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Structural and phase stability of the Pd-plated Ti3(Al, Si)C2–TiC composite at elevated temperatures was analyzed by the in situ X-ray diffraction method using synchrotron radiation. Porous Ti3(Al, Si)C2–TiC composite was prepared by spark plasma sintering of preceramic paper with 90 wt % of a Ti3(Al, Si)C2 powder filler at 1000°C and 20 MPa. The sintered composite was covered with a Pd film via electroless plating. During in situ investigation, the Pd-plated composite was linearly heated from 25 to 1000°C and annealed for 1 h at a maximum temperature. Structural and phase analysis reveals a formation of new Pd2Si, PdAl, and PdCx phases. It was noted that the newly formed phases began to be formed during heating at ~750°C. Scanning electron microscopy showed that the obtained Ti3AlSiC2–TiC composite had a well-developed porous structure where some pores were filled with Pd. After high-temperature treatment, Pd could be detected at depths up to 5 μm into the Ti3AlSiC2–TiC composite. [ABSTRACT FROM AUTHOR]

This scientific paper aims to provide a thorough examination of the current state of research on nanomaterials in the context of Low Energy Nuclear Reactions (LENR). The paper explores various nanomaterials, their synthesis methods, and their impact on facilitating and enhancing LENR processes. Special attention is given to the unique properties of nanomaterials that make them particularly suitable for LENR applications, such as increased surface area, quantization effects, and improved hydrogen absorption kinetics. The review also delves into experimental findings and theoretical models that shed light on the mechanisms through which nanomaterials induce and support LENR. The sustained interest in LENR arises from experiments consistently demonstrating the potential for significant energy gains, suggesting cost-effective energy production. Furthermore, these processes exhibit advantages such as negligible radiation during operation, minimal radioactive waste, and the absence of greenhouse gas emissions. While the path to commercialization is lengthy, strides are being made by various companies recognizing the challenge of consistently producing materials to reliably trigger LENR. Current research focuses on employing nanoparticles to reliably induce LENR, drawing inspiration from reports indicating the efficacy of loose nanoparticles in triggering these reactions. The hypothesis posits that nanoparticles affixed to surfaces enhance performance and ease of handling in research and commercial setups. The rationale for using nanoparticles lies in their ability to facilitate hydrogen penetration into solid materials, crucial for observing LENR phenomena. This capability is attributed to the substantial surface area of nanoparticles, allowing them to absorb more reactants like hydrogen. Recent studies delve into understanding the behavior of metallic nanoparticles concerning the energy spectrum of electrons and implanted ions as a function of particle size. Notably, as nanoparticles decrease in size, quantization effects emerge, potentially modifying the interaction of quasiparticles within nanoclusters. Specific examples, such as Pd-Rh alloys, demonstrate accelerated hydrogen uptake kinetics in nanoparticles compared to bulk materials, emphasizing the importance of nanoscale properties. This topic provides a broad scope for exploring the intersection of nanomaterials and LENR, allowing for an in-depth analysis of the current state of research and the potential for future advancements. By understanding and harnessing the unique properties of nanomaterials, significant progress can be made in the field of LENR, potentially leading to practical and sustainable energy solutions. Graphical abstract for LENR review article. [ABSTRACT FROM AUTHOR]

FinTech stocks are an important new asset class that reflects the rapidly growing FinTech sector. This paper studies the practical implications of using gold, silver, and basket-of-precious-metals (gold, silver, platinum, palladium) ETFs to diversify risk in FinTech stocks. Downside risk reduction is estimated using relative risk ratios based on CVaR. The analysis shows that gold provides the most downside risk protection. For a 5% CVaR, a 30% portfolio weight for gold reduces the downside risk by about 25%. The minimum variance and minimum correlation three-asset (FinTech, gold, and silver) portfolios (with portfolio weights estimated using a TVP-VAR model) have the highest risk-adjusted returns (Sharpe ratio, Omega ratio) followed by the fixed-weight FinTech and gold portfolio. These results show the benefits of diversifying an investment in FinTech stocks with precious metals. These results are robust to weekly or monthly portfolio rebalancing and reasonable transaction costs. [ABSTRACT FROM AUTHOR]

The phosphinito–phosphinous acid ligand (PAP) is a singular bidentate-like self-assembled ligand exhibiting dissymmetric but interchangeable electronic properties. This unusual structure has been used for the generation of active palladium hydride through alcohol oxidation. In this paper, we report the first theoretical highlight of the adaptative modulation ability of this ligand within a direct H-abstraction path for Pd and Pt catalyzed alcohol oxidation. A reaction forces study revealed rearrangements in the ligand self-assembling system triggered by a simple proton shift to promote the metal hydride generation via concerted six-center mechanism. We unveil here the peculiar behavior of the phosphinito–phosphinous acid ligand in this catalysis. [ABSTRACT FROM AUTHOR]

2D palladium nanostructures enable sensitive room‐temperature detection of H2. However, they can be limited by stability and fabrication costs. Stability may be improved by alloying Pd with other metals, while cost could be reduced by using paper as a substrate. An ultra‐low‐cost sensor using Pd alloy (PdMoY) nanosheets (NS) on paper is reported. The 2D Pd alloy nanosheets are prepared by a solution‐phase route, drop cast onto paper (≈1 × 1 cm) with silver contacts drawn on it, and dried. The same material is deposited on an interdigitated electrode (IDE). Both sensors are tested for response to hydrogen in air. The resistance of the paper‐based sensor decreased by ≈18.7% in 1% H2, which is about 40 times the response of the IDE‐based sensor. Its H2 limit of detection (1 ppm) is also lower than that of the IDE‐based sensor (5 ppm). Compared to pristine Pd NS, PdMoY NS are more stable to repeated H2 pulses without any signs of buckling or cracks. The nanosheets are also deposited by inkjet printing to produce functional sensors, providing a simple route to manufacturing of ultra‐low‐cost gas sensors for use in fuel‐cell vehicles and related infrastructure. [ABSTRACT FROM AUTHOR]

