Planar Pd Research Articles

Molecular recognition on the surface of concentrated hydrochloric acid: Hydration configuration-driven preferential recognition of Rh (III) anions with inner-coordinated water molecules

Comprehension of selective recognition of anions is confined to a phenomenological list of solvents, hardly surpassing Pedersen’s empirical observations of cationic-crown ether binding. In this work, a novel strategy employing thin-layer oil membrane extraction (TOMX) on the surface of concentrated hydrochloric acid is proposed for controllable recognition and separation of anions with different hydration configurations. Four typical chloric-complexing anions, RhCl63−, PdCl42−, PtCl62− and FeCl4−, usually coexisting in the concentrated hydrochloric acid leaching solutions of precious metal concentrates were focused. A surprising phenomenon was noticed that the octahedral RhCl5(H2O)2− anions with inner-coordinated water molecules were preferentially recognized by 18C6 macrocyclic molecule. However, the planar quadrilateral Pd (II) chloric-complexing anions with a hydration configuration via water molecules attacking the central Pd (II) atoms along the Z-axis direction can be separated subsequently. The Pt (IV) and Fe (III) chloric-complexing anions respectively with an octahedral and tetrahedral outer-coordinated hydration shell configuration were the last to be recognized. Such an order in extracting Rh (III) > Pd (II) > Pt (IV) > Fe (III) anions depends on their hydration capacity and the preferential affinity towards the interface, which is almost impossible during the conventional stirring and oil droplet dispersed extraction. Because of a lower concentration of dissociated hydrogen ions on the surface of concentrated hydrochloric acid compared to its bulk concentrations, the hydration of those chloric-complexing anions was enhanced. The Rh (III) anions with inner-coordinated water molecules exhibit a higher interfacial affinity than other anions. The water molecules entering the inner coordination layer of Rh (III) chloric-complexing anions, cooperating with its outer-coordinated hydration shell, act as a hydrogen bond “water bridge” to interact with 18C6 molecules, which makes it easier to feel the influence from the aqueous laminar shear flow under the thin-layer oil membrane, thereby driving the preferential recognition of easily hydrated Rh (III) anions at the interface. The controllable “water bridge” interactions driven by shear flow can be activated or deactivated on the surface of concentrated hydrochloric acid by adjusting the shear flow rate. This work lays a foundation for the future development of a controllable flexible molecular recognition technology at liquid–liquid interfaces.

Structural and biological studies of mononuclear metal (II) complexes containing hetero ligand based on 3‐acetylpyridine thiosemicarbazone

The Schiff base (3‐APT) was a bidentate ligand produced from the condensation between 3‐acetylpyridine and the amine group of thiosemicarbazide. Metal chelates were successfully obtained with formulas [Cu(3‐APT)2X]X, [Ni(3‐APT)2]X2.H2O and [Pd(3‐APT)X2] (where 3‐APT = 3‐acetylpyridine thiosemicarbazone and X = Cl−). The characterization was performed by various physicochemical tools. The studied (3‐APT) ligand had two donor sites through both azomethine nitrogen and thiocarbonyl sulfur. The characterization tools observed the presence of two different geometric shapes. The square planar structure in the case of both nickel (II) and palladium (II) chelates and the square pyramidal structure in the case of copper (II) complex. The characterization involved a 1HNMR study for the (3‐APT) ligand and its square planar Pd (II) and Ni (II) chelates. The density functional theory was used to structurally optimize the synthesized ligand and its chelates. The antibacterial activity was evaluated using different types of bacteria showing superior results. The breast (MCF‐7) cell line was selected to investigate the cytotoxic effect of formed compounds. The palladium (II) complex was the most cytotoxic effective compound with the least IC50 value. Further theoretical molecular docking study was performed to observe the active sites in the selected proteins during their interactions with our compounds.

Planar hot-electron photodetection with polarity-switchable photocurrents controlled by the working wavelength.

Hot-electron photodetection is attracting increasing interests. Based on internal photoemission mechanism, hot-electron photodetectors (HE PDs) convert incident photon energy into measurable photocurrent. To obtain polarity-switchable photocurrent, one often applies electric bias to reverse the hot-electron flow. However, the employment of bias reduces the device flexibility and increasing the bias voltage degrades the detectivity of the device. Herein, we design a planar HE PD with the polarity-switchable photocurrent controlled by the working wavelength. Optical simulations show that the device exhibits two absorption peaks due to the resonances of two Tamm plasmons (TPs). Electrical calculations predict two corresponding TP-assisted responsivity peaks, but with opposite photocurrent polarities, which are determined by the hot-electron flows with opposite directions. We find that the hot-electron flows are closely related with the population differences of TP-induced hot electrons in two electrodes. We further demonstrate that the photocurrent polarity of the HE PD can be switched by altering working wavelength from one TP wavelength to the other. We believe that this approach paves a route to achieve flexible hot-electron photodetection for extensive applications.

Pd(II)-complexes of telluro-substituted Schiff base ligands: Effect of the pendant alkyl group on Suzuki and Heck coupling through in situ generated palladium nanoparticles

Two telluro-substituted Schiff bases L1/L2 having different pendant carbon chains (−Me in L1 and − C10H21 in L2) and their corresponding square planar Pd(II)-complexes (1/2) have been synthesized and their structural characterization has been carried out using multinuclear NMR and elemental analysis. The ligand L2 showed a Smectic liquid crystalline phase and melts at 81 °C into isotropic liquid whereas L1 and complexes (1/2) did not show any liquid crystalline property. The square planar Pd(II)-complexes (1/2) have been formed through the coordination of ligands (L1/L2) respectively in mono-anionic tridentate mode (Te,N,O−) and the fourth coordination sphere at the palladium center is occupied with chloride ion. Both complexes 1/2 (1 to 2 mol%) have beenexamined as a catalyst for Suzuki and Heck coupling reactions and their activity depends significantly on the length pendant alkyl chain. The results obtained from Hg-/PPh3-poisoning and three phase test on Suzuki-Miyaura coupling indicate the participation of both homogeneous as well as heterogeneous palladium species protected with the ligand or its fragment.

Fabrication of Hierarchical, Porous, Bimetallic, Zeolitic Imidazolate Frameworks with the Incorporation of Square Planar Pd and Its Catalytic Application.

Bimetallic zeolitic imidazolate frameworks (ZIFs) containing two different metal ions can exhibit superior performances when applied in heterogeneous catalysis. Herein, we present a facile one-pot synthesis method for PdCo-ZIFs with various Pd/Co ratios, where Pd(II) ions are successfully incorporated into the Co node sites of the ZIF structure. The local structure of the bimetallic ZIFs was comprