. Herein we report the design, synthesis, and characterization of a ternary 0D organic metal halide hybrid, (HMTA)₄PbMn_0.69Sn_0.31Br₈, in which the organic cation N‐benzylhexamethylenetetrammonium (HMTA⁺, C₁₃H₁₉N₄⁺) cocrystallizes with PbBr₄^2?, MnBr₄^2?, and SnBr₄^2?. The wide band gap of the organic cation and distinct optical characteristics of the three metal bromide anions enabled the single‐crystalline “host–guest” system to exhibit emissions from multiple “guest” metal halide species simultaneously. The combination of these emissions led to near‐perfect white emission with a photoluminescence quantum efficiency of around 73 %. Owing to distinct excitations of the three metal halide species, warm‐ to cool‐white emissions could be generated by controlling the excitation wavelength.     

A New Approach for the Determination of Organobromine in Harmful Waste

Determination and estimation of organic sulphur, nitrogen, phosphor and halides in harmful chemical waste and estimation of emission of SO₂, NO_X, HCI, HBr or HI during incineration are the primary task of risk assessment. In our paper we present a new analytical approach for determination of bromine in a heterogeneous sample. The method applied is based on combustion of chemical waste under oxygen atmosphere (pressure 20 bars) and transformation to corresponding anions. These anions can be measured by ion chromatography. Using this method all hetero atoms can be transformed to corresponding anions (except for oxygen) and can be measured by ion chromatography. In this paper we report of determination of bromine content of chemical waste. During the combustion of organobromine compounds different types of inorganic bromine are formed. All types of bromine must be converted to Br^–. To fulfil it the above, ascorbic acid solution was used for absorbing and transforming all types bromine compounds to Br^–. We will discuss all the details about this new approach and give all the parameters to get efficient conversion from organic bromine to bromide anions.This revised version was published online in November 2005 with corrections to the Cover Date.     

Application of organic selenides and tellurides in organic synthesis

This paper describes the progress on the synthesis of organic selenides and tellurides and their application in organic synthesis.Low valent selenium and telluronium compounds having high reducing selectivity can be used to form carbon-hydrogen bonds as special reducing reagents.Telluronium ylides can react with aldehydes and ketones by Wittig-type condensation to produce (E)-configuration alkenes stereoselectively.α-Phenylselanyl arsonium ylides were prepared by transyl-idation reaction of arsonium ylides with phenylselanyl halides which can undergo Wittig-type reactions with carbonyl compounds to give (Z)-α-selanyl-α,β-unsaturated compounds with high stereoselectiv-ity.Zirconium,tin,boron,halogen,metal or hetero-atom were introduced in organoselenium and telluronium compounds as new difunctional group reagents.Under transition metal catalysis,the corresponding cross coupling reactions provide new methods of formation of carbon-carbon double bonds,which were used in the stereoselective synthesis of     

Reactions of Halogen Azides

Until recently, the explosive nature of halogen azides made these compounds unsuitable for preparative uses and greatly impeded investigation of their physical properties. Reactions of ClN₃ and BrN₃ with metal halides, metal carbonyls, and organometallic compounds to from metal azide halides, nitride halides, carbonyl azide halides, and alkylmetal azides were reported only very recently. The stability relationships of the halogen azides are discussed.     

Novel Approach to the Synthesis of Phosphorus Sulfur Organic Compounds and Their Metal Complexes

Abstract

The reaction of elemental phosphorus (P_{ti 4}) and sulfur with protonodonor reagents (alcohols, phenols, and thiols) has been studied in the presence of amines and complexes based on trialkyltrithiophosphites and transition metal halides. A novel approach to the synthesis of phosphorus sulfur organic compounds has been proposed on the basis of these reactions.     

Chemistry of iron carbonyl anions: Selective reduction of nitroarenes and α, β-unsaturated carbonyl compounds,and reductive dehalogenation of organic halides by (C2H5)4N+ HFe3(CO)11−

The tetraethylammonium undecacarbonylhydridotriferrate [(C₂H₅)₄N⁺ HFe₃(CO)₁₁^?] (I): which can be easily prepared in a two-step sequence from iron pentacarbonyl, triethylamine and tetraethylammonium chloride, selectively reduces nitroarenes to amines and α, β-unsaturated carbonyl compounds to the corresponding saturated compounds both in good yield. I reacts with some organic halides to give dehalogenated products.     

Synthesis,Characterization and Photoluminescence of Lanthanide Metal‐organic Frameworks,Constructed from Triangular 4,4′,4″‐s‐triazine‐1,3,5‐triyl‐p‐aminobenzoate Ligands

Eight isomorphous metal‐organic frameworks: [Ln₂(TATAB)₂(H₂O)(DMA)₆]·5H₂O (Ln = Sm ( 1 ), Eu ( 2 ), Gd ( 3 ), Tb ( 4 ), Dy ( 5 ), Er ( 6 ), Tm ( 7 ), Yb ( 8 )); TATAB = 4,4′,4″‐s‐triazine‐1,3,5‐triyl‐p‐aminobenzoate, DMA = N,N‐dimethylacetamide), were synthesized by the self‐assembly of lanthanide ions, TATAB, DMA and H₂O. Single‐crystal X‐ray crystallography reveals they are three dimensional frameworks with 2‐fold interpenetration. Solid‐state photoluminescence studies indicate ligand‐to‐metal energy transfer is more efficient for compounds 2 and 4 which exhibit intense characteristic lanthanide emissions at room temperature.     

Reactions of benzoyl(carbonyl)transition metal complexes with LiNMe2: on the feasibility of a reaction route to α-keto amide through an acyl(carbamoyl)cobalt intermediate

CO-coordinated benzoyltransition metal complexes, PhCOCo(CO)₃L (L  PPh₃, PCy₃, and PMe₃), PhCOMn(CO)₅, have been prepared and their reactions with LiNMe₂ examined. The reactions give α-keto amide (PhCO-CONMe₂) after treating the systems with Br₂ or organic halides.