Search Results (284)

This work presents the synthesis and structural characterization of a previously unknown palladium(II) complex with (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide, which in the solid state forms a highly symmetric tetrametallic metallamacrocycle. The structure of the synthesized (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide and corresponding palladium(II) complex was established by ¹H, ¹³C–{¹H}, ¹H–¹³C HMQC, and ¹H–¹³C HMBC NMR spectroscopy; IR and UV spectroscopy; mass spectrometry; TGA/DSC analyses; and single-crystal X-ray diffraction. Full article

A strategy for the selective C–H silylation of 7-phenyl-1H-indoles has been established via palladium(II)/norbornene cooperative catalysis. This method employs norbornene (NBE) as both a C–H activation mediator and an alkylating agent to access arylsilanes with exceptional selectivity. Kinetic isotope effect (KIE) studies revealed that C–H cleavage is the rate-determining step, consistent with a mechanism proceeding through an eight-membered palladacycle. Full article

This paper describes the synthesis, characterization and application in hydrogenation catalysis of triphenylphosphine-stabilized palladium and rhodium species on SBA-15. The materials were achieved by synthesizing a triethoxysilyl-functionalized triphenylphosphine ligand through the reaction of (2-chloromethylphenyl)diphenylphosphine and (3-mercaptopropyl)triethoxysilane. Treatment of this ligand with the appropriate palladium(II) and rhodium(I) complexes produced the corresponding transition metal complexes, which were then immobilized on the support material. The final catalysts were obtained by treating these precursor materials with dihydrogen at elevated temperatures. These catalysts are highly active in the hydrogenation of a wide range of olefins under mild conditions. XPS studies on one of the palladium catalysts reveal that only a part of the metal is reduced, with almost no further reduction of the remaining palladium(II) species observed after tenfold recycling and reuse of the material. Full article

Non-stoichiometric tungsten carbide WC_1−x layers (~20 mm thickness) were used as a reductant substrate to deposit palladium nanoparticles under open-circuit conditions in aqueous solutions. The prepared Pd(WC_1−x)/TEG electrodes (TEG—thermally expanded graphite) were studied by a complex of modern physical methods: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Raman Spectroscopy. The reduction of Pd(II) species to the metallic state was confirmed by XPS and XRD. The coherent scattering domain (CSD) for Pd particles was determined using the Scherrer formula (peak broadening analysis) with the LaBeil profile fitting the XRD pattern. It was ca. 16 nm, which would correspond to a specific surface area of palladium of 30.9 m²·g⁻¹, assuming a spherical shape of its particles. According to electrochemical studies, the specific area of palladium is significantly lower (8.5 m²·g⁻¹ in 0.1 M PdCl₂ after 2 h of deposition), which is due to the inevitable coalescence of metal nanoparticles during the currentless deposition process. Pd(WC_1−x) composites demonstrated high catalytic activity in the hydrogen evolution reaction (HER) and formic acid oxidation reaction (FAOR). Thus, currentless deposition can be considered as a relatively simple method for producing electrode catalysts. Full article

New copper(II) (C1) and palladium(II) (C2) complexes with S,O-tetradentate ligand (L) derived from thiosalicylic and thiopropionic acids were synthesized. In cell-based assays, (C1) exhibited the most pronounced activity within the tested compound series and was therefore advanced for mechanistic evaluation in 4T1 triple-negative breast cancer cells. (C1) significantly reduced 4T1 cell viability by inducing early and late apoptosis, accompanied by mitochondrial membrane depolarization and enhanced cytochrome C release. Consistently, (C1) increased the Bax/Bcl-2 ratio, promoting a pro-apoptotic shift. In parallel, (C1) triggered autophagy, as evidenced by decreased p62 and LC3B levels, induced G0/G1 cell-cycle arrest, and suppressed proliferative signaling by downregulating Ki67, cyclin D, and phosphorylated AKT. The DNA-binding studies showed moderate to strong affinity, favoring minor groove binding, with higher affinity for (C1) than for (C2). Tryptophan fluorescence quenching indicated a strong interaction with BSA via a predominantly static mechanism, more pronounced for (C1). Molecular docking at the DNA and BSA binding sites corroborated experimental findings and suggested favorable interactions between the complexes and apoptosis-related proteins (CASP3, BAX, and BCL2). The integrated experimental and computational data identify (C1) as a biologically active compound with multimodal biological effects in vitro, supporting further structural optimization and mechanistic investigation. Full article