To stabilize the detection signal of palladium-based hydrogen sensors on paper substrates, a graphite intermediate layer was painted on the surface of paper. The graphite-on-paper (GOP) substrate offers advantages such as good thermo-electrical conductivity, low cost, and uncomplicated preparation technology. Quasi-1-dimensional palladium (Pd) thin films with 8 nm and 60 nm thicknesses were deposited on the GOP substrates using the vacuum evaporation technique. Thanks to the unique properties of the GOP substrate, a continuous Pd microfiber network structure appeared after deposition of the ultra-thin Pd film. Additionally, the sensing performance of the palladium-based hydrogen sensor was not affected, whether using GOP or paper substrate at 25 °C. Surprisingly, heating-induced loss of sensitivity was restrained due to the increased electrical conductivity of the GOP substrate at 50 °C. [ABSTRACT FROM AUTHOR]

Bimetallic platinum-containing catalysts are deemed promising for electrolyzers and proton-exchange membrane fuel cells (PEMFCs). A significant number of laboratory studies and commercial offers are related to PtNi/C and PtCo/C electrocatalysts. The behavior of PtPd/C catalysts has been studied much less, although palladium itself is the metal closest to platinum in its properties. Using a series of characterization methods, this paper presents a comparative study of structural characteristics of the commercial PtPd/C catalysts containing 38% wt. of precious metals and the well-known HiSpec4000 Pt/C catalyst. The electrochemical behavior of the catalysts was studied both in a three-electrode electrochemical cell and in the membrane electrode assemblies (MEAs) of hydrogen–air PEMFCs. Both PtPd/C samples demonstrated higher values of the electrochemically active surface area, as well as greater specific and mass activity in the oxygen reduction reaction in comparison with conventional Pt/C, while not being inferior to the latter in durability. The MEA based on the best of the PtPd/C catalysts also exhibited higher performance in single tests and long-term durability testing. The results of this study conducted indicate the prospects of using bimetallic PtPd/C materials for cathode catalysts in PEMFCs. [ABSTRACT FROM AUTHOR]

Palladium (Pd) coated copper (PCC) wire is an emerging bonding wire that has been widely researched. In this paper, the effects of electronic flame-off (EFO) current and EFO time on the free air ball (FAB) morphology of four PCC wires with Pd layer thicknesses of 60, 80, 100, and 120 nm, respectively, are first investigated. The larger the EFO current or the longer the EFO time, the larger the FAB diameter. The EFO time or EFO current setting is either too high or too low to form a FAB with good morphology. Taking the ratio of FAB diameter to wire diameter as 2 as the standard, the EFO current of 48 mA and the EFO time of 700 μs are selected as the optimal EFO parameter combination. Under this parameter combination, the symmetry, roundness, and surface smoothness of the FAB of the four PCC wires are all at a better level. It is found that the FAB surface Pd coverage of PCC wire with 120 nm Pd layer thickness is higher through the corrosion test. The Pd transfer law on the FAB at different EFO times under optimal EFO current is also studied. The results show that with the prolongation of the EFO time, the Pd on the FAB surface is gradually transferred from the neck to the middle and lower parts. This study can provide technical reference for the selection of Pd layer thickness and EFO parameters of PCC wire. [ABSTRACT FROM AUTHOR]

The present study aims to verify the autumn effect in the gold market, first presented 10 years ago by Dirk Baur in the paper "The autumn effect of gold" and to investigate the calendar effects occurring for other precious metals. This empirical research is presented in a way to place the results obtained in the context of the Efficient Market Hypothesis (EMH) and the more current Adaptive Market Hypothesis (AMH). The study was conducted as an extended reproduction of the Baur study. The main conclusion is that, the autumn effect on the gold market has been reversed and replaced by the winter effect, which is linked to the AMH. An equally interesting calendar effect was observed for silver. Platinum and palladium saw an increase in prices in January, but given the patterns in the gold market, it is very likely that this phenomenon will also change over time. [ABSTRACT FROM AUTHOR]

Despite the widespread use of well-defined PdII complexes as pre-catalysts for cross-coupling processes, the role of the throw-away ligand is still underexplored. In this work we focused on the complexes of the type [Pd(NHC)(η3-R-allyl)Cl] (NHC = N-heterocyclic carbene) and we investigated the influence of the R substitution on the allyl moiety. Starting from the already described [Pd(IPr)(η3-cinnamyl)Cl] and [Pd(IPr*)(η3-cinnamyl)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, IPr* = N,N′-1,3-bis[2,6-bis(diphenylmethyl)-4-methylphenyl]imidazol-2-ylidene) we prepared eight new complexes bearing new substitutions on the cinnamyl motif and we tested them in the C–N bond formation to evaluate the effect of the throw-away ligand modification in the catalytic activity. In addition, we studied the undesired formation of the less active off-cycle [Pd I2 (NHC)2(η3-R-allyl)(μ-Cl)] dimers from the corresponding PdII complexes to evaluate the role of the new throw-away ligands on the inhibition of this process. [ABSTRACT FROM AUTHOR]

In light of the burgeoning biological applications associated with xanthones, the development of highly efficient synthetic methodologies for their production has emerged as a pivotal objective of chemical research. Amidst the array of available protocols, the oxidative carbonylation of diaryl ethers with carbon monoxide (CO) stands out as a notably uncomplicated route, often necessitating stoichiometric oxidants. Herein, we present a feasible approach employing unsymmetrical-waveform alternating current (AC) electrolysis to facilitate Pd-catalysed oxidative C–H/C–H carbonylation. Leveraging a straightforward catalytic system, we demonstrate the conversion of diverse diaryl ethers into xanthones with moderate to commendable yields. Our mechanistic investigations illuminate the indispensable role played by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in the electrochemical system, particularly its ability to recycle heterogeneous palladium species within the solution. [ABSTRACT FROM AUTHOR]

A highly sensitive fluorescence sensor for monitoring low concentrations of hydrogen peroxide was designed. The sensor employs the commercially available palladium or platinum metal on activated charcoal as catalysts to decompose hydrogen peroxide into water and molecular oxygen. The produced oxygen concentration can be measured in real time using an oxygen-sensitive layer doped with photostable oxygen probes. The sensor exhibits high sensitivity that is able to measure hydrogen peroxide concentration down to 20 ppb and can measure hydrogen peroxide concentration in the range of 0.1–100 ppm and 0.02–100 ppm, respectively. The response is fully reversible and the typical response time is less than one minute, which makes it suitable to continuously measure hydrogen peroxide over a long duration. Due to the excellent batch-to-batch consistency of palladium or platinum metal on activated charcoal, the sensor can be massively produced with good reproducibility and affordable price, which holds great potential for constructing sensors for industrial and practical applications. [ABSTRACT FROM AUTHOR]

