Interaction Of Pd Research Articles

The best of both worlds in material synthesis to understand metal-support interactions

The best of both worlds in material synthesis to understand metal-support interactions

Highly Selective Hydrogenation of Phenols to Cyclohexanone Derivatives Using a Palladium@N-Doped Carbon/SiO2 Catalyst

A new palladium-based heterogeneous material was synthesized by means of immobilization of Pd(OAc)2/1,10-phenanthroline on commercially available SiO2 and subsequent pyrolysis at 600 °C for 2 h in air, namely, a Pd@N-doped carbon/SiO2 catalyst. The obtained catalyst was studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) techniques, and was effectively applied in the highly selective hydrogenation of phenols to give the corresponding cyclohexanone derivatives with 93–98% yields at 100 °C under 0.4 MPa H2 in EtOH. It was demonstrated that introducing nitrogen could effectively promote the Pd dispersion and enhance the electronic interaction of Pd, both of which facilitate the improvement of the catalytic activity and selectivity. The likely reaction pathway was outlined to elucidate the selective hydrogenation mechanism according to experimental results.

Preparation of supported In2O3/Pd nanocatalysts using natural pollen as bio-templates for CO2 hydrogenation to methanol: Effect of acid-etching on template

The conversion of CO2 into value-added chemicals is an effective way to mitigate the environmental problems caused by huge anthropogenic CO2 emissions. Although In2O3/Pd catalyst possesses excellent catalytic performance in CO2 hydrogenation to methanol, the formation of Pd-In alloy on the catalyst surface greatly reduces the yield of methanol. Herein, we adopt a natural biomaterial (viz., rape pollen) as a template to synthesize hierarchically structured bio-In2O3 and bio-In2O3/Pd catalysts. In particular, we found that the pretreatment of pollen using hydrochloric acid (HCl) played a critical role in determining catalytic performance. A series of bio-In2O3 were prepared by using the pollen templates with different etching degrees, and then the bio-In2O3-x/Pd catalysts (x denoted as the amount of HCl, mL) were prepared using an impregnation-reduction method. It was surprising that the CO2 conversion of bio-In2O3–15/Pd catalyst was 8.2% with methanol selectivity of 74.7%, which was much better than the bio-In2O3–0/Pd (2.6% and 54.6%, respectively). The dramatic enhancement was due to that the acid-etched pollen template owns a hollow cage-like structure and abundant surface functional groups (-NH2 and -COOH), which is beneficial to the growth of In2O3 with a high amount of surface oxygen vacancies. Also, the bio-In2O3/Pd catalyst (prepared with untreated pollen template) was more prone to form Pd-In alloys as a result of the strong interaction between Pd with In2O3. In contrast, the In2O3 spatial distribution of bio-In2O3–15/Pd was more uniform with an appropriate interaction of Pd with In2O3 that inhibited the formation of Pd-In alloys. Even Pd loaded on commercial In2O3 exhibited inferior performance (3.4% CO2 conversion and 81% methanol selectivity) to bio-In2O3–15/Pd catalyst. Accordingly, the present work offers a green and efficient method to prepare supported In2O3/Pd catalysts by using the acid-etched pollen as a template.

Geochemical evolution of PGE-sulfide mineralization of the Khudolaz differentiated complex in the South urals: The role of R-factor and hydrothermal alteration

