Novel activated NIR-II fluorescence/Ratio photoacoustic probe for dual-modality accurate imaging of palladium ions overload in mouse liver.

Palladium contaminants can pose risks to human health and the natural environment. Once Pd2+ enters the body, it can bind with DNA, proteins, and other macromolecules, disrupting cellular processes and causing serious harm to health. Therefore, it becomes critical to develop simple, highly selective and precise methods for detecting Pd2+in vivo. Here, we have successfully developed the first activated second near-infrared region fluorescence (NIR-II FL) and ratio photoacoustic (PA) probe NYR-1 for dual-modal accurate detection of Pd2+ levels. NYR-1 is capable of rapidly (< 60 s) and sensitively detection of Pd2+ in solution, providing switched on NIR-II FL920 and ratio PA808/PA720 dual-mode signal change. More notably, the probe NYR-1 was successfully used for non-invasive imaging of Pd2+ overload in mouse liver by NIR-II FL/Ratio PA dual-modality imaging technology for the first time. Thus, this work opens up a promising dual-modal detection method for the precise detection of Pd2+ in organisms and in the environment.

Steering the Selective Production of Glycolic Acid by Electrocatalytic Oxidation of Ethylene Glycol with Nanoengineered PdBi-Based Heterodimers.

Heterodimers of metal nanocrystals (NCs) with tailored elemental distribution have emerged as promising candidates in the field of electrocatalysis, owing to their unique structures featuring heterogeneous interfaces with distinct components. Despite this, the rational synthesis of heterodimer NCs with similar elemental composition remains a formidable challenge, and their impact on electrocatalysis has remained largely elusive. In this study, Pd@Bi-PdBi heterodimer NCs are synthesized through an underpotential deposition (UPD)-directed growth pathway. In this pathway, the UPD of Bi promotes a Volmer-Weber growth mode, allowing for judicious modulation of core-satellite to heterodimer structures through careful control of supersaturation and growth kinetics. Significantly, the heterodimer NCs are employed in the electrocatalytic process of ethylene glycol (EG) with high activity and selectivity. Compared with pristine Pd octahedra and common PdBi alloy NC, the unique heterodimer structure of the Pd@Bi-PdBi heterodimer NCs endows them with the highest electrocatalytic performance of EG and the best selectivity (≈93%) in oxidizing EG to glycolic acid (GA). Taken together, this work not only heralds a new strategy for UPD-directed synthesis of bimetallic NCs, but also provides a new design paradigm for steering the selectivity of electrocatalysts.

Palladium-Catalyzed Inward Isomerization Hydroaminocarbonylation of Alkenes.

In contrast to the kinetically favored outward isomerization-hydrocarbonylation of alkenes, the disfavored inward isomerization-hydrocarbonylation of alkenes remains an important challenge. Herein, we have developed a novel and effective palladium-catalyzed inward isomerization-hydroaminocarbonylation of unactivated alkenes and aniline hydrochlorides for the formation of synthetically valuable α-aryl carboxylic amides in high yields and high site-selectivities. The high efficiency of the reaction is attributed to a relay catalysis strategy, in which the Markovnikov-favored [PdH]-PtBu3 catalyst is responsible for inward isomerization, while the [PdH]-Ruphos catalyst is responsible for hydroaminocarbonylation of the resulting conjugated aryl alkenes. The reaction exhibits highly functional group tolerance and provides a new method for formal carbonylation of remote C(sp3)-H bond.

Beyond Tertiary Amines: Introducing Secondary Amines via Palladium/Norbornene-Catalyzed Ortho Amination.

Since the discovery of the palladium/norbornene (Pd/NBE)-catalyzed ortho amination in 2013, escaping the limitation of only yielding tertiary anilines has been a long-standing challenge in the past decade. Here, we describe that, by carefully choosing the phosphine ligand and NBE mediator, installation of a N-mono-alkylamino group becomes feasible. The reaction tolerates a wide range of aryl iodide substrates and various N-mono-tertiary alkylamine-derived electrophiles. Both ipso alkenylation and alkynylation can be realized. The synthetic utility of this method is exemplified in the formation of primary amino group via selective deprotection and streamlined access to N-heterocycles. Preliminary success of installing a bulky N-secondary alkylamino group and mechanistic understanding of the decomposition pathways of mono N-alkylamine electrophiles have been obtained.

Enhanced hydrodechlorination of 4-chlorophenol through carboxymethylcellulose-modified Pd/Fe nanosuspension synthesized by one-step methods.