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The objective of this paper is to evaluate the effect of a nanostructured C-Pd film deposited in the gate area of a field-effect transistor (FET) with a carbon–palladium composite gate (C-Pd/FET) on the hydrogen-sensing properties of the transistor. The method of preparing a field-effect transistor (FET) with a C-Pd film deposited as a gate and the properties of such a transistor and the film itself are presented. The C-Pd film deposited by PVD method on the gate area serves as an active layer. The PVD process was carried out in a dynamic vacuum of 10−5 mbar from two separated sources—one containing fullerenes (C60) and the other containing palladium acetate. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS, EDX) and electrical property studies were used to the characterize C-Pd films and FET/C-Pd structures. SEM observations revealed the topography of C-Pd films and FET/C-Pd transistors. EDS/EDX microanalysis was applied to visualize the arrangement of elements on the studied surfaces. The changes in electrical properties (resistance and relative resistance) due to the presence of hydrogen were studied in a designed and computerized experimental set-up. The enhanced properties of the FET/C-Pd transistor are demonstrated in terms of hydrogen detection. [ABSTRACT FROM AUTHOR]

Hallmark of a successful catalyst is its high efficiency, economic aspects, operational simplicity, extensive reusability, higher environment friendliness, and potential use in multiple industrial applications. Herein, a facile protocol involving a catalyst with Pd nanoparticles supported on cellulose paper (also known as a "dip‐catalyst") for the hydrogenation of a series of quinolines, nitroarene, and C−C bond formation reactions in most benign solvents such as water is described. The mere insertion/removal of the "dip‐catalyst" strip enables instantaneous start/stop of the reaction, which enhances its reusability and ease of separation of products. Cellulose paper (CP) strips decorated with Pd nanoparticles (Pd/CP) are prepared by the reduction of K2PdCl4 soaked strips using formic acid as reductant. The resulting spherical shaped Pd particles, confirmed by scanning electron microscopy, form stable catalysis centers on the support. XRD signature confirms the crystallinity of the Pd nanoparticles and the TEM images display 15–20 nm size particles uniformly decorating CP. X‐ray photoelectron spectroscopy indicates the formation of metallic Pd. The catalyst is tested for the C−C bond formation reactions. Pd/CP catalyzed Suzuki‐Miyaura coupling reaction demonstrate >99% conversion with optimum selectivity. On the other hand, Mizoroki‐Heck reaction produced 87% conversion with the reaction of 4‐methoxycarbonyl phenylboronic acid and iodobenzene in ethanol:water (1 : 1 v/v) using KOH as base. The developed Pd/CP construct produces >99% of the pyridine‐ring hydrogenated product on quinoline hydrogenation using tetrahydroxydiboron (THDB) as the hydrogen source. Diverse and highly reducible functional groups were also evaluated for transfer hydrogenation, which demonstrates a high efficiency in terms of both reactivity and selectivity. The used catalysts are recyclable for the multiple cycles. [ABSTRACT FROM AUTHOR]

Post-synthetic modification of proton-conducting metal–organic frameworks (MOFs) by loading small molecules capable of generating protons into pores is an efficient approach for developing a new type of material with improved ionic conductivity. Herein, the synthesis, characterization and proton conductivity of a novel electroneutral MOF based on palladium(II) meso-tetrakis(4-(phosphonatophenyl))porphyrinate, IPCE-1Pd, are reported. The exposure of the obtained framework to imidazole by the diffusion vapor method has surprisingly led to its complete crystal-to-crystal MOF-to-HOF transformation, resulting in the formation of a novel hydrogen-bonded organic framework (HOF) IPCE-1Pd_Im, which is the first example of such kind of structural change among all known MOFs. This modification has led to an almost 25-fold increase in the proton conductivity in comparison with the pristine MOF, reaching up to 6.54 × 10−3 S cm−1 at 85 °C and 95% relative humidity, which is one of the highest values among all known porphyrin-based HOFs. [ABSTRACT FROM AUTHOR]

Current routes to boronic acids and their corresponding esters to be used in subsequent Suzuki–Miyaura (SM) cross couplings impact the cost, waste, and safety concerns associated with generating these materials. A new method for installing the ethyl pinacol boronic ester, or B(Epin) derivative leads to stable borylated products under near-neat conditions using high concentrations of a green solvent and moderate reaction temperatures, catalyzed by relatively low palladium loadings. Alternatively, the newly fashioned Ar–B(Epin) can be generated in situ and used directly in the same pot for SM reactions leading to aromatic and heteroaromatic residues characteristic of the biaryl products being formed. An array of complex targets, including API-related products, can be generated via this green and environmentally responsible methodology. [ABSTRACT FROM AUTHOR]

Metals such as silver, gold, platinum, palladium, and rhodium are widely used in automotive sensors and communication devices Sensor frameworks are comprehensively conveyed in a collection of purposes going from military to environmental and helpful examination. In various applications, for instance, target following, disaster area perception and gate crasher area, metallic sensor network habitually work in unfriendly and unattended circumstances. Subsequently, there is a strong prerequisite for getting the distinguishing data and identifying readings. In remote circumstances, an enemy can see the radio traffic too as can catch or between rupt the exchanged messages. Thusly, various shows and estimations don't simply work in that frame of mind without having palatable wellbeing endeavours. Consequently, security winds up one of the critical worries while illustrating security shows in resource constrained wireless sensor networks (WsNs). The ebb and flow paper are a fair endeavour to draw in the consideration of the peruses towards the design, conventions and elements of remote sensor network on the grounds that comprehensively conveyed in a variety of purposes going from military to biological and helpful examination. The present paper is an honest attempt to attract the attention of the readers towards the architecture, protocols and functions of metallic wireless sensor network because it is broadly conveyed in an assortment of uses going from military to ecological and restorative research. [ABSTRACT FROM AUTHOR]

