PdCl2 Research Articles

Syntheses, characterization and DFT studies of two new (π-allyl) palladium(II) complexes of β-8,9-dihydrohimachalene

Catalytic hydrogenation of β-himachalene, the main constituent of Atlas cedar’s essential oil, led to the formation of β-8,9-dihydrohimachalene (2,6,6,9-tetramethylbicyclo[5.4.0]undeca-1-ene). This latter when treated with palladium(II) chloride gives neutral bis(chloro)-bridged cyclopalladated dimers, [Pd2C12(C15H25)2] (di-μ-chloro-bis{[(1,2,15-η)-2,6,6,9-tetramethylbicyclo[5.4.0]undeca-1-ene]palladium), with a high regio- and stereoselectivity, which is stable under air and moisture. Its reaction with triphenylphosphine provided a monomer (π-allyl-β-8,9-dihydrohimachalene) palladium(triphenylphosphine) complex. Both complexes were characterized by 1H and 13C NMR spectroscopy and single crystal X-ray diffraction. DFT calculations were conducted on both compounds in order to predict their optimized structures, the frontier molecular orbitals and the global reactivity descriptors. A good correlation of bond lengths and angles with the experimental data was found at the B3LYP/6-31 +G(d,p) basis set. Moreover, Hirshfeld surface (HS) and 2D fingerprint analyses revealed an intermolecular hydrogen bond of 2.56 Å for the monomer palladium complex, which is close to the experimental value, along with an intramolecular close contact dominated by H-H interactions in both compounds.

Ultrasensitive carbon monoxide detector based on palladium chloride hole array in a silver film at room temperature

Ultrasensitive carbon monoxide detector based on palladium chloride hole array in a silver film at room temperature

Metallic–Organic Cages (MOCs) with Heterometallic Character: Flexibility-Enhancing MOFs

The dichotomy between metal–organic frameworks (MOFs) and metal–organic cages (MOCs) opens up the research spectrum of two fields which, despite having similarities, both have their advantages and disadvantages. Due to the fact that they have cavities inside, they also have applicability in the porosity sector. Bloch and coworkers within this evolution from MOFs to MOCs manage to describe a MOC with a structure of Cu2 paddlewheel Cu4L4 (L = bis(pyrazolyl)methane) with high precision thanks to crystallographic analyses of X-ray diffraction and also SEM-EDX. Then, also at the same level of concreteness, they were able to find the self-assembly of Pd(II)Cl2 moieties on the available nitrogen donor atoms leading to a [Cu4(L(PdCl2))4] structure. Here, calculations of the DFT density functional allow us to reach an unusual precision given the magnitude and structural complexity, explaining how a pyrazole ring of each bis(pyprazolyl)methane ligand must rotate from an anti to a syn conformation, and a truncation of the MOC structure allows us to elucidate, in the absence of the MOC constraint and its packing in the crystal, that the rotation is almost barrierless, as well as also explain the relative stability of the different conformations, with the anti being the most stable conformation. Characterization calculations with Mayer bond orders (MBO) and noncovalent interaction (NCI) plots discern what is important in the interaction of this type of cage with PdCl2 moieties, also CuCl2 by analogy, as well as simple molecules of water, since the complex is stable in this solvent. However, the L ligand is proved to not have the ability to stabilize an H2O molecule.

Delayed Hypersensitivity Reaction to Iodinated-Contrast Following Lumbar Epidural Steroid Injection: Case Report

BACKGROUND: Delayed hypersensitivity reactions to an iodinated radiologic contrast are a form of hypersensitivity reactions that occurs anywhere from one hour up to 10 days after exposure to the causative agent. CASE REPORT: We present a case of a 54-year-old woman with a history of a single minor reaction to an intravenous iodinated contrast consisting of only abdominal pain who developed a maculopapular exanthema 7 days after exposure to iohexol, an iodinated radiological contrast, during a lumbar epidural steroid injection. The patient was later treated with topical betamethasone with resolution of cutaneous symptoms within 2 weeks. The patient then underwent patch testing, which revealed a positive result for palladium (II) chloride; to date, there has been no documented association in the literature between palladium (II) chloride and iohexol. CONCLUSION: DHRs to an iodinated radiologic contrast can range from cutaneous manifestations to lethal presentations, such as Stevens-Johnson syndrome and toxic epidermal necrolysis, with the most common form being a maculopapular exanthema as experienced by our patient. Testing can be performed to determine the causative agent of the DHR and to find an alternative agent if a radiologic contrast is required. Caution must be taken if using an alternative contrast agent as there is significant cross-reactivity to other iodinated radiologic contrasts. KEY WORDS: Delayed hypersensitivity reaction, iodinated contrast, maculopapular exanthema, palladium, case report

