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The document is a contents list for the journal "Chemical Communications" published in 2024. It includes highlights, feature articles, and communications on various topics related to chemistry. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The contents list provides a range of research articles on topics such as catalysts, perovskites, photoluminescence, and electrocatalysis. [Extracted from the article]

Developed here is a highly fluorescent organic N,O bidentate BF2 complex from isoxazole in the presence of a Ru(II) catalyst. Herein, the complexation proceeds via a selective N–O cleavage of the isoxazole ring. The complex shows absorption (λmax,abs) in the range of 352–363 nm with an extinction coefficient (ε) in the range of 8000–64 000 M−1 cm−1, and fluorescence emission (λmax,em) in the range of 413–485 nm with a Stokes shift of 61–125 nm having quantum yield up to 33%. Apart from the solution state, the solid BF2 complex 2u exhibits absorption at 405 nm and strong fluorescence emission at 550 nm with a quantum yield of 26.9%. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "A robust and porous titanium metal-organic framework for gas adsorption, CO2 capture and conversion" published in the journal Dalton Transactions. The correction notice, numbered 12797, acknowledges an error in the original article but does not provide any specific details about the nature of the error or the correction made. The article itself explores the topic of a titanium metal-organic framework and its potential applications in gas adsorption, CO2 capture, and conversion. The journal, published by The Royal Society of Chemistry, covers a wide range of topics in inorganic chemistry and is a respected resource in the field. [Extracted from the article]

Electrocatalytic water splitting is a promising production method for green hydrogen; however, its practical application is limited by the lack of robust catalysts for the cathode hydrogen evolution reaction (HER). Recently, the use of Ru in electrocatalytic HER has become a research hotspot because Ru has a metal–hydrogen bond strength similar to that of Pt – known for its excellent HER activity – but has a lower cost than Pt. Numerous modification strategies are available to further improve the HER activity of metal Ru such as vulcanisation, phosphating and atomisation. The atomisation strategy has attracted much attention owing to its extremely high Ru atomic utilisation efficiency and tunable electronic structures. However, isolated studies could not effectively address the bottlenecks. Therefore, to promote the effective exploration of Ru-based single-atom catalysts and clarify the research status in this field, studies on related topics (e.g. Ru single-atom catalysts, Ru dual-atom catalysts, composite catalysts containing single-atom Ru and Ru nanoparticles) have been systematically and briefly summarised herein. Finally, the research challenges and prospects of Ru-based single-atom catalysts in the HER field have been discussed, which may provide valuable insights for further research. [ABSTRACT FROM AUTHOR]

Chemical Communications is a journal published by The Royal Society of Chemistry, which is a leading chemistry community. The journal features articles on various topics in the chemical sciences. The current issue includes articles on utilizing trees to produce advanced materials, the synthesis of borylated polyene building blocks, and the use of self-assembling short peptide amphiphiles as delivery agents in antibacterial research. It also includes communications on topics such as the reduction of SO2, the decomposition of ammonia, and the shaping of CPO-27-M through crystallization. The journal aims to provide original discoveries and contribute to scientific progress. [Extracted from the article]

The reaction of [Ru(dmso)4Cl2] with a potassium salt of four xanthate (RO–C(＝S)S−; R = Me, Et, iPr and tBu) ligands (depicted as Ln; n = 1–4) in hot methanol afforded a group of mixed-ligand complexes of type [Ru(Ln)2(dmso)2]. The crystal structures of all the four complexes have been determined, which show that the xanthate ligands are bound to the metal center forming four-membered chelates and dmso is coordinated through sulfur and they are mutually cis. The relative thermodynamic stability of this cis and the other possible trans-isomers of these complexes has been assessed with the help of DFT calculations, which have revealed that the cis-isomer is the more stable isomer. The coordinated dmso in the [Ru(Ln)2(dmso)2] complexes could be easily displaced by chelating bidentate ligands (depicted as L′) to furnish complexes of type [Ru(Ln)2(L′)], as demonstrated through isolation of two such complexes, viz. [Ru(L3)2(bpy)] and [Ru(L2)2(phen)] (bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline). The crystal structure of [Ru(L3)2(bpy)] has been determined and the structure of [Ru(L2)2(phen)] has been optimized by the DFT method. The electronic spectra of the four [Ru(Ln)2(dmso)2] complexes and the two derivatives ([Ru(Ln)2(L′)]; n = 3, L′ = bpy; n = 2, L′ = phen), recorded in dichloromethane solutions, show intense absorptions spanning the visible and ultraviolet regions, which have been analyzed by the TDDFT method. The [Ru(Ln)2(dmso)2] complexes are found to serve as efficient catalyst precursors for the acceptorless dehydrogenation of 2-propanol followed by crossed-aldol condensation with substituted benzaldehydes (and related aldehydes), using tert-butoxide as the co-catalyst, producing dibenzylideneacetone derivatives in good yields. [ABSTRACT FROM AUTHOR]