Tritium resulting from separation processes is being stored in metal hydrides. In time, because of radioactive decay, tritium converts into 3He, which accumulates in the storage vessel. The recovery of 3He is a topic of high interest because of its wide range of applications in health care, security, and advanced research. Currently, at ICSI Râmnicu Vâlcea, a method is under development based on gas chromatography, Pd/Ag membrane permeation, and cryogenic distillation for 3He separation and enrichment having as sources both the cover gas of nuclear reactors and tritium storage containers. This paper reports the investigation of using Pd/Ag membranes for helium separation from hydrogen isotopes by experimental determination of the operating performance of the membrane in view of process integration. Tests have been performed at different temperatures in the domain of 100°C to 350°C for different hydrogen partial pressures in the upstream side of the membrane in the domain of 150 to 300 kPa, while the downstream part was continuously purged with a preliminary vacuum pump. The results for the membrane parameters are in good agreement with previous literature reports and will be utilized for the dimensioning and establishing of operating parameters of the membrane used for intermediate separation of helium isotopes from hydrogen. [ABSTRACT FROM AUTHOR]

The optical spectra of the palladium monosulfide (PdS) molecule in gas phase have been investigated for the first time through laser-induced fluorescence (LIF) and single-vibronic-level (SVL) emission spectroscopies. The I3Σ− − X3Σ− transition system containing 16 vibronic bands was identified in the LIF spectra, covering the energy range of 22 030–23 400 cm−1. The spectra with rotational resolution allowed for the determination of the molecular constants in both the ground X and excited I electronic states, involving the spin–orbit splitting, rotational constant, vibrational frequency, and isotope shift. Isotopically resolved SVL emission spectra permitted the observation of the spin–orbit splitting, vibrational frequency, and vibrational isotope shift of the X3Σ−0+,1 and A3Π2,1,0−,0+ states as they transitioned from the excited I state to the vibrational levels of the X and A states. Ab initio calculations presented plenty of the Λ-S and Ω states of PdS below 28 000 cm−1 and provided strong support for the assignments of the experimental observation. [ABSTRACT FROM AUTHOR]

Domino reactions are essential for advancing organic synthesis. This study introduces novel thioamide-based precursors for a palladium-catalyzed selective domino heteroarylation process. The method efficiently produces benzothieno[2,3- b ]quinolones with yields ranging from moderate to very good. By employing aryl chlorides, the efficiency of the domino hetero-annulation process is comparable to that of aryl bromides. Executing a one-pot, two-step reaction also delivered a single domino product with high selectivity. The strategy involved fine-tuning substituent reactivity, utilizing electron-rich arenes, and forming metallocycles with nucleophilic sulfur, consistently yielding a single product. The proposed mechanism is corroborated by mechanistic studies. [ABSTRACT FROM AUTHOR]

NHC-based pincers (NHC = N-heterocyclic carbene) have been broadly employed as supporting platforms, and their palladium complexes have found many synthetic applications. However, previous studies mainly focused on the NHC pincers of palladium featuring an oxidation number of +II. In contrast, oxidation of these well-defined Pd(II) species and the study of their fundamental high-valent Pd chemistry remain largely undeveloped. In addition, from a perspective of PdII/PdIV catalysis, the reactivity and degradation of NHC pincers in catalytically relevant reactions have not been well understood. In this work, a series of Pd(II) complexes supported by a well-known NHC^Aryl^NHC pincer platform have been prepared. Their reactivity towards various oxidizing reagents, including halogen surrogates, electrophilic fluorine reagents, and alkyl/aryl halides, has been examined. In some cases, ambient-characterizable high-valent Pd NHCs, which have been scarcely reported, were obtained. The carbenes incorporated into the pincer framework proved to be effective spectator donors. In contrast, the central aryl moiety exhibits versatile reactivity and collapse pathways, allowing it to function either as a spectator or a non-innocent actor. [ABSTRACT FROM AUTHOR]

Carbon–phosphorus bond formation is of great importance in synthetic chemistry. A versatile strategy for the formation of carbon–phosphorus bonds involves the addition of phosphorus radicals to π-systems. However, the generation methods of phosphorus radicals are primarily restricted to homolytic cleavage of phosphorus–hydrogen bonds with excess peroxides or toxic metal salts as oxidants. Herein, we introduce a photoinduced palladium-catalyzed generation of phosphorus radicals using inexpensive and readily available Cl–phosphine oxides and Cl–phosphates as the phosphorus radical precursors. The key step for this strategy lies in the reductive activation of phosphorus–chloride bonds with the excited palladium complex under visible light irradiation. The involvement of phosphorus radicals has been evidenced by EPR spectroscopy and radical trapping experiments. Based on this strategy, both phosphinyl and phosphonyl groups could be regiospecifically incorporated into simple alkenes and heteroaromatic compounds via radical mediated carbon–phosphorus bond formation. Besides, carbon–phosphorus difunctionalization of alkenes was also achieved to afford phosphorylated oxindoles. [ABSTRACT FROM AUTHOR]

In this research palladium(II) chloride, PdCl2, reacts with (4ʹ-bromobiphenyl-4-yl)diphenylphosphine compound, Br(C6H4)2P(C6H5)2, to give trans-PdCl2L2 [L: Br(C6H4)2P(C6H5)2] complex. trans-dichloro bis(4ʹ-bromobiphenyl-4-yl)diphenylphosphine palladium(II) complex has been characterized by elemental analysis, FT-IR, ¹H, 31P and 13C NMR. The catalytic performance of this complex has been rigorously evaluated and compared in the context of Suzuki-Miyaura and Mizoroki-Heck coupling reactions. It is noteworthy that under specific optimal conditions, including solvent type, base type, base quantity, catalyst quantity, and temperature, this complex serves as an efficient and suitable catalyst for the synthesis of biphenyl aryl halide derivatives. The resulting yield in these processes strongly supports the efficacy of this complex as a catalyst. [ABSTRACT FROM AUTHOR]

