Bis{(S)-(-)-N-[(2-biphen-yl)methyl-idene]-1-(4-meth-oxy-phen-yl)ethyl-amine-κN}di-chlorido-palladium(II).

The PdII complex bis-{(S)-(-)-N-[(biphenyl-2-yl)methyl-idene]1-(4-meth-oxy-phen-yl)ethanamine-κN}di-chlorido-palladium(II), [PdCl2(C22H21NO)2], crystallizes in the monoclinic Sohncke space group P21 with a single mol-ecule in the asymmetric unit. The coordination environment around the palladium is slightly distorted square planar. The N-Pd-Cl bond angles are 91.85 (19), 88.10 (17), 89.96 (18), and 90.0 (2)°, while the Pd-Cl and Pd-N bond lengths are 2.310 (2) and 2.315 (2) Šand 2.015 (2) and 2.022 (6) Å, respectively. The crystal structure features inter-molecular N-H⋯Cl and intramolecular C-H⋯Pd inter-actions, which lead to the formation of a supramolecular framework structure.

Surface crystallized supramolecular to achieve highly dispersed ultrafine nano-palladium in-situ deposition to promote thermal/electrocatalytic reduction.

To promote the greening and economization of industrial production, the development of advanced catalyst manufacturing technology with high activity and low cost is an indispensable part. In this study, nitrogen-doped hollow carbon spheres (NHCSs) were used as anchors to construct a supramolecular coating formed by the self-assembly of boron clusters and ß-cyclodextrin by surface crystallization strategy, with the help of the weak reducing agent characteristics of boron clusters, highly dispersed ultra-small nano-palladium particles were in-situ embedded on the surface of NHCSs. The deoxygenation hydrogenation of nitroaromatics and the reduction of nitrate to ammonia were used as the representatives of thermal catalytic reduction and electrocatalytic reduction respectively. The excellent properties of the constructed Pd/NHCSs were proved by the probe reaction. In the catalytic hydrogenation of nitroaromatics to aminoaromatics, the reaction kinetic rate and activation energy are at the leading level. At the same time, the constructed Pd/NHCSs can also electrocatalytically reduce nitrate to high value-added ammonia with high activity and selectivity, and the behavior of Pd/NHCSs high selectivity driving nitrate conversion was revealed by density functional theory and in situ attenuated total reflection Fourier transform infrared (ATRFTIR) technique. These results all reflect the feasibility and superiority of in-situ anchoring ultra-small nano-metals as catalysts by surface crystallization to build a supramolecular cladding with reducing properties, which is an effective way to construct high-activity and low-cost advanced catalysts.

Synthesis of Aryl Naphthoquinones and Maleimides via Pd(II)-Catalyzed Template-Assisted m-C(sp2)-H Functionalization Reaction.

An efficient approach for the synthesis of substituted aryl naphthoquinones via a Pd(II)-catalyzed template-assisted m-C(sp2)-H bond functionalization reaction of arylmethane sulfonates have been demonstrated. The method involves usage of less expensive and abundant pharmacologically important scaffold naphthoquinone. A wide range of arylmethane sulfonates were examined and found to be compatible with the protocol. The protocol has also been further extended to the synthesis of various substituted aryl maleimide scaffolds. A plausible reaction mechanism has also been proposed to account for the selective distal m-C(sp2)-H bond functionalization reaction.

Advancement in Synthetic Strategies of Phosphorus Heterocycles: Recent Progress from Synthesis to Emerging Class of Optoelectronic Materials.

Organophosphorus heterocycles have long been acknowledged for their significant potential across diverse fields, including catalysis, material science, and drug development. Incorporating phosphorus functionalities into organic compounds offers a means to effectively tailor their medicinal properties, augment biological responses, and enhance selectivity and bioavailability. The distinctive physical and photoelectric characteristics of phosphorus-containing conjugated compounds have garnered considerable interest as promising materials for organic optoelectronics. These compounds find extensive utility in various applications such as light-emitting diodes, photovoltaic cells, phosphole-based fluorophores, and semiconductors.

Magnesium(II) Porphyrazine with Thiophenylmethylene Groups-Synthesis, Electrochemical Characterization, UV-Visible Titration with Palladium Ions, and Density Functional Theory Calculations.