Three-Component Domino Reaction of Thioamide, Isonitriles, and Water: Selective Synthesis of 1,2,4-Thiadiazolidin-3-ones and (E)-N-(1,2-Diamino-2-thioxoethylidene)benzamides.

The three-component domino reaction of thioamides, benzyl isocyanide, and water in the presence of a catalytic amount of both Pd(dppf)Cl2 and Cu(OAc)2 afforded novel 1,2,4-thiadiazolidin-3-one cyclic compounds, whereas the same reaction with tertiary alkylisonitriles in the presence of rare earth metal salt [La(OTf)3] resulted in (E)-N-(1,2-diamino-2-thioxoethylidene)benzamide open-chain products. This divergent reaction enabled the one-pot construction of five (N-S, C-S, C-O, and two C-N) or four (C-S, C-N, C-O, and C-C) new chemical bonds. Mechanism studies indicate that the oxygen atom of the product was derived from H2O.

Peculiarities of electrocatalytic and corrosion behavior of palladium and palladium-molybdenum electrolytic deposits

PdMo deposits (∼22 at.% Mo) are obtained on the surface of glassy carbon electrodes by electrodeposition in galvanostatic mode from aqueous ammonium-acetate solutions containing palladium(II) chloride and ammonium heptamolybdate. The deposits are characterized by SEM, XRD, XPS, ICP–AES, and CV methods. It was found that the most of palladium is in a metallic state in the surface layers of the deposits, whereas molybdenum is in the forms of oxides in them. The effect of molybdenum inclusion in the palladium deposits on their anodic dissolution in 0.5 M H2SO4 is studied by cycling electrode potential in the range of 0.30 – 1.25 V (RHE) in various regimes with simultaneous determination of quantities of metals passed into the solution. The joint analysis of both coulometric and analytical data showed that Mo addition to palladium causes a decrease in the specific solubility of the deposits. This analysis also made it possible to conclude that Pd dissolution predominantly occurs on the part of the surface, which is not occupied by oxides. The addition of molybdenum to palladium deposits causes a sharp decrease in their activity in formic acid oxidation reaction (FAOR) and some increase in the activity in methanol oxidation reaction (MOR) in 0.5 M H2SO4. This can be explained by the different role of oxygen-containing species in the mechanisms of FAOR and MOR.

FORMACIÓN DE NANOPARTÍCULAS DE PALADIO POR EL MÉTODO DE LOSPOLIOLES: INFLUENCIA DE LAS CONDICIONES ALCALINAS

The effect of sodium hydroxide (NaOH) on the size of palladium (Pd) nanoparticles obtained by the simple polyol route was studied. Nanoparticles were synthesized at room temperature using palladium(II) chloride (PdCl2) and NaOH dissolved in ethylene glycol (EG) as reduction reaction promoters. No protective agents or stabilizers were used. We monitored the reaction kinetics and the growth of the nanoparticles by UV-vis spectroscopy and their crystallinity by powder X-ray diffraction (XRD) as a function of NaOH concentration. Crystallite size was evaluated from the diffraction pattern. We found that nanoparticle growth is strongly influenced by the NaOH: Pd molar ratio. Crystallite sizes from 2 to 24 nm were obtained for molar ratios ranging from 1 to 33. At lower concentrations of NaOH, the nucleation and growth process of the nanoparticles were found to be controlled by the reduction of the Pd ion precursors.At higher concentrations, the intermediate reduction of Pd-Cl-OH species determines the nanoparticle growth rate resulting in the formation of the smallest final-size nanoparticles.

