Luminescence of Sm3+ in double perovskite-type Ba2SrWO6 for insect trapping.

The predominant method for pest control has been the use of pesticides, which have been shown to have detrimental effects on soil, freshwater, and crop quality. Therefore, the development of novel and sustainable crop protection strategies has become increasingly imperative. In this study, a novel orange-red emitting Ba2SrWO6: Sm3+ phosphor was synthesized using the high-temperature solid-state reaction. Under ultraviolet excitation, the phosphors showed obvious emission peaks at 575, 614, and 662 nm. The Ba2SrWO6: Sm3+ was used to fabricate a fluorescence film with polydimethylsiloxane (PDMS), and attracted twice as many insects as the blank control group under 365 nm ultraviolet light. This material holds great potential as a fluorescent agent for insect trapping in the pest control fields of tea, cotton, eggplant, rice, potato, grape, and other agricultural industries. Our findings provide an eco-friendly approach to pest management for the increment of food production.

Synthesis, supramolecular aggregation, and NIR-II phosphorescence of isocyanorhodium(i) zwitterions.

Development of new second near-infrared (NIR-II, 1000-1700 nm) luminophores is highly desirable, and d8 square-planar metal complexes with NIR-II phosphorescence have been rarely reported. Herein, we explore an asymmetric coordination paradigm to achieve the first creation of NIR-II phosphorescent isocyanorhodium(i) zwitterions. They show a strong tendency for aggregation in solution, arising from close Rh(i)⋯Rh(i) contacts that are further intensified by π-π stacking interactions and the hydrophilic-hydrophobic effect. Based on such supramolecular aggregation, zwitterions 2 and 5 are found to yield NIR-II phosphorescence emissions centered at 1005 and 1120 (1210, shoulder) nm in methanol-water mixed solvents, respectively. These two bands show red shifts to 1070 and 1130 (1230, shoulder) nm in the corresponding polymer nanoparticles in water. The resulting polymer nanoparticles can brighten in vivo tumor issues in the NIR-II region with a long-circulating time. In view of the synthetic diversity established by the asymmetric coordination paradigm, this work provides an extraordinary opportunity to explore NIR-II luminophores.

Monitoring chlorophyll changes during Tencha processing using portable near-infrared spectroscopy.

Monitoring chlorophyll during Tencha (the raw ingredient for matcha) processing is critical for determining the matcha's color and quality. The purpose of this study is to explore the mechanism of chlorophyll changes during Tencha processing and evaluate the viability of predicting its content by a portable near-infrared (NIR) spectrometer. The Tencha samples' spectral data were first preprocessed using various preprocessing techniques. Subsequently, iteratively variable subset optimization (IVSO), bootstrapping soft shrinkage (BOSS), and competitive adaptive reweighted sampling (CARS) were used to optimize and build partial least square (PLS) models. The CARS-PLS models achieved the best predictive accuracy, with correlation coefficients of prediction (Rp) = 0.9204 for chlorophyll a, Rp = 0.9282 for chlorophyll b, and Rp = 0.9385 for total chlorophyll. These findings suggest that NIR spectroscopy could be used as a surrogate for immediate quantification and monitoring of chlorophyll during Tencha processing.

Synthesis of Co2-xNixO2 (0 < x < 1.0) hexagonal nanostructures as efficient bifunctional electrocatalysts for overall water splitting.