The disadvantages of Cisplatin in anticancer treatment are connected to its poor selectivity, resistance developed of cancers to the drug, and its toxicity against normal organs. An important strategy in anticancer treatment is the synthesis and clinical investigation of non-platinum metal complexes with superior anticancer activity and improved selectivity compared to Cisplatin, combined with lower toxicity, fewer side effects and decreased resistance of cancer to the drug. In the current study, we aim to summarize the potential of important non-platinum metal-based organic compounds as therapeutic agents against different cancer cell types. The review covers the general principles of chemotherapy. A literature analysis shows that organic complexes of the metalloids arsenic (As), boron (B), antimony (Sb), and selenium (Se), and of metals, such as Ag, Au, Co, Cu, Fe, Mn, Mo, Ni, Zn, Ce, Ga, Gd, Ir, Os, Pd, Re, Rh, Ru, Ti, and V, have been investigated for potential applications in cancer therapy. This is due to their antiproliferative effects against different cancer types: lung [Cd(II), Co(II), Cu(II), Ni(II), Mn(II), Ru(II), Zn(II)]; breast [Ag(I), Cu(I), Cu(II), Ir(III), Ni(II), Mn(II),. Rh(III), Ru(II)]; gastric [Cu(II), Cu(II)-La(III)]; colon [Ag(I), Cu(II), Ir(III), Pd(II), Rh(III), Ru(II), vanadium(V)]; colorectal [Ag(I), Co(II), Cu(II), Zn(II)]; liver [Ag(I), Co(II), Cu(II), Gd(III), vanadium(V)]; pancreatic [vanadium(IV)]; bladder [Ag(I), Cu(II), Ru(II)]; cervical [Ag(I), Au(I), Cu(I), Cu(II), Fe(II), Ir(III), Rh(III), Ru(II)]; testicular [vanadium(IV)]; prostate [Cu(II), Pd(II), Zn(II)]; leukemia [Ag(I), Co(II), Cu(II), Pd(II), Zn(II)]; sarcoma [Co(II), Ni(II), Zn(II)]; mesothelioma [Cu(II)]; neuroblastoma [Cu(II)]; glioma [Cu(II)]; and melanoma [Au(I), Cu(II), Pd(II), Ru(II)]. The main goals for increasing anticancer metal-based complexes include increasing anticancer activity and selectivity, reducing toxicity, and avoiding cancer cell resistance. Compared to Cisplatin, organocomplexes of copper, ferrocene, and ruthenium are more active. Ruthenium and copper complexes, in particular, are also more selective. Notably, ruthenium and ferrocene derivatives are less toxic than Cisplatin. Lastly, cancers appear to exhibit less resistance against copper, gold, ruthenium, palladium, and ferrocene complexes. Full article

Background: The newly synthesized palladium(II) complex [Pd(L1)Cl]Cl (where L1 = N²,N⁶-bis(5-methylhthiazol-2-yl)pyridine-2,6-dicarboxamide) has demonstrated significant in vitro antitumor activity. In this study, the effects of this complex on the immune response and its antimicrobial potential were evaluated. Methods: Splenocytes isolated from mice were treated with lipopolysaccharide (LPS)/Concanavalin A (ConA) along with the Pd(II) complex. The concentrations of IFN-γ, IL-17, IL-4, TNF-α, IL-1β, and IL-10 were measured using commercial ELISA kits. The antimicrobial effect was tested against reference strains of Gram-positive and Gram-negative bacteria, as well as yeast. The Minimal Inhibitory Concentration (MIC) was determined via the broth microdilution method, followed by the determination of Minimal Bactericidal/Fungicidal concentrations (MBC/MFC). Results: The Pd(II) complex induced an increase in the concentration of all tested cytokines compared to untreated cells. Co-treatment with Pd(II) complex and LPS significantly increased the levels of IFN-γ, IL-1β, and IL-17 compared to the LPS-only-stimulated group. Co-treatment with ConA and the Pd(II) complex resulted in a significant increase in TNF-α and IL-17 levels, whereas a significant decrease was observed in the concentrations of IL-10, IL-4, and IFN-γ compared to the ConA-only-stimulated group. The tested complex showed weak to moderate antimicrobial activity, Gram-positive bacteria showed better susceptibility to the examined complex compared to Gram-negative. Conclusions: Results of the study indicate that the Pd(II) complex exhibits a significant immunomodulatory effect on splenocytes, alongside weak to moderate antimicrobial activity. Full article