Palladized iron (Pd/Fe) represents one of the most common modification strategies for nanoscale zero-valent iron (nZVI). Most studies prepared Pd/Fe by reducing iron salts and depositing Pd species on the surface of pre-synthesized nZVI, which can be called the two-step method. In this study, we proposed a one-step method to obtain Pd/Fe by the concurrent formation of Fe0 and Pd0 and investigated the effects of these two methods on 4-chlorophenol (4-CP) removal, with carboxymethylcellulose (CMC) coated as a surface modifier. Results indicated that the one-step method, not only streamlined the synthesis process, but also Pd/Fe-CMCone-step, synthesized by it, exhibited a higher 4-CP removal rate (97.9%) compared to the two-step method material Pd/Fe-CMCtwo-step (82.4%). Electrochemical analyses revealed that the enhanced activity of Pd/Fe-CMCone-step was attributed to its higher electron transfer efficiency and more available reactive species, active adsorbed hydrogen species (Hads*). Detection of intermediate products demonstrated that, under the influence of Pd/Fe-CMCone-step, the main route of 4-CP was through hydrodechlorination (HDC) to form phenol and H* was the main active specie, supported by EPR tests, quenching experiments and product analysis. Additionally, the effects of initial 4-CP concentration, initial pH, O2 concentration, anions such as Cl-, SO42-, HCO3-, and humic acid (HA) were also investigated. In conclusion, the results of this study suggest that Pd/Fe-CMCone-step, synthesized through the one-step method, is a convenient and efficient nZVI-modifying material suitable for the HDC of chlorinated organic compounds.

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines.

Herein, we report a visible-light-mediated palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines, affording unsaturated γ- and ε-amino acid derivatives with diverse structures. In this methodology, the diazo compound readily transforms into a hybrid α-ester alkylpalladium radical with the release of dinitrogen. The radical intermediate selectively adds to the double bond of a 1,3-diene or allene, followed by the allylpalladium radical-polar crossover path and selective allylic substitution with the amine substrate, thereby leading to a single unsaturated γ- or ε-amino acid derivative. This approach proceeds under mild and simple reaction conditions and shows high functional group tolerance, especially in the incorporation of various bioactive molecules. The studies on scale-up reactions and diverse derivatizations highlight the practical utility of this multicomponent reaction protocol.

Synthesis, theoretical analysis, and biological properties of a novel tridentate Schiff base palladium (II) complex.

Schiff base complexes play a crucial role in bioinorganic chemistry. A novel curcumin/phenylalanine tridentate Schiff base ligand and its palladium (II) complex were synthesized so that they were stable in aqueous buffer. The structure of the complex was investigated using a variety of methods, including DFT, NBO analysis, FMOs, and MESP. The interaction of the complex with a plasmid (pUC19) and CT-DNA was studied. The anticancer, antibacterial, and antioxidant activities of the complex were examined. The statistical analysis of the MTT assay was compared using the 1-way ANOVA and Tukey test. Results showed that the complexes were stable in aqueous buffer, pH 8. The extrinsic fluorescence emission of the plasmid and CT-DNA was quenched while interacting with the complex. The complex had an IC50 of 72.47 µM against MCF-7 cells. The ANOVA and Tukey analysis of MTT data demonstrated a statistically significant difference between groups (P < 0.0001). The minimum inhibitory concentrations (MIC) of the complex for E. coli and S. aureus were 300 and 200 µg/mL, with 96.3 and 95.2% biofilm growth inhibition at 250 µg/mL, respectively. The sample concentrations contributing to 50% radical inhibition in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) test for curcumin, ligand, and palladium (II) complex were 33.62, 21.27, and 51.26 µM, respectively. The results suggest that the complex interaction with DNA is one of the potential mechanisms for eliminating cancer cells and bacteria in the planktonic and biofilm. On the other hand, while stability in an aqueous buffer at pH 8 increases, the modified curcumin antioxidant effect decreases.

Catalytic Asymmetric Cascade Dearomatization of Indoles via a Photoinduced Pd-Catalyzed 1,2-Bisfunctionalization of Butadienes.

Photoinduced Pd-catalyzed bisfunctionalization of butadienes with a readily available organic halide and a nucleophile represents an emerging and attractive method to assemble versatile alkenes bearing various functional groups at the allylic position. However, enantiocontrol and/or diastereocontrol in the C-C or C-X bond-formation step have not been solved due to the open-shell process. Herein, we present a cascade asymmetric dearomatization reaction of indoles via photoexcited Pd-catalyzed 1,2-biscarbonfunctionalization of 1,3-butadienes, wherein asymmetric control on both the nucleophile and electrophile part is achieved for the first time in photoinduced bisfunctionalization of butadienes. This method delivers structurally novel chiral spiroindolenines bearing two contiguous stereogenic centers with high diastereomeric ratios (up to >20:1 dr) and good to excellent enantiomeric ratios (up to 97:3 er). Experimental and computational studies of the mechanism have confirmed a radical pathway involving excited-state palladium catalysis. The alignment and non-covalent interactions between the substrate and the catalyst were found to be essential for stereocontrol.