Designing low-cost and high-performance bifunctional electrocatalysts towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is vitally important for water splitting. Herein, we synthesize Co2-xNixO2 (0 < x < 1.0) hexagonal nanosheets with different Co/Ni molar ratios via a facile coprecipitation process followed by calcination under an Ar atmosphere. Changing the Co/Ni molar ratios of the Co2-xNixO2 products is found to have a momentous influence on the microstructures, specific surface areas and electrocatalytic performances. At a Co/Ni molar ratio of 0.6, the Co1.4Ni0.6O2 nanosheet exhibits the largest specific surface area of 60.63 m2 g-1, the best OER with an onset overpotential of 278.5 mV, and HER of 72.8 mV as a bifunctional electrocatalyst. Meanwhile, the minimum Tafel slope is 113.6 mV dec-1 for OER and 77.4 mV dec-1 for HER. The Co1.4Ni0.6O2 nanosheet has excellent OER and HER activity at 0.1 mg cm-2 trace loading. Moreover, we construct an overall water splitting cell using the Co1.4Ni0.6O2 bifunctional electrocatalyst in a two-electrode system to further demonstrate the practical application, which needs a cell voltage of 1.75 V at a current density of 10 mA cm-2 and exhibits great long-term stability. These results provide an efficient strategy for the rational design of Co-based oxides towards bifunctional overall water electrocatalysts.

Trimethylphosphate as a Methylating Agent for Cross Coupling: A Slow-Release Mechanism for the Methylation of Arylboronic Esters.

A methyl group on an arene, despite its small size, can have a profound influence on biologically active molecules. Typical methods to form a methylarene involve strong nucleophiles or strong and often toxic electrophiles. We report a strategy for a new, highly efficient, copper and iodide co-catalyzed methylation of aryl- and heteroarylboronic esters with the mild, nontoxic reagent trimethylphosphate, which has not been used previously in coupling reactions. We show that it reacts in all cases tested in yields that are higher than those of analogous copper-catalyzed reactions of MeOTs or MeI. The combination of C-H borylation and this methylation with trimethylphosphate provides a new approach to the functionalization of inert C-H bonds and is illustrated by late-stage methylation of four medicinally active compounds. In addition, reaction on a 200 mmol scale demonstrates reliability of this method. Mechanistic studies show that the reaction occurs by a slow release of methyl iodide by reaction of PO(OMe)3 with iodide catalyst, rather than the typical direct oxidative addition to a metal center. The low concentration of the reactive electrophile enables selective reaction with an arylcopper intermediate, rather than nucleophilic groups on the arylboronate, and binding of tert-butoxide to the boronate inhibits reaction of the electrophile with the tert-butoxide activator to form methyl ether.

Characterization of active compounds from Gracilaria lemaneiformis inhibiting the protein tyrosine phosphatase 1B activity.

Gracilaria lemaneiformis, an edible alga, with various bioactivities is a traditional dish and a favorite food. In the present study, its n-hexane extract showed strong protein tyrosine phosphatase 1B inhibitory activity after screening. To understand the activity composition, nineteen compounds were identified from this extract by GC-MS. The protein tyrosine phosphatase 1B inhibitory activity of the identified compounds was further screened by means of molecular docking individually. As a result, 2,2'-methylenebis-6-(1,1-dimethylethyl)-4-methyl-phenol with the lowest binding energy of -6.70 kcal mol-1 was discovered from the complex extract, and its inhibitory activity against protein tyrosine phosphatase 1B was proved in vitro. The IC50 value was 53.27 ± 0.54 µM. Therefore, this compound and its source Gracilaria lemaneiformis were suggested to be utilized as a functional food with potential protein tyrosine phosphatase 1B inhibitory activity.

Markovnikov-Selective Palladium Catalyst for Carbonylation of Alkynes with Heteroarenes.

A new class of palladium catalysts, based on heterocyclic diphosphines, was rationally designed and synthesized. Application of one of these catalysts allows novel Markovnikov-selective carbonylation of non-activated alkynes with heteroarenes to give the corresponding branched α,ß-unsaturated ketones in excellent yields (up to 97 %) and regioselectivities (b/l up to 99:1). In addition to heteroarenes, other common nucloephiles (alcohol, phenol, amine, and amide) furnish the desired carbonylation products smoothly in high yields.

Rapid prediction and identification of lipase inhibitors in volatile oil from Pinus massoniana L. needles.

