Unique Reaction Research Articles

Solid state debromination of C60Br24 back to C60 with cesium iodide: kinetics, thermodynamics and mechanism

The bromofullerene C60Br24 undergoes a complete and quantitative debromination to C60 when it is mixed and ground in the solid state with cesium iodide (CsI). The kinetics of this unique solid state debromination reaction was studied with FT-IR spectroscopy on C60Br24 embedded in CsI pellet. The debromination rate constant was measured k = 8.4 x 10−4 s−1 and found independent from the C60Br24 concentration. Chemical thermodynamics calculations show that the C60Br24 debromination in CsI matrix is characterized by a largely favorable free energy of reaction (ΔGr) and the reaction is exothermal. A debromination mechanism is discussed in terms of concerted elimination of the bromide anions and formation of carbocations on the fullerene cage in agreement with the E1 type elimination reaction mechanism. The carbocations sites are reduced to radicals and stabilized as trivinylmethyl radicals (the reduction occurs by the action of iodide ions of CsI which are oxidized to molecular iodine) and then a rearrangement of the double bonds leads back to C60 quantitatively.

A designed Copper Histidine-brace enzyme for oxidative depolymerization of polysaccharides as a model of lytic polysaccharide monooxygenase

The "Histidine-brace" (His-brace) copper-binding site, composed of Cu(His)2 with a backbone amine, is found in metalloproteins with diverse functions. A primary example is lytic polysaccharide monooxygenase (LPMO), a class of enzymes that catalyze the oxidative depolymerization of polysaccharides, providing not only an energy source for native microorganisms but also a route to more effective industrial biomass conversion. Despite its importance, how the Cu His-brace site performs this unique and challenging oxidative depolymerization reaction remains to be understood. To answer this question, we have designed a biosynthetic model of LPMO by incorporating the Cu His-brace motif into azurin, an electron transfer protein. Spectroscopic studies, including ultraviolet-visible (UV-Vis) absorption and electron paramagnetic resonance, confirm copper binding at the designed His-brace site. Moreover, the designed protein is catalytically active towards both cellulose and starch, the native substrates of LPMO, generating degraded oligosaccharides with multiturnovers by C1 oxidation. It also performs oxidative cleavage of the model substrate 4-nitrophenyl-D-glucopyranoside, achieving a turnover number ~9% of that of a native LPMO assayed under identical conditions. This work presents a rationally designed artificial metalloenzyme that acts as a structural and functional mimic of LPMO, which provides a promising system for understanding the role of the Cu His-brace site in LPMO activity and potential application in polysaccharide degradation.

A strategic approach towards mass balance investigations in pharmaceutical drug substance release testing: A peculiar out of specification case study encountered during API manufacture

Mass balance in drug substances release testing is a critical quality attribute in pharmaceutical manufacturing that continues to challenge modern analytical characterization. This specific perspective of mass balance is lacking in literature, and the following work addresses the knowledge gap related to this topic by examining an in-depth case study and detailing the systematic investigation into mass imbalance observed during release testing of a small molecule API. The process followed a logical stepwise progression beginning with most probable causes and expanded to more obscure causes that require a deeper examination of the API in question until the undetected impurity in question was finally identified. The discovered impurity was eventually found to be formed from a unique side reaction that led to the formation of API-related oligomer impurities, which had eluded conventional small molecule release testing strategies. Ultimately, the characterization gap was traced back to deficiency in the LC results of the developed API purity methods. More importantly, this gap provides an ideal opportunity to highlight common oversights and pitfalls encountered in early phase pharmaceutical development especially as it relates to the method development of truly representative chromatography methods in the API characterization. The work reflects on the key lessons learned from the highlighted pitfalls that were encountered in this case study and offers strategic insights to guide and to improve the development workflow for drug substance characterization strategies.

Promoting OH- Adsorption and Diffusion Enables Ultrahigh Capacity and Rate Capability of Nickel Sulfide Cathode for Aqueous Alkaline Zn-Based Batteries.

