Addition Of Pd Research Articles

Upcycling PET wastes into high value-added 1,4-cyclohexanedimethanol (CHDM) via tandem reactions

Upcycling polyethylene terephthalate (PET) wastes into high value-added oxygenated chemicals is desirable, yet it remains challenging. Herein, we develop a novel strategy to convert PET into 1,4-cyclohexanedimethanol (CHDM) via two steps, the conversion of PET to dimethyl 1,4-cyclohexanedicarboxylate (DMCD) over Ni-based catalysts, followed by the hydrogenolysis of DMCD to CHDM over a CuMgAl catalyst. The key step is the production of DMCD from PET in one-pot reaction and an unprecedent yield of 86.5% DMCD yield is achieved over Pd-modified Ni/CeO2 catalyst, which to the best of our knowledge is the highest yield reported to date. Comprehensive characterizations demonstrate that the addition of Pd enhances hydrogen dissociation, but weakens the adsorption activation ability for C–O bond in esters, thus DMCD selectivity is improved. Over CuMgAl catalyst, DMCD is directly converted into CHDM with 83.8% yield. Furthermore, the techno-economic analysis proves the economic feasibility of converting PET into CHDM via our proposed strategy. The study provides a promising and effective approach to upcycle PET wastes into high value-added products.

Ag-Pd nanoalloy film with ultra-high thermal and electrochemical stability for power electronic packaging

Nano-Ag paste is a popular material in power electronic packaging, while its microstructure is unstable at high temperatures and suffers from electrochemical migration. In this work, Ag-Pd nanoalloy film has been prepared by the pulsed laser deposition, and been sintered at low temperature for packaging. The thermal stability is significantly improved at 300 ℃ when Ag is alloyed with Pd. The Pd addition significantly increased the diffusion activation energy of Ag atoms and reduced the diffusion coefficient. The Ag-Pd sintered layer exhibited a stable microstructure at 300 °C or even 500 °C, which indicated that Ag-Pd nanoalloy had the potential to serve at high temperatures. Ag-Pd nanoalloy will preferentially generate a PdO passivation film and cover the anode surface, thereby slowing down the dissolution of the Ag and improving its resistance to electrochemical migration. This work provides theoretical studies and insights into the applications of Ag-Pd nanoalloys in high-reliability power electronics.

Synchronously improving glass forming ability and mechanical properties by Pd alloying Zr-Al-Cu bulk metallic glass

In this work, the influences of Pd addition on the glass-forming ability (GFA), thermal behaviors, mechanical properties and microstructure of the Zr60Al10Cu30 bulk metallic glasses (BMGs) were systematically investigated. Our study shows that proper addition of Pd can simultaneously improve the GFA, strength and plasticity of BMGs. The BMGs with Pd contents of 2.5 at.% and 5 at.% exhibit high GFA of 10 mm and 12 mm, high strength of 1852 MPa and 1858 MPa, and good plasticity of 4.3 % and 5.9 %, respectively, all of them are much higher than those of Zr60Al10Cu30 BMGs. It is revealed that alloying BMGs with proper Pd promotes the formation of a higher degree of icosahedral clusters, which is responsible for improved GFA and strength, and simultaneously encourages a decrease in the volume of shear transition zone (STZ) and the amount of imperfect ordered packing (IOP) clusters, which are responsible for the enhanced plasticity. Our findings indicate that the synergistic effect of short-range ordered structures induced by alloying amorphous alloys plays an important role in simultaneously improving the GFA and mechanical properties, providing valuable insights for BMG design.