Simultaneous reduction of 4-nitrophenol, 4-nitroaniline and methylene blue organic pollutants via TiO2 supported Pd(II) complex catalyst bearing 2-(6-methylpyridin-2-yl)-1H-benzimidazole type ligand

In this study, 2-(6-methylpyridin-2-yl)-1H-benzimidazole derivative ligand (L) and its Pd(II) complex (Pd(L)Cl2) were synthesized and characterized by spectroscopic techniques. The crystal structure of L was characterized by X-ray diffraction method, and the structural, spectroscopic and electronic properties were obtained using density functional method (DFT). The catalyst material of the Pd(II) complex was prepared by attaching the complex to the titanium dioxide (TiO2) inorganic support material at a ratio 15 % (15 % Pd(L)Cl2-TiO2). 15 % Pd(L)Cl2-TiO2 catalyst material was characterized by FT-IR, TG, SEM-EDX and XRD analysis methods and used as catalyst in the catalytic reduction of 4-nitrophenol (4-NP), 4-nitroaniline (4-NA) and methylene blue (MB) organic pollutants. High conversion values were obtained for the reduction of 4-NP, 4-NA and MB substrates by 15 % Pd(L)Cl2-TiO2 catalyst material as a synergistic result of the unique catalytic properties of the Pd metal and the photocatalyst property of the TiO2 semiconductor that used as the inorganic support material.

C-H functionalization of quinoline N-oxides catalyzed by Pd(II) complexes: a computational study.

Pd(II) catalysts, particularly the acetate salt in acetic acid, tended to favor regioselective C-H activation of quinoline N-oxides (QOs) at the C2 position. However, Pd(II)Cl2 was shown to catalyze their C-H activation at C8 and, in the presence of water, C8-H activation was accompanied by the formation of 2-quinolinones. The aim of the DFT study described in this work was to shed light on the complete mechanism of these competing catalytic reactions, when PdCl2 reacts with QO and benzaldehyde in dichloroethane. C-H activation of QO was the first step of the reaction and involved either a metallacycle, with a CQO-Pd(II) σ-bond and a C(8)-H-Pd(II) agostic bond, or an η3-QO complex, with three carbon atoms of the heteroring of QO binding PdCl2. The first situation led to the unusual C8 activation and the second to C2 activation. The σ-metallacycle undergoes C8-H activation and the energy of the TOF determining the transition state to form the product is ∼17 kcal mol-1, while for the reaction through the π-metallacycle (C2-H activation) the corresponding energy is higher (∼29 kcal mol-1) and thus is not competitive under the same conditions. The reaction proceeding through the σ-complex, activating the C8 position, is preferred, in agreement with experimental results. Both reactions involve oxidation of Pd(II) to Pd(IV) and the catalyst is regenerated. When small amounts of water are added to the reaction mixture, C8-H activation (acylation) results from the same σ-metallacycle with the same barrier, but the simultaneous formation of 2-quinolinones is more complicated. It starts with OH- attack at the C2 position, and is followed by the migration of two hydrogen atoms, and the final reductive elimination step ends with Pd(0). The higher barriers for the migration and reoxidation of Pd(0) are associated with the more demanding reaction conditions. The different reactivity of Pd(II)(OAc)2 under analogous conditions is clarified, as it is only capable of forming the above mentioned π-complex and thus of activating the C2 position of QO. This catalyst can preferentially activate the C8-H bond under rather different conditions, including in particular acetic acid medium, as shown by other authors.

Synthesis, characterization, and reactivity of [Pd(phosphine)(py)Cl2] (PEPPSI) and [Pd(phosphine)Cl2]2 complexes.

The synthesis of novel phosphine palladium PEPPSI and dimer complexes bearing RuPhos, SPhos and XPhos phosphines is reported. The crystal structures of XPhos Pd PEPPSI with pyridine, SPhos Pd PEPPSI with 3-chloropyridine as throw-away ligands and the RuPhos palladium dimer were obtained and compared with previously reported congeners. The catalytic activity of these novel complexes was examined via a C-N coupling reaction involving 4-chloroanisole and morpholine. RuPhos complex 2b proved most active, leading to 97% yield with a low (0.2 mol%) catalyst loading, while phosphine palladium dimers showed significantly lower catalytic activity. However, the addition of 3-pentanone as an activator/stabilizer significantly improved the yields of phosphine dimers and PEPPSI complexes when the reactions were performed in THF.