The presented studies aimed to evaluate the peripheral coordinating properties of a novel porphyrinoid family representative preceded by its synthesis for potential sensing purposes. Two synthetic pathways were employed to a obtain maleonitrile derivative, further used as a starting material in the cyclotetramerization reaction. In the first one, DAMN was used in sequential double-reductive alkylation with 2-thiophene-carboxyaldehyde and sodium borohydride. In the second, DAMN was used in a one-pot reaction with 2-thiophene-carboxyaldehyde in the presence of a 5-ethyl-2-methylpyridine borane complex in methanol and acetic acid. Following the Linstead approach, the cyclization reaction led to a novel symmetrical magnesium(II) octaaminoporphyrazine with methyl(2-thiophenylmethylene) substituents. The macrocycle's electrochemical properties were assessed by cyclic and differential pulse voltammetries revealing one reduction and two oxidation peak potentials. The additional spectroelectrochemical measurements showed formation of a cationic form of the macrocycle at an applied potential of 0.6 V. The coordinating properties due to the palladium ion of novel porphyrazines were measured with the use of titration combined with UV-vis spectrometry. The titration of Pd2+ revealed the good sensing activity of porphyrazine in the range of 0.1 to 5 palladium molar equivalents. In addition, Pd2+ ions coordination was also assessed by electrochemical studies, indicating the peak potential shift of 0.1 V in the presence of metal cations. DFT calculations showed the good agreement between theoretical and experimental data in the UV-vis and 1H NMR studies.

Highly Dispersed Pd@ZIF-8 for Photo-Assisted Cross-Couplings and CO2 to Methanol: Activity and Selectivity Insights.

Our study unveils a pioneering methodology that effectively distributes Pd species within a zeolitic imidazolate framework-8 (ZIF-8). We demonstrate that Pd can be encapsulated within ZIF-8 as atomically dispersed Pd species that function as an excited-state transition metal catalyst for promoting carbon-carbon (C-C) cross-couplings at room temperature using visible light as the driving force. Furthermore, the same material can be reduced at 250 °C, forming Pd metal nanoparticles encapsulated in ZIF-8. This catalyst shows high rates and selectivity for carbon dioxide hydrogenation to methanol under industrially relevant conditions (250 °C, 50 bar): 7.46 molmethanol molmetal-1 h-1 and >99%. Our results demonstrate the correlations of the catalyst structure with the performances at experimental and theoretical levels.

Separation of Pd from Pt and Rh by solvent extraction method from waste solution.

The paper investigated the possibility of extractive separation of palladium from platinum and rhodium with ionic liquid Cyphos IL 101. A technological solution obtained by dissolving waste materials was used as the test material. Based on the experiments performed, it was found that a 10% (v/v) solution of the Cyphos IL 101 ionic liquid in toluene allows the extraction of both Pd and Pt with an efficiency of 99% from the initial solution when extraction is carried out at the pH 0.5, vorg:vaq phase ratio 1:1 and contact time of 15 min. Moreover, the research proved that it is possible to separate Pd from Pt at the stripping stage using a 0.1 mol/dm3 thiourea solution while maintaining a high selectivity coefficient.

Visualization of Electrooxidation on Palladium Single Crystal Surfaces via In Situ Raman Spectroscopy.

The electrooxidation of catalyst surfaces is across various electrocatalytic reactions, directly impacting their activity, stability and selectivity. Precisely characterizing the electrooxidation on well-defined surfaces is essential to understanding electrocatalytic reactions comprehensively. Herein, we employed in situ Raman spectroscopy to monitor the electrooxidation process of palladium single crystal. Our findings reveal that the Pd surface's initial electrooxidation process involves forming *OH intermediate and ClO4- ions facilitate the deprotonation process, leading to the formation of PdOx. Subsequently, under deep electrooxidation potential range, the oxygen atoms within PdOx contribute to creating surface-bound peroxide species, ultimately resulting in oxygen generation. The adsorption strength of *OH and the coverage of ClO4- can be adjusted by the controllable electronic effect, resulting in different oxidation rates. This study offers valuable insights into elucidating the electrooxidation mechanisms underlying a range of electrocatalytic reactions, thereby contributing to the rational design of catalysts.

Voltammetric determination of hydrogen peroxide at decorated palladium nanoparticles/poly 1,5-diaminonaphthalene modified carbon-paste electrode.