Reaction of a sterically demanding iminophosphorano-phosphine, Ph2PCH2Ph2P＝NAr* (here onwards referred to as PCPNAr*; Ar* = 2,6-dibenzhydryl-4-methylphenyl), (1) with [Ru(η6-p-cymene)Cl2]2 yielded three different types of complex, [RuCl2{(η6-p-cymene)(PCPNAr*)-κ1-P}] (2), [RuCl{(P(O)CPNAr*)(κ2-N,C)(C-η6-arene)}] (3) and [RuCl{(POCP＝NAr*)(κ2-N,C-o)(C-η6-arene)}] (4), depending on the reaction conditions via CH activation, tethered η6-arene coordination, ortho-metallation or P＝N bond cleavage/rearrangement reactions. Interestingly, a similar reaction in CH3CN in the presence of AgBF4 resulted in the insertion of CH3CN into the P＝N bond to form a novel metallacycle [Ru(NCMe)3{(PC2P＝N(CH3)C＝NAr*)-κ3-N,N,P}][BF4]2 (5) containing 4- and 5-membered rings via an aza-Wittig type reaction. Complex 4 showed very good catalytic activity in the transfer hydrogenation of carbonyl compounds. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Chemical Communications" published on July 4, 2024. It includes articles on various topics such as the aggregation and phase separation of a-synuclein in Parkinson's disease, the design of stimuli-responsive materials using cleavable azobenzene linkers, and the selective encapsulation of carboxylic acid dimers. The journal is published by The Royal Society of Chemistry, a leading chemistry community, and covers both natural and synthetic polymers. The document also provides information on the application of polymers and the journal's open access policy. [Extracted from the article]

The ruthenium (Ru)-based functional structure has been well understood in catalytic performance due to its special particularity in structural fabrication. In this work, the controllable synthesis of core–shell Ru nanomaterials is first reported, which were not only realized via ice bath conditions with amorphous characterization but also showed a flexible design in the controllable synthesis of crystalline Ru after high intensity focused ultrasound (HIFU) treatment. The achieved amorphous Ru particles (∼115 ± 3 nm) and crystalline Ru (∼5 ± 0.5 nm) exhibit hydrogen peroxide catalytic performance and can be considered as an electrochemical sensing platform. The Km value of core–shell Ru for 3,3′,5,5′-tetramethylbenzidine (TMB) was 0.221 mM, which exhibits higher affinity for TMB and prominent catalytic performance than horseradish peroxidase (HRP). For selectivity and sensitivity towards the detection of H2O2 molecules, it expressed a wide linear range from 0.5 to 100 mM with an H2O2 detection limit of 1.45 μM (S/N = 3) and a sensitivity of 2.07 μA μM−1. After HIFU treatment, the diameter of the achieved crystalline Ru was about one-twentieth that of the core–shell Ru structure. An enhancement in catalytic performance was observed as a sensor platform for detecting H2O2, its detection range was wider, from 0.5 to 110 mM, its limit of detection was 0.007 μM (S/N = 3), and it exhibited a higher sensitivity of 443 μA μM−1. Hence, this flexible design in the synthesis of Ru NMs (amorphous and crystalline in status) could provide a novel synthetic strategy and make achievements in catalytic performance. [ABSTRACT FROM AUTHOR]

The document is the contents list for the journal "Chemical Communications" published in 2024. It includes a variety of articles on topics such as bond formation, catalysis, spectroscopy, and materials science. The journal is published by The Royal Society of Chemistry and is dedicated to sustainable chemistry and new solutions. The articles cover a range of research areas and provide valuable insights into the field of chemistry. [Extracted from the article]

The document is a contents list for the journal "Chemical Communications" published in 2024. It includes various articles on topics such as catalyst design for carbon nanotubes, hydrogen bond types, DNA aptamer molecules, plutonium peroxides, and C-H alkylation. The journal is published by The Royal Society of Chemistry and focuses on connecting the world with the chemical sciences. [Extracted from the article]

As a dual-functional catalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), Ru clusters have great potential, but there are certain difficulties regarding their stability on the substrate and the tunability of their electronic environment. Here, the S doped graphited biochar aerogel electrocatalyst was designed and synthesized using terrestrial lignin and algal polysaccharide as a carbon substrate. The Ru clusters were anchored on the S-doped carbon aerogel (P-Ru/SC) by carefully designing the Ru-S bond via a novel plasma assisted high temperature carbonization treatment. The optimized P-Ru/SC-2 catalyst exhibits excellent electrocatalytic performance for the HER and OER, achieving ultra-small overpotentials of 119.6 mV and 193.4 mV at 10 mA cm-2. The dual-electrode requires only 1.47 V to reach 10 mA cm-2. It is worth noting that a large number of S sites on graphited carbon can strongly interact with the Ru clusters, significantly improving the catalytic activity and stability for the HER and OER. [ABSTRACT FROM AUTHOR]

In this work, Ru nanoparticles doped with Mo on reduced graphene oxide (RuMo/rGO) are prepared through synchronous reduction of RuCl3, MoCl5, and graphene oxide. The compositions, morphologies, and structures of the as-prepared RuMo/rGO composites are fully characterized. Their catalytic properties in oxidative cleavage of β-O-4 linkages in lignin model compounds and lignin are explored. It is illustrated that with O2 as the oxidant RuMo/rGO shows overall better catalytic performance in the oxidative cleavage of β-O-4 linkages than the catalysts, such as Ru/rGO and RuCo/rGO, reported in our previous work. The catalytic mechanism is elaborated through experiments and density functional theory (DFT) calculation. Pronouncedly, we show that the as-doped Mo can effectively boost the molecular oxygen activation process and the adsorption of β-O-4 model compounds on the Ru nanoparticle surface on rGO, and thus enhance the catalytic activity. It is demonstrated meanwhile that RuMo/rGO can catalyze the depolymerization of organosolv birch lignin yielding 17.1% aromatic compounds under relatively mild conditions (100 °C, 0.3 MPa O2, 12 h, pH = 12). [ABSTRACT FROM AUTHOR]