WET TREATMENT AND THE BEHAVIOR OF ELECTROLESS NI-P DEPOSITION AT 40 °C ON POLISHED ALUMINA

The morphology and adhesion strength of the autocatalytic electroless nickel phosphorus (Ni-P) film, deposited at 40 ºC on polished alumina (Al2O3 99.6%) substrate, pretreated by sulfur/nitric solution, sensitizing with acid stannous chloride and activated using palladium chloride solutions, was studied using contact angle (CA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), mechanical profilometer (DekTak), and direct laser writer (“maskless lithography”). The results showed that after treatment of the polished Al2O3 substrate, it presented a high performance in the electroless deposition of Ni-P thin-film at low temperature (40 ºC). It was obtained a more compact and continuous film, with small grain size and strong adherence.

Facile synthesis of a new covalent organic nanosheet (CON-KEY1) based on polyamide links as an effective heterogeneous catalyst in C-C cross coupling reactions.

C-C coupling reactions represent a fundamental synthetic methodology widely employed in academic and industrial settings. Herein, we present a report on developing and synthesizing a heterogeneous catalyst that is environmentally compatible and has recycling capabilities. Furthermore, the utilization of this catalyst for C-C coupling reactions was explored. A novel amide-based CON was prepared via the reaction of a novel [2,2'-bipyridine]-5,5'-diamine (BDA) and 1,3,5-tris(4-carboxyphenyl) (TCB). TCB was activated with carbonyl diimidazole (CDI) and then reacted with BDA to synthesize favorable CON (i.e., CON-KEY1). Finally, the CON synthesized was reacted with palladium chloride ions, and the palladium-containing organocatalytic complex was decorated with the abbreviated Pd/CON-KEY1. This new heterogeneous complex was fully characterized through the required techniques, including FT-IR, EDX, XRD, TEM, SEM, ICP, TGA-DTA, N2 isotherms, and elemental mapping analysis. Computer simulation results include a multi-sheet 2D framework proposed by CON-KEY1. As a result, palladium ions were found to be arranged between the layers and on the CON surface. This heterogeneous complex functioned as a catalyst precursor in both the Suzuki-Miyaura coupling reaction of aryl boronic acids with aryl halides and the Heck reaction of aryl halides with acrylate derivatives or styrene. The desired coupling products with various functional groups were successfully attained with excellent yields of up to 98%. Simple set-up, improved yields, short reaction times, non-toxic solvents, catalyst durability, and high turnover frequency are among the distinct advantages of this synthetic method. Some other outstanding features of this catalytic system include convenient separation of catalysts and products, high yields, almost complete conversion, high selectivity, and good turnover frequency (TOF). The results show that the highest product efficiency in the reaction was achieved in the shortest possible time using Pd/CON-KEY1. Theoretical studies demonstrated the precedence of the palladium complexation with nitrogen atoms of CON-KEY1 rather than oxygen ones. Natural Bond Orbital (NBO) analysis affirmed that the system with Pd-N bonds (Eg = 0.089 eV) is more reactive with high electron conductivity compared to the Pd-O system (Eg = 0.120 eV).

Recovery of Palladium from Acidic Solution Using Polyethylenimine-Crosslinked Calcium Silicate Hydrate Derived from Oyster Shell Waste: Adsorption and Mechanisms

In this work, a new adsorbent with effective Pd(II) adsorption ability was synthesized using an oyster shell and fumed silica as the matrix materials and polyethyleneimine as the functional ligand. The adsorption performance of the developed adsorbent was evaluated for the recovery of palladium chloride ions (Pd(II)) from strong acid solutions. To understand the characteristics of the materials used in the study, samples were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), and zeta potential analysis. Zeta potential analysis revealed that the isoelectric point of polyethylenimine-crosslinked calcium silicate hydrate (PEI-CSH) was 9.85. Isotherm experiments revealed that the maximum Pd(II) uptake estimated by the Langmuir model was 156.03 mg/g, which was 22.4 and 35.6 times higher than that of the oyster shell powder (OSP) and calcium silicate hydrate (CSH), respectively. The Pd(II) adsorption equilibrium was established in 180 minutes, according to kinetic experiments. These results suggested the possibility of Pd(II) recovery from oyster shell-based adsorbent. Through five adsorption and desorption cycles, the reusability of PEI-CSH was confirmed. PEI-CSH can therefore be considered a potential adsorbent for Pd(II) recovery.