Aqueous alkaline Zn-based batteries (AAZBs) possess great promise for large-scale applications thanks to their higher discharging plateau and unique reaction mechanism. However, the capacity and rate capability of Ni-based cathodes are still unsatisfactory due to their insufficient OH- adsorption and diffusion ability. Herein, heterostructured Ni3 S2 /Ni(OH)2 nanosheets with outstanding electrochemical performance are synthesized via a facile chemical etching strategy. The heterostructured Ni3 S2 /Ni(OH)2 nanosheet cathode shows significantly increased capacity and rate capability due to its boosted OH- adsorption and diffusion ability compared to Ni3 S2 . Consequently, the assembled Zn//Ni3 S2 /Ni(OH)2 cell can deliver an ultrahigh capacity of 2.26mAhcm-2 , an excellent rate performance (0.91mAhcm-2 at 100mAcm-2 ) and a satisfying cycling stability (1.01mAhcm-2 at 20mAcm-2 after 500 cycles). Moreover, a prominent energy density of 3.86mWhcm-2 is obtained, which exceeds the majority of recently reported AAZBs. This work is expected to provide a new modification direction for developing high-performance nickel sulfide cathode for AAZBs.

Preorganized Internal Electric Field Promotes a Double-Displacement Mechanism for the Adenine Excision Reaction by Adenine DNA Glycosylase.

Adenine DNA glycosylase (MutY) is a monofunctional glycosylase, removing adenines (A) misinserted opposite 8-oxo-7,8-dihydroguanine (OG), a common product of oxidative damage to DNA. Through multiscale calculations, we decipher a detailed adenine excision mechanism of MutY that is consistent with all available experimental data, involving an initial protonation step and two nucleophilic displacement steps. During the first displacement step, N-glycosidic bond cleavage is accompanied by the attack of the carboxylate group of residue Asp144 at the anomeric carbon (C1'), forming a covalent glycosyl-enzyme intermediate to stabilize the fleeting oxocarbenium ion. After departure of the excised base, water nucleophiles can be recruited to displace Asp144, completing the catalytic cycle with retention of stereochemistry at the C1' position. The two displacement reactions are found to mostly involve the movement of the oxocarbenium ion, occurring with large charge reorganization and thus sensitive to the internal electric field (IEF) exerted by the polar protein environment. Intriguingly, we find that the negatively charged carboxylate group is a good nucleophile for the oxocarbenium ion, yet an unactivated water molecule is not, and that the electric field catalysis strategy is used by the enzyme to enable its unique double-displacement reaction mechanism. A strong IEF, pointing toward 5' direction of the substrate sugar ring, greatly facilitates the second displacement reaction at the expense of elevating the barrier of the first one, thereby allowing both reactions to occur. These findings not only increase our understanding of the strategies used by DNA glycosylases to repair DNA lesions, but also have important implications for how internal/external electric field can be applied to modulate chemical reactions.

A sonochemical approach for a silver particle layer SERS substrates preparation and subsequent application in qualitative analysis

We present an easy and efficient method for silver particle layer SERS substrate preparation that combines a modified Tollens’ approach with using ultrasound to obtain unique reaction conditions by generating high-energy hot-spots as the arising acoustic cavities implode. The silver layers were deposited on various substrates in a one-step reduction process of silver nitrate. Three different reductants (maltose, glucose, ascorbic acid) were used to obtain silver particle layers with different particle sizes, morphologies, and inter-particle distances. To further optimize the properties of the silver particles for SERS and to provide higher signal enhancement, all the prepared nanoparticle layers were activated in 4 M Cl− solution. The size of silver particles was in most samples under 100 nm and the particles formed clusters, but they were also present on the surface individually. In some of the activated substrates, bigger particles (0.5–1 μm) occur as well. The activated as well as non-activated substrates were tested as SERS substrates using 10−5 M adenine as a model analyte. Laser wavelengths of 455 nm, 532 nm, 633 nm, 780 nm, and 785 nm were used for the SERS measurements. High enhancement factors up to 3.5·105 and 2.8·105 were obtained for SERS measurements using lasers of 532 nm and 780 nm, respectively.