Implementing a sustainable process for the recovery of palladium from spent catalysts at industrial scale: A LCA approach.

Due to its unique physicochemical properties, palladium is widely used in several industry applications (e.g., vehicle emission control). In view of the circular economy, it is essential to explore secondary sources of palladium, such as urban mines. Current technologies for effective palladium recovery involve high energy consumption and severe environmental impact. More recently, a novel green method for recovering palladium from spent catalysts through a combination of mild acidic leaching and photodeposition on ZnO nanoparticles was proposed on a laboratory scale. In the present study, the environmental impacts of this recovery method, properly upscaled and modelled, was assessed by employing the LCA approach. Specifically, a comparative LCA was carried out for the process with as well as without recycling key components, such as Cu (II) and NaCl for the leaching solution and ZnO. The outcomes identified critical areas and drove the investigation of alternative process configurations to reduce its environmental footprint, such as the use of carbon dioxide in the photodeposition process with the aim of decreasing the resulting terrestrial ecotoxicity. This study marks a significant step forward in advancing research toward industrial-scale implementation of palladium recovery. It provides valuable insights for researchers in the field of green physicochemical processes for metal recovery, thus offering guidance for future decision-making towards more sustainable practices.

Palladium-Catalyzed Atroposelective Suzuki-Miyaura Coupling to Construct Axially Chiral Tetra-Substituted α-Boryl Styrenes.

Palladium-catalyzed Suzuki-Miyaura (SM) coupling is a valuable method for forming C─C bonds, including those between aryl moieties. However, achieving atroposelective synthesis of axially chiral styrenes via SM coupling remains challenging. In this study, a palladium-catalyzed atroposelective Suzuki-Miyaura coupling between gem-diborylalkenes and aryl halides is presented. Using the monophosphine ligand Me-BI-DIME (L2), a range of axially chiral tetra-substituted acyclic styrenes with high yields and excellent enantioselectivities are successfully synthesized. Control experiments reveal that the gem-diboryl group significantly influences the product enantioselectivities and the coupling prefers to occur at sites with lower steric hindrance. Additionally, the alkenyl boronate group in the products proves versatile, allowing for various transformations while maintaining high optical purities.

(2,2'-Bi-pyridine-κ2N,N')(4,4'-dimeth-oxy-2,2'-bipyridine-κ2N,N')palladium(II) bis-(tri-fluoro-meth-anesulfonate).

In the title complex salt, [Pd(C10H8N2)(C12H12N2O2)](CF3SO3)2, the palladium(II) atom is fourfold coordinated by two chelating ligands, 2,2'-bi-pyridine and 4,4'-dimeth-oxy-2,2'-bi-pyridine, in a distorted square-planar environment. In the crystal, weak π-π stacking inter-actions between the 2,2'-bi-pyridine rings [centroid-to-centroid distances = 3.8984 (19) Å] and between the 4,4'-dimeth-oxy-2,2'-bi-pyridine rings [centroid-to-centroid distances = 3.747 (18) Å] contribute to the alignment of the complex cations in columns parallel to the b-axis direction.

Regio- and Chemoselective Palladium-Catalyzed Additive-Free Direct C─H Functionalization of Heterocycles with Chloroaryl Triflates Using Pyrazole-Alkyl Phosphine Ligands.

A series of new pyrazole-alkyl phosphine ligands with varying cycloalkyl ring sizes that enable additive-free regio- and chemoselective C─H arylation of heterocycles are reported. Excellent α/ß selectivity of various heterocycles such as benzo[b]thiophene, thiophene, furan, benzofuran, and thiazole can be achieved using these ligands, along with excellent chemoselectivity of C─Cl over C─OTf of chloroaryl triflates. Mechanistic studies supported by both experimental findings and density functional theory calculations indicate that the pyrazole phosphine ligands with optimal ring sizes allow the reaction to proceed with a lower energy barrier via a concerted metalation-deprotonation pathway.

Stabilized Palladium Nanoparticles from Bis-(N-benzoylthiourea) Derived-PdII Complexes as Efficient Catalysts for Sustainable Cross-Coupling Reactions in Water.