Ultrastrong and ductile FeNi-based alloys through Pd-containing multicomponent L12-type precipitates

Precipitation strengthening stands as a paramount strategy for enhancing the mechanical properties of FeNi-based alloys. Conventional precipitates used for strengthening typically contain only two major constituent elements selected from Ni, Al, and Ti. However, knowledge about the intrinsic properties and strengthening mechanisms of multicomponent precipitates remains limited. Here, we propose introducing novel multicomponent L12-type precipitates containing palladium (Pd) to strengthen FeNi-based alloys. The strengthened FeNi alloy achieves an eightfold increase in strength compared to the FeNi matrix while maintaining good ductility. Using meticulous micro-characterization and energy-dispersive X-ray spectroscopy (EDS) techniques, in conjunction with first-principles calculations, this study investigated the effects of Pd addition on the thermodynamic stability, morphology, coherency, and strengthening mechanisms of the precipitates. Results indicate that the addition of Pd induces the nucleation of L12-type precipitates, increases their ductility, and eliminates anisotropy in the shear modulus of the precipitates. Excessive Pd content can alter the shape of precipitates from spherical to acicular due to increased interfacial mismatch between the precipitates and the FeNi matrix. These insights shed light on the impact of Pd addition on the intrinsic properties of L12-type precipitates, offering a promising pathway for the design of advanced FeNi-based alloys with optimized mechanical performance.

Tailored copper-based cathode design advances economic viability of electrocatalytic nitrate treatment with ammonia recovery in a scalable flow reactor

Electrocatalytic reduction is a promising alternative to remove nitrate (NO3–) from water and potentially recover value-added ammonia, but advancements are needed to reduce costs and promote technology adoption. Five monometallic catalysts on activated carbon cloth (ACC) electrodes were evaluated for electrocatalytic NO3– treatment in a previously developed scalable flow reactor. We report Cu and, for the first time, In (as In2O3) are the best performing catalysts regarding NO3– reduction activity (0.45–2.4 L gmetal–1 min–1), Faradaic efficiency (FE), and NH4+ selectivity, with intermediate NO2– accumulation using Cu and NH2OH using In. We discovered trace Pd addition (i.e., 0.01 wt%) to Cu eliminates NO2– accumulation, while approximately doubling activity, and boosting FE and NH4+ selectivity (99 %). Activity of Cu–Pd/ACC decreased with repeated treatment cycles but was easily recovered in situ via electrochemical regeneration. Electrocatalytic NO3– reduction costs with the Cu–Pd electrode were estimated less than IX or catalytic treatment, indicating economic viability.

Microstructural evolution in doped high entropy alloys NiCoFeCr-3X (X=Pd/Al/Cu) under irradiation

Commonly studied equatomic single-phase FCC high entropy alloys based on 3d transition metals like NiCoFeCr do not provide adequate strength and radiation resistance at high doses for nuclear structural applications. In the current study, the major alloying effects like lattice distortion, ordering and clustering tendencies were investigated by adding low concentration of Pd, Al, or Cu respectively to study the doping effects on the ion irradiation response of NiCoFeCr alloy. The alloys were irradiated with 3 MeV Ni2+ ions at 500 °C to a fluence of 1 × 1017/cm2 at a beam flux of approximately 2.8 × 1012 ions/cm2/s. The microstructural evolution upon irradiation i.e., formation of dislocation networks, radiation induced segregation and precipitation, and void formation were studied in detail. Post-irradiation characterization results showed that a Pd addition leads to a high void nucleation rate but controlled void growth, which may be attributed to increased lattice distortion. In Al added HEA, our microstructural analysis indicates that radiation induced ordered L12 precipitates do not affect void swelling significantly. Cu addition led to Cu precipitation that drastically suppressed dislocation density and void swelling of the alloy. Additionally, a model was developed to qualitatively describe the trend in void swelling of typical FCC alloys under ion irradiation. This model was able to qualitatively explain the suppression and reappearance of void swelling in ion irradiated alloys that generally occurs near the region with peak implanted ion concentration.