Exploring the Divergent Reactivity of Vinyl Radicals Emanating from Alkynes and Thiols via Photoredox Catalysis.

Organic chemistry has seen a surge in visible-light-driven transformations, which offer unique reaction pathways and access to new synthetic possibilities. We aim to provide a comprehensive understanding of state-of-the-art photo-mediated alkyne functionalization, with a focus on the reactive behavior of vinyl radicals. This review outlines our contributions to the field, including developing new methods for forming carbon-carbon and carbon-heteroatom bonds.

Substituent effects of amines on genipin dye formation – Insights into dye origin

Genipin, a naturally occurring iridoid, represents an interesting class of reactive dyes. This colorless molecule produces brilliant blue dyes in the presence of primary aliphatic amines. The mechanism behind this unique reaction has been suggested to proceed via an oxidative polymerization reaction. By utilizing aromatic amines, we demonstrate that the dye absorption properties can be redshifted to form green dyes as opposed to the blue that is most associated with aliphatic amines. These results led us to explore the mechanism of dye formation using X-Ray crystallography, DFT calculations, electrochemical experiments, mass spectrometry, and EPR spectroscopy on slightly structurally perturbed genipin scaffolds. Herein we report the first findings of a crystallographically characterized pseudoazulenic genipin dye intermediate and the impacts of redox chemistry on the resulting dyes, which shows electrochromic reversibility.

Annulation‐Induced Hidden Reactivity of the 1,2,4‐Triazole Backbone

AbstractTriazoles are an important class of compounds with widespread applications. Functionalization of the triazole backbone is thus of significant interest. In comparison to 1,2,3‐triazoles, C−H activation‐functionalization of the congeners 1,2,4‐triazoles is surprisingly underdeveloped. Indeed, no such C−H activation‐functionalization has been reported for 4‐substituted 1,2,4‐triazole cores. Furthermore, although denitrogenative ring‐opening of 1,2,3‐triazoles is well‐explored, 1,2,4‐triazole/triazolium substrates have not been known to exhibit N−N bond‐cleaving ring‐opening reactivity so far. In this work, we unveiled an unusual hidden reactivity of the 1,2,4‐triazole backbone involving the elusive N−N bond‐cleaving ring‐opening reaction. This new reactivity was induced by a Satoh‐Miura‐type C−H activation‐annulation at the 1,2,4‐triazole motif appended with a pyridine directing group. This unique reaction allowed ready access to a novel class of unsymmetrically substituted 2,2′‐dipyridylamines, with one pyridine ring fully‐substituted with alkyl groups. The unsymmetrical 2,2′‐dipyridylamines were utilized to access unsymmetrical boron‐aza‐dipyridylmethene fluorescent dyes. Empowered with desirable optical/physical properties such as large Stokes shifts and suitable hydrophobicity arising from optimal alkyl chain length at the fully‐substituted pyridine‐ring, these dyes were used for intracellular lipid droplet‐selective imaging studies, which provided useful information toward designing suitable lipid droplet‐selective imaging probes for biomedical applications.

Annulation-Induced Hidden Reactivity of the 1,2,4-Triazole Backbone.