The article highlights the results of mineralogical and geochemical studies of disseminated Cu-Ni-PGE sulfide mineralization from three intrusions of the Khudolaz Differentiated Complex (KDC) in the South Urals. Sulfide mineral assemblages are shown to have formed across a wide temperature range (about 1100–150 °C) during the cooling of an immiscible sulfide melt and subsequent hydrothermal dissolution and redeposition of sulfides. During the solidification process, a crystallization of sulfide solid solutions (mss, iss, etc.) occurred, from which pyrrhotite, pentlandite, and chalcopyrite were subsequently exsoluted. The oxidation, substitution and dissolution of primary sulfides at the hydrothermal stage led to the formation of mineral aggregates of complex morphology, containing complete or partial pseudomorphs of secondary sulfides, silicates and oxides, as well as redeposited sulfide aggregates. According to LA ICP MS data for sulfides and the bulk trace element composition of ores, the depletion of sulfide minerals by some chalcophile and platinum-group elements (PGE) took place during their hydrothermal alteration (partial dissolution and replacement). Secondary sulfides such as pyrite and violarite largely inherited the geochemical features of the primary minerals during pseudomorphic replacement of pyrrhotite and pentlandite. The redeposited sulfides (pyrite and chalcopyrite) are primarily enriched by chalcophile trace elements. Leaching of PGEs from pyrrhotite and pentlandite took place during hydrothermal alteration. Here, the most significant loss was determined for Te, resulting in the depletion of sulfide minerals and ores in Te by about 5 times. The identified decrease of Te/Sb values in altered sulfides by a factor of 3–20 indicates an enrichment in Sb and a high Dhydrothermal fluid/sulfide partition coefficient (≫ 1). It is shown that the hydrothermal fluid was enriched in Sb. On the other hand, the S/Se value increases by a factor of ~ 1.5, demonstrating an Se mobility during metasomatic processes comparable to other chalcogenides.Based on the study of assemblages and traced evolution of the chemical composition of PGE minerals, three stages of mineralization are proposed: 1) crystallization of immiscible chalcogenide and highly fractionated sulfide melts; 2) segregation of isomorphic impurities of chalcogenides and PGE during the sulfides exsolution from sulfide solid solutions; 3) interaction of Pd leached from primary sulfide and PGE minerals with Sb-rich hydrothermal fluid.The calculated value of the R-factor (150–502) indicates a moderate productivity of the KDC intrusions for Cu-Ni sulfide mineralization, but a rather low potential for PGE. Although the degree of primary sulfide melt PGE-enrichment is not inferior to that of many Cu-Ni-PGE deposits in the world, the economic potential of the Khudolaz Complex intrusions is significantly reduced by their small sizes. At the same time, the strong depletion of primary sulfides in Ni, Cu, Pd, and Pt during hydrothermal alteration led to the enrichment of host rocks in the external contact.

Voltammetric Determination of Pd(II) Using 5-Hydroxyimino-4-imino-1,3-thiazolidin-2-one after a Thermal Activation of the Interaction

The interaction of Pd(II) with 5-hydroxyimino-4-imino-1,3-thiazolidin-2-one (HITO) was investigated over the pH range of 1.0–10.0. Optimal conditions for the voltammetric determination of Pd(II) were established. A new voltammetric method of Pd(II) determination by the peak of complex using NaCl as a supporting electrolyte at pH 2.0 was developed with the limit of detection 2.0∙10-7 M. The study of the method’s selectivity was presented in the work. The correctness of the method was confirmed by the analysis of model solutions and the real sample (resistor SP5-35B).

Selective hydrogenation of cinnamaldehyde to cinnamyl alcohol over palladium/zirconia in microwave protocol

Hydrogenation of aldehydes (RHO) is one of the frequently used reactions in organic synthesis and pharmaceuticals industries. In this contribution, we have synthesized control shaped and nano-sized tetragonal zirconia (t-ZrO2), palladium supported on zirconia (Pd/t-ZrO2) and nickel promoted palladium supported on zirconia (Ni-Pd/t-ZrO2) though modified microwave irradiation method. All the prepared samples were characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Diffractometry (XRD), Thermal Gravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) surface area and pore size analysis, and Fourier Transform Infrared Spectroscopy (FT-IR). Theoretical calculation (DFT) revealed high interaction of Pd with t-ZrO2(101) surface. Furthermore, adsorption energy, support relaxation and charge transfer studies confirmed the stability of Pd on t-ZrO2(101) surface. The catalytic activity of catalysts was tested for cinnamaldehyde (CAL) hydrogenation in a modified microwave reactor. The comparative study of microwave irradiated (MW) and conventional heating (C-Heating) systems show supremacy of MW over C-Heating by a factor of 46% under optimal reaction parameters for Pd/t-ZrO2 catalyst. The stability, life span, conversion and selectivity of Pd/t-ZrO2 under MW system suggest the applicability of the catalysts for a variety of organic hydrogenation reactions.