The 5 wt% Ru/AC catalysts were prepared using the impregnation method. The catalysts were characterized by N2 physical adsorption, XRD, SEM, EDX, TEM and ICP-AES. The catalytic activity and stability of the catalysts in decomposing hydroxylamine nitrate (HAN) and hydrazine nitrate (HN) in nitric acid were evaluated. The results demonstrated that the Ru/AC catalyst effectively decomposed HAN and HN with complete conversion under moderate reaction conditions (60–90 °C). When used for an extended duration of 1580 hours in radioactive nitric acid waste liquid, this catalyst displayed a remarkable processing capacity of 6.32 kilograms per gram of catalyst. Due to its environmentally friendly nature resulting from harmless gas product formation along with its simple device structure design, this protocol offers practicality and economic attractiveness. [ABSTRACT FROM AUTHOR]

A potassium (K)-promoted Ru-based siliceous molecular sieve catalyst, K-nRu-MCM-41, was successfully synthesized via a hydrothermal method. The combined analysis of XRD, FT-IR and XPS data revealed that Ru exists in the framework of the molecular sieves as RuO2 species, leading to structural alterations. SEM and TEM images demonstrated that Ru doping disrupts the morphology of the molecular sieves, while K addition effectively preserves the original morphology and further enhances particle dispersion. The ammonia decomposition performance test indicated that K promotes the activity of the molecular sieve catalysts. At 450 °C and 12 000 mL gcat−1 h−1, K-4Ru-MCM-41 achieved 82.7% ammonia conversion and 253.6 mmol gRu−1 min−1 hydrogen production, respectively, which was a 7.6% increase in ammonia conversion compared with 4Ru-MCM-41. Furthermore, the K-4Ru-MCM-41 catalyst exhibited excellent reusability, maintaining its stable catalytic activity performance after 30 h. [ABSTRACT FROM AUTHOR]

In this study, a trimetallic catalyst, NiWRu@NF, is electrodeposited onto nickel foam using chronoamperometry to enhance the hydrogen evolution reaction (HER) in alkaline water electrolysis. The catalyst combines nickel, tungsten, and ruthenium components, strategically designed for efficiency and cost-effectiveness, hydroxyl transfer and water dissociation, and acceleration of hydrogen combination, respectively. Evaluation of NiWRu@NF reveals exceptional performance, with a low overpotential of -50 mV and high current density of -10 mA cm-2, signifying its efficiency in promoting HER. Tafel values further corroborate the catalyst's effectiveness, indicating a rapid reaction rate of hydrogen evolution in such a highly alkaline medium compared to other controls studied along with it. This study underscores the significance of NiWRu@NF in advancing alkaline HER kinetics, paving the way for more efficient electrolysis processes. [ABSTRACT FROM AUTHOR]

The preparation of alanine from waste polylactic acid (PLA) is not only an effective way to recycle waste plastics, but also of great significance to develop a green, clean and efficient amino acid production process. In this work, we studied the synthesis of alanine by amination of PLA with ammonia solution over different types of supported bimetallic catalysts without external hydrogen. It was found that the bimetallic catalyst consisting of Ru and a non-precious metal Co supported on TiO2 (Ru–Co/TiO2) was efficient for the reaction. The selectivity of alanine and turnover frequency (TOF) were 65.2% and 1.5 h−1, respectively. The synergistic effect existing between Ru and Co in the catalyst was crucial for the catalytic performance, and the content of precious metal Ru in the catalyst was lower. This was the first attempt to introduce a non-precious metal component into the catalyst for the amination of polylactic acid to alanine through thermocatalysis. [ABSTRACT FROM AUTHOR]

In this study, eleven Ru-based dyes have been theoretically designed by substitution of different anchors. Their light harvesting capability in dye-sensitized solar cells (DSSCs) and non-linear optical (NLO) properties were subsequently explored. The structural, optoelectronic and NLO properties of these Ru(II) complexes are analyzed using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods in both the gas phase and acetonitrile. The results illustrate that the changing of the anchoring groups on the bpy ligand of complex [Ru(bpy)2(NCS)2] could reduce the energy gap (Eg), redshift the maximum absorption wavelengths (λmax), increase the oscillator strength (ƒ) and light-harvesting efficiency (LHE), and enhance the driving force of injection (ΔGinj), thus amplifying the efficiency of the DSSC. According to the results, the presence of nitro (–NO2) anchors in the complex [Ru(bpy)2(NCS)2] (Ru-dye 8) led to a reduction in open circuit voltage (Voc = 0.45 eV), while significantly decreasing the energy gap (2.05 eV) and notably increasing the excitation wavelength (657 nm). Ru-dye 9 exhibited the largest static first hyperpolarizability (β0 = 273 × 10−30 e.s.u.) compared to the other Ru-dyes. This study provides valuable insights into the understanding of Ru-based dyes in DSSC devices and NLO materials. [ABSTRACT FROM AUTHOR]

The document is a contents list for the New Journal of Chemistry, providing a range of research topics for library patrons interested in chemistry. It includes articles on the transformation of CO2, mechanochromic photoluminescence, nanocellulose-based electrocatalysts, bone formation rate prediction, and the synthesis of halogenated benzimidazolyl-C nucleosides. The journal also covers industrial chemistry, material innovations, and interdisciplinary features. Additionally, the document includes a retraction notice for a previous paper. [Extracted from the article]

