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A visible-light induced selective oxidation of sulfides to sulfoxides or sulfones was reported at ambient temperature in H2O under catalyst-free conditions, using oxygen as a green oxidant. The surfactants play a key role in this oxidation, and sulfoxides or sulfones were obtained in high yields, respectively, promoted by different surfactants. [ABSTRACT FROM AUTHOR]

The potential of filter algorithms in improving spectral model performance was evaluated. A total of 329 animal and vegetable oil samples were used to collect attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectra. Fisher discriminant analysis (FDA), support vector machine (SVM), decision tree (DT), K-nearest neighbor analysis (KNN), and multilayer perceptron neural network (MLP) were considered to build models. Three filter algorithms, finite length unit impulse response filter (FIR), infinite length impulse response filter (IIR) and wavelet transform (WT), were evaluated to enhance the performance of the models. The Morlet basis function was the most suitable wavelet transform, accurately classifying 90.3% of the training set and 94.4% of the test set. The MLP algorithms were demonstrated to be superior to the others. The best performance was obtained using low-pass or band-stop filters that provided 100% accuracy with the MLP model. The reported method is demonstrated to be affordable and easy-to-use in forensic analysis. [ABSTRACT FROM AUTHOR]

Xanthine can be converted into uric acid, and a high concentration of xanthine in the human body can cause many diseases. Therefore, it is important to develop a sensitive, simple, and reliable approach for measuring xanthine in biological liquids. Hence, a ratiometric surface-enhanced Raman spectroscopy (SERS) sensing strategy with one signal probe was exploited for reliable, sensitive, and quantitative monitoring of serum xanthine. 3-Mercaptophenylboronic acid (3-MPBA) was used as a typical reference with a Raman peak at 996 cm−1. First, 3-MPBA was bound to gold nanoflowers@silica (GNFs@Si) through Au–S bonds. Xanthine oxidase (XOD) catalyzed the oxidation of xanthine into H2O2 on GNFs@Si. Afterward, the obtained H2O2 further reduced 3-MPBA to 3-hydroxythiophenol (3-HTP) accompanied by the emergence of a new Raman peak at 883 cm−1. Meanwhile, the Raman intensity at 996 cm−1 remained constant. Therefore, the ratio of I883/I996 increased with the increasing of xanthine concentration, thus realizing quantitative detection of xanthine. As a result, a ratiometric SERS sensor for the detection of xanthine was proposed with a detection limit of 5.7 nM for xanthine. The novel ratiometric SERS sensor provides a new direction for analyzing other biomolecules with high sensitivity and reliability. [ABSTRACT FROM AUTHOR]

Various indole-containing compounds have shown impressive pharmaceutical activities against a variety of diseases. However, the functionalization of indoles usually relies on systems that use organic solvents, which do not meet the criteria for green and sustainable chemical development. To address this issue, regiospecific sulfenylation, selenylation, and telluration of indoles were developed using H2 O as solvent. The highly efficient chalcogenylation of indoles was achieved utilizing CsOH as a promoter, thus avoiding the use of expensive transition-metal catalysts. This newly developed protocol is characterized by its outstanding features including simple operation, mild conditions, wide substrate scope, excellent functional group tolerance, and recyclability, leading to the convenient synthesis of 3-chalcogenyl-indoles. [ABSTRACT FROM AUTHOR]

The humidity stability and phase transition mechanism of the all-inorganic perovskite CsPbI2Br based on an optimized dual-source co-evaporation preparation process are investigated at the film interface level. It is found that the CsPbI2Br films annealed at 300 °C for several minutes exhibit a best crystallinity and photoelectric properties. The as-grown CsPbI2Br film is confirmed to be a α phase with a dark brown cubic crystal structure and an average visible transparency of 35.9%. But it will be transformed into its δ phase with a transparent orthorhombic crystal structure and an average visible transparency of 80.3% after a certain amount of moisture exposure. Compared with the α phase film, the electronic structure of the δ phase has also changed significantly with a VBM shift of about 0.32 eV to high binding energy. The results of AR-XPS show that the water molecules in perovskite CsPbI2Br after a moisture exposure only adsorb on the surface rather than penetrate the interior of the lattice. When water molecules adsorb on the lattice surface, halide ions should migrate towards the lattice surface due to their high hydration enthalpy, resulting in halide vacancies within the lattice and causing the reduction of energy barrier for phase transition from α phase to δ phase. So the CsPbI2Br film will transform from its α phase to δ phase induced by water vapor, and this phase transition will be reversed to some extent after another annealing. [ABSTRACT FROM AUTHOR]