High-fat diet-induced diabetes leads to vascular alterations, pericyte reduction, and perivascular depletion of microglia in a 6-OHDA toxin model of Parkinson disease

BackgroundDiabetes has been recognized as a risk factor contributing to the incidence and progression of Parkinson’s disease (PD). Although several hypotheses suggest a number of different mechanisms underlying the aggravation of PD caused by diabetes, less attention has been paid to the fact that diabetes and PD share pathological microvascular alterations in the brain. The characteristics of the interaction of diabetes in combination with PD at the vascular interface are currently not known.MethodsWe combined a high-fat diet (HFD) model of diabetes mellitus type 2 (DMT2) with the 6-OHDA lesion model of PD in male mice. We analyzed the association between insulin resistance and the achieved degree of dopaminergic nigrostriatal pathology. We further assessed the impact of the interaction of the two pathologies on motor deficits using a battery of behavioral tests and on microglial activation using immunohistochemistry. Vascular pathology was investigated histologically by analyzing vessel density and branching points, pericyte density, blood–brain barrier leakage, and the interaction between microvessels and microglia in the striatum.ResultsDifferent degrees of PD lesion were obtained resulting in moderate and severe dopaminergic cell loss. Even though the HFD paradigm did not affect the degree of nigrostriatal lesion in the acute toxin-induced PD model used, we observed a partial aggravation of the motor performance of parkinsonian mice by the diet. Importantly, the combination of a moderate PD pathology and HFD resulted in a significant pericyte depletion, an absence of an angiogenic response, and a significant reduction in microglia/vascular interaction pointing to an aggravation of vascular pathology.ConclusionThis study provides the first evidence for an interaction of DMT2 and PD at the brain microvasculature involving changes in the interaction of microglia with microvessels. These pathological changes may contribute to the pathological mechanisms underlying the accelerated progression of PD when associated with diabetes.

Studies of Nature of Uncommon Bifurcated I-I···(I-M) Metal-Involving Noncovalent Interaction in Palladium(II) and Platinum(II) Isocyanide Cocrystals.

Two isostructural trans-[MI2(CNXyl)2]·I2 (M = Pd or Pt; CNXyl = 2,6-dimethylphenyl isocyanide) metallopolymeric cocrystals containing uncommon bifurcated iodine···(metal–iodide) contact were obtained. In addition to classical halogen bonding, single-crystal X-ray diffraction analysis revealed a rare type of metal-involved stabilizing contact in both cocrystals. The nature of the noncovalent contact was studied computationally (via DFT, electrostatic surface potential, electron localization function, quantum theory of atoms in molecules, and noncovalent interactions plot methods). Studies confirmed that the I···I halogen bond is the strongest noncovalent interaction in the systems, followed by weaker I···M interaction. The electrophilic and nucleophilic nature of atoms participating in I···M interaction was studied with ED/ESP minima analysis. In trans-[PtI2(CNXyl)2]·I2 cocrystal, Pt atoms act as weak nucleophiles in I···Pt interaction. In the case of trans-[PdI2(CNXyl)2]·I2 cocrystal, electrophilic/nucleophilic roles of Pd and I are not clear, and thus the quasimetallophilic nature of the I···Pd interaction was suggested.

Experimental and Molecular Docking Studies on the Interaction of a Water-Soluble Pd(II) Complex Containing β-Amino Alcohol with Calf Thymus DNA.