Catalytic activity of a palladium(ii) complex modified on multi-wall carbon nanotubes: an efficient catalyst for the Suzuki cross-coupling reaction

We prepared a novel palladium (Pd) catalyst by loading palladium chloride onto novel functionalized multi-wall carbon nanotubes (MWCNTs). The Pd(ii)/MWCNT complex efficiently and selectively catalyzed large-scale synthesis of target molecules with high yield and large turnover numbers.

Expanded Ligands Based upon Iron(II) Coordination Compounds of Asymmetrical Bis(terpyridine) Domains.

The synthesis and characterization of two tritopic ligands containing a 2,2':6',2″-terpyridine (tpy) metal binding domain and either a 3,2':6',3″- or a 4,2':6',4″-tpy domain are detailed. The synthetic routes to these ligands involved the [Pd(dppf)Cl2]-catalyzed coupling of a boronic ester-functionalized 2,2':6',2″-tpy with bromo-derivatives of 3,2':6',3″-tpy or 4,2':6',4″-tpy. The 2,2':6',2″-tpy domains of the tritopic ligands preferentially bind Fe2+ in reactions with iron(II) salts leading to the formation of two homoleptic iron(II) complexes containing two peripheral 3,2':6',3″-tpy or 4,2':6',4″-tpy metal-binding sites, respectively. These iron(II) complexes are potentially tetratopic ligands and represent expanded versions of tetra(pyridin-4-yl)pyrazine.

Palladium-Catalyzed Synthesis of Novel Quinazolinylphenyl-1,3,4-thiadiazole Conjugates

Two novel series of symmetrical and unsymmetrical conjugates, in which 1,3,4-thiadiazole and 4-N,N-dimethylaminoquinazoline scaffolds were connected via 1,4-phenylene linker, were synthetized in high yields by Suzuki cross-coupling reactions. The elaborated protocol makes use of bromo-substituted quinazolines, boronic acid pinacol ester or diboronic acid bis(pinacol)ester of 2,5-diphenyl-1,3,4-thiadiazole, catalytic amounts of [1,10-bis(diphenylphosphino)ferrocene]dichloropalladium(II) Pd(dppf)Cl2, sodium carbonate, and tetrabutylammonium bromide, which plays the role of a phase-transfer catalyst. The structures of prepared compounds were confirmed by 1H NMR, 13C NMR, UV-VIS, IR and HRMS. For the target compounds, the fluorescence spectra were measured to determine their quantum yields and Stokes shifts. The study revealed that among the tested compounds, two highly-conjugated derivatives (8a, 9a), in which 1,3,4-thiadiazole core is connected to 4-(N,N-dimethylamino)quinazoline via a double 1,4-phenylene linker, exhibit high quantum yields of fluorescence and strong fluorescence emission.

Palladacycle versus coordination complex of palladium(II) with a bulky organophosphorus (P,N) ligand: Application in catalysis of allylation of aldehydes

Palladacyclic complex 1 [Pd(L1)Cl] [L1: anthracene–9-yl–CH = N(CH2)2–PPh2 behaving as (P, N, C−) ligand] has been prepared, and characterized using multi-nuclei NMR spectroscopic, high resolution mass spectrometric (HRMS) and single-crystal X-ray diffraction (SC-XRD) techniques. This palladacycle 1 and the 2 [i.e., Pd(L1)Cl2, a square planar Pd(II) complex of the same ligand] have anthracene core, imine functionality and P,N donors. Both the 1 and 2 have been explored as potential catalysts for allylation of aldehydes with allyltributylstannnane. Both the complexes show good efficiency towards this CC coupling reaction. Various aldehydes such as 4–bromobenzaldehyde, 4–chlorobenzaldehyde, 2–bromobenzaldehyde, 2–chlorobenzaldehyde, 4–methoxybenzaldehyde, 4–methylbenzal dehyde, 4–nitrobenzaldehyde pyridine–2–carboxaldehyde and furfural have been explored for this reaction. Effect of presence of Pd–C bond is noticed on the catalytic performance. The palladacyclic complex 1 is more efficient than coordination complex 2 as the Pd-C bond of metallacyclic complex increases the rate of dissociation of Pd-Cl bond and therefore helping in easy participation and increased efficiency of complex 1 in catalysis.