Triazoles are an important class of compounds with widespread applications. Functionalization of the triazole backbone is thus of significant interest. In comparison to 1,2,3-triazoles, C-H activation-functionalization of the congeners 1,2,4-triazoles is surprisingly underdeveloped. Indeed, no such C-H activation-functionalization has been reported for 4-substituted 1,2,4-triazole cores. Furthermore, although denitrogenative ring-opening of 1,2,3-triazoles is well-explored, 1,2,4-triazole/triazolium substrates have not been known to exhibit N-N bond-cleaving ring-opening reactivity so far. In this work, we unveiled an unusual hidden reactivity of the 1,2,4-triazole backbone involving the elusive N-N bond-cleaving ring-opening reaction. This new reactivity was induced by a Satoh-Miura-type C-H activation-annulation at the 1,2,4-triazole motif appended with a pyridine directing group. This unique reaction allowed ready access to a novel class of unsymmetrically substituted 2,2'-dipyridylamines, with one pyridine ring fully-substituted with alkyl groups. The unsymmetrical 2,2'-dipyridylamines were utilized to access unsymmetrical boron-aza-dipyridylmethene fluorescent dyes. Empowered with desirable optical/physical properties such as large Stokes shifts and suitable hydrophobicity arising from optimal alkyl chain length at the fully-substituted pyridine-ring, these dyes were used for intracellular lipid droplet-selective imaging studies, which provided useful information toward designing suitable lipid droplet-selective imaging probes for biomedical applications.

Enhancing catalytic oxidation of toluene over Ag/Co3O4 by regulating Ag-Co interaction

Tuning the interaction between Ag and its supporters has been well accepted as a desirable way that adjusting the physicochemical properties and the catalytic performance of Ag-based catalysts. In this work, an in-situ surface reaction strategy was proposed to prepare high-performance Ag/Co3O4 catalyst by controlling the Ag-Co interaction for the purpose of efficient degradation of aromatic VOCs. The results of characterizations confirmed that the unique surface reaction strategy was conducive to anchoring Ag on the surface of Co3O4 and significantly enhanced Ag-Co interaction, as a result, Co-O bond was weakened by charge transfer between Ag and Co species, which showed great advantages in improving the reactivity of lattice oxygen species and in accelerating the adsorption of gaseous oxygen. Benefiting from this, 1%Ag/Co3O4-R synthesized by surface reaction method exhibited the best catalytic efficiency (T90 = 238 °C), excellent stability and admirable cyclic stability. In-situ DRIFTS spectroscopy investigation revealed that the loading of Ag remained unchanged reaction path of the catalytic oxidation of toluene, and benzoate was deemed a decisive stage in the oxidation course of toluene.

(Invited) Regimes of Reaction-Diffusion Processes Nearby the Plasma-Liquid Interface

Plasma-liquid systems are usually comprised of an atmospheric-pressure plasma electrode and a liquid surface, which can have a bubbly and irregular, or a smooth surface. When coupled with a metal counter electrode immersed in the liquid, this configuration has been shown to form capable electrochemical systems that can degrade recalcitrant pollutants, conduct organic chemistry and when reactive gases are used, can create unique gas-liquid reaction pathways for important processes such as N2 fixation and CO2 utilization. Up to date, many different types of plasmas with different frequencies, plasma electrode shapes, gas flow rates and applied powers have been utilized in literature. One common aspect of most plasma sources in plasma-liquid systems is that the current density at the interface is much higher than in conventional electrochemical systems. Consequently, the observed rate constants of some of the plasma-assisted processes mentioned above have been found to fall in a rather narrow range of values, despite the vast differences in plasma sources. This is an indication of mass transport playing a crucial role in the observed kinetics. This argument is supported by experimental results obtained through changing current in continuous plasmas and changing frequency in pulsed plasmas.When mass transport rate is of the same order with reaction rate or slower, the observed picture for kinetics requires a mathematical description of the interplay of reaction and diffusion to elucidate intrinsic kinetic data. A phenomenological, yet practical and predictive modeling framework has not yet been established for plasma-liquid systems. Despite new kinetics that arise from the unique species produced at the plasma liquid interface, gas-liquid contacting is a well-established field in chemical engineering. In this talk, early chemical engineering studies on gas-liquid contacting will be summarized and the reaction-diffusion models developed through these studies will be applied to plasma-electrochemical systems. According to the theory, multiple regimes of reaction-diffusion processes must exist, and some of these regimes can be reduced to simpler analytical models that allow compact expressions for the observed rate constant and faradaic efficiency. Examples on applying the modeling framework to published experimental data will be given and the criteria that determine the validity of the model equations will be discussed.