The interaction of water-soluble and fluorescent [Pd (HEAC) Cl2] complex, in which HEAC is 2-((2-((2-hydroxyethyl)amino)ethyl)amino) cyclohexanol, with calf thymus DNA (ct-DNA) has been studied. This study was performed using electronic absorption and fluorescence emission spectroscopies, cyclic voltammetry and circular dichroism analyses, dynamic viscosity measurements, and molecular docking theory. From hypochromic effect observed in ct-DNA absorption spectra, it was found that the Pd(II) complex could form a conjugate with ct-DNA strands through the groove binding mode. The Kb values obtained from fluorescence measurements clearly assert the Pd(II) complex affinity to ct-DNA. The fluorescence quenching of the DNA-Hoechst compound following the successive additions of the Pd(II) complex to the solution revealed that the Pd(II) complex is located in the ct-DNA grooves, and Hoechst molecules have been released into solution; moreover, the resulting measurements from relative viscosity authenticate the Pd(II) complex binding to the grooves. Negative quantities of thermodynamic parameters imply that the Pd(II) complex binds to ct-DNA mainly by the hydrogen bonds and van der Waals forces; also, the Gibbs-free energy changes show the exothermic and spontaneous formation of the Pd(II) complex-DNA system. The electrochemical behavior of the Pd(II) complex in the attendance of ct-DNA was investigated using the cyclic voltammetry method (CV). Several quasi-reversible redox waves were observed along with increasing the anodic/cathodic peak currents, as well as a shift in anodic/cathodic peak potentials. Circular dichroism (CD) observations suggested that the Pd(II)-DNA interaction could alter ct-DNA conformation. The results of molecular modeling confirmed that groove mechanism is followed by the Pd(II) complex to interact with ct-DNA.

Coordination from Heteroscorpionate Ligand Towards Pd(II) via Pd⋅⋅⋅Hδ−C(sp3) Interaction: Structural and Catalytic Studies

AbstractThe coordination ability of the heteroscorpionate ligand 2,2‐bis(3,5‐dimethylpyrazol‐1‐yl)‐1‐p‐tolylethanol (1) towards palladium (II) dihalides was evaluated. The structures of the respective palladium complexes (2 and 3) were elucidated in solution by NMR spectroscopy, and their molecular structures were established by single crystal X‐ray diffraction analyses. Both studies revealed the existence of Pd⋅⋅⋅Hδ−C(sp3) anagostic interactions. The molecular structure of complexes 2 and 3 displays coordination of ligand 1 to palladium in a κ3‐NNH tridentate fashion via two nitrogen atoms and one δ‐anagostic H⋅⋅⋅Pd interaction. The metal center exhibits a square pyramidal geometry. The distances of anagostic Hδ⋅⋅⋅Pd interactions ranged from 2.566 to 2.576 Å. The δ‐anagostic H⋅⋅⋅Pd interactions in complexes 2 and 3 were also identified by Bader's quantum theory of atoms in molecules (QTAIM) and non‐covalent interaction (NCI) analysis. The catalytic efficiencies of complexes 2 and 3 in the Suzuki‐Miyaura cross‐coupling reactions were evaluated and the results showed that palladium (II) dibromide complex is the most efficient of the series. Complex 3 was also evaluated in Mizoroki‐Heck cross‐coupling reactions.

Doping and Stress Induced Raman Shifts in Pd-Decorated CVD Grown Graphene

In this article, we study the interactions of graphene and Pd by using Raman spectroscopy. Graphene grown by chemical vapor deposition (CVD) method was decorated with Pd films with varying thickness ranging from 5 to 25 nm. It has been shown that the positions of both G and 2D peaks in Raman spectra of Pd-graphene (Pd-G) composite are shifted in both sides of the main peaks of graphene and highly dependent on the thickness of the Pd over layer. A blue shift in both G and 2D bands has been observed for lower Pd thickness (≤10 nm). This blue shift is the resultant of the holes doping in graphene due to a work function difference between graphene and Pd. However, strain-induced red shifts in these Raman bands of graphene have been observed for higher Pd thickness (≥15 nm).

A Zeolite‐confined Pd/Acid Sites for High Efficiency of B−H Cleavage

AbstractConfining noble nanometal in zeolite framework is a promising way to improve its efficiency and durability for catalytic reactions. Herein, the synergistic effect of Pd nanoparticles and intrinsic acid sites in zeolite on promoting hydrogen generation performance is demonstrated. Pd nanoparticles are embedded into macroporous ZSM‐5 (designed as Pd@ZSM‐5) via a steam‐thermal strategy. The confined Pd and acid sites in Pd@ZSM‐5 synergistically promote the activation of ammonia borane (AB) and water molecules, resulting in the enhanced H2 generation rates for AB hydrolysis. The interaction of Pd and acid sites in zeolite is further confirmed by solid‐state NMR techniques and the key aspect is the confinement effect of zeolite. Furthermore, Pd@ZSM‐5 shows high activity and durability in tandem hydrogenation of nitrobenzene.