In this work, the Keggin-type tri- and mono-palladium-substituted silicotungstates (POMs) were constructed by the reaction of tri- and monovacant silicotungstates ([SiW9O34]10− or [SiW11O39]8−) with palladium chloride. The as-obtained potassium salts of POMs demonstrated that Pd2+ ions were incorporated into POM frameworks. Notably, Pd nanoparticles were formed when the tri-palladium-substituted Keggin-type POM salts were reduced by H2. It was found that [SiW9O34]10− anions could act as multivacant coordination ligands to effectively stabilize palladium nanoparticles. The Pd nanoparticles were catalytically active for the reductive amination of carbon dioxide, and the formylamides were achieved in high yields under mild reaction conditions with methanol as the solvent. Notably, the Pd nanocatalyst exhibited outstanding recyclability and was recycled at least eight times without any obvious loss of the catalytic activity. The characterization by HAADF-STEM revealed that Pd nanoparticles formed a stable structure with POMs. Further studies demonstrated that the N-formylation reaction proceeds by the "methyl formate" pathway, involving CO2 activation by an in situ reaction with methanol and K2CO3 to generate potassium methyl carbonate. H2 underwent heterolytic dissociation with the assistance of a base over a Pd0–SiW9 catalyst, leading to one proton bound to carbonates and the hydride on a Pd atom (Pd–H). Moreover, the coupling of potassium methyl carbonate and Pd–H species afforded methyl formate intermediates in methanol, and then the reaction of methyl formate with amines gave formamides. This catalytic system demonstrated the benefits of excellent reactivity, stability, and recyclability for the N-formylation reaction. [ABSTRACT FROM AUTHOR]

This paper reports the construction of racemic and enantiopure (D‐ and L‐) fluorene and fluorenone‐based novel unnatural amino acid derivatives. The Pd(II)‐catalyzed bidentate directing group‐aided arylation of prochiral β‐C(sp3)‐H bonds in racemic, enantiopure carboxamides of amino acids with iodofluorenes was reported. The construction of novel examples of fluorene and fluorenone motifs containing amino acids comprising of norvaline, leucine, phenylalanine, norleucine, 2‐aminooctanoic acid derivatives having the anti‐stereochemistry (with good enantiopurity) was accomplished. The construction of bis fluorenyl alanine scaffolds and fluorenyl motif‐containing non‐α‐amino acid (aminoalkanoic acid) derivatives was also reported. Examples of removal of the directing group (8‐aminoquinoline) and phthalimide‐protecting group present in the fluorenyl‐based unnatural amino acid derivatives have been shown. Accordingly, fluorene motif‐based amino acid esters and free amino group‐containing unnatural amino acid derivatives were synthesized. The stereochemistry of the major (anti) diastereomers obtained via the prochiral β‐C(sp3)‐H arylation of norvaline, leucine, phenylalanine, norleucine, 2‐aminooctanoic acid derivatives was ascertained from the X‐ray structure of a representative compound. Fluorene‐ and fluorenone‐based motifs are vital skeletons in materials and medicinal chemistry research. Accordingly, this work is a contribution towards enriching the library of fluorene and fluorenone unnatural amino acid scaffolds. [ABSTRACT FROM AUTHOR]

Carbonylative Suzuki–Miyaura coupling is an attractive and efficient strategy for preparation of diaryl ketones. Carbonylative Suzuki–Miyaura coupling reactions are difficult and palladium complexes are efficient and popular catalysts. The use of palladium complexes as catalysts allows the reaction to be carried out under milder conditions and the diaryl ketone products are prepared with good to high yields. The use of nanocatalysts has become an effective strategy for performing complex reactions especially carbonylative Suzuki–Miyaura coupling because nanocatalysts have characteristics of both homogeneous and heterogeneous catalytic systems. In this review, we study the application of palladium nanocatalysts for preparation of diaryl ketones through carbonylative Suzuki–Miyaura coupling reactions of aryl halides, arylboronic acids and carbonyl sources. Based on an internet code survey and research, this paper is the first review on the use of palladium nanocatalysts in carbonylative Suzuki–Miyaura coupling reactions. We believe this review will be a valuable source for chemists working in the field of the use of palladium nanocatalysts or carbonylative Suzuki–Miyaura coupling reactions. : [ABSTRACT FROM AUTHOR]

We have developed an efficient and versatile approach for the synthesis of a family of 1,2,3-triazole-based mesoionic N-heterocyclic olefin (mNHO) ligands and investigated their coordination to palladium, gold, and boron hydride experimentally and computationally. We reacted mNHOs obtained through deprotonation of the corresponding methylated and ethylated 1,3,4-triaryl-1,2,3-triazolium salts with [Pd(allyl)Cl]2 to give the corresponding [Pd(η³-allyl)Cl(mNHO)] coordination complexes. 13C NMR data revealed the strong s-donor character of the mNHO ligands, consistent with the calculated bond orders and atomcondensed charges. Furthermore, we also synthesized [AuCl(mNHO)] and a BH3-mNHO adduct by reacting the triazolium salts with AuCl(SMe2) and BH3·THF, respectively. The BH3-mNHO adduct was tested in the reduction of select aldehydes and ketones to alcohols. [ABSTRACT FROM AUTHOR]

Platinum group metals (PGM) and cerium as one of the rare-earth elements are considered as critical raw materials, thus their recycling and re-use is of utmost importance. Among the PGMs, platinum (Pt), palladium (Pd), and rhodium (Rh) are the basic and most valuable metals used in catalytic converters. Due to the high price of PGMs, there are already recycling routes in Europe and especially in Germany. For PGM and rare-earth elements, research is focusing on greener, plain recovery techniques, which utilize milder reagents, offer better energy efficiency, and replace the existing recycling routes. In this work, a hydrometallurgical process is proposed to add a hydrometallurgy method to the mostly pyrometallurgical industrial recycling routes, resulting in recovery rates for cerium and PGMs of 63.21% and only 1.03% with sulfuric acid, respectively. With hydrochloric acid, the leaching efficiency for cerium is even lower, and for PGM it is comparable. In the method proposed in the present paper, the main PGMs remain in monoliths and can be recycled in existing recycling routes like pyrometallurgical recycling. [ABSTRACT FROM AUTHOR]

This work describes a new well-defined, air-stable, phosphine free palladium(II) [Pd(L)Cl] (1) catalyst. This catalyst was utilized for N-alkylation of amines and indole synthesis where H2O was found to be the by-product. A broad range of aromatic amines were alkylated using this homogeneous catalyst with a catalyst loading of 0.1 mol%. Greener aromatic and aliphatic primary alcohols were utilized and a hydrogen auto-transfer strategy via a metal–ligand cooperative approach was investigated. The precursor of the antihistamine-containing drug molecule tripelennamine was synthesized on a gram scale for large-scale applicability of the current synthetic methodology. A number of control experiments were performed to investigate the possible reaction pathway and the outcomes of these experiments indicated the azo-chromophore as a hydrogen reservoir during the catalytic cycle. [ABSTRACT FROM AUTHOR]