Investigations of Charge Transfer Processes on Plasmonic Cathode Electrodes

The establishment of efficient light energy conversion system is an important issue in the field of photoelectrochemical region. For the realization of it, the wide-band semiconductor electrode could be the good candidate. However, semiconductor electrodes often have the limitation to the ultraviolet region because of their band gap energy. Because the sunlight energy mainly consists of visible light, the visible-light induced photoenergy conversion is a challenging issue. As the breakthrough for it, recently, the combination of the plasmonic metal nanostructures with wide semiconductor electrodes has been received much attention because of the addition of visible light response characters. Up to now, the various systems of the anodic reaction controls have been established. Recently, the cathode system which can control the reduction reactions at metal semiconductor interfaces have been reported via the introduction of plasmonic metal nanostructures into the p-type semiconductor electrodes. In our previous study, we have established the plasmonic photocathode by using the Ag nanostructures with the p-type GaP electrode [1]. In this system, it can be considered as the holes excited in the metal structures injected into the valence band of the p-type semiconductor and the remained electron are consumed in the hydrogen evolution reaction. In addition, we have observed the unique pH dependence on the hydrogen evolution which could not be observed on conventional metal electrodes. For understanding the unique reaction selectivity on the plasmonic cathode electrode, the detail understanding about both the charge transfer process and absolute electrochemical potential of generated electrons. In this study, we have attempted to obtain such information through the various chemical reactions using the various types of plasmonic structures. Through the various photoelectrochemical measurements, we have confirmed the changes in the electrochemical potential of excited electrons depending on the optical characters of plasmonic structures. The unique molecular selectivity was also observed. Our current research would provide the novel insight for the accurate design of the high efficient visible light conversion device.[1] H. Minamimoto et al., Chem. Lett., 2020, 49, 806.

QS21-Initiated Fusion of Liposomal Small Unilamellar Vesicles to Form ALFQ Results in Concentration of Most of the Monophosphoryl Lipid A, QS21, and Cholesterol in Giant Unilamellar Vesicles.

Army Liposome Formulation with QS21 (ALFQ), a vaccine adjuvant preparation, comprises liposomes containing saturated phospholipids, with 55 mol% cholesterol relative to the phospholipids, and two adjuvants, monophosphoryl lipid A (MPLA) and QS21 saponin. A unique feature of ALFQ is the formation of giant unilamellar vesicles (GUVs) having diameters >1.0 µm, due to a remarkable fusion event initiated during the addition of QS21 to nanoliposomes containing MPLA and 55 mol% cholesterol relative to the total phospholipids. This results in a polydisperse size distribution of ALFQ particles, with diameters ranging from ~50 nm to ~30,000 nm. The purpose of this work was to gain insights into the unique fusion reaction of nanovesicles leading to GUVs induced by QS21. This fusion reaction was probed by comparing the lipid compositions and structures of vesicles purified from ALFQ, which were >1 µm (i.e., GUVs) and the smaller vesicles with diameter <1 µm. Here, we demonstrate that after differential centrifugation, cholesterol, MPLA, and QS21 in the liposomal phospholipid bilayers were present mainly in GUVs (in the pellet). Presumably, this occurred by rapid lateral diffusion during the transition from nanosize to microsize particles. While liposomal phospholipid recoveries by weight in the pellet and supernatant were 44% and 36%, respectively, higher percentages by weight of the cholesterol (~88%), MPLA (94%), and QS21 (96%) were recovered in the pellet containing GUVs, and ≤10% of these individual liposomal constituents were recovered in the supernatant. Despite the polydispersity of ALFQ, most of the cholesterol, and almost all of the adjuvant molecules, were present in the GUVs. We hypothesize that the binding of QS21 to cholesterol caused new structural nanodomains, and subsequent interleaflet coupling in the lipid bilayer might have initiated the fusion process, leading to creation of GUVs. However, the polar regions of MPLA and QS21 together have a "sugar lawn" of ten sugars, the hydrophilicity of which might have provided a driving force for rapid lateral diffusion and concentration of the MPLA and QS21 in the GUVs.

Direct microwave energy input on a single cation for outstanding selective catalysis.

Microwave (MW)-driven catalytic systems are attracting attention not only as an aggressive electrification strategy of the chemical industry but also as creating a unique catalytic reaction field that conventional equilibrium heating cannot achieve. This study unlocked direct and selective heating of single alkali metal cations in the pores of aluminosilicate zeolites under MW. Selectively heated Cs+ cations in FAU zeolite exhibited selective CH4 combustion performance, that is, COx generation at the heated Cs+ cations selectively occurred while side reactions in the low-temperature gas phase were suppressed. The Cs-O pair distribution function revealed by synchrotron-based in situ x-ray total scattering gave us direct evidence of peculiar displacement induced by MW, which was consistent with the results of molecular dynamics simulation mimicking MW heating. The concept of selective monoatomic heating by MW is expected to open a next stage in "microwave catalysis" science by providing physicochemical insights into "microwave effects."

Predicting photooxidant concentrations in aerosol liquid water based on laboratory extracts of ambient particles

Abstract. Aerosol liquid water (ALW) is a unique reaction medium, but its chemistry is poorly understood. For example, little is known of photooxidant concentrations – including hydroxyl radicals (⚫OH), singlet molecular oxygen (1O2*), and oxidizing triplet excited states of organic matter (3C*) – even though they likely drive much of ALW chemistry. Due to the very limited water content of particles, it is difficult to quantify oxidant concentrations in ALW directly. To predict these values, we measured photooxidant concentrations in illuminated aqueous particle extracts as a function of dilution and used the resulting oxidant kinetics to extrapolate to ALW conditions. We prepared dilution series from two sets of particles collected in Davis, California: one from winter (WIN) and one from summer (SUM). Both periods are influenced by biomass burning, with dissolved organic carbon (DOC) in the extracts ranging from 10 to 495 mg C L−1. In the winter sample, the ⚫OH concentration is independent of particle mass concentration, with an average value of 5.0 (± 2.2) × 10−15 M, while in summer ⚫OH increases with DOC in the range (0.4–7.7) × 10−15 M. In both winter and summer samples, 3C* concentrations increase rapidly with particle mass concentrations in the extracts and then plateau under more concentrated conditions, with a range of (0.2–7) × 10−13 M. WIN and SUM have the same range of 1O2* concentrations, (0.2–8.5) × 10−12 M, but in WIN the 1O2* concentration increases linearly with DOC, while in SUM 1O2* approaches a plateau. We next extrapolated the relationships of oxidant formation rates and sinks as a function of particle mass concentration from our dilute extracts to the much more concentrated condition of aerosol liquid water. Predicted ⚫OH concentrations in ALW (including mass transport of ⚫OH from the gas phase) are (5–8) × 10−15 M, similar to those in fog/cloud waters. In contrast, predicted concentrations of 3C* and 1O2* in ALW are approximately 10 to 100 times higher than in cloud/fogs, with values of (4–9) × 10−13 M and (1–5) × 10−12 M, respectively. Although ⚫OH is often considered the main sink for organic compounds in the atmospheric aqueous phase, the much higher concentrations of 3C* and 1O2* in aerosol liquid water suggest these photooxidants will be more important sinks for many organics in particle water.

Cyclodextrin glucanotransferase: fundamentals and biotechnological implications.