In this work, palladium nanoparticles (PdNPs)/p1,5-DAN/ carbon paste electrode (CPE) and p1,5-DAN/CPE sensors have been developed for determination of hydrogen peroxide. Both sensors showed a highly sensitive and selective electrochemical behaviour, which were derived from a large specific area of poly 1,5 DAN and super excellent electroconductibility of PdNPs. PdNPs/p1,5-DAN/CPE exhibited excellent performance over p1,5-DAN/CPE. Thus, it was used for detecting hydrogen peroxide (H2O2) with linear ranges of 0.1 to 250 µM and 0.2 to 300 µM as well as detection limits (S/N = 3) of 1.0 and 5.0 nM for square wave voltammetry (SWV) and cyclic voltammetry (C.V) techniques, respectively. The modified CPE has good reproducibility, adequate catalytic activity, simple synthesis and stability of peak response during H2O2 oxidation on long run that exceeds many probes. Both reproducibility and stability for H2O2 detection are attributable to the PdNPs immobilized on the surface of p1,5-DAN/CPE. The modified CPE was used for determining H2O2 in real specimens with good stability, sensitivity, and reproducibility.

Palladium(0) and Brønsted Acid Co-catalyzed Enantioselective Hydro-Cyclization of 2,4-Dienyl Hydrazones and Oximes.

The transition metal-catalyzed asymmetric hydro-functionalization of 1,3-dienes has been well explored, but most reactions focus on electron-neutral substrates in an intermolecular manner. Here we first demonstrate that readily available 2,4-dienyl hydrazones and oximes can be efficiently utilized in the hydro-cyclization reaction under co-catalysis of a Brønsted acid and a chiral palladium complex, furnishing multifunctional dihydropyrazones and dihydroisoxazoles, respectively. Diverse substitution patterns for both types of electron-deficient diene compounds are tolerated, and corresponding heterocycles were generally constructed with moderate to excellent enantioselectivity, which can be elaborated to access products with higher molecular complexity and diversity. Control experiments and density functional theory calculations support that α-regioselective protonation of dienyl substrates by acid and concurrent π-Lewis base activation of Pd0 complex is energetically favoured in the formation of active π-allylpalladium intermediates, and an outer-sphere allylic amination or etherification mode is adopted to deliver the observed cyclized products enantioselectively.

Palladium-103 (103Pd/103mRh), a promising Auger-electron emitter for targeted radionuclide therapy of disseminated tumor cells - absorbed doses in single cells and clusters, with comparison to 177Lu and 161Tb.

Early use of targeted radionuclide therapy (TRT) to eradicate disseminated tumor cells (DTCs) might offer cure. Selection of appropriate radionuclides is required. This work highlights the potential of 103Pd (T1/2 = 16.991 d) which decays to 103mRh (T1/2 = 56.12 min) then to stable 103Rh with emission of Auger and conversion electrons. Methods: The Monte Carlo track structure code CELLDOSE was used to assess absorbed doses in single cells (14-µm diameter; 10-µm nucleus) and clusters of 19 cells. The radionuclide was distributed on the cell surface, within the cytoplasm, or in the nucleus. Absorbed doses from 103Pd, 177Lu and 161Tb were compared after energy normalization. The impact of non-uniform cell targeting, and the potential benefit from dual-targeting was investigated. Additional results related to 103mRh, if used directly, are provided. Results: In the single cell, and depending on radionuclide distribution, 103Pd delivered 7- to 10-fold higher nuclear absorbed dose and 9- to 25-fold higher membrane dose than 177Lu. In the 19-cell clusters, 103Pd absorbed doses also largely exceeded 177Lu. In both situations, 161Tb stood in-between 103Pd and 177Lu. Non-uniform targeting, considering four unlabeled cells within the cluster, resulted in moderate-to-severe dose heterogeneity. For example, with intranuclear 103Pd, unlabeled cells received only 14% of the expected nuclear dose. Targeting with two 103Pd-labeled radiopharmaceuticals minimized dose heterogeneity. Conclusion: 103Pd, a next-generation Auger emitter, can deliver substantially higher absorbed doses than 177Lu to single tumor cells and cell clusters. This may open new horizons for the use of TRT in adjuvant or neoadjuvant settings, or for targeting minimal residual disease.

Restructuring and Hydrogen Evolution on Sub-Nanosized PdxBy Clusters.