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki-Miyaura, Mizoroki-Heck, Hiyama, Buchwald-Hartwig, Hirao and Sonogashira-Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective and very versatile. The nanoparticles responsible for these catalytic reactions were analyzed and studied. Their usefulness is demonstrated after several tests and analyses. The heterogeneous character of this species in water was also confirmed.

Organotransition Metal Chemistry of Terpenes: Syntheses, Structures, Reactivity and Molecular Rearrangements.

The impact of organometallic chemistry on the terpene field only really blossomed in the 1960s and 1970s with the realisation that carbon-carbon bond formation under mild conditions could be achieved by using nickel or iron carbonyls as synthetic reagents. Concomitantly, the development of palladium derivatives capable of the controlled coupling of isoprene units attracted the attention of numerous highly talented researchers, including future Nobel laureates. We discuss briefly how early work on the syntheses of simple monoterpenes soon progressed to sesquiterpenes and diterpenes of increasing complexity, such as humulene, flexibilene, vitamin A, or pheromones of commercial value, in particular those used in perfumery (muscone, lavandulol), or grandisol and red scale pheromone as replacements for harmful pesticides. As the field progressed, there has been more emphasis on developing organometallic routes to enantiopure rather than racemic products, as well as gaining precise mechanistic data on the transformations, notably the course of metal-promoted molecular rearrangements that have long been a feature of terpene chemistry. We note the impact of the enormously enhanced analytical techniques, high-field NMR spectroscopy and X-ray crystallography, and their use to re-examine the originally proposed structures of terpenes and their organometallic derivatives. Finally, we highlight the very recent ground-breaking use of the crystalline sponge method to acquire structural data on low-melting or volatile terpenes. The literature cited herein covers the period 1959 to 2023.

Palladium Phthalocyanine Nanowire-Based Highly Sensitive Sensors for NO2(g) Detection.

Palladium phthalocyanine (PdPc) nanowires (NWs) were developed to achieve the gas sensing of NO2 in the sub-parts-per-million (ppm) range. Non-substituted metal phthalocyanine are well known for their p-type semiconducting behavior, which is responsible for its gas-sensing capabilities. Nanofabrication of the PdPc NWs was performed by physical vapor deposition (PVD) on an interdigitated gold electrode (IDE). The coordination of palladium in the structure was confirmed with UV-Vis spectroscopy. Gas-sensing experiments for NO2 detection were undertaken at different sensed gas concentrations from 4 ppm to 0.5 ppm at room temperature. In this work, the responses at different gas concentrations are reported. In addition, structural studies of the PdPc NWs with scanning electron microscopy (SEM) and electron-dispersive X-ray diffraction (EDS) are shown.

Polarization Property Associated with Surface Plasmon Resonance in a Palladium Thin-Film Coated Aluminum Grating in a Conical Mounting and Its Application to Hydrogen Gas Detection.

We have investigated a polarization property of the (specularly) reflected light from an aluminum grating, coated with a palladium (Pd) thin-film on its surface. The polarization property, which is associated with surface plasmon resonance (SPR), and occurs in the Pd thin-film on the aluminum grating in a conical mounting, is observed as a rapid change in the normalized Stokes parameter s3, around the resonance angle, θsp, at which point, SPR occurs. The sensing technique used the rapid change in s3 to allow us to successfully detect a small change in the complex refractive index of the Pd thin-film layer upon exposure to hydrogen gas, with a concentration near the lower explosion level. Experimental results showed that the sensing technique provided a sensitive and stable response when the Pd thin-film layer was exposed to gas mixtures containing hydrogen at concentrations of 1 to 4% (by volume) in nitrogen.

Halo-1,2,3-triazole: valuable compounds to access biologically relevant molecules.

1,2,3-triazole is an important building block in organic chemistry. It is also now well known as bioisostere for various functions, such as the amide or the ester bond, positioning it as key pharmacophore in medicinal chemistry and it has found applications in various fields including life sciences. Attention was first focused on the synthesis of 1,4-disubstituted 1,2,3-triazole molecules but 1,4,5-trisubstituted 1,2,3-triazoles have emerged as valuable molecules due to the possibility to expand the structural modularity. In the last decade, methods mainly derived from the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction have been developed to access halo-triazole compounds and have been applied to nucleosides, carbohydrates, peptides and proteins. In addition, late-stage modification of halo-triazole derivatives by metal-mediated cross-coupling or halo-exchange reactions offers the possibility to access highly functionalized molecules that can be used as a tools for chemical biology. This review summarizes the synthesis, the functionalization, and the applications of 1,4,5-trisubstituted halo-1,2,3-triazoles in biologically relevant molecules.