The search for new anticancer agents with improved efficacy and reduced toxicity has intensified interest in metal-based compounds. In this study, two novel palladium(II) complexes, synthesized from Schiff base ligands derived from 5-chloro-salicylaldehyde and p-hydroxybenzylamine or tyramine, were chemically characterized and biologically evaluated. Both complexes exhibited significant cytotoxic activity against the MCF-7 breast cancer cell line in a dose- and time-dependent manner, with Pd2 showing slightly higher potency. Morphological analysis of treated cells indicated that apoptosis is the predominant mechanism of cell death. To gain deeper insight into the potential mechanisms underlying the observed anticancer activity, several biologically relevant targets were investigated. Enzyme kinetics revealed that the complexes act as uncompetitive inhibitors of liver catalase, suggesting a possible role in the induction of oxidative stress. Fluorescence studies demonstrated that Pd2 interacts with CT-DNA through combined intercalative and minor groove binding modes and exhibits significant binding affinity toward human serum albumin, predominantly at Sudlow’s site I. Molecular docking analysis further supported favorable interactions with catalase, estrogen receptor α, and B-form DNA, providing structural insight into the experimentally observed biological effects. Overall, the study explores multiple potential mechanisms of anticancer action, underscoring the promising therapeutic potential of these palladium(II) complexes, while antitumor activity has been initially assessed using a MCF-7 cell line as a preliminary model. Full article

A series of Group 10 metal dithiocarbonate complexes [M(S₂COⁱPr)₂] (M = Ni 1, Pd 2, Pt 3) was prepared following procedures from the literature and cocrystallized with the ditopic σ/π-hole donor 1,4-diiodotetrafluorobenzene. Single-crystal X-ray diffraction revealed a consistent I···S halogen bonding motif alongside a remarkable diversity in metal-involving interactions across the Ni–Pd–Pt triad. While nickel(II) exhibits strong electrophilic M···S semicoordination, the palladium(II) center displays ambiphilic behavior, and platinum(II) acts exclusively as a nucleophile via π-hole···M bonding. Comprehensive density functional theory studies, including molecular electrostatic potential (MEP) mapping, quantum theory of atoms in molecules/noncovalent interaction plot analyses, and energy decomposition analysis, were used to quantify this competitive balance. The results demonstrate that the increasing nucleophilicity from Ni to Pt, supported by shifting MEP minima and stronger π-hole stabilization energies, dictates the preference for nucleophilic over electrophilic metal-centered contact. Full article

Under aqueous conditions, transition-metal catalysis offers an attractive platform for greener C–N bond formation by reducing reliance on hazardous organic solvents. Herein, we report a microwave-assisted palladium-catalyzed selective N-arylation of anilines with 2,3-dihalopyridines in water. Systematic optimization revealed that a catalyst system comprising PdCl₂(1,10-phenanthroline)₂ and (±)-BINAP in the presence of K₃PO₄ enables efficient coupling under microwave irradiation. Under the optimized conditions (PdCl₂(1,10-Phenanthroline)₂, 2 mol%; (±)-BINAP, 3 mol%; K₃PO₄, 3.5 equiv; H₂O, 2.5 mL; 150 °C; 30 min), the coupling of aniline with 2,3-dichloropyridine afforded the corresponding aminopyridine product in up to 91% isolated yield. The method was extended to various 2,3-dihalopyridines and substituted anilines, providing moderate to excellent yields with good regioselectivity. Mechanistically, the transformation is consistent with a Pd(0)/Pd(II) catalytic cycle involving oxidative addition, amido complex formation, and reductive elimination. Full article

Ionic liquid (IL) N-methyl-N′-1-(4-t-butylphenylphosphinyl)butylimidazolium bis(trifluoromethylsulphonyl) imide was used for the first time as an ion carrier in membrane systems to selectively transport Au(III), Pt(IV), and Pd(II) ions. Au(III), Pd(II), and Pt(IV) were transported from HCl solutions utilizing a polymer inclusion membrane (PIM) with cellulose triacetate as the support, o-nitrophenyl pentyl ether as the plasticizer, and ionic liquid as the mentioned ion carrier. The modifications of source and receiving aqueous phase compositions are examined. High selectivity for Au(III) using the ionic liquid in the membrane was achieved at elevated HCl concentrations (≥0.5 M). When a 0.010 M KI solution was used as the receiving phase and a membrane with the optimal composition was applied, the extraction of Au(III) ions reached a maximum recovery rate of 93%. Moreover, PIM studies showed that carrier molecules doped in the membrane creates complexes with the Au(III) ion with a molar ratio of 1:1. The extractability of Au(III) through PIMs exceeded that of other metal ions, with the selectivity of transported metal ions ranked as follows: Au(III) >> Pt(IV), Pd(II). The recovery factors for gold, platinum, and palladium ions after 6 h of transport were 94%, 8%, and 1%, respectively. Full article