As a Pt-group element, Pd has been regarded as one of the alternatives to Pt-based catalysts for the hydrogen evolution reaction (HER). Herein, we performed density functional theory (DFT) computations to explore the most stable structures of PdxBy (x = 6, 19, 44), revealed the in situ structural reconstruction of these clusters under acidic conditions, and evaluated their HER activity. We found that the presence of B can prevent underpotential hydrogen adsorption and activate the H atoms on the cluster surface for the HER. The theoretical calculations show that the reaction barrier for the HER on ~1 nm sized Pd44B4 can be as low as 0.36 eV, which is even lower than for the same-sized Pt and Pd2B nanoparticles. The ultra-high HER activity of sub-nanosized PdxBy clusters makes them a potential new and efficient HER electro-catalyst. This study provides new ideas for evaluating and designing novel nanocatalysts based on the structural reconstruction of small-sized nanoparticles in the future.

Enamine Synthesis via Regiocontrolled 6-endo-dig and 5-exo-dig Tethered Carboamination of Propargylic Alcohols.

Enamines are versatile building blocks for the synthesis of biologically active compounds. Nevertheless, only a limited number of strategies have been reported for preparing trisubstituted enamines in a regio- and stereoselective manner. Herein, we report a regiocontrolled 6-endo and 5-exo tethered carboamination of propargylic alcohols for the synthesis of trisubstituted enamines. High regioselectivity was achieved through fine-tuning of the amine protecting group during the Pd-catalyzed carboamination. The introduced trifluoromethylated tether enables further stereoselective functionalizations, such as hydrogenation and fluorination.

A novel "turn-on" NIR fluorescent probe based on benzothianone for the detection of palladium species and its application in cell and zebrafish.

The development of an efficient palladium probe holds significant application value, considering the detrimental impact of palladium contaminants on human health. Thus, it is critical to create a sensitive detection method. To this end, a fluorescent probe TM-TPA-Pd based on benzothianone structure was designed, using allyl carbonate as the Pd0 recognition unit. TM-TPA-Pd exhibited high sensitivity (1.4 eq), selectivity, near-infrared (NIR) fluorescence (798 nm), and low detection limit (0.46 µM) for Pd0 with a rapid "turn-on" fluorescence signal (5 min). Furthermore, TM-TPA-Pd has extremely low cytotoxicity and has been successfully applied to detecting cells and zebrafish, which has great potential for palladium detection in biological systems.

Synergistic manipulation of sulfur vacancies and palladium doping of In2S3 for enhanced photocatalytic H2 production.

In this study, a simple one-pot synthesis process is employed to introduce Pd dopant and abundant S vacancies into In2S3 nanosheets. The optimized Pd-doped In2S3 photocatalyst, with abundant S vacancies, demonstrates a significant enhancement in photocatalytic hydrogen evolution. The joint modification of Pd doping and rich S vacancies on the band structure of In2S3 result in an improvement in both the light absorption capacity and proton reduction ability. It is worth noting that photogenerated electrons enriched by S vacancies can rapidly migrate to adjacent Pd atoms through an efficient transfer path constructed by Pd-S bond, effectively suppressing the charge recombination. Consequently, the dual-defective In2S3 shows an efficient photocatalytic H2 production rate of 58.4 ± 2.0 µmol·h-1. Additionally, further work has been conducted on other ternary metal sulfide, ZnIn2S4. Our findings provide a new insight into the development of highly efficient photocatalysts through synergistic defect engineering.

Transition Metal-Driven Selectivity in Direct C-H Arylation of Imidazo[2,1-b]Thiazole.

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.

Promoting Photon-to-Chemical Conversion through a Dielectric Antenna-Hybrid Bilayered Reactor Configuration.

The application of scattered light via an antenna-reactor configuration is promising for converting thermocatalysts into photocatalysts. However, the efficiency of dielectric antennas in photon-to-chemical conversion remains suboptimal. Herein, we present an effective approach to promote light utilization efficiency by designing dielectric antenna-hybrid bilayered reactors. Experimental studies and finite-difference time-domain simulations demonstrate that the engineered SiO2-carbon/metal dielectric antenna-hybrid bilayered reactors exhibit a synergy of absorption superposition and electric field confinement between carbon and metals, leading to the improved absorption of scattered light, upgraded charge carriers density, and ultimately promoted photoactivity in hydrogenating chlorobenzene with an average benzene formation rate of 18 258 µmol g-1 h-1, outperforming the reported results. Notably, the carbon interlayer proves to be more effective than the commonly explored dielectric TiO2 interlayer in boosting the benzene formation rate by over 3 times. This research paves the way for promoting near-field scattered photon-to-chemical conversion through a dielectric antenna-hybrid reactor configuration.

