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The photolysis of four typical NBFRs, hexabromobenzene (HBB), pentabromotoluene (PBT), pentabromobenzyl acrylateare (PBBA) and pentabromoethylbenzene (PBEB), were explored under different irradiation light wavelengths, initial concentrations and organic solvents. Density functional theory was used for chemical calculation to explore the internal mechanism of solvent effect. All degradation kinetics conformed to the first-order kinetic model. Under different irradiation light wavelengths, the degradation rates were in the following order: 180~400 nm (0.1702~0.3008 min−1) > 334~365 nm (0.0265~0.0433 min−1) > 400~700 nm (0.0058~0.0099 min−1). When the initial concentration varied from 0.25 mg/L to 1 mg/L, the degradation rate decreased from 0.0379~0.0784 min−1 to 0.0265~0.0433 min−1 under 334~365 nm irradiation, which might be attributed to the reduction in light energy received per unit area and competition from intermediate metabolites. In different organic solvents, the degradation rates were in the order of acetone (0.1702~0.3008 min−1) > toluene (0.0408~0.0534 min−1) > n-hexane (0.0124~0.0299 min−1). Quantum chemical calculation and analysis showed that the energy change in electron transfer between solvent and NBFRs was the key factor to solvent effect in the degradation of NBFRs. The active sites and degradation pathways of NBFRs were also speculated, the nucleophilic reaction of the Br atom on a benzene ring was the main process of photodegradation and it was preferential to remove the bromine and then the ethyl group on the benzene ring. Our research will be helpful in predicting and evaluating their photochemical behavior in different environment conditions.

A simple and efficient protocol for silver-promoted direct C-H phosphonation of 1-naphthylamine derivatives with H-phosphonates was described. This reaction proceeded smoothly for 1-naphthylamine derivatives at the C4 site, providing a facile and efficient route to 4-phosphonated 1-naphthylamine derivatives. This phosphonation could tolerate a diverse type of functional groups at the pyridinyl and naphthyl moieties. Further functionalization of the phosphonated product was also explored at the C2 and C8 sites, such as fluoridation, methylation, methoxylation, and amination. In addition, DFT studies of the reaction intermediate showed that the most electrophilic reactive site is at the C4 site in the naphthyl ring.

Transition metal chalcogenides are considered as promising alternative materials for lithium-ion batteries owing to their relatively high theoretical capacity. However, poor cycle stability combined with low rate capacity still hinders their practical applications. In this work, the Cu-N chemical bonding directed the stacking Cu2−xSe nanoplates (DETA-Cu2−xSe) is developed to solve this issue. Such unique structure with small nanochannels can enhance the reactive site, facilitate the Li-ion transport as well as inhibit the structural collapse. Benefitting of these advantages, the DETA-Cu2−xSe exhibits high specific capacity, better rate capacity and long cyclability with the specific capacities of 565 mAh g−1 after 100 cycles at 200 mA g−1 and 368 mAh g−1 after 500 cycles at 5000 mA g−1. This novel DETA-Cu2−xSe structure with nanochannels is promising for next generation energy storage and the synthetic process can be extended to fabricate other transition metal chalcogenides with similar structure.

Isolation of the atomic O radical anion bound to a metal ion (metal-oxyl) on solid surfaces is highly desirable for an understanding of how we should design the surface structure for using oxyl as the reactive site. Owing to the analytical difficulty of oxyl, however, even identification of oxyl remains scarce. Herein, we report isovalent ZnII-oxyl and GaIII-oxyl bonds isolated in the zeolite matrix. Close similarities in reactivity, spectroscopic property, and bonding nature were observed between them, but their site requirements were entirely different; the former is generated at the monovalent ion-exchangeable site, whereas the latter at the divalent ion-exchangeable site. This study strongly suggests that tuning the polarization of the metal-oxygen bond using the charge-controlled lattice oxygens is a useful way to constrain surface metal-oxyl bonds.