A facile method based on gas chromatography-mass spectrometry (GC-MS) and molecular docking was established to analyze, identify, and predict lipase inhibitors in volatile oil from Pinus massoniana L. needles (PMLN). The volatile oil, with an IC50 value of 15.25 ± 0.06 µg/mL, exhibited potential inhibitory activity against lipase in vitro. In total, 33 compounds were identified from the volatile oil through GC-MS analysis. The major compounds in the volatile oil were ß-pinene (39.24%), α-pinene (14.68%), germacrene D (9.08%), caryophyllene (6.94%), α-terpineol (5.39%), ß-phellandrene (4.82%), and D-limonene (3.93%). The identified compounds were individually docked with lipase as the target through molecular docking. Among the compounds, longifolene characterized by preferable binding energy and the good inhibition constant exhibited potential lipase inhibitory activity. The IC50 value of longifolene was 25.10 ± 0.49 µM, indicating that this compound is the active ingredient responsible for the lipase inhibitory activity of PMLN volatile oil.

Rational approach to solvent system selection for liquid-liquid extraction-assisted sample pretreatment in counter-current chromatography.

A rational liquid-liquid extraction approach was established to pre-treat samples for high-speed counter-current chromatography (HSCCC). n-Hexane-ethyl acetate-methanol-water (4:5:4:5, v/v) and (1:5:1:5, v/v) were selected as solvent systems for liquid-liquid extraction by systematically screening K of target compounds to remove low- and high-polarity impurities in the sample, respectively. After liquid-liquid extraction was performed, 1.4g of crude sample II was obtained from 18.5g of crude sample I which was extracted from the flowers of Robinia pseudoacacia L., and then separated with HSCCC by using a solvent system composed of n-hexane-ethyl acetate-methanol-water (1:2:1:2, v/v). As a result, 31mg of robinin and 37mg of kaempferol 7-O-α-l-rhamnopyranoside were isolated from 200mg of crude sample II in a single run of HSCCC. A scale-up separation was also performed, and 160mg of robinin with 95% purity and 188mg of kaempferol 7-O-α-l-rhamnopyranoside with 97% purity were produced from 1.2g of crude sample II.

DNA Deformation-Coupled Recognition of 8-Oxoguanine: Conformational Kinetic Gating in Human DNA Glycosylase.

8-Oxoguanine (8-oxoG), a mutagenic DNA lesion generated under oxidative stress, differs from its precursor guanine by only two substitutions (O8 and H7). Human 8-oxoguanine glycosylase 1 (OGG1) can locate and remove 8-oxoG through extrusion and excision. To date, it remains unclear how OGG1 efficiently distinguishes 8-oxoG from a large excess of undamaged DNA bases. We recently showed that formamidopyrimidine-DNA glycosylase (Fpg), a bacterial functional analog of OGG1, can selectively facilitate eversion of oxoG by stabilizing several intermediate states, and it is intriguing whether OGG1 also employs a similar mechanism in lesion recognition. Here, we use molecular dynamics simulations to explore the mechanism by which OGG1 discriminates between 8-oxoG and guanine along the base-eversion pathway. The MD results suggest an important role for kinking of the DNA by the glycosylase, which positions DNA phosphates in a way that assists lesion recognition during base eversion. The computational predictions were validated through experimental enzyme assays on phosphorothioate substrate analogs. Our simulations suggest that OGG1 distinguishes between 8-oxoG and G using their chemical dissimilarities not only at the active site but also at earlier stages during base eversion, and this mechanism is at least partially conserved in Fpg despite a lack of structural homology. The similarity also suggests that lesion recognition through multiple gating steps may be a common theme in DNA repair. Our results provide new insight into how enzymes can exploit kinetics and DNA conformational changes to probe the chemical modifications present in DNA lesions.

The scope and mechanism of palladium-catalysed Markovnikov alkoxycarbonylation of alkenes.