CO2 hydrogenation to methanol on intermetallic PdGa and PdIn catalysts and the effect of Zn co-deposition

The behaviour of Pd deposited on Ga2O3 and In2O3 by CVI is compared for the hydrogenation of CO2 to methanol. Ga2O3 alone is inactive, but In2O3 has good conversion, and selectivity as high as 89 % to CH3OH. The addition of Pd to the catalysts had relatively little effect for In2O3, but in contrast, the addition of Pd to Ga2O3, has a very big effect, inducing high activity and selectivity to methanol. Both oxides form Pd intermetallics - Pd2In3 and Pd2Ga. However, for the In catalysts there is also a thick (∼3 nm) overlayer of the oxide, while for the Ga catalyst there was no such overlayer. Hence this is why addition of Pd to the Indium catalysts has relatively little effect on performance compared with Ga. Furthermore, the effect of Pd and Zn co-deposition on Ga₂O₃ and In₂O₃ was investigated, as well as the effect of the support morphology. Upon co-deposition of Pd and Zn, and after reduction, the Pd2In3 catalyst remains phase stable, whereas the Pd2Ga alloy is replaced by PdZn, and is improved in methanol yield.

The Effect of d10 Precious Elements on Structural, Magnetic and Elastic Properties of MnPt Alloy: A First-Principles Study.

MnPt's exceptional stability and extremely high Néel temperature have generated a lot of interest in data storage applications. Previously, it was reported experimentally that the MnPt alloy shows ferromagnetic (FM) behavior at room temperature. In this study, the effects of partial substitution of Pt with Pd, Au, and Ag on magnetic properties is investigated using density functional theory. The stability of Mn50Pt50-xMx (M = Pd, Au, Ag, x = 6.25, 12.5, 18.75) alloys was assessed by determining their thermodynamic, magnetic, and mechanical properties. The calculated lattice constants of Mn50Pt50 agree well with available theoretical results. The Mn50Pt50-xMx alloys' formability was assessed by measuring the thermodynamic stability using the heat of formation. It was found that B2 Mn50Pt50-xPdx alloys (0 ≤ x ≤ 18.75) are thermodynamically stable due to the negative heat of formation close to that of a pristine MnPt alloy. Based on the elasticity results, the B2 Mn50Pt50-xPdx is most likely to undergo martensitic transformation for the entire considered composition range. From the calculated values of the Poisson's ratio, it is shown that an increase in Pd, Ag, and Au effectively improves the ductility of the B2 Mn50Pt50-xMx compounds. It was revealed that ferromagnetism is maintained with Pd addition but significantly reduced in the case of Au and Ag. Thus, this work showed that density functional theory can be exploited to propose new possible compositions for future magnets in spintronic applications.

Optimization on removal of 2,4-dichlorophenol by sodium carboxymethyl cellulose modified nanoscale Pd/Fe bimetal with response surface methodology

2,4-dichlorophenol (2,4-DCP) is a toxic and harmful organic intermediate widely used in industrial production. Recently, the utilization of nano-zero-valent iron (NZVI) for 2,4-DCP treatment has gained significant popularity, but the deactivation and agglomeration of NZVI always appear and continue to present challenges. To address these issues, sodium carboxymethyl cellulose (CMC) and noble metal catalyst Pd are used as stabilizers to improve the removal efficiency of NZVI on 2,4-DCP. The CMC-modified nanoscale Pd/Fe bimetal (CMC-Pd/Fe) particles were prepared by the liquid phase reduction method and characterized by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results showed that the addition of Pd and CMC succeeded in ameliorating the aggregation of NZVI. A five-level-four-factor central composite design (CCD) of response surface methodology (RSM) was used to optimize the removal of 2,4-DCP by CMC-Pd/Fe and explored the factors influencing the removal of 2,4-DCP, including the amount of catalyst, the initial pH of the system, the time of reaction, and the initial concentration of 2,4-DCP. A statistically significant and well-fitting quadratic regression model was successfully constructed to predict 2,4-DCP removal efficiency. The high F-value of 14.35, very low p-value (<0.0001), nonsignificant Lack of Fit, and appropriate coefficient of determination of 0.9399 demonstrate a good correlation between the experimental and predicted values of the proposed model. The analyses of variance reveal catalyst amount and reaction time have a positive effect on the removal efficiency of 2,4-DCP and the CMC-Pd/Fe catalyst amount shows the most apparent significance, with PC (percent contribution) greater than 26. Conversely, pH and 2,4-DCP concentration have a negative impact on the removal process. The optimum condition is 1.10 g/L of catalyst amount, 5.63 of pH, 2.31 h of reaction time, and 20 mg/L of initial 2,4-DCP concentration. The validation results from parallel experiments showed that the average removal efficiency of 2,4-DCP reached 96.32% under the optimal conditions.