A case study of Pd⋯Pd intramolecular interaction in a benzothiazole based palladacycle; catalytic activity toward amide synthesisviaan isocyanide insertion pathway

An acetate bridged benzothiazole palladacycle containing a metallophilic intramolecular Pd⋯Pd interaction was anchored on SBA-15 to form a catalyst for amide synthesis.

Photo-driven selective CO2 reduction by H2O into ethanol over Pd/Mn–TiO2: suitable synergistic effect between Pd and Mn sites

The Mn–Pd interaction of Pd/Mn–TiO2 is a promising catalyst to enhance C2H5OH selectivity since Pd with a strong ability to capture and transport electrons and Mn with multifarious activation of the reactant (CO2 and H2O).

Catalytic Consequences of Supported Pd Catalysts on Dehydrogenative H2 Evolution from 2-[(n-Methylcyclohexyl)methyl]piperidine as the Liquid Organic Hydrogen Carrier

Herein, nanoporous Al2O3, CeO2, TiO2, ZrO2, and SnO2 were used as the supports for Pd nanoparticles, and effects of surface characteristics on catalytic performances for dehydrogenation of 2-[(n-methylcyclohexyl)methyl]piperidine (H12-MBP) as the H2-rich liquid organic hydrogen carrier were investigated. The H2 yield, dehydrogenation rate, product selectivity, and recyclability of the supported Pd catalysts depended on the metal oxide support and Pd loading. The H2 yield and reaction rate of the Al2O3 supporting 5 wt % Pd with a mean size of 5.76 nm were the highest (75.8%) and the fastest (k1 = 0.076 min–1), respectively, of all the catalysts. CeO2 exhibited the highest reducibility and the best supporting ability for Pd nanoparticles, which thus dispersed Pd with the smallest mean size of 3.45 nm. Although this catalyst exhibited a lower H2 yield (67.1%) and a slower reaction rate (k1 = 0.030 min–1) than Al2O3, it showed the best recyclability without a significant loss of activity during four consecutive runs, which could be attributed to the strong metal–support interaction of Pd to the surface of CeO2. The H2 yield and the dehydrogenation rate were systematically correlated with the surface characteristics of the metal oxides, such as acidity, adsorption affinity (adsorption energy), and charge transfer value of H12-MBP, which were determined via combined experimental and theoretical studies.

Physiologically Based Pharmacokinetic/Pharmacodynamic Modeling to Predict the Impact of CYP2C9 Genetic Polymorphisms, Co-Medication and Formulation on the Pharmacokinetics and Pharmacodynamics of Flurbiprofen.

Physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models can serve as a powerful framework for predicting the influence as well as the interaction of formulation, genetic polymorphism and co-medication on the pharmacokinetics and pharmacodynamics of drug substances. In this study, flurbiprofen, a potent non-steroid anti-inflammatory drug, was chosen as a model drug. Flurbiprofen has absolute bioavailability of ~95% and linear pharmacokinetics in the dose range of 50–300 mg. Its absorption is considered variable and complex, often associated with double peak phenomena, and its pharmacokinetics are characterized by high inter-subject variability, mainly due to its metabolism by the polymorphic CYP2C9 (fmCYP2C9 ≥ 0.71). In this study, by leveraging in vitro, in silico and in vivo data, an integrated PBPK/PD model with mechanistic absorption was developed and evaluated against clinical data from PK, PD, drug-drug and gene-drug interaction studies. The PBPK model successfully predicted (within 2-fold) 36 out of 38 observed concentration-time profiles of flurbiprofen as well as the CYP2C9 genetic effects after administration of different intravenous and oral dosage forms over a dose range of 40–300 mg in both Caucasian and Chinese healthy volunteers. All model predictions for Cmax, AUCinf and CL/F were within two-fold of their respective mean or geometric mean values, while 90% of the predictions of Cmax, 81% of the predictions of AUCinf and 74% of the predictions of Cl/F were within 1.25 fold. In addition, the drug-drug and drug-gene interactions were predicted within 1.5-fold of the observed interaction ratios (AUC, Cmax ratios). The validated PBPK model was further expanded by linking it to an inhibitory Emax model describing the analgesic efficacy of flurbiprofen and applying it to explore the effect of formulation and genetic polymorphisms on the onset and duration of pain relief. This comprehensive PBPK/PD analysis, along with a detailed translational biopharmaceutic framework including appropriately designed biorelevant in vitro experiments and in vitro-in vivo extrapolation, provided mechanistic insight on the impact of formulation and genetic variations, two major determinants of the population variability, on the PK/PD of flurbiprofen. Clinically relevant specifications and potential dose adjustments were also proposed. Overall, the present work highlights the value of a translational PBPK/PD approach, tailored to target populations and genotypes, as an approach towards achieving personalized medicine.