The availability of catalytic sites for contact with reactants is a key issue to improve the performance of a catalyst, where constructing hollow structured nanomaterials has been considered as an effective strategy. Here, an N-doped carbon supported Ru catalyst with an interior cavity was synthesized by etching a MOF-derived core–shell precursor, in which metal Ru can be highly dispersed in the porous shell. This catalyst shows 98.7% conversion and >99% selectivity towards p-chloroaniline in the hydrogenation of p-chloronitrobenzene, which is better than the corresponding supported catalyst. Moreover, it also displays excellent stability with 5 cycle runs and good substrate universality for the hydrogenation of extensive substituted nitroarenes. Various characterization techniques and control experiments reveal the advantage of the unique structure to promote the mass transport and adsorption of reactant molecules on Ru sites. This work provides a novel strategy to design an efficient Ru-based catalyst for chemoselective hydrogenation. [ABSTRACT FROM AUTHOR]

The synthesis of ruthenium-complexes with cyclic (amino)(barrelene)carbenes (namely CABCs) as ligands is reported. Isolated in moderate to good yields, these new complexes showed impressive thermal stability at 110 °C over several days. Good catalytic performances were demonstrated in various ring-closing metathesis (RCM), macrocyclic–RCM, ring-closing enyne metathesis (RCEYM), cross-metathesis (CM), and ring-opening cross metathesis (ROCM) reactions. [ABSTRACT FROM AUTHOR]

A convenient method for Z → E geometry isomerization of aryl–aryl (stilbenes), alkyl–aryl, and alkyl–alkyl alkenes was developed. This user-friendly method utilized a popular commercial Hoveyda–Grubbs ruthenium olefin metathesis catalyst in the presence of sodium formate in toluene and is characterized by good functional group compatibility, including halogen, ester, aldehyde, and acetal functions. This research originated from trials on the valorization of a waste by-product resulting from the industrial synthesis of a valuable API—rosuvastatin. [ABSTRACT FROM AUTHOR]

Upcycling biodegradable polyester waste into value-added chemicals can not only avoid CO2 emissions but also achieve sustainable carbon recycling. Herein, we report a one-pot catalytic process to deconstruct polycaprolactone into 6-aminocaproic acid (EACA) and caprolactam (CPL), two monomers of nylon-6, using aqueous ammonia and Ru catalysts. No additional hydrogen is required, and the total yield of EACA and CPL could reach 90.2% using a ternary catalyst, Ru/CeO2/RGO, at 140 °C. It is verified that 6-hydroxyhexanoic acid and 6-hydroxyhexanoamide are the initial intermediates resulting from polycaprolactone decomposition, which undergo dehydrogenation, amination and re-hydrogenation to transform into EACA and 6-aminohexanoamide over the Ru catalyst. The hydrolysis of 6-aminohexanoamide produces EACA, and the reverse reaction between dehydration of EACA and hydrolysis of CPL results in their coexistence. The protocol demonstrated here provides a novel route to recycle polycaprolactone to valuable chemicals. [ABSTRACT FROM AUTHOR]

A comprehensive density functional theory investigation has been presented towards the comparison of the C–H activation reactivity between high-valent iron-oxo and ruthenium-oxo complexes. A total of four compounds, e.g., [Ru(IV)O(tpy-dcbpy)] (1), [Fe(IV)O(tpy-dcbpy)] (1′), [Ru(IV)O(TMCS)] (2), and [Fe(IV)O(TMCS)] (2′), have been considered for this investigation. The macrocyclic ligand framework tpy(dcbpy) implies tpy = 2,2′:6′,2′′-terpyridine, dcbpy = 5,5′-dicarboxy-2,2′-bipyridine, and TMCS is TMC with an axially tethered –SCH2CH2 group. Compounds 1 and 2′ are experimentally synthesized standard complexes with Ru and Fe, whereas compounds 1′ and 2 were considered to keep the macrocycle intact when switching the central metal atom. Three reactants including benzyl alcohol, ethyl benzene, and dihydroanthracene were selected as substrates for C–H activation. It is noteworthy to mention that Fe(IV)O complexes exhibit higher reactivity than those of their Ru(IV)O counterparts. Furthermore, regardless of the central metal, the complex featuring a tpy-dcbpy macrocycle demonstrates higher reactivity than that of TMCS. Here, a thorough analysis of the reactivity-controlling characteristics—such as spin state, steric factor, distortion energy, energy of the electron acceptor orbital, and quantum mechanical tunneling—was conducted. Fe(IV)O exhibits the exchanged enhanced two-state-reactivity with the quintet reactive state, whereas Ru(IV)O has only a triplet reactive state. Both the distortion energy and acceptor orbital energy are low in the case of Fe(IV)O supporting its higher reactivity. All the investigated C–H activation processes involve a significant contribution from hydrogen tunneling, which is more pronounced in the case of Ru, although it cannot alter the reactivity pattern. Furthermore, it has also been found that, independent of the central metal, aliphatic hydroxylation is always preferable to aromatic hydroxylation. Overall, this work is successful in establishing and investigating the cause of enzymes' natural preference for Fe over Ru as a cofactor for C–H activation enzymes. [ABSTRACT FROM AUTHOR]