A convenient and metal-free protocol for the synthesis of 2-arylthio(seleno)imidazoles from imidazoles and disulfides (diselenides) was developed through the direct thiolation (selenylation) of imidazoles promoted by 0.5 equiv. of iodine. This process is scalable and tolerates a wide spectrum of disulfides (diselenides) to deliver products in high yields. Compared with previous methods, this protocol has the advantages of a simple operation, wide functional group tolerance and good yields, providing an efficient route to 2-arylthio(seleno)imidazoles, which are key structural scaffolds of many natural products. Image 1 • A convenient and metal-free protocol for the synthesis of 2-arylthio(seleno)imidazoles. • This process is scalable and tolerates a wide spectrum of disulfides (diselenides). • This method showed considerable advantages such as simple operation, wide functional group tolerance and good yields. • A plausible mechanistic approach has also been proposed. [ABSTRACT FROM AUTHOR]

A heterogeneous Pd‐Cu NWs‐catalyzed expeditious and solvent‐free synthesis of propargylamines via A3‐coupling of aldehydes, alkynes, and amines has been proposed. A wide range of aldehydes, alkynes and amine substrates undergo A3‐coupling to produce propargylamines in good to excellent yields with good functional tolerance, such as that towards alkoxy, hydroxy, C‐X (X = F, Cl, Br) as well as amide and C=C bonds. Furthermore, the catalyst could be recovered easily and reused for at least 5 cycles without showing significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

The aim of this paper was to explore the non‐destructive application of fusion spectra model for characterization and differentiation of electrostatic copying papers that could be favourable to give forensic aid in legal cases. Two hundred fifty electrostatic copy paper samples were collected from various markets. All samples were subjected to surface‐enhanced Raman spectroscopy (SERS) analysis from 3500 to 400 cm−1 Raman shift range and attenuated total reflection‐Fourier transform infrared spectrum (ATR‐FTIR) analysis from 4000 to 400 cm−1 wavenumber range, respectively. The spectral data refracted the constituents present in the electrostatic copy papers were cellulose, inorganic filler calcium carbonate and barium sulfate. Fisher discriminant analysis (FDA), multi‐class support vector machine (MSVM) and decision tree (DT) algorithms were used to build the model. The precision rate, recall rate, F‐score and total accuracy were considered as indicators to evaluate the model's performance. The results showed that fusion models were superior to single model. The feature layer fusion model based on MSVM algorithm gave a differentiating power of 100% by grouping all the sample groups. This study demonstrated that spectral fusion model is a feasible and reliable approach for fast and non‐destructive differentiation of electrostatic copying papers. It has great potential in real application scenarios. [ABSTRACT FROM AUTHOR]

Chemodivergent tandem radical cyclization offers exciting possibilities for the synthesis of structurally diverse cyclic compounds. Herein, we revealed a chemodivergent tandem cyclization of alkene‐substituted quinazolinones under metal‐ and base‐free conditions, this transformation is initiated by alkyl radicals produced from oxidant‐induced α‐C(sp3)−H functionalization of alkyl nitriles or esters. The reaction resulted in the selective synthesis of a series of mono‐ and di‐alkylated ring‐fused quinazolinones by modulating the loading of oxidant, reaction temperature, and reaction time. Mechanistic investigations show that the mono‐alkylated ring‐fused quinazolinones is constructed by the key process of 1,2‐hydrogen shift, whereas the di‐alkylated ring‐fused quinazolinones is mainly achieved through crucial steps of resonance and proton transfer. This protocol is the first example of remote second alkylation on the aromatic ring via α‐C(sp3)−H functionalization and difunctionalization achieved by association of two unsaturated bonds in radical cyclization. [ABSTRACT FROM AUTHOR]

A novel 5-exo-dig/6-endo-trig bicyclization of 1,6-enynes with sulfonyl hydrazides in the aqueous phase using the cheap and available tetrabutylammonium iodide (TBAI)–tert-butyl hydroperoxide (TBHP) combined system is reported. The resulting reaction of diverse nitrogen- and oxygen-polyheterocycles displays high chemical selectivity, high step-economy, and a moderate substrate scope. Moreover, iodosulfonylation can be realized by modulating the structure of the 1,6-enynes. [ABSTRACT FROM AUTHOR]

A novel one-pot approach for the synthesis of ( Z )-vinylic selenosulfides is demonstrated through the thioselenation of a wide range of alkynes with unsymmetrical diorganoyl dichalcogenides (RSSePh) catalyzed by cesium hydroxide monohydrate, avoiding the use of the transition metal catalyst and the previous preparation of chalcogen alkynes. Other outstanding features include mild reaction conditions, high regio- and stereo-selectivity, excellent yields and wide functional group tolerance. [ABSTRACT FROM AUTHOR]

A convenient and efficient method for the synthesis of O,O -dialkyl- Se -aryl phosphoroselenoates is described via a one pot reaction of diaryl diselenide and O,O -dialkylphosphonate catalyzed by KOH assisted by a co-catalyst of calix[4]arene 3 . The calix[4]arene 3 can be recycled for five times with good yields of the desired products for the reaction. This protocol provide a simple and efficient method for the synthesis of O,O -dialkyl- Se -aryl phosphoroselenoates, avoiding the use of toxic reagents and expensive catalysts. [ABSTRACT FROM AUTHOR]