Transmembrane Chloride Transport by Diphosphine‐Pd(II) Complexes: Effect of the Ligand Geometry

AbstractTransmembrane chloride transport is a fundamental biological process, and its impairment is at the origin of severe genetic diseases such as cystic fibrosis. Synthetic anion carriers able to transport chloride and other anions across biological membranes are considered as putative candidates for treating these syndromes. We have proposed diphosphine–Pd(II) complexes as a new class of anion carriers and in this contribution we have investigated the ionophoric activity of a family of Pd(II) complexes with diphosphine chelating ligands differing for the ligand bite angle that is varied from 71° (dppm) to 98° (dppb). Moreover, in the case of the dppe ligand we also investigated the effect of the introduction in the ligand structure of alkyl substituents of increasing length and hydrophobicity and of electron donor and withdrawing substituents. All the complexes investigated are able to transport chloride across the phospholipid membrane of liposomes and the most important parameter influencing their relative efficacy is the lipophilicity of the complex with the highest activity observed for [Pd(pEt‐dppe)Cl2]. On the contrary the bite angle of the ligand appears to be not relevant while the activity is diminished by the insertion of both EWG and EDG groups on the phenyl substituents of the phosphine ligands. Finally, also Ni(II) and Cu(I) complexes display ionophoric activity demonstrating that the transport ability of metal complexes is not limited to Pd(II) metal ion.

Synthesis and Theoretical Studies of Biologically Active Thieno Nucleus Incorporated Tri and Tetracyclic Nitrogen Containing Heterocyclics Scaffolds via Suzuki Cross-Coupling Reaction.

A new series of thieno nucleus embellished trinuclear (19, 20) and tetranuclear (21-24) nitrogen heteroaryl have been synthesized by the Suzuki cross-coupling reaction using bis(triphenylphosphine)palladium(II) dichloride. All the synthesized compounds were characterized by IR, 1 H-NMR, 13 CNMR and Mass spectral properties. In vitro antibacterial studies of the synthesized compound were conducted using broth microdilution assay employing Gram-positive and Gram-negative strains and half-maximal inhibitory concentration (IC50 ) was determined. The result showed that compound 20 possess best antibacterial activity against S. aureus and E. coli with IC50 values of 60 μg mL-1 and 90 μg mL-1 . Further to determine the mode of antibacterial action, compounds 20 and 21 were examined for in vitro bacterial dehydrogenase inhibitory assay. To understand the binding affinity of the synthesized compounds, the docking study was performed in the bacterial dehydrogenase enzyme by AutoDock Vina software and structure was confirmed by Discovery Studio Visualizer. All the synthesized compounds were docked in a good manner within the active sites of the bacterial dehydrogenase enzyme and exhibited good binding energies.

Palladium encapsulated nanofibres for scavenging ethylene from sapota fruits.

Scavenging ethylene is a useful intervention during the transportation and storage of tropical climacteric fruits like sapota. Sapota (Manilkara achras Mill.) is a delicious tropical fruit with a very high respiration rate and poor shelf life. To prolong its post-harvest shelf life, the use of palladium chloride in electrospun nanomats was evaluated at a concentration varying from 1 to 4% levels. Encapsulation of 1-2% PdCl2 in nanomats increased the ethylene scavenging capacity (ESC) by 47-68%. Although, upon encapsulation, both PdCl2 and potassium permanganate showed significantly the same ethylene scavenging activity, the efficacy of PdCl2 was found better in presence of sapota fruits. The PdCl2 nanomats were brighter (L* > 73) in colour compared to the potassium permanganate mat. The placement of nanomats (2 cm2 × 9 cm2) in corrugated fibre board boxes in which the sapota was packed showed higher quality indices (firmness, TSS, ascorbic acid, and phenolics) along with lower PLW and respiration rate during the 8 days of storage period. Compared to control (8.35%), physiological loss in weight of 4.47% was recorded in fruits stored with ethylene scavenging nanomats. PdCl2 encapsulated PVA nanomats can emerge as a promising option for the retention of quality in fruits during storage and transit.