The first ever homobimetallic catalyst which efficiently catalyzes the reductive amination (RA) reaction of carbonyl compounds in water is described herein. Two new Ru(II) compounds, homobimetallic [(p-cymene)2(RuCl)2L1] (Ru1) and monometallic [(p-cymene)(RuCl)L2] (Ru2) (where L1 = 2,2′-((1E,1′E)-((3,3′,5,5′-tetraisopropyl-[1,1′-biphenyl]-4,4′diyl)bis-(azaneylylidene))bis(methaneylylidene))diphenoxide) and L2 = (2,6-(((diisopropylphenyl)-imino)methyl)phenoxide) incorporating Schiff-base ligands have been synthesized and characterized by various spectroscopic and analytical techniques. Their molecular structures have been deduced by X-ray diffraction measurements. Both complexes, which are water/air stable at room temperature as well as at high temperature, were employed as catalysts for RA in aqueous media using formate buffer as the hydrogen source. Complex Ru1, in the presence of formic acid/formate buffer as the hydrogen source, catalyzes one-pot RA production of secondary amines in ∼99% yield with just 0.05 mol% of the catalyst exhibiting a turnover number (TON) of 1920 and a turnover frequency (TOF) of 480 h−1. When the catalyst loading was further reduced to 0.0001 mol%, the highest reported TON and TOF for any RA reactions were observed (4.3 × 104 and 107 × 103 h−1, respectively), albeit with reduced selectivity. A comparative study between Ru1 and Ru2 reveals that complex Ru1 is more chemo-selective for the formation of a secondary amine, attributable to a cooperative effect. This cooperative effect is further substantiated through extensive computational methodologies involving Density Functional Theory (DFT) calculations on both bimetallic and monometallic Ru(II) complexes along a hybrid-model complex. [ABSTRACT FROM AUTHOR]

Two rigid β-elimination immune PCcarbeneP pincer ligands, differing in their electron donor properties by variation of the substitution pattern on the aromatic linker arms, were complexed to ruthenium to form the dichlorides LRRuCl2 (R = H or NMe2). These compounds were converted to hydrido chlorides by treatment with dihydrogen (H2) and a base. By converting to tert-butoxide derivatives in situ under an atmosphere of H2, the poly hydride PCalkylP complexes LHRRu(H)3 compounds were generated. In these complexes, H2 has added across the Ru＝C bond in the PCcarbeneP starting materials. The polyhydrides are dynamic in solution and extensive NMR studies helped to elucidate the speciation and fluxional processes operative in this dynamic system. The polyhydride complexes react rapidly with CO2 to give the PCcarbeneP formato hydride complexes LRRu(H)-κ2-O2CH. For R = H, the 1,2-hydride shift from the anchoring alkyl of the PCalkylP carbon to the metal is reversible, but for R = NMe2 it is irreversible. The CO2 incorporated into the formato ligand of these compounds exchanges with free CO2via a bimolecular mechanism that is more rapid for R = NMe2 than for R = H; plausible explanations for this observation are proffered. Experiments designed to evaluate the efficacy of the R = NMe2 formato hydride complex as a catalyst precursor for CO2 hydrogenation to formate salts reveal poor performance in comparison to state-of-the-art ruthenium-based catalysts. This is due primarily to the precipitation of a dimeric μ-κ2-κ1-CO3 carbonate complex that is not an active catalyst for the reaction. [ABSTRACT FROM AUTHOR]

Two rigid β-elimination immune PCcarbeneP pincer ligands, differing in their electron donor properties by variation of the substitution pattern on the aromatic linker arms, were complexed to ruthenium to form the dichlorides LRRuCl2 (R = H or NMe2). These compounds were converted to hydrido chlorides by treatment with dihydrogen (H2) and a base. By converting to tert-butoxide derivatives in situ under an atmosphere of H2, the poly hydride PCalkylP complexes LHRRu(H)3 compounds were generated. In these complexes, H2 has added across the Ru＝C bond in the PCcarbeneP starting materials. The polyhydrides are dynamic in solution and extensive NMR studies helped to elucidate the speciation and fluxional processes operative in this dynamic system. The polyhydride complexes react rapidly with CO2 to give the PCcarbeneP formato hydride complexes LRRu(H)-κ2-O2CH. For R = H, the 1,2-hydride shift from the anchoring alkyl of the PCalkylP carbon to the metal is reversible, but for R = NMe2 it is irreversible. The CO2 incorporated into the formato ligand of these compounds exchanges with free CO2via a bimolecular mechanism that is more rapid for R = NMe2 than for R = H; plausible explanations for this observation are proffered. Experiments designed to evaluate the efficacy of the R = NMe2 formato hydride complex as a catalyst precursor for CO2 hydrogenation to formate salts reveal poor performance in comparison to state-of-the-art ruthenium-based catalysts. This is due primarily to the precipitation of a dimeric μ-κ2-κ1-CO3 carbonate complex that is not an active catalyst for the reaction. [ABSTRACT FROM AUTHOR]