Dithiolate-Based Scorpion Arm Ligand Synthesis and Characterization

Redox flow batteries (RFBs) play a vital role in the efficient and reliable utilization of renewable energy sources by providing a means to capture and store excess energy for later use.1–6 The synthesis and characterization of a novel scorpionate arm ligand, i-mntPy- (2,2-dicyano-1-pyridin-2-ylmethyl-1,1-dithiolate), are presented in this study. The ligand i-mntPy- was synthesized through a multistep synthetic route, starting from commercially available precursors. The chemical structure of the ligand was confirmed using various spectroscopic techniques, including NMR spectroscopy, ESI-MS, and Elemental analysis. Furthermore, the coordination ability of i-mntPy- to facilitate 2e- transfer in M(II/IV) coordination environment was investigated by the computational study and addition of Ni(II) and Pd(II) ions in the i-mntPy- solution. The results demonstrate the successful synthesis and characterization of the novel scorpionate arm ligand i-mntPy-, which coordinates with d8 metal centers and holds promise for future applications in coordination chemistry and energy storage. References (1) Mazumder, Md. M. R.; Jadhav, R. G.; Minteer, S. D. Phenyl Acrylate-Based Cross-Linked Anion Exchange Membranes for Non-Aqueous Redox Flow Batteries. ACS Mater. Au 2023. https://doi.org/10.1021/acsmaterialsau.3c00044.(2) Rahaman Mazumder, M. M.; Islam, R.; Khan, M. A. R.; Anis‐Ul‐Haque, K. M.; Rahman, M. M. Efficient AcFc‐[Fe III (Acac) 3 ] Redox Couple for Non‐aqueous Redox Flow Battery at Low Temperature. Chem. – Asian J. 2023, 18 (1). https://doi.org/10.1002/asia.202201025.(3) Mazumder, Md. M. R.; Dalpati, N.; Pokkuluri, P. R.; Farnum, B. H. Zinc-Catalyzed Two-Electron Nickel(IV/II) Redox Couple for Multi-Electron Storage in Redox Flow Batteries. Inorg. Chem. 2022, 61 (48), 19039–19048. https://doi.org/10.1021/acs.inorgchem.2c03124.(4) Mazumder, Md. M. R.; Burton, A.; Richburg, C. S.; Saha, S.; Cronin, B.; Duin, E.; Farnum, B. H. Controlling One-Electron vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate. Inorg. Chem. 2021, acs.inorgchem.1c01699. https://doi.org/10.1021/acs.inorgchem.1c01699.(5) MAZUMDER MDMOTIURRAHAMAN, Islam R. Temperature-dependent study of AcFc-FeIII(acac)3 redox couple for non-aqueous redox flow battery. ChemRxiv. Cambridge: Cambridge Open Engage; 2022; https://doi.org/10.26434/chemrxiv-2022-3177p(6) Islam, R.; Mazumder, M. M. R.; Farnum, B. H. Solvent Dependent Spectroscopic and Electrochemical Studies of Nickel (II) Diethyldithiocarbamate for Energy Storage. ECS Meet. Abstr. 2021, MA2021-01 (1), 54–54. https://doi.org/10.1149/ma2021-01154mtgabs. Figure 1

Pd-Promoted Bi2Zr2O7 Pyrochlore for Soot Particulate combustion: the Impact of Pd Distributing Location and Valence State on the Reactivity