The Pd (II) Reduction Mechanisms in Bacillus megaterium Y-4 Revealed by Proteomic Analysis.

Many studies have been conducted on the microbial reduction of Pd (II) to palladium nanoparticles (Pd-NPs) due to the environmental friendliness, low cost, and the decreased toxicity of Pd (II) ions. In this study, we investigate the reduction mechanism of Pd (II) by Bacillus megaterium Y-4 through proteomics. The data are available via ProteomeXchange with identifier PXD049711. Our results revealed that B. megaterium Y-4 may use the endogenous electron donor (NAD(P)H) generated by nirB, tdh, and fabG and reductase to reduce Pd (II) to Pd-NPs. The expression levels of fabG, tdh, gudB, and rocG that generate NAD(P)H were further increased, and the number of reduced Pd-NPs was further increased with the exogenous electron donor sodium formate. Endogenous electron mediators such as quinones and flavins in B. megaterium Y-4 can further enhance Pd (II) reduction. The findings provided invaluable information regarding the reduction mechanism of Pd (II) by B. megaterium Y-4 at the proteome level.

Efficient and Selective Removal of Palladium from Simulated High-Level Liquid Waste Using a Silica-Based Adsorbent NTAamide(C8)/SiO2-P.

In order to realize the effective separation of palladium from high-level liquid waste (HLLW), a ligand-supported adsorbent (NTAamide(C8)/SiO2-P) was prepared by the impregnation method in a vacuum. The SiO2-P carrier was synthesized by in situ polymerization of divinylbenzene and styrene monomers on a macroporous silica skeleton. The NTAamide(C8)/SiO2-P adsorbent was fabricated by impregnating an NTAamide(C8) ligand into the pore of a SiO2-P carrier under a vacuum condition. The adsorption performance of NTAamide(C8)/SiO2-P in nitric acid medium has been systematically studied. In a solution of 0.2 M HNO3, the distribution coefficient of Pd on NTAamide(C8)/SiO2-P was 1848 mL/g with an adsorption percentage of 90.24%. With the concentration of nitric acid increasing, the adsorption capacity of NTAamide(C8)/SiO2-P decreases. Compared to the other 10 potential interfering ions in fission products, NTAamide(C8)/SiO2-P exhibited excellent adsorption selectivity for Pd(II). The separation factor (SFPd/other metals > 77.8) is significantly higher than that of similar materials. The interference of NaNO3 had a negligible effect on the adsorption performance of NTAamide(C8)/SiO2-P, which maintained above 90%. The adsorption kinetics of Pd(II) adsorption on NTAamide(C8)/SiO2-P fits well with the pseudo-second order model. The Sips model is more suitable than the Langmuir and Freundlich model for describing the adsorption behavior. Thermodynamic analysis showed that the adsorption of Pd(II) on NTAamide(C8)/SiO2-P was a spontaneous, endothermic, and rapid process. NTAamide(C8)/SiO2-P also demonstrated good reusability and economic feasibility.

Application of a magnetically separable Zr-MOF for fast extraction of palladium before its spectrophotometric detection.

In this research, a novel magnetic zirconium-based metal-organic framework (Fe3O4@SiO2@MIP-202, MMOF), was fabricated, fully characterized, and applied for the batch-mode solid phase extraction of trace amounts of Pd2+ ions from water and wastewater samples before its spectrophotometric detection. Pd2+ ions were desorbed from MMOF by nitric acid and were complexed by treating with KI solution to have a maximum absorbance at 410 nm. The synthesized MMOF composite showed a very large surface area (65 m2.g- 1), good magnetization (1.7 emu.g- 1) and a large pore volume (0.059 cm3.g- 1) with adsorption capacity of 194.5 mg of Pd2+ ions/g of the adsorbent. This nanosorbent boasts chemo-mechanical stability, high adsorption capacity due to its vast active sites, and facile recovery facilitated by its magnetic properties. Parameters affecting the extraction efficiency of the method were optimized as pH of the sample 7.4, volume of the sample 25 mL, 15 mg adsorbent, 1 mL of 0.1 M HNO3 eluent, with 10 and 15 min as the extraction and desorption times, respectively. The calibration curve was found to be linear across the 10.0-1500.0 µg.L- 1 range with a limit of detection of 1.05 µg.L- 1. The obtained extraction efficiency and enrichment were 98% and 245, respectively. The total analysis time was less than 30 min. This MMOF has never been used for the extraction of Pd2+ ions before.