Cyclodextrin glucanotransferase (CGTase) is an extracellular enzyme of the GH13 α-amylase family that catalyzes a unique intramolecular reaction known as cyclization to transform α-1, 4-glucans and similar starches into cyclodextrins. They also catalyze intermolecular transglycosylation reactions namely coupling, disproportionation, and some hydrolyzing effects on starch. The monomeric structures of the CGTase exhibit five domains (A, B, C, D, and E domains) with different molecular weights and amino acid sequences depending on the source. Among bacteria, Bacillus genus covers approximately 90% of the CGTase producers, while other genera like Klebsiella, Paenibacillus, and Thermoanaerobacter also shown decent contributions in recent studies. CGTase production is highly supported by alkaliphilic bacteria under submerged fermentation rather than solid-state fermentation. The bacterial sources, biochemical properties, production conditions, and structure of CGTases are compiled in this review. Cyclodextrins have the unique property of making inclusion complexes with various compounds, hence widely used in the food, pharmaceutical, cosmetics, laundry, and chemical sectors. This review presents a comprehensive view of CGTase produced by Bacillus spp., and other bacterial genera like Klebsiella, Paenibacillus, and Microbacterium. It also gives insight of the properties and recent biotechnological applications of cyclodextrins. KEY POINTS: • Transglycosylation reactions catalyzed by CGTase and their structural properties. • Comparative data of CGTase production by various genera and Bacillus spp. • Structures, properties, and applications of different cyclodextrins.

Exploring Novel Synthetic Concepts and Strategies Using Mechanochemistry

Abstract In the field of organic synthesis, a ball-milling synthetic technique has garnered significant attention in recent years as an eco-friendly and sustainable alternative to traditional solution-based methods. In addition to its environmental benefits, solid-state organic synthesis using mechanochemical protocols enables access to novel areas of chemical space that are unavailable by conventional solution-based reactions. In this context, we are interested in designing and developing new organic transformations based on the unique solid-state reaction environment and the use of mechanical forces in a ball mill. In this Account, we highlight our latest findings concerning the creation of novel synthetic concepts and strategies. These approaches harness the distinctive reaction environment of mechanochemistry, rather than merely transferring well-established reactions from solution-based protocols to mechanochemical conditions.

Plasmon-Driven Photochemical Reduction Reaction on Silver Nanostructures for Green Fabrication of Superhydrophobic Surface.

Green fabrication of superhydrophobic surface by water-based processing is still challenging, because introduction of the substances with hydrophilic moieties compromises its superhydrophobicity. Herein, a plasmon-driven photochemical reduction reaction under ultraviolet light (UVA) irradiation is first discovered and is applied to deoxygenation of hydrophilic organic adsorbates on rough nano-Ag coating for the formation of stable superhydrophobic surface. A nano-Ag coating with strong localized surface plasmon resonance in the UVA region is prepared by a water-based silver mirror reaction and results in a unique chemical reduction reaction on its surface. Consequently, the low residual hydrophilic functionalities and the formed cross-linked structure of the adsorbate on Ag nanoparticles (NPs) enables the coating to exhibit stable superhydrophobicity against to both air and water. The superhydrophobic Ag NP-coated sandpaper can also be used as a surface-enhanced Raman scattering (SERS) substrate to concentrate aqueous analytes for trace detection.

Synthesis and Reactivity of Trifluoromethylthiophosphonium Salts†

Comprehensive SummaryThis article described an unprecedented synthesis of trifluoromethylthiophosphonium salts from allyl trifluoromethyl sulfoxide and phosphines in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) through Mislow‐Evans‐type rearrangement. The resulting trifluoromethylthiophosphonium salts were firstly isolated and fully characterized. These fluoroalkylphosphonium salts, as exemplified by trifluoromethylthio triphenylphosphonium salt (6a), exhibited unique and versatile reaction with nucleophiles and deoxygenative trifluoromethylthiolation reaction of carboxylic acids. Furthermore, the photoredox catalytic tunable radical hydrotrifluoromethylation and hydrotrifluoromethythiolation of unactivated alkenes with 6a was successfully developed.