A robust diphosphine-ruthenium(II) complex has been developed that can efficiently catalyze hydromethylation of N-heteroarenes to form N-methyl saturated N-heterocycles viz the reduction of N-heterocycles coupled with C–N bond formation. Both indoles and quinolines can be transformed to their corresponding N-methyl indolines and N-methyl 1,2,3,4-tetrahydroquinolines with high conversion (e.g., 12 indoles and 9 quinolines). On the basis of a series of experiments, a possible mechanism has been proposed to account for the hydrogenation and methylation processes involved in the catalytic pathway. More importantly, this approach provides a potential route for using DME as a methyl source for the production of N-methyl saturated N-heterocycles via hydromethylation. [ABSTRACT FROM AUTHOR]

Dehydrogenation of ammonia borane to well-defined products is an important but challenging reaction. A dinuclear ruthenium complex with a Ru–Ru bond bearing a diazadiene (dad) unit and olefins as non-innocent ligands catalyzes the highly selective formation of conjugated polycondensed borazine oligomers (BxNxHy), predominantly B21N21H18, the BN analogue of superbenzene. [ABSTRACT FROM AUTHOR]

The development of an effective molecular catalyst to reduce hydrazine efficiently to ammonia using a suitable reductant and proton source is demanding. Herein, an unprecedented air-stable, phosphine-free ruthenium complex is used as a potent catalyst for hydrazine hydrate reduction to generate ammonia using SmI2 and water under ambient reaction conditions. Maximizing the flow of electrons from the reductant to the hydrazine hydrate via the metal centre results in a greater yield of ammonia while minimizing the evolution of H2 gas as a competing product. [ABSTRACT FROM AUTHOR]

This study introduces an efficient strategy for promoting the synthesis of γ-valerolactone (GVL) via levulinic acid (LA) hydrogenation. A series of hyper-crosslinked porous polymer (HCP) supported Ru catalysts with different monomers were prepared. The wettabilities were controlled by the surface functional groups. The hydrophobic catalysts showed much higher activity than the hydrophilic ones in the hydrogenation of LA to GVL, highly possible due to the substrate enrichment. Further insight showed that the reaction proceeded through the 4-HVA route. These results illustrated the importance of surface wettability in bio-based molecule upgrading, which is beneficial for catalyst design. [ABSTRACT FROM AUTHOR]

New 1,2-azolylamidino complexes fac-[RuCl(DMSO)3(NHC(R)az*-κ²N,N)]OTf [R = Me (2), Ph (3); az* = pz (pyrazolyl, a), indz (indazolyl, b)] are synthesized via chloride abstraction from their corresponding precursors cis,fac-[RuCl2(DMSO)3(az*H)] (1) after subsequent base-catalyzed coupling of the appropriate nitrile with the 1,2-azole previously coordinated. All the compounds are characterized by ¹H NMR, 13C NMR and IR spectroscopy. Those derived from MeCN are also characterized by X-ray diffraction. Electrochemical studies showed several reduction waves in the range of −1.5 to −3 V. The electrochemical behavior in CO2 media is consistent with CO2 electrocatalytic reduction. The catalytic activity expressed as [icat(CO2)/ip(Ar)] ranged from 1.7 to 3.7 for the 1,2-azolylamidino complexes at voltages of ca. −2.7 to −3 V vs. ferrocene/ferrocenium. Controlled potential electrolysis showed rapid decomposition of the Ru catalysts. Photocatalytic CO2 reduction experiments using compounds 1b, 2b and 3b carried out in a CO2-saturated MeCN/TEOA (4 : 1 v/v) solution containing a mixture of the catalyst and [Ru(bipy)3]2+ as the photosensitizer under continuous irradiation (light intensity of 150 mW cm−2 at 25 °C, λ > 300 nm) show that compounds 1b, 2b and 3b allowed CO2 reduction catalysis, producing CO and trace amounts of formate. The combined turnover number for the production of formate and CO is ca. 100 after 8 h and follows the order 1b < 2b ≈ 3b. [ABSTRACT FROM AUTHOR]

A polypyridyl-imidazole-based bridging ligand, 2-(4-(4,5-di(pyridine-2-yl)-1H-imidazole-2-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (phen-H2PhImz-bpy), possessing three bidentate coordinating sites, has been designed in this work. The bridging ligand is employed to synthesize mono-, bi-, and trimetallic Ru(II) complexes in combination with terminal bipyridine units for the systematic modulation of photophysical and redox properties upon sequential incorporation of the metal unit into the bridge. All the compounds are characterized via NMR spectroscopy and electrospray ionization mass spectrometry. Absorption and both steady-state and time-resolved emission spectroscopic investigations of the ligand as well as Ru(II) complexes are thoroughly conducted in different solvents. The redox behaviors of the complexes are examined through cyclic voltammetry (CV) in acetonitrile. The focus of the investigation is centered on the systematic modulation of MLCT absorption and emission as well as the redox behavior of the complex entity upon the gradual incorporation of the Ru2+ unit into the complex backbone. The emission energy, quantum yield and lifetime are found to decrease systematically with an increase in the Ru2+ unit in the complex backbone and a linear relationship is observed in each case. A good correlation is also observed between the emission energies of complexes with their respective ΔE1/2 values (the difference between the first oxidation and first reduction potential). [ABSTRACT FROM AUTHOR]

The developed bifunctional NNN–Ru complex features a high catalytic efficiency for the selective production of hydrogen and glycolic acid from ethylene glycol under mild reaction conditions, where a TON of 6395 was achieved. Tuning the reaction conditions afforded further dehydrogenation of the organic substrate with higher hydrogen production, and a higher TON of 25 225 was attained. The scale-up reaction yielded 1230 mL of pure hydrogen gas under the optimized reaction conditions. The role of the bifunctional catalyst was studied and mechanistic investigations were performed. [ABSTRACT FROM AUTHOR]