The interaction and orientation of hypochlorous acid (HOCl) on the ice surface has been of great interest as it has important implications to ozone depletion. As HOCl interacts with the ice surface, previous classical molecular dynamics simulations suggest its OH moiety orients to the outside of the ice surface, whereas the quantum calculations performed at 0 K indicate its Cl atom is exposed. To resolve this contradiction, herein, Born-Oppenheimer molecular dynamics simulations are adopted, and the results suggest that at ambient temperature, the interaction between HOCl with interfacial water is dominated by the robust H-bond of (HOCl)H-O(H2O). As a result, the HOCl mainly acts as the proton donor to the water surface, which thus can participate in proton transfer reactions via the promotion of interfacial water. Moreover, the Cl atom of HOCl is found to be exposed to the outside of the water surface. Therefore, during the heterogeneous reactions of HOCl on the water surface, the Cl atom becomes the reactive site and is easily attacked by other species.

A series of main-chain benzoxazine oligomers with different methyl substitutions are successfully synthesized. Chemical structures are analyzed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Effects of methyl substitutions on chemical shifts of protons in oxazine ring and thermal properties, including glass transition temperature, thermal stability, and char yield, are discussed. The influences of methyl substitutions on different positions are demonstrated: (i) substitution on phenols induces obvious increase in curing temperature while substitution on amine does not show apparent impact; (ii) substitution at different positions results in T g variation, following the sequence of none-substitution > substitution at end-capping > substitution on diamines in main-chain > substitution on bisphenols in main-chain; and (iii) substitution at end-capping would cause apparent deterioration in thermal stability while substitution on diamines in main-chain would benefit thermal stability and char yield. Experimental results and related explanations are provided in detail.

Current synthetic strategies involving π-system coupling reactions for the molecular design of luminescent materials suffer from the challenging precise synthesis on the desired reactive site and also difficulty in solubility derived from the rigid structures of π-systems. Herein, a novel and versatile triarylmethanolation strategy for the molecular design of luminescent materials with facile synthesis and good solubility is reported. The prepared luminescent materials exhibit unique amorphization-induced emission (AmIE) behaviours, which represent an entropy-favoured and ubiquitous type of aggregation-induced emission that is currently famous and is contrary to crystallization-induced emission. Due to the outstanding AmIE behaviours, the luminescent materials exhibit applications in the fields of rewritable display and storage, extremely sensitive explosive detection at the ppb level, and high-efficiency artificial light-harvesting system with an antenna effect up to 21.3. This work therefore expands the methodology, structure, and functionality libraries of luminescent materials with outstanding properties in the application fields of explosive detection, energy transfer, and artificial light-harvesting systems.

We herein present a reactive site regulation strategy for fabricating well-defined Janus and core@shell gold nanorod-Cu2-xS dual metal-semiconductor plasmonic supraparticles. In addition to enhanced photothermal efficiency and photostability, the nanohybrids possess synergetic photo-thermal and chemical dynamic therapy and corresponding application potential.

Utilizing the C4 reactive site of cyclopropyl ketones and a chiral N,N'-dioxide-scandium(iii) complex as a catalyst, a concise ring-opening/cyclization/thio-Michael cascade method was developed for the synthesis of chiral benzothiazole derivatives from a simple 2-aminothiophenol material. The kinetic resolution and the origin of stereoselectivity were elucidated via a possible catalytic model.

Metal-organic polyhedra (MOPs) are discrete, intrinsically-porous architectures that operate at the molecular regime and, owing to peripheral reactive sites, exhibit rich surface chemistry. Researchers have recently exploited this reactivity through post-synthetic modification (PSM) to generate specialised molecular platforms that may overcome certain limitations of extended porous materials. Indeed, the combination of modular solubility, orthogonal reactive sites, and accessible cavities yields a highly versatile molecular platform for solution to solid-state applications. In this feature article, we discuss representative examples of the PSM chemistry of MOPs, from proof-of-concept studies to practical applications, and highlight future directions for the MOP field., This work was supported by the Spanish MINECO (project RTI2018-095622-B-I00) and the Catalan AGAUR (project 2017 SGR 238). It was also funded by the CERCA Programme/Generalitat de Catalunya and through a fellowship (LCF/BQ/PR20/11770011) from the “la Caixa” Foundation (ID 100010434). ICN2 is supported by the Severo Ochoa programme from the Spanish MINECO (Grant No. SEV-2017-0706).