Abstract LB-392: Optimizing dual immuno-oncology combinations with a virtual tumor

Abstract The purpose of the study was to investigate the application of a ‘virtual tumor' (‘VT') technology to optimizing the dosing and scheduling of dual immuno-oncology combinations in order to maximize the immunopotentiation and anti-tumor efficacy.The tumor microenvironment and local immune response play a key role in cancer biology, and immune resistance is a feature of many cancers. Immune checkpoints suppress the ability of the immune system to destroy cancer cells, and are a clear therapeutic target. However, response rates for such therapies are generally low. While anti-tumor efficacy can be improved by combining agents that target immune checkpoints with selected conventional anti-cancer therapies[1], the potential of immune-checkpoint blockade could be further unlocked through combination instead with other immunotherapies[2]. However, dosing and scheduling of immunotherapy combinations need to be optimized to take full advantage of a limited window for immunopotentiation[1]. Modelling can be used to deliver insights to help optimize such combination immunotherapies. We have developed a preclinical and a clinical VT technology that can predict how a tumor will respond to drug exposure[3]. This integrated PK/PD simulation platform can be used to optimize drug dosing and scheduling, and to design new combination therapies. The VT technology integrates pharmacokinetic and pharmacodynamic effects and models the way individual cells behave within a tumor population. These agent-based methods are particularly suitable for modeling not only tumor cells, but also other cell populations - such as those involved in the immune response - and also interactions between cells. Here we describe our recent development and application of the VT technology for modeling preclinical efficacy of novel immuno-oncology combinations.Building upon previous work, in which the VT platform was extended by the addition of a module that captured the synergistic interaction of PD(L)-1 blockade with conventional anticancer therapies[4], we have further expanded the model to allow simulation of immuno-checkpoint block with other immunotherapies. This module captures the mechanisms by which immunotherapies activate the innate antitumor immune response, either through immune-checkpoint block or by targeting immunosuppression by MDSC within the tumor microenvironment. Through a preclinical case study derived from the literature[5] and additional data available in the public domain, we demonstrate that the extended VT can be applied to simulate the efficacy of PD-1 blockade combined with an anti-C5a agent, and show that the combination treatment delays tumor progression. Furthermore, we demonstrate that the model can be applied to optimize the timing of the two therapies in order to maximize overall efficacy. Our enhanced VT capability represents a key step towards a strategic tool for optimizing dosing and scheduling of immuno-oncology combinations. [1] Ott, PA et al., Journal for ImmunoTherapy of Cancer 5, 16 (2017). [2]. Galon, J. & Bruni, D. Nature Reviews Drug Discovery (2019) [3]. Orrell, D. & Fernandez, E. Innovations in Pharmaceutical Technology 60-62 (2011). [4]. Brightman, FA et al., Abstract 4866. Cancer Res 75, 4866-4866 (2015). [5] Ajona, D. et al. Cancer Discov 7, 694-703 (2017). Citation Format: Fernando Ortega, Frances A. Brightman, Christophe Chassagnole. Optimizing dual immuno-oncology combinations with a virtual tumor [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-392.