To resolve white plastic pollution and the human carbon footprint, we report an efficient green approach to quantitatively convert polyethylene terephthalate (PET) to high-density C6–C8 cyclic hydrocarbons via single-step water-assisted hydrodeoxygenation (HDO) over a Ru/TiO2 catalyst in a biphasic system. To understand the structure–activity relationships of supported metal catalysts in PET HDO, acidic and neutral support-loaded Ru catalysts were prepared, characterized, and evaluated in mono- and biphasic systems. An experimental study revealed that Ru/TiO2 effectively catalyzed the production of C6–C8 cyclic hydrocarbons from PET. Under mild conditions (220 °C, 50 bar H2, 12 h), the catalyst completely converted PET into fuel-range C6–C8 cyclic hydrocarbons at a remarkably high selectivity of 96.8–99.2%. The catalyst successfully cleaved all C–O bonds in the aromatic plastic in a water–dodecane (O/W) biphasic system via the favorable effects of the metal-acid bifunction, hydrophilicity, and high dispersion of small Ru particles on the support. Due to its hydrophilic behavior, the nanosized catalyst formed stable Pickering emulsion droplets in the biphasic system. The presence of these droplets increased the selectivity towards C6–C8 hydrocarbons by forming a reaction interface with a large area between the oil and water layers. This improves accessibility to the active sites of the catalyst, stabilizes the intermediates, and enhances mass transfer and the separation of the target products. Furthermore, using a model compound study, we identified the pathway involved in the HDO reaction. Moreover, the addition of water to the biphasic system significantly increased the rate of proton transfer on the catalyst support. This study presents an excellent single-step catalytic pathway for application in synthesizing C6–C8 cyclic hydrocarbons using PET waste in a water-assisted biphasic system, providing a viable solution for plastic recycling. [ABSTRACT FROM AUTHOR]

Well-crafted semiconductors exhibiting favorable band structures and strong electron-donating properties can provide a viable pathway for solar-driven nitrogen activation under ambient conditions. In this study, we demonstrate that the nitrogen photo-fixation process can be enhanced by introducing oxygen vacancies and a Ru co-catalyst. The Ru-loaded ZrO2−x photocatalyst achieved an impressive NH3 production rate of 3256 μg g−1 h−1 under visible light irradiation (at 400 nm). Defective ZrO2−x with its enhanced reducing ability and narrow band gap possesses a low work function and excellent electron-donating capability, resulting in remarkable photocatalytic performance for ammonia synthesis under visible light. The supported Ru co-catalyst induces upward band bending in defective ZrO2−x, forming an interfacial Schottky barrier that facilitates the separation of photogenerated charge carriers and provides energetic electrons for nitrogen activation. Mott–Schottky photocatalysts with enhanced back donation ability establish a one-way channel for the transmission of photoexcited electrons, thereby further improving the photocatalytic performance of ammonia synthesis at room temperature. [ABSTRACT FROM AUTHOR]

Herein, we report the development of ruthenium-catalysed cross-coupling reaction of β-ketoamides as alkenyl electrophiles with organoboronates. This reaction presumably proceeds via the cleavage of the alkenyl C–N bond of the β-enaminoamide, which is generated in situ from the β-ketoamide and pyrrolidine, and is promoted by a nearby amide directing group and a ruthenium catalyst. [ABSTRACT FROM AUTHOR]

For effective overall water splitting (OWS) in alkaline media, a novel Ru-doped bimetal oxide (Ru-NiCo2O4) catalyst deposited onto a conductive nickel foam (NF) is fabricated by a multi-step hydrothermal reaction, ion exchange, and subsequent annealing process. The distinctive 3D nanoneedle-like arrays not only provide an even distribution of Ru decorated NiCo2O4, but also expose additional active sites, facilitating electron transport and improving reaction kinetics. Besides, density functional theory (DFT) studies elucidate the electronic structure regulation in Ru-NiCo2O4 and the modification of the d-band center optimizes H* adsorption energy, which considerably increased the hydrogen production efficiency. Considering the aforementioned advantages, the as-prepared Ru-NiCo2O4 electrocatalyst exhibits greatly improved catalytic activity, requiring only 25 mV and 249 mV at 10 mA cm−2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, as well as robust stability. Amazingly, the Ru-NiCo2O4 electrode in a two-electrode alkaline electrolyzer only needs 1.55 V to produce 10 mA cm−2, making it more efficient than the commercial RuO2‖‖Pt/C electrode (1.62 V). More importantly, 0.33 M urea only needs a low voltage of 1.427 V to drive the urine-mediated electrolysis, which is about 123 mV less than the urea-free electrolysis cell. This work presents an effective electronic structure engineering approach based on heteroatom doping that may be extended to design and fabricate novel high-performance OWS catalysts. [ABSTRACT FROM AUTHOR]

In this study, ruthenium-doped CoFe-based layered double hydroxides on Ni foam (CoFe-ZLDH/Ru@NF) were fabricated via an etching-precipitation strategy. The resultant CoFe-ZLDH/Ru@NF exhibited excellent activity, showing low overpotentials of 219.8 mV and 60.9 mV to reach the current density of 10 mA cm−2 for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. As a bifunctional electrocatalyst, it was assembled in an anion exchange membrane water electrolyser (AEMWE) unit, performing as an anode and cathode simultaneously, which only required a cell voltage of 2.33 V to accomplish the industrial level current density of 1 A cm−2 and operated steadily for over 12 h, making it promising for utilization in hydrogen production. [ABSTRACT FROM AUTHOR]