Nickel(II) and palladium(II) ions are capable of forming complexes with macrocyclic terapyrrole structures such as the porphyrin or corrin ring. Many different derivatives of these complexes are synthesized and studied because these compounds have potential numerous applications, including catalysis, various light-driven chemical reactions and processes related to intramolecular and intermolecular energy redistribution. Nickel porphyrins exhibit neither fluorescence nor phosphorescence when excited with light; however, palladium porphyrins, when excited to the singlet state, very quickly transform into the triplet state, and unlike nickel porphyrins, deactivation of the excited states occurs by phosphorescence. Palladium corrin has dual luminescent properties and exhibits both a weak fluorescence and strong phosphorescence. These photophysical differences are based on the complex energetic redistribution of singlet and triplet excited states interacting with each other in the intersystem crossing process. Based on the results of calculations at the DFT/TDDFT and CASSCF/NEVPT2 levels of theory, the structure of electronic excited states of model nickel(II) and palladium(II) complexes with corrin and porphyrin macro-rings was characterized and potential paths of photophysical processes leading to the occupancy of low-lying triplet states were described. In nickel complexes, very low-energy triplet states are the main cause of the rapid radiationless deactivation of excited states via triplet photophysical pathways. Full article

Organometallic and metal–organic compounds are widely used in different fields of chemistry and allied disciplines, including bioinorganic and medicinal chemistry. Of particular interest is the development of novel potential anticancer agents based on palladium(II) complexes of the so-called pincer-type ligands, featuring a specific monoanionic tridentate framework. In this work, hybrid imine–thiocarbamate ligands are shown to readily undergo direct cyclopalladation in solution and under solvent-free conditions, in particular upon mechanochemical activation, yielding a series of Pd(II) pincer complexes. The latter exhibit promising cytotoxic activity against several solid and hematopoietic cancer cell lines. Full article

Ethylene cross-bridged tetraazamacrocycles have been used to stabilize first-row transition metal complexes for applications under harsh conditions, such as biomedical imaging and aqueous oxidation catalysis. We have applied these ligands to the synthesis of complexes of a larger second row transition metal, namely, square pyramidal Pd²⁺ complexes, which may be useful for future catalytic processes. We now report the synthesis and crystal structure determination of four novel Pd²⁺ complexes of the general formula [PdLCl]PF₆, where L is the dimethyl ethylene cross-bridged derivative of 12aneN4 (cyclen), 13aneN4 (homocyclen), or 14aneN4 (cyclam), or the dibenzyl ethylene cross-bridged derivative of 14aneN4 (cyclam). Solid-state structures of all four complexes can be described as a distorted square pyramidal with τ₅ values ranging from 0.01 to 0.20, with three macrocycle nitrogen atoms and one chloride in the square base and the fourth ligand nitrogen constrained by the cross-bridge to the axial position. Cyclic voltammetry of the complexes in acetonitrile shows stabilization of the Pd³⁺ oxidation state by all four complexes. Electronic spectroscopy reveals the typical behavior for square pyramidal Pd²⁺. Full article

Lanthanide coordination polymers have been developed at a fast rate during the past two decades due to their appealing applications in the modern field of materials science and emerging technologies like luminescence, magnetism, sensing, gas adsorption, and catalysis. The role of lanthanides in imparting specific properties to the coordination polymers has been fully documented in extensive studies carried out by numerous research groups. It has been shown that because lanthanide(III) ions possess a variable coordination number, they readily build two-dimensional and three-dimensional architectures with definite channels, permanent pores, and distinct surface areas. Due to their strong oxophilic propensity and hard Lewis acid character, lanthanides favor the construction of stable coordination polymers and MOF configurations by strongly binding the coordinating groups of the organic linkers. Associated with palladium complexes, the lanthanide ions provide synergistic effects with Lewis acid sites, beneficial to the catalytic activity. These attractive characteristics of lanthanides enabled them to be fruitfully applied in Pd-Ln coordination polymers with catalytic properties. This review covers an array of Pd-Ln coordination polymers applied as heterogeneous catalysts in Suzuki–Miyaura C(sp²)-C(sp²) cross-coupling reactions. The activity and chemoselectivity of Pd(II) ions and Pd nanoparticles associated in coordination polymers with different lanthanides from a selected array of rare earth elements (Eu, Sm, Eu, Gd, Pr, Nd, Ce, La, or Tb) is discussed. High yields (>99%) are attained under optimized reaction conditions. The specific role of lanthanides and organic ligands in creating sustainable and recyclable heterogeneous Pd catalysts is evidenced. Mechanistic aspects of the C(sp²)-C(sp²) cross-coupling reactions are considered. The synergistic interaction between lanthanides and palladium as well as with the organic ligands is highlighted. Full article