Electrochemical CO2 reduction on Pd-modified Cu foil

Bimetallic catalysts can improve CO2 reduction efficiency via the combined properties of two metals. CuPd shows enhanced CO2 reduction activity compared to copper alone. Using differential electrochemical mass spectrometry (DEMS) and electrochemical infrared (IR) spectroscopy, volatile products and adsorbed intermediates were measured during CO2 and CO reduction on Cu and CuPd. The IR band corresponding to adsorbed CO appears 300 mV more positive on CuPd than that on Cu, indicating acceleration of CO2 reduction to CO. Electrochemical IR spectroscopy measurements in CO-saturated solutions reveal similar potentials for CO adsorption and CO32− desorption on CuPd and Cu, indicating that CO adsorption is controlled by desorption of CO32−. DEMS measurements carried out during CO reduction at both electrodes showed that the onset potential for reduction of CO to CH4 and CH3OH on CuPd is about 200 mV more positive than that on Cu. We attribute these improvements to interaction of Cu and Pd, which shifts the d-band center of the Cu sites.

A Pd(II) complex derived from pyridine-2-carbaldehyde oxime ligand: Synthesis, characterization, DNA and BSA interaction studies and in vitro anticancer activity

A novel Pd(II) complex, [Pd(C6H5N2O)2], containing pyridine-2-carbaldehyde oxime ligand has been synthesized and characterized using elemental analysis, Fourier-transform infrared, nuclear magnetic resonance and mass spectroscopy. The single crystal structure of this Pd(II) complex has been determined by X-ray crystallography. Based on the DNA binding studies including ultraviolet visible spectrophotometry, fluorescence emission titration and viscosity measurement, the interaction of Pd(II) complex with calf thymus DNA occurs by groove binding. In the absence of an external reductant, the Pd(II) complex cleaves the supercoiled double-stranded DNA under physiological conditions. Moreover, in the presence of Pd(II) complex, the Bovine Serum Albumin microenvironment and secondary structure change. On the basis of the competitive experiments using site markers, the complex is mainly located in site I of the protein. The binding of the Pd(II) complex to DNA was modeled using molecular docking. The antitumor impacts of the ligand and the Pd(II) complex were evaluated in vitro against the mouse colon carcinoma (C26) and melanoma (B16–F0) tumor cell lines. The antitumor activity has been significantly improved by the complexation process. IC50 values smaller than those of cisplatin have been shown by the Pd(II) complex and oxime ligand against cancer cell lines. In addition, Pd(II) complex has been tested against NIH normal fibroblast cells. Consequently, Pd(II) complex may be considered a selective compound against cancer cells, according to the SI definition.

Enhanced active site extraction from perovskite LaCoO3 using encapsulated PdO for efficient CO2 methanation

The extraction of metallic nanoparticles from perovskite-type oxides (ABO3) under mild reducing conditions is a novel way to prepare well-dispersed supported catalysts (B/AOδ). Herein, we found that the encapsulated PdO in perovskite LaCoO3 ([email protected]3) could facilitate the phase transformation of the perovskite structure at a low temperature owing to both strong H2 spillover of Pd and intimate interaction between the encapsulated PdO and LaCoO3. The pure LaCoO3 without PdO was relatively inert to CO2 hydrogenation (CO2 conversion <4%). In contrast, [email protected]3 exhibited excellent CO2 methanation performance with 62.3% CO2 conversion and >99% CH4 selectivity. The characterization results demonstrated that the catalytically active Co2C was in-situ formed by carburization of the extracted Co0 during CO2 methanation for the [email protected]3 sample. Whereas, the LaCoO3 with surface supported PdO (PdO/LaCoO3) showed a weak interaction and remained a perovskite structure with few Co2C active centers after the catalytic reaction, which was similar to the parent LaCoO3. Accordingly, the PdO/LaCoO3 showed an inferior catalytic performance with 31.8% CO2 conversion and 87.4% CH4 selectivity. Therefore, the designed encapsulation structure of PdO within perovskite is critical to extract metallic NPs from perovskite-type oxides, which has the potential to prepare other integrated nanocatalysts based on perovskite-type oxides.