In this study, Pd has been adopted to modify Bi2Zr2O7 pyrochlore on the surface (Pd/Bi2Zr2O7) or in the bulk (Pd-Bi2Zr2O7) by using different methods. Compared with the unmodified Bi2Zr2O7, the addition of Pd significantly improves the reactivity, following the sequence of Bi2Zr2O7 < Pd-Bi2Zr2O7 < Pd/Bi2Zr2O7. For Pd/Bi2Zr2O7, both PdO and metallic Pd0 are formed and located mainly on its surface, which is favorable for the activity. In contrast, for Pd-Bi2Zr2O7, the Pd species are majorly doped into the pyrochlore matrix at B-site as Pd2+ and Pd4+, which in fact restricts the activity. Furthermore, Pd modification can promote the generation of active O2− and O22- species, especially when Pd locates on the surface. As discovered, the distribution locations and valence states of Pd, together with the number of reactive surface oxygen sites, determines the activity.

Synthesis of 2D zeolitic imidazolate frameworks based on Co(II) and Pd(II): Effect of Pd(II) addition on the CO2 cycloaddition with epichlorohydrin

Carbon dioxide (CO2) cycloaddition with epoxide can yield value-added cyclic carbonates with 100 % atom efficiency. Moreover, zeolitic imidazolate frameworks (ZIFs) have emerged as promising catalysts for this reaction as their basic and acidic sites can effectively activate CO2 and epoxide molecules. Here, novel mixed-metal ZIFs containing Pd and Co ions (PdCo-ZIFs) that are linked by benzimidazole ligands were synthesized, after which their structures were comprehensively characterized. Despite the inherent two-dimensional nanosheet structure of Co-ZIF, PdCo-ZIFs exhibited a large surface area, with a hierarchical porous structure and profoundly increased active site concentrations (10–20 times higher than those of Co-ZIFs), exhibiting significantly increased catalytic activity toward CO2 cycloaddition. Additionally, the relationship between the catalytic activity and structural characteristics of ZIFs correlated, and the representative Pd2Co8-ZIF catalyst achieved a maximum product yield of 97.3 %, with a high turnover number (5754) and turnover frequency (479 h−1) for cyclic carbonates, attributed to the well-developed porous structure and defect sites that could not be observed in single-metal ZIF materials.

Synthesis of Highly Substituted Pyrrolo[1,2‐a]quinoline‐3,5‐diones through Ag(I) Catalyzed Cyclization of 4‐Hydroxyquinolinyl‐2‐ynones

AbstractAn efficient synthetic route to access highly substituted pyrrolo[1,2‐a]quinoline‐3,5‐diones in which the core is formed by fusion of quinolone and pyrrolone moieties is discussed. The method involves Ag(I) catalyzed cyclization of 4‐Hydroxyquinolinyl‐2‐ynones which in turn may be accessed from kynurenic acid derivatives through Weinreb amide intermediate, followed by alkyne addition. Studies involving substrates with different substitution pattern revealed that factors increasing the nucleophilicity of quinoline nitrogen or Lewis acid‐coordination of the ynone unit gives high yields in short reaction times. It was possible to execute tandem cyclization‐arylation sequence by using Pd(II) generated by oxidative addition of Pd(0) with aryl iodide as the electrophilic species to get substitution pattern as seen in Discoipyrrole A.

Catalytic removal of harmful volatile organic compounds by reutilizing zinc rods waste from spent batteries as a palladium catalyst support

The emission of volatile organic compounds (VOCs) has led to significant deterioration in air quality, making it imperative to ensure that these compounds are removed from emission sources before they are released into the atmosphere. In this context, the present study recycled spent primary batteries to use their zinc rods waste (ZRW) as a palladium catalyst support for the removal of harmful VOCs. To this end, palladium supported on ZRW (Pd/ZRW) catalysts were prepared and tested for the catalytic oxidation of benzene, methylbenzene and 1,2-dimethylbenzene. The physicochemical properties of the Pd/ZRW catalysts were carefully characterized by ICP-OES, BET, SEM, XRD, FE-TEM, XPS, and H2-TPR analyses. The main component of ZRW was identified as ZnO. Consistent with expectations, increases in the loading of Pd from 0.1 to 1.0 wt% in the Pd/ZRW catalysts resulted in enhanced VOCs removal efficiency. The reaction temperature required for the complete oxidation (100% removal efficiency) of methylbenzene and 1,2-dimethylbenzene on the 1.0 wt% Pd/ZRW catalyst was below 340 °C at a gas hourly space velocity of 50,000 h−1. TEM, XPS, and H2-TPR results implied that the enhancement of catalytic activity with the addition of Pd could be attributed to the readily movable surface lattice oxygen as well as the active component (Pd species). Ultimately, ZRW of spent primary batteries appear to show promise as a catalyst support for VOCs removal. This study has introduced a novel strategy for reducing air pollutants by utilizing waste, which promotes the disposal of hazardous solid waste and ensures clean air quality.