Hydroesterification reactions represent a fundamental type of carbonylation reaction and constitute one of the most important industrial applications of homogeneous catalysis. Over the past 70 years, numerous catalyst systems have been developed that allow for highly linear-selective (anti-Markovnikov) reactions and are used in industry to produce linear carboxylates starting from olefins. In contrast, a general catalyst system for Markovnikov-selective alkoxycarbonylation of aliphatic olefins remains unknown. In this paper, we show that a specific palladium catalyst system consisting of PdX2/N-phenylpyrrole phosphine (X, halide) catalyses the alkoxycarbonylation of various alkenes to give the branched esters in high selectivity (branched selectivity up to 91%). The observed (and unexpected) selectivity has been rationalized by density functional theory computation that includes a dispersion correction.

Selective Palladium-Catalyzed Aminocarbonylation of Olefins to Branched Amides.

A general and efficient protocol for iso-selective aminocarbonylation of olefins with aliphatic amines has been developed for the first time. Key to the success for this process is the use of a specific 2-phosphino-substituted pyrrole ligand in the presence of PdX2 (X=halide) as a pre-catalyst. Bulk industrial and functionalized olefins react with various aliphatic amines, including amino-acid derivatives, to give the corresponding branched amides generally in good yields (up to 99 %) and regioselectivities (b/l up to 99:1).

Bioassay-guided isolation of an active compound with protein tyrosine phosphatase 1B inhibitory activity from Sargassum fusiforme by high-speed counter-current chromatography.

A rapid and efficient method using high-speed counter-current chromatography was established for the bioassay-guided separation of an active compound with protein tyrosine phosphatase 1B inhibitory activity from Sargassum fusiforme. Under the bioassay guidance, the ethyl acetate extract with the best IC50 value of 0.37 ± 0.07 µg/mL exhibited a potential protein tyrosine phosphatase 1B inhibitory activity, which was further separated by high-speed counter-current chromatography. The separation was performed with a two-phase solvent system composed of n-hexane/methanol/water (5:4:1, v/v). As a result, dibutyl phthalate (19.7 mg) with the purity of 95.3% was obtained from 200 mg of the ethyl acetate extract. Its IC50 was 14.05 ± 0.06 µM, which was further explained by molecular docking. The result of molecular docking showed that dibutyl phthalate enfolded in the catalytic site of protein tyrosine phosphatase 1B. The main force between dibutyl phthalate and protein tyrosine phosphatase 1B was the hydrogen bond interaction with Gln266. In addition, hydrogen bond, van der Waals force and hydrophobic interaction with the amino acids (Ala217, Ile219, and Gly220) were also responsible for the stable protein-ligand complex.

Palladium-Catalyzed Aminocarbonylation of Allylic Alcohols.

A benign and efficient palladium-catalyzed aminocarbonylation reaction of allylic alcohols is presented. The generality of this novel process is demonstrated by the synthesis of ß,γ-unsaturated amides including aliphatic, cinnamyl, and terpene derivatives. The choice of ligand is crucial for optimal carbonylation processes: Whereas in most cases the combination of PdCl2 with Xantphos (L6) gave best results, sterically hindered substrates performed better in the presence of simple triphenylphosphine (L10), and primary anilines gave the best results using cataCXium® PCy (L8). The reactivity of the respective catalyst system is significantly enhanced by addition of small amounts of water. Mechanistic studies and control experiments revealed a tandem allylic alcohol amination/C-N bond carbonylation reaction sequence.

Palladium-catalysed hydroamidocarbonylation of 1,3-dienes.

Herein, we report our recent result on the development of the selective catalytic method towards the synthesis of ß,γ-unsaturated imides via Pd-catalysed hydroamidocarbonylation of conjugated dienes. Note that this reaction proceeds under acid additive free conditions. Various dienes, including those of high industrial value (e.g. isoprene, 1,3-butadiene), are shown to be compatible with our established method (28 examples, 40-99% yield), which leads to the corresponding ß,γ-unsaturated imides in a highly efficient and atom-economic fashion.

A dynamic checkpoint in oxidative lesion discrimination by formamidopyrimidine-DNA glycosylase.