One of the key steps in producing value-added chemicals from biomass-derived compounds is the conversion of levulinic acid (LA) into useful products. In the present work, a novel catalyst was prepared by immobilizing ruthenium nanoparticles on bimodal N,S-doped ordered mesoporous carbon (IBOMC). Various analytical methods, including TEM, XRD, XPS and N2 adsorption-desorption, were used to characterize both IBOMC and the synthesized catalyst (Ru@IBOMC). Ru@IBOMC was then successfully utilized in the continuous flow catalytic hydrogenation of LA to γ-valerolactone and N-containing heterocycles at room temperature. The effects of different reaction variables (such as temperature, H2 gas pressure, solvent, LA concentration, and flow rate) were examined. This catalytic protocol exclusively affords quantitative yields of γ-valerolactone at room temperature under continuous flow conditions under 30 bar H2 pressure. The catalyst also exhibits excellent activity for producing N-containing heterocycles at room temperature by using either aniline or acetonitrile as the amine source. The catalyst shows consistent performance for at least 72 hours without significant loss of activity and selectivity in a wide range of solvents, giving an excellent weight hourly space velocity (WHSV) of 48 h-1. These results confirmed that nitrogen and sulfur active centres in IBOMC can effectively stabilize ruthenium nanoparticles and synergistically enhance the performance of Ru active centers in the hydrogenation of LA. [ABSTRACT FROM AUTHOR]

The amount of dopant used in conventional cases for improving catalytic performance is higher than 5%. In this work, a strategy to enhance the ammonia synthesis performance of a Ru/CeO2 catalyst by using trace Pr (0.1 mol%) is reported. Owing to the improvement of oxygen defects, Ce3+ concentration and interfaced Ru species, the hydrogen adsorption was enhanced, and the desorption of hydrogen species would be promoted. As a result, Ru/CeO2 with 0.1 mol% Pr shows 1.4 times higher ammonia synthesis rate and excellent stability compared to Ru/CeO2 or the sample with high Pr loading (50 mol% Pr). This study provides a new idea for the design of high-efficiency ammonia synthesis catalysts. [ABSTRACT FROM AUTHOR]

The utilization of stimuli-responsive hydrogels as bifunctional catalysts for an aqueous sequential organic transformation to prepare chiral organic molecules is not only environmentally friendly, but also complements the synthetic limitations of mutually contradictory multistep reactions. However, finding a solution to the incompatible issue arising from complicated multicomponent cross-interactions in sequential transformations is a significant challenge. To address this issue, we have developed a core–shell-structured hydrogel as a site-isolated bifunctional catalyst. This catalyst features thermoresponsive poly(N-isopropylmethacrylamide) with a switching function via a reversible transition between its hydrogel and solution phases that perfectly matches a temperature-tuned base-catalyzed aldol condensation/oxa-Michael addition at 70 °C and the ruthenium-catalyzed dynamic kinetic resolution asymmetric transfer hydrogenation (DKR-ATH) process at 40 °C. As we envisioned, through the harmonization of the conflicting sequential reactions, this aldol condensation/oxa-Michael addition/DKR-ATH cascade process can be achieved by transitioning from being incompatible to compatible, enabling direct access to chiral chromanols with 1,3-positioned dual stereocenters from commercially available ortho-hydroxyl arylketones and aldehydes. Mechanistic investigations, which involve monitoring the cascade reaction and analyzing the deuterium-labeling experiments, reveal a domino-like aldol condensation/oxa-Michael addition/DKR-ATH sequential route comprising an initial aldol condensation/oxa-Michael addition followed by the subsequent DKR-ATH process. [ABSTRACT FROM AUTHOR]

Valorization of cellulose, hemicellulose, and lignin into value-added industrially relevant chemicals is important to achieve sustainability goals that various governments and industries have set. In view of this, the oxidative synthesis of 2,5-furandicarboxylic acid (FDCA) from 5-hydroxymethyl furfural (HMF) as an analogous compound to terephthalic acid in the synthesis of PEF is interesting to researchers. Though advancements in the oxidation of HMF have been made, the efficient synthesis of HMF, its storage, and isolation are great challenges due to its instability under normal conditions. While purified HMF can be used to synthesize FDCA, it is imperative to use crude HMF for the synthesis of FDCA since several techno-economical studies reveal that the purification of HMF is the most cost-intensive step. Herein, we demonstrate the oxidation of crude HMF, synthesized in the laboratory to FDCA, using nonprecious-based mixed metal oxides in the aqueous medium in the presence of oxygen/air. Among various catalysts, Cu–Mn catalyst at 120 °C within 8 h in the presence of oxygen (10 bar) could yield 90% FDCA. This activity was comparable with that of the commercially available and well-studied Ru/C (5 wt%) catalyst (93% yield). In addition, the role of HMF purity, air as an oxidant, and the influence of temperature, pressure, and time is systematically studied. It is also demonstrated that FDCA formation proceeds via HMFCA and FFCA formation. The isolation of FDCA and its purity (>99%) is corroborated with various techniques such as NMR, IR, and HRMS. [ABSTRACT FROM AUTHOR]