Behavior of a Dynamic Covalent Library Driven by Combined Pd(II) and Biphasic Effectors for Metal Transport between Phases.

This work reports the effect of Pd(II) as chemical effector on an acylhydrazone-based dynamic covalent library (DCL) in biphasic systems (water/chloroform). The constituents of the DCL are self-built and distributed in the two phases, two of them are lipophilic enough to play the role of a carrier agent that may transfer Pd(II) from the aqueous phase to the organic phase. Upon addition of Pd(II), the DCL of components exhibits a strong amplification of the constituent that is the most adapted to stabilize Pd(II) in chloroform as well as its agonist in water. This evolution is driven by the combination of the interaction of the DCL with Pd(II) and the presence of the two phases. This study paves the way to a novel approach for liquid/liquid extraction and metal recovery by means of adaptive extractant species generated in situ by a DCL.

Effect of Pd addition in BNi-2 interlayer on microstructure and properties in the TLP joints of FeCoNiTiAl and FGH98 alloys

L12-strengthed High-entropy alloys (HEAs) have attracted much attention in the field of manufacturing components that need to serve in high-temperature environments like aviation engine due to their high strength, toughness, and excellent high-temperature mechanical performance. Moreover, owing to great comprehensive mechanical properties, powder metallurgy (PM) superalloys have been widely applied for fabricating key parts of aircraft engine such as turbine disks. Hence, joining the two kinds of alloys is significant and potential in the engine manufacturing field. The key points to achieve joint with high strength and ductility (even at high temperature) were composition design of interlayer and the optimization of bonding parameters. In this study, Transient liquid phase (TLP) bonding was applied for joining HEA of FeCoNiTiAl and FGH98 superalloy using BNi-2 interlayer with addition of Pd. The experimental results demonstrate there were multiple second phases including γ’, borides (M3B2 and TiB2), etc., precipitated in the TLP joint. Furthermore, with the bonding time increased, accumulation of Al diffused from BMs can lead to a eutectic reaction of L → γ’ + AlPd + Cr5B3 occurred in the centerline of joint, which was harmful to the joint properties. Therefore, after bonding for 30 min at 1150 °C, owing to homogeneous joint microstructure of no defects and little eutectic compounds, the highest shear strength of 934 MPa was achieved.

Engineering Soluble Diketopyrrolopyrrole Chromophore Stacks from a Series of Pd(II)-Based Ravels.

A strategy to engineer the stacking of diketopyrrolopyrrole (DPP) dyes based on non-statistical metallosupramolecular self-assembly is introduced. For this, the DPP backbone is equipped with nitrogen-based donors that allow for different discrete assemblies to be formed upon the addition of Pd(II), distinguished by the number of π-stacked chromophores. A Pd3 L6 three-ring, a heteroleptic Pd2 L2 L'2 ravel composed of two crossing DPPs (flanked by two carbazoles), and two unprecedented self-penetrated motifs (a Pd2 L3 triple and a Pd2 L4 quadruple stack), were obtained and systematically investigated. With increasing counts of stacked chromophores, UV/Vis absorptions red-shift and emission intensities decrease, except for compound Pd2 L2 L'2 , which stands out with an exceptional photoluminescence quantum yield of 51 %. This is extraordinary for open-shell metal containing assemblies and explainable by an intra-assembly FRET process. The modular design and synthesis of soluble multi-chromophore building blocks offers the potential for the preparation of nanodevices and materials with applications in sensing, photo-redox catalysis and optics.