Synthesis of 4-acetyl-substituted azoles (1,2,3-triazole, 1,2,3-thiadiazole, and 1,2-oxazole) is reported. Organocatalytic reactions of 4-acetyl-1,2,3-triazoles with aryl azides were used to obtain bis-1,2,3-triazoles containing directly linked ring systems. The reactions of 4-acetylazoles with DMF–DMA led to the formation of enamines. It was found that the acetyl and methyl groups in 4-acetyl-5-methyl-1,2,3-thiadiazole competed for the role of reactive site. The obtained enamines reacted with aryl azides, forming bisheterocycles that were linked by a carbonyl group. The structures of the synthesized compounds were proved by NMR spectroscopy, mass spectrometry, and X-ray structural analysis.

This work describes the copper-catalyzed C sp -chalcogen bond formation through cross-coupling reactions of propynylbenzamides and diorganyl dichalcogenides at room temperature, under open atmosphere. Generally, the reactions have proceeded very smoothly, affording the new class of organochalcogen-containing propynylbenzamides in good yields. Notably, this protocol showed to be tolerant to neutral, electron-donating and electron-withdrawing substituents present in both reaction substrates. In addition, the applicability of the carbon-chalcogen bond as a reactive site has been proved by successfully employment of the N -methyl- N -(3-(butylselanyl)prop-2-yn-1-yl)benzamide as a precursor in palladium-catalyzed Suzuki and Sonogashira type reactions.

An efficient method for the selective C-difluoromethylation of carbon acids with the reagent TMSCF2 Br has been developed. A variety of structurally diverse sp3 - and sp-hybridized carbon nucleophiles, including esters, amides, fluorenes, terminal alkynes, β-ketoesters, malonates, and other activated C-H nucleophiles, could be efficiently and selectively transformed into the corresponding C-difluoromethylated products under mild conditions. This protocol is also effective for the late-stage difluoromethylation of pharmaceutically relevant molecules and can be readily scaled up. Moreover, ambident substrates with more than one reactive site towards difluorocarbene can be difluoromethylated orthogonally using TMSCF2 Br.

Theoretical studies on predicting potential reactive sites of attractive compounds are of significance, which are capable of providing deeper insight into their chemical behaviors as well as foundations for discovering new drug molecules. The 3,9-diazatetraasterane derivatives are a kind of cage compounds equipping with potent biological activities. In this paper, predication of reactive sites of 3,9-diazatetraasteranes bearing phenyl and ester groups (6,12-diphenyl-3,9-diazahexacyclo[6.4.0.02.7.04.11.05.10]-dodecane-1,5,7,11-tetracarboxylate) was carried out by the conceptual density functional theory. Firstly, a conformational search of 3,9-diazatetraasterane was performed by molecular dynamics simulations associating with Quantum Mechanics calculations in order to obtain relative stable conformers. And then the reactive site prediction of 3,9-diazatetraasterane was carried out by the Fukui function and condensed Fukui function. The results exhibited that the potentially chemical reactive site is the N atom of 3,9-diazatetraasterane scaffold, which is readily attacked by electrophilic agent. Meanwhile, the calculated results were validated by experimental outcomes in the derivation of 3,9-diazatetraasteranes.

Spectral and basic properties of heterosubstituted porphyrins of anionic type have studied by means of spectrophotometric titration in comparison with their structural analog — tetraphenylporphine tetrasulfonic acid. The parameters of electronic absorption spectra and concentration ranges of existence of the mono- and diprotonated forms of the studied ligands as well as the constants of basic dissociation have been determined. Comparative analysis of the effect of the reactive site modification and the medium composition on the basicity of the compounds has been performed.

A novel fluorescent probe 8-HB was developed with a BODIPY as a fluorophore and 8-substituted hydrazine as a reactive site for sensitive and selective detection of nitric oxide (NO), generating major fluorescent dehydrazinated BODIPY and minor non-fluorescent azide BODIPY. Moreover, 8-HB can achieve specific imaging of endogenous NO in living cells.

Following high levels of efficacy in PrEP clinical trials, demonstration projects were launched to assess its real-world effectiveness when rolled out as part of programmes. Based on an ethnographic study of a PrEP demonstration project in South India among female sex workers, we analyse a curious set of narratives in which participants claim PrEP as a ‘cure all’ for a range of physical ailments. What becomes clear is how participation in this project has intensified a relationship with their bodies, one that has led these women to reflect on and track various changes pertaining to bodily wellness. ‘The body’ becomes a highly reactive site that entangles global HIV science, sex workers’ engagements in health promotion, and regimes of self-care. Engaging with these local biologies holds important insights for designing and implementing future biomedical interventions.