In continuation of our previous works on the cytotoxic properties of organopalladium compounds, in this contribution we describe the first systematic study of the anticancer activity of Pd(II)–aryl complexes. To this end, we have prepared and thoroughly characterized a wide range of palladium derivatives bearing different diphosphine, aryl and halide ligands, developing, when necessary, specific synthetic protocols. Most of the synthesized compounds showed remarkable cytotoxicity towards ovarian and breast cancer cell lines, with IC50 values often comparable to or lower than that of cisplatin. The most promising complexes ([PdI(Ph)(dppe)] and [PdI(p-CH3-Ph)(dppe)]), characterized by a diphosphine ligand with a low bite angle, exhibited, in addition to excellent cytotoxicity towards cancer cells, low activity on normal cells (MRC5 human lung fibroblasts). Specific immunofluorescence tests (cytochrome c and H2AX assays), performed to clarify the possible mechanism of action of this class of organopalladium derivatives, seemed to indicate DNA as the primary cellular target, whereas caspase 3/7 assays proved that the complex [PdI(Ph)(dppe)] was able to promote intrinsic apoptotic cell death. A detailed molecular docking analysis confirmed the importance of a diphosphine ligand with a reduced bite angle to ensure a strong DNA–complex interaction. Finally, one of the most promising complexes was tested towards patient-derived organoids, showing promising ex vivo cytotoxicity. [ABSTRACT FROM AUTHOR]

The four new ligands, dialkyl esters of (S,S)-propylenediamine-N,N′-di-(2,2′-di-(4-hydroxy-benzil))acetic acid (R2-S,S-pddtyr·2HCl) (R = ethyl (L1), propyl (L2), butyl (L3), and pentyl (L4)) and corresponding palladium(II) complexes have been synthesized and characterized by microanalysis, infrared, 1H NMR and 13C NMR spectroscopy. In vitro cytotoxicity was evaluated using the MTT assay on four tumor cell lines, including mouse mammary (4T1) and colon (CT26), and human mammary (MDA-MD-468) and colon (HCT116), as well as non-tumor mouse mesenchymal stem cells. Using fluorescence spectroscopy were investigated the interactions of new palladium(II) complexes [PdCl2(R2-S,S-pddtyr)]; (R = ethyl (C1), propyl (C2), butyl (C3), and pentyl (C4)) with calf thymus human serum albumin (HSA) and DNA (CT-DNA). The high values of the binding constants, Kb, and the Stern–Volmer quenching constant, KSV, show the good binding of all complexes for HSA and CT-DNA. The mentioned ligands and complexes were also tested on in vitro antimicrobial activity against 11 microorganisms. Testing was performed by the microdilution method, where the minimum inhibitory concentration (MMC) and the minimum microbicidal concentration (MMC) were determined. [ABSTRACT FROM AUTHOR]

Immobilized Pd‐catalyzed Suzuki‐Miyaura coupling under continuous‐flow conditions using a packed‐bed reactor, representing an efficient, automated, practical, and safe technology compared to conventional batch‐type reactions. The core objective of this study is the development of an active and durable catalyst. In contrast to supported Pd nanoparticles, the attachment of Pd complexes onto solid supports through well‐defined coordination sites is considered a favorable approach for preparing highly dispersed and stabilized Pd species. These species can be directly employed in various flow reactions without the need for pre‐treatment. This concept paper explores recent achievements involving the application of immobilized Pd complexes as precatalysts for continuous‐flow Suzuki‐Miyaura coupling. Our focus is to elucidate the significance of the designed catalyst structures in relation to their catalytic performance under flow conditions. Additionally, we highlight various reaction systems and catalyst packing methods, emphasizing their crucial roles in establishing a practical synthesis process. [ABSTRACT FROM AUTHOR]

Exploration of novel chiral pharmaceutical candidates is motivation to immersive efforts among synthetic chemists. Achieving skeletal construction and chiral diversity in a highly efficient manner is a momentous goal in the chemical society. Unfortunately, current methods for chiral induction focus primarily on a specific site. Herein, we realized the asymmetric chain-walking arylation of alkenyl alcohols for the construction of multisite tertiary and quaternary stereocenters in high yields and enantioselectivity. This new operation-friendly strategy carries substantial potential for future industrialization. [ABSTRACT FROM AUTHOR]

The recovery of palladium from aqueous solutions is important due to its critical role in various industrial applications and the growing demand for sustainable resource management. This study investigates the potential of hybrid materials composed of Mg3Al layered double hydroxides (LDHs), chitosan, and ionic liquids (methyl trialchil ammonium chloride) for the efficient adsorption of palladium ions from low-concentration aqueous solutions. Comprehensive characterization techniques, including X-ray diffraction (RX), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TG), were employed to elucidate the structural and compositional properties of the hybrid materials. The results of the batch adsorption experiments demonstrate that each component contributes synergistically to the adsorption process, significantly enhancing the overall efficacy of palladium recovery. Furthermore, the method of preparing the adsorbent material was found to impact the effectiveness of palladium recovery. Among the materials tested, the chitosan/Mg3Al/IL hybrid exhibited the highest adsorption capacity (qmax = 98 mg/g), suggesting that the ionic liquid functionalization is most beneficial when applied during the hybrid material synthesis, rather than during the LDH synthesis process. This research underscores the viability of hybrid materials as a sustainable approach to palladium recovery, contributing to advancements in environmental remediation technologies. [ABSTRACT FROM AUTHOR]

The development of new catalytic systems that enable regio- and chemoselective construction of diversely functionalized oxazocines is an important topic in organic synthesis and pharmacochemistry. Herein, a novel Pd/Mengphos complex was designed and applied in a palladium-catalyzed high-order [4+4] cycloaddition of 2-substituted allylic carbonates to α,β-unsaturated imines, allowing facile access to versatile oxazocines in good yields with excellent b / l and Z / E selectivities (up to 92% yield and complete b / l and Z / E selectivities). The reaction exhibited a broad substrate scope, mild reaction conditions, and good functional group compatibility. In addition, an asymmetric version has also been tested, affording the desired oxazocines in moderate to good enantioselectivity. [ABSTRACT FROM AUTHOR]