Palladium-Catalyzed Remote C-H Functionalization: Non-Covalent Interactions and Reversibly Bound Templates.

Pd-catalysis has stood as a pivotal force in synthetic transformations for decades, maintaining its status as a paramount tool in the realm of C-H bond activation. While functionalization at proximal positions has become commonplace, achieving selective and sustainable access to distal positions continues to captivate scientific endeavors. Recently, a noteworthy trend has emerged, focusing on the utilization of non-covalent interactions to address the challenges associated with remote functionalization. The integration of these non-covalent interactions into palladium catalysis stands as a justified response to the demands of achieving selective transformations at distal positions. This review delves into the latest advancements and trends surrounding the incorporation of non-covalent interactions within the field of palladium catalysis. Furthermore, it is noteworthy to emphasize that multifunctional templates, particularly those harnessing hydrogen bonding, present an elegant and sophisticated approach to activate C-H bonds in a highly directed fashion. These templates showcase versatility and demonstrate potential applications across diverse contexts within the area of remote functionalization.

Numerical Study towards In Vivo Tracking of Micro-/Nanoplastic Based on X-ray Fluorescence Imaging.

There is a rising awareness of the toxicity of micro- and nanoplastics (MNPs); however, fundamental precise information on MNP-biodistribution in organisms is currently not available. X-ray fluorescence imaging (XFI) is introduced as a promising imaging modality to elucidate the effective MNP bioavailability and is expected to enable exact measurements on the uptake over the physical barriers of the organism and bioaccumulation in different organs. This is possible because of the ability of XFI to perform quantitative studies with a high spatial resolution and the possibility to conduct longitudinal studies. The focus of this work is a numerical study on the detection limits for a selected XFI-marker, here, palladium, to facilitate the design of future preclinical in vivo studies. Based on Monte Carlo simulations using a 3D voxel mouse model, the palladium detection thresholds in different organs under in vivo conditions in a mouse are estimated. The minimal Pd-mass in the scanning position at a reasonable significance level is determined to be <20 ng/mm2 for abdominal organs and <16 µg/mm2 for the brain. MNPs labelled with Pd and homogeneously distributed in the organ would be detectable down to a concentration of <1 µg/mL to <2.5 mg/mL in vivo. Long-term studies with a chronic MNP exposure in low concentrations are therefore possible such that XFI measurements could, in the future, contribute to MNP health risk assessment in small animals and humans.

Ultrasmall Pd nanoparticles supported on a metal-organic framework DUT-67-PZDC for enhanced formic acid dehydrogenation.

The highly dispersed ultrasmall palladium nanoparticles (Pd NPs) (1.7 nm) were successfully immobilized on a N-containing metal-organic framework (MOF, DUT-67-PZDC) using a co-reduction method, and it is used as an excellent catalyst for formic acid dehydrogenation (FAD). The optimized catalyst Pd/DUT-67-PZDC(10, 10 wt% Pd loading) shows 100% hydrogen (H2) selectivity and formic acid (FA) conversion at 60 °C, and the commendable initial turnover frequency (TOF) values of 2572 h-1 with the sodium formate (SF) as an additive and 1059 h-1 even without SF, which is better than most reported MOF supported Pd monometallic heterogeneous catalysts. The activation energy (Ea) of FAD is 43.2 KJ/mol, which is lower than most heterogeneous catalysts. In addition, the optimized catalyst Pd/DUT-67-PZDC(10) maintained good stability over five consecutive runs, demonstrating only minimal decline in catalytic activity. The outstanding catalytic performance could be ascribed to the synergistic corporations of the unique structure of DUT-67-PZDC carrier with hierarchical pore characteristic, the metal-support interaction (MSI) between the active Pd NPs and DUT-67-PZDC, the highly dispersed Pd NPs with ultrafine size serve as the catalytic active site, as well as the N sites on the support could act as the proton buffers. This work provides a new paradigm for the efficient H2 production of FAD by constructing highly active heterogeneous Pd-based catalysts using MOF supports.