Thioredoxins are regulatory proteins that reduce disulfide bonds on target proteins. NaTrxh, which belongs to the plant thioredoxin family h subgroup 2, interacts and reduces the S-RNase enhancing its ribonuclease activity seven-fold, resulting an essential protein for pollen rejection in Nicotiana. Here, the crystal structure of NaTrxh at 1.7 A by X-ray diffraction is reported. NaTrxh conserves the typical fold observed in other thioredoxins from prokaryotes and eukaryotes, but it contains extensions towards both N- and C-termini. The NaTrxh N-terminal extension participates in the reduction of S-RNase, and in the structure reported here, this is orientated towards the reactive site. The interaction between SF11-RNase and the NaTrxh N-terminal was simulated and the short-lived complex observed lasted for a tenth of ns. Moreover, we identified certain amino acids as SF11-RNase-E155 and NaTrxh-M104 as good candidates to contribute to the stability of the complex. Furthermore, we simulated the reduction of the C153-C186 SF11-RNase disulfide bond and observed subtle changes that affect the entire core, which might explain the increase in the ribonuclease activity of S-RNase when it is reduced by NaTrxh.

(±)-Dasycarpidone ((1R,5S)-12-ethyl-2-methyl-1,2,3,4,5,7-hexahydro-6H-1,5-methanoazocino[4,3-b]indol-6-one) was investigated by using the quantum chemical calculations. All DFT-based analyses were performed by B3LYP, B3LYP-GD3BJ, and M06HF functionals. In addition to the structural and spectroscopic verification of the compound, the solvent effect on the electronic and physical properties was investigated in CHCl3 phase. HOMO& LUMO plots were visualized to represent the reactive site of the compound. NBO results revealed that the resonance interactions (n→π*) are a great role contributed to the lowering of the stabilization energy. 2009 Elsevier Ltd. All rights reserved.

When aprotic Li-O2 batteries recharge, the solid Li2O2 in the positive electrode is oxidized, which often exhibits a continuous or step increase in the charging potential as a function of the charging capacity, and its origin remains incompletely understood. Here, we report a model study of electro-oxidation of a Li2O2 film on an Au electrode using voltammetry coupled with in situ Raman spectroscopy. It was found that the charging reaction initializes at the positive electrode|Li2O2 interface, instead of the previously presumed Li2O2 surface, and consists of two temporally and spatially separated Li2O2 oxidation processes, accounting for the potential rise during charging of Li-O2 batteries. Moreover, the electrode surface-initialized oxidation can disintegrate the Li2O2 film resulting in a loss of Li2O2 into electrolyte solution, which drastically decreases the charging efficiency and highlights the importance of using soluble electro-catalyst for the complete charging of Li-O2 batteries.

Cooperative catalysis has attracted tremendous attention in recent years, emerging as a key strategy for the development of novel atom-economic and environmentally more benign catalytic processes. In particular, Noyori-type complexes with metal-nitrogen bonds have been extensively studied and evolved as privileged catalysts in hydrogenation chemistry. In contrast, catalysts containing metal-sulfur bonds as the reactive site are out of the ordinary, despite their abundance in living systems, where they are assumed to play a key role in biologically relevant processes. For instance, the heterolysis of dihydrogen catalyzed by [NiFe] hydrogenase is likely to proceed through cooperative H-H bond splitting at a polar nickel-sulfur bond. This Account provides an overview of reported metal-sulfur complexes that allow for cooperative E-H bond (E = H, Si, and B) activation and highlights the potential of this motif in catalytic applications. In recent years, our contributions to this research field have led to the development of a broad spectrum of synthetically useful transformations catalyzed by cationic ruthenium(II) thiolate complexes of type [(DmpS)Ru(PR

CO oxidation is a typical heterogeneous catalytic reaction. Development of active and stable low-temperature CO oxidation catalysts has been one of the hot topics in the field of catalysis. In this work, we explored the catalytic application of a series of Au catalysts supported on CeO2 foam using a modified deposition-precipitation method for CO oxidation. Among them, the catalyst with 1.1% Au loading content showed the highest catalytic activity, leading to the CO total conversion at 20 °C. Based on the strategy of stepwise reduction of Au loading content, we finally obtained the atomically monodisperse Au/CeO2 catalyst with high stability and strong resistance to elevated temperature, on which in situ DRIFTS analysis and DFT study were further performed to study the possible reactive site. Our results implied that the Au atoms on the CeO2 foam are the more stable sites for CO adsorption on the catalysts.