Herein we report synthesis of pyrene-azobenzene dyads using the Pd(II)-catalyzed directing-group-assisted arylation of the ortho C(sp2)–H bond of pyrenecarboxamides as a key transformation. Many examples of directly connected pyrene-azobenzene dyads (without any linker) and glycine-based azobenzene-pyrene dyads have been synthesized. Initial incorporation of an acetanilide unit in the pyrene skeleton through Pd(II)-catalyzed directing-group-assisted ortho C(sp2)–H arylation by using iodoacetanilide was followed by the transformation of the acetanilide into an azobenzene unit to give the pyrene-azobenzene dyad. UV-Vis spectroscopic studies were performed to get the absorption properties (λmax (nm)) of all the compounds. Preliminary photoswitching studies in both forward and reverse directions and their related thermal reverse Z → E isomerization kinetics measurements were ascertained for representative compounds. Considering the importance of pyrene and azobenzene linked motifs as important chromophore-based photoswitchable molecules in chemical, materials, and supramolecular sciences research fields, this work enriches the library of pyrene-azobenzene dyads. [ABSTRACT FROM AUTHOR]

A number of new deoxyvasicinone (2,3‐dihydropyrrolo[2,1‐b]quinazolin‐9(1H)‐one) and mackinazolinone (6,7,8,9‐tetrahydro‐11H‐pyrido[2,1‐b]quinazolin‐11‐one) derivatives with aryl substituents at C7/C8 and at C5 are reported. These compounds are rare representatives of their kind and were prepared in high yields by Suzuki‐Miyaura cross‐coupling reactions between 7‐bromo‐2,3‐dihydro[2,1‐b]quinazoline‐9‐(1H)‐one, 5,7‐dibromo‐2,3‐dihydro[2,1‐b]quinazoline‐9‐(1H)‐one or 8‐bromomackinazolinone and respective arylboronic acids with palladium acetate as the catalyst. The products were characterized spectroscopically and, in addition, by X‐ray crystal structure analyses in six cases. [ABSTRACT FROM AUTHOR]

A comprehensive investigation of hydrogen grabbing towards the formation of hetero-clusters of AlGaN–H, Si–AlGaN–H, Ge–AlGaN–H, Pd–AlGaN–H, and Pt–AlGaN–H was carried out using DFT computations at the CAM–B3LYP–D3/6-311+G (d,p) level of theory. The notable fragile signal intensity close to the parallel edge of the nanocluster sample might be owing to silicon or germanium binding-induced non-spherical distribution of Si–AlGaN or Ge–AlGaN hetero-clusters. Based on TDOS, the excessive growth technique of doping silicon, germanium, palladium, or platinum is a potential approach to designing high-efficiency hybrid semipolar gallium nitride devices in a long-wavelength zone. Therefore, it can be considered that palladium or platinum atoms in the functionalized Pd–AlGaN or Pt–AlGaN might have more impressive sensitivity for accepting the electrons in the process of hydrogen adsorption. The advantages of platinum or palladium over aluminum gallium nitride include its higher electron and hole mobility, allowing platinum or palladium doping devices to operate at higher frequencies than silicon or germanium doping devices. In fact, it can be observed that doped hetero-clusters of Pd–AlGaN or Pt–AlGaN might ameliorate the capability of AlGaN in transistor cells for energy storage. [ABSTRACT FROM AUTHOR]

Consideration is given to modern industrial materials for manufacture of membranes oriented toward hydrogen separation from process gas mixtures. Mechanisms for separation of gases on membranes of various materials are given. Fundamental advantages and disadvantages of polymer and metal membranes and also areas for their development are shown. [ABSTRACT FROM AUTHOR]

Pulsed current has proven to be a promising alternative to direct current in electrochemical deposition, offering numerous advantages regarding deposit quality and properties. Concerning the electrodeposition of metal alloys, the role of pulsed current techniques may vary depending on the specific metals involved. We studied an innovative tin–ruthenium electroplating bath used as an anti-corrosive layer for decorative applications. The bath represents a more environmentally and economically viable alternative to nickel and palladium formulations. The samples obtained using both direct and pulsed currents were analyzed using various techniques to observe any differences in thickness, color, composition, and morphology of the deposits depending on the pulsed current waveform used for deposition. [ABSTRACT FROM AUTHOR]

In the present study, an electrochemically reduced graphene oxide/palladium-modified glassy carbon electrode (ERGO-Pd/GCE) was successfully synthesized by single-step electrodeposition and employed for the determination of norepinephrine (NE). The modified GCE exhibited enhanced sensitivity towards the simultaneous and selective determination of NE, uric acid (UA), and ascorbic acid (AA). The electrochemical performances were evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA). This sensor was also effective for the simultaneous detection of epinephrine (EP), UA, and AA. Moreover, the sensor showed outstanding long-term stability, reproducibility, and repeatability. Thus, the electrochemical sensor developed in this study was successfully employed for real samples, such as human blood serum. [ABSTRACT FROM AUTHOR]

A selective direct arylation of the different Csp2‐H bonds of imidazo[2,1‐b]thiazole with (hetero) aryl halides can be achieved simply by switching from a palladium catalyst system to the use of stoichiometric amounts of copper. The observed selectivity, also rationalized by DFT calculations, can be explained by a change in the mechanistic pathways between electrophilic palladation and base‐promoted C−H metalation. [ABSTRACT FROM AUTHOR]

It is proposed to use the idea of the rate of hydrogen crossing the metal boundary for the calculation of the hydrogen permeability of palladiumcontaining membranes. The corresponding kinetic coefficient of proportionality between the hydrogen flux density and the hydrogen chemical-potential jump at the metal boundary is introduced. Criteria for distinguishing between diffusion-limited and surface-limited regimes based on the introduced kinetic coefficients are established. This coefficient is amenable to relatively simple experimental determination by a bending-rebending study of a palladium cantilever. The hydrogen flux density through the membrane is calculated as a function of the diffusion coefficient, membrane thickness, and kinetic coefficients at the entrance and exit surfaces. As revealed, the hydrogen flux density and concentration profile within the membrane are influenced by membrane thickness and the rates of hydrogen penetration at the input and output surfaces. Furthermore, it is proposed a simple scheme for calculating the hydrogen permeability of palladium-containing membranes, providing insights for membrane design and optimization. The concentration of atomic hydrogen at the inlet and outlet of the membrane is determined. The results of hydrogen-permeability calculation converge with relevant literature data. This study sheds light on the factors governing the hydrogen permeability in palladium membranes and offers valuable insights for the development of high-performance hydrogen-separation technologies. [ABSTRACT FROM AUTHOR]