In contrast to proteins recognizing small-molecule ligands, DNA-dependent enzymes cannot rely solely on interactions in the substrate-binding centre to achieve their exquisite specificity. It is widely believed that substrate recognition by such enzymes involves a series of conformational changes in the enzyme-DNA complex with sequential gates favoring cognate DNA and rejecting nonsubstrates. However, direct evidence for such mechanism is limited to a few systems. We report that discrimination between the oxidative DNA lesion, 8-oxoguanine (oxoG) and its normal counterpart, guanine, by the repair enzyme, formamidopyrimidine-DNA glycosylase (Fpg), likely involves multiple gates. Fpg uses an aromatic wedge to open the Watson-Crick base pair and everts the lesion into its active site. We used molecular dynamics simulations to explore the eversion free energy landscapes of oxoG and G by Fpg, focusing on structural and energetic details of oxoG recognition. The resulting energy profiles, supported by biochemical analysis of site-directed mutants disturbing the interactions along the proposed path, show that Fpg selectively facilitates eversion of oxoG by stabilizing several intermediate states, helping the rapidly sliding enzyme avoid full extrusion of every encountered base for interrogation. Lesion recognition through multiple gating intermediates may be a common theme in DNA repair enzymes.

Palladium-Catalyzed Hydroamidocarbonylation of Olefins to Imides.

Carbonylation reactions allow the efficient synthesis of all kinds of carbonyl-containing compounds. Here, we report a straightforward synthesis of various imides from olefins and CO for the first time. The established hydroamidocarbonylation reaction affords imides in good yields (up to 90 %) and with good regioselectivity (up to 99:1) when applying different alkenes and amides. The synthetic potential of the method is highlighted by the synthesis of Aniracetam by intramolecular hydroamidocarbonylation.

Active destabilization of base pairs by a DNA glycosylase wedge initiates damage recognition.

Formamidopyrimidine-DNA glycosylase (Fpg) excises 8-oxoguanine (oxoG) from DNA but ignores normal guanine. We combined molecular dynamics simulation and stopped-flow kinetics with fluorescence detection to track the events in the recognition of oxoG by Fpg and its mutants with a key phenylalanine residue, which intercalates next to the damaged base, changed to either alanine (F110A) or fluorescent reporter tryptophan (F110W). Guanine was sampled by Fpg, as evident from the F110W stopped-flow traces, but less extensively than oxoG. The wedgeless F110A enzyme could bend DNA but failed to proceed further in oxoG recognition. Modeling of the base eversion with energy decomposition suggested that the wedge destabilizes the intrahelical base primarily through buckling both surrounding base pairs. Replacement of oxoG with abasic (AP) site rescued the activity, and calculations suggested that wedge insertion is not required for AP site destabilization and eversion. Our results suggest that Fpg, and possibly other DNA glycosylases, convert part of the binding energy into active destabilization of their substrates, using the energy differences between normal and damaged bases for fast substrate discrimination.

Selective palladium-catalyzed aminocarbonylation of 1,3-dienes: atom-efficient synthesis of ß,γ-unsaturated amides.

Carbonylation reactions constitute important methodologies for the synthesis of all kinds of carboxylic acid derivatives. The development of novel and efficient catalysts for these transformations is of interest for both academic and industrial research. Here, the first palladium-based catalyst system for the aminocarbonylation of 1,3-dienes is described. This atom-efficient transformation proceeds under additive-free conditions and provides straightforward access to a variety of ß,γ-unsaturated amides in good to excellent yields, often with high selectivities.

Selective ruthenium-catalyzed methylation of 2-arylethanols using methanol as C1 feedstock.

We describe the selective cross coupling of methanol and 2-arylethanols using a combination of Ru-MACHO (RuHCl(PNP(Ph))CO) and Shvo's diruthenium complex as catalysts. The desired domino transformation takes place via so-called borrowing hydrogen methodology, which constitutes an ideal example of green chemistry.