Peroxynitrite (ONOO-) has been proven to participate in various physiological and pathological processes, and may also be a contributing factor in many diseases. In view of this, there is a need to develop detection tools for unambiguously tracking a small amount of endogenous ONOO- to reveal its exact mechanisms. In this paper, a colorimetric and red-emitting fluorescent probe Red-PN, based on a rhodamine-type fluorophore and hydrazide reactive site is described. The probe Red-PN possesses the advantages of rapid response (within 5 s), visual color change (from colorless to pink), preeminent sensitivity (detection limit = 4.3 nM) and selectivity. Because of these outstanding performances, it was possible to accurately detect endogenous ONOO-. It was encouraging that the probe Red-PN could be used effectively for tracking the relatively low levels of endogenous and exogenous ONOO- in living cells and zebrafish. Thus, it is envisioned that the probe Red-PN would have promising prospects in applications for imaging ONOO- in a variety of biological settings.

Isoniazid is the most important heterocyclic moiety in organic and medicinal chemistry due to the presence of reactive site in the molecule, which extends its application in various fields. Isoniazid is the most important first-line drug used in the treatment of tuberculosis. The interesting molecular design of isoniazid makes them apt moieties in drug design. In this review, our aim is to summarize recent synthetic strategies and pharmacological properties of isoniazid derivatives

Aldehydes with bulky substituents in the ortho-positions have been historically difficult in porphyrin synthesis, presumably owing to steric hindrance around the reactive site. We have used mechanochemistry for the simple, room-temperature synthesis of tetra-meso-substituted porphyrins. In the present study, mesitaldehyde undergoes acid-catalyzed mechanochemical condensation with pyrrole to give meso-tetrakis[2,4,6-(trimethyl)phenyl]porphyrin (TMP) after oxidation in solution. Yields are similar to those obtained using high-temperature porphyrin synthesis, although they remain significantly lower than some optimized room-temperature, solution-based methods. Yields of the mechanochemical synthesis were found to increase slightly upon longer exposure to an organic oxidizing agent in solution. This indicates that the mechanochemical condensation step may be more successful than initially realized. This work shows that mechanochemistry is a successful, simple, room-temperature method for producing tetra-meso-substituted porphyrins with bulky substituents.

Rationale Neonicotinoid pesticides and their metabolites have been indicated as contributing factors in the decline of honey bee colonies. A thorough understanding of neonicotinoid toxicity requires knowledge of their metabolites and environmental breakdown products. This work investigated the rapid degradation of the neonicotinoid nitenpyram in finished drinking water. Methods Nitenpyram reaction products were characterized using liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOFMS). A software algorithm that compared degraded and control samples was utilized to facilitate efficient data reduction. Fragmentation pathways for six reaction products and nitenpyram were proposed using predictive software and manual product ion analysis. Results This study showed that nitenpyram degradation in unpreserved finished drinking water was likely the result of oxidation, hydrolysis and reaction with Cl2. Structures for six nitenpyram reaction products were proposed that suggest the C9/C11 olefin as the key reactive site. Conclusions Similarities between the identified nitenpyram reaction products and imidacloprid metabolites highlight the importance of this study, as the toxicity of neonicotinoids to pollinators has been linked to their metabolites. Based on the proposed reaction mechanisms, the identified nitenpyram reaction products in finished drinking water could also be present in the environment and water treatment facilities. As such, identifying these degradation products will aid in evaluating the environmental impact of neonicotinoid pesticides. Copyright © 2016 John Wiley & Sons, Ltd.

New indolocarbazole derivatives have been synthesized via Cadogan reaction. It has been found that the reductive cyclization of 3-(2-nitrophenyl)carbazoles prefers to take place on 4-position instead of 2-position in carbazole rings. Because electrophilic substitution was one of the main steps in Cadogan reaction and the Fukui function analysis for 9-methyl-3-(2-nitrophenyl)-9 H -carbazole revealed that more positive part of f − ( r ) function was localized at 4-position than at 2-position in carbazole, the 4-position was the favorite reactive site for the reductive cyclization. Such regioselective Cadogan reaction would be useful for the synthesis of π-extended N -fused heteroacenes with desired functionalities.