The urine/urea oxidation reaction through catalysts with a higher performance in direct urea microfluidic fuel cells (DUµFC) is a promising method for power generation due to the large amount of human and animal urine containing 2–2.5 wt% urea. This paper presents a study that used urea as fuel in a DUµFC in the presence of palladium supported by reduced graphene oxide (rGO) for power generation. Some parameters, such as urea, KOH and H2SO4 concentration and flux rate, among others, are optimized in order to carry out the evaluation of urine samples as fuel in an air-breathing microfluidic fuel cell. The results show that the Pd/rGo catalyst mixed with Nafion® in the anodic compartment is dispersed and attached to the paper fibers, generating electrical contact and giving rise to the reactions of interest. In addition, XRD analysis confirmed the successful deposition of Pd and rGo on the substrate. These electrochemical results are promising, since, despite the decrease in the general performance of the DUµFC under ideal conditions with respect to normal cells, the generation of energy from urine was demonstrated. [ABSTRACT FROM AUTHOR]

To improve the hydrogen detection performance, a flexible palladium-based hydrogen sensor was designed and fabricated on normal photocopy paper. The paper substrate offers advantages such as light weight, low cost, flexibility and unique surface texture. A conventional vacuum evaporation technique was utilized for 60 nm palladium deposition on the paper and glass substrates. The unique surface texture of the paper effectively increased the surface area to volume ratio for the sensing element, which achieved a higher gas response with faster speed than the glass-based sensor. In addition, we investigated the temperature impacts on sensing performance of the paper-based hydrogen sensor at room temperature and 50 °C. Furthermore, the flexibility test results of the paper-based hydrogen sensor showed that the sensing performances were impervious to mechanical bending of 5.7°. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed cross-coupling reactions, including the Suzuki, Stille, and Negishi couplings, have emerged as essential methodologies in contemporary organic synthesis. Nevertheless, there is still a lack of comprehensive understanding of the molecular processes involved in these significant events that lead to the formation of C-C and C-heteroatom bonds. This paper provides a complete analysis of the fundamental mechanistic investigations conducted on the primary crosscoupling processes facilitated by palladium catalysts. The present study focuses on the examination of kinetic aspects of several stages within the catalytic cycle, namely oxidative addition, transmetalation, and reductive elimination, in the context of diverse palladium-catalyzed coupling reactions. This paper examines the influence of ligands, substrates, reaction conditions, and additives on the kinetics and mechanism of the reaction. This study emphasizes the significance of computational investigations in enhancing our understanding of Pd catalyst speciation and the architectures of intermediates. This study aims to identify both overarching patterns and variations in the systems under investigation. Additionally, the present obstacles in comprehensively understanding the specific intricacies of these mechanisms are delineated. A comprehensive comprehension of catalytic pathways will serve as the fundamental basis for the development of enhanced Pd catalysts and the expansion of these reactions to novel substrates. The inclusion of mechanistic information will provide valuable insights to develop more efficient catalytic systems based on palladium. [ABSTRACT FROM AUTHOR]

Designing a stable, efficient, highly selective, and low-cost dehydrogenation catalyst, using formic acid to produce hydrogen energy, is challenging even today. This paper reports a facile preparation method of constructing Pd–Co alloy-composite catalyst for hydrogen production using formic acid by heterogeneous catalyst decomposition. The results demonstrate that introducing a nonprecious cobalt metal could significantly reduce precious palladium metal usage. Moreover, the particle size reduces from 13.50 nm (without Co) to 3.4 nm (with Co). More importantly, the Pd2+ amount in the catalyst affect the catalytic decomposition of formic acid to produce hydrogen. Additionally, Pd0.9Co0.1/C650 exhibits excellent catalytic activity and cyclic catalytic stability and it is one of the best non-precious metal doped Pd-based catalysts. The development of a synthetic method with the addition of nonprecious metal in this paper opens up a new avenue for cheap and efficient catalysts for application scenarios of hydrogen production. H2 production by formic acid dehydrogenation. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Furans bearing alkynyl substituents are highly useful in organic synthesis. However, the methodologies to access these important furan derivatives are rather limited. We herein report an efficient synthesis of alkynylated furan derivatives based on Pd‐catalyzed oxidative cross‐coupling reaction between allenyl ketones and terminal alkynes. This novel synthesis of alkynylated furans with wide substrate scope is operationally simple and tolerates various functional groups. Mechanistically, the formation of the palladium carbene through cycloisomerization and the subsequent alkynyl migratory insertion are proposed as the key steps in the transformation. The reaction reported in this paper further demonstrates the generality of the carbene‐based cross coupling. [ABSTRACT FROM AUTHOR]

In this paper, the polymerization of butyl acrylate (BA) in the presence of palladium nanoparticles (Pd NPs) has been investigated. A series of organic halides such as carbon tetrachloride (CCl4), ethyl 2-bromopropionate (EBP), ethyl 2-chloropropionate (ECP) and ethyl α-bromophenylacetate (α-EBP) were employed to initiate the polymerization of BA in the presence of Pd NPs. An ultrahigh molecular weight poly(butyl acrylate) (PBA) with a number average molecular weight (Mn) up to 1.86 × 106 Da and polydispersity index (PDI) of 2.38 was synthesized by using α-EBP as an initiator in the presence of 10.5 ppm of Pd NPs at 60 ºC. The orders of polymerization with respect to α-EBP, Pd NPs and BA were determined to be 0.48, 0.86, and 0.95 respectively according to the kinetic investigation. A mechanistic investigation revealed that the reaction of α-EBP and Pd NPs resulted in a generation of α-EBP residue radical to initiate the polymerization of BA around the surface of Pd NPs. [ABSTRACT FROM AUTHOR]