Pd(II)‐vermittelte Assemblierung einer Reihe von löslichen Diketopyrrolopyrrol‐Chromophor‐Stapeln**

AbstractEs wird eine Strategie zur Stapelung von Diketopyrrolopyrrol‐Farbstoffen (DPP) vorgestellt, die auf einem nicht‐statistischen Ansatz zur metallosupramolekularen Selbstassemblierung beruht. Dazu wird das DPP‐Grundgerüst mit stickstoffbasierten Donoren ausgestattet, die bei Zugabe von Pd(II) Kationen die Bildung verschiedener diskreter Strukturen ermöglichen, welche sich durch die Anzahl der π‐gestapelten Chromophore unterscheiden. Ein Pd3L6‐Dreiring, eine heteroleptische Pd2L2L′2‐Anordnung, bestehend aus zwei sich kreuzenden DPPs (flankiert von zwei Carbazolen), und zwei bisher unbeschriebene, sich selbst durchdringende Motive (ein Pd2L3‐Dreifach‐ und ein Pd2L4‐Vierfachstapel) wurden erhalten und systematisch untersucht. Mit zunehmender Anzahl gestapelter Chromophore kommt es zu einer Rotverschiebung der UV/Vis‐Absorption und einer Abnahme der Emissionsintensität, mit Ausnahme der Verbindung Pd2L2L′2, die eine außergewöhnlich hohe Photolumineszenz‐Quantenausbeute von 51 % aufweist. Dies ist unüblich für Verbindungen, die offenschalige Metallionen enthalten, und lässt sich durch einen intramolekularen FRET‐Prozess erklären. Das modulare Design solcher löslicher Multi‐Chromophor‐Bausteine eröffnet Möglichkeiten für die Herstellung von Nanobauteilen und ‐materialien mit Anwendungen in den Bereichen Sensorik, Photo‐Redox‐Katalyse und Optik.

Palladium-catalyzed allylation of 2- and 4-alkylpyridines via N-allyl alkylidene dihydropyridine intermediates

A method to introduce allyl or cinnamyl groups to the picolyl positions of 2- or 4-alkylpyridines is described. Substituted N-allyl pyridinium salts are first treated with base (KOtBu) followed by catalytic [(η3-allyl)PdCl]2 and PPh3 to result in formal Pd-catalyzed transfer of N-allyl groups to the pyridine periphery. The reaction is believed to proceed through initial formation of nucleophilic alkylidene dihydropyridine intermediates that react with (π-allyl)Pd(II) electrophiles, thereby regenerating N-allyl pyridinium cations. Catalytic turnover and liberation of pyridine products is then achieved by oxidative addition of Pd(0) to these activated allyl groups.

Reaction-Induced Metal-Metal Oxide Interactions in Pd-In2 O3 /ZrO2 Catalysts Drive Selective and Stable CO2 Hydrogenation to Methanol.

Ternary Pd-In2 O3 /ZrO2 catalysts exhibit technological potential for CO2 -based methanol synthesis, but developing scalable systems and comprehending complex dynamic behaviors of the active phase, promoter, and carrier are key for achieving high productivity. Here, we show that the structure of Pd-In2 O3 /ZrO2 systems prepared by wet impregnation evolves under CO2 hydrogenation conditions into a selective and stable architecture, independent of the order of addition of Pd and In phases on the zirconia carrier. Detailed operando characterization and simulations reveal a rapid restructuring driven by the metal-metal oxide interaction energetics. The proximity of InPdx alloy particles decorated by InOx layers in the resulting architecture prevents performance losses associated with Pd sintering. The findings highlight the crucial role of reaction-induced restructuring in complex CO2 hydrogenation catalysts and offer insights into the optimal integration of acid-base and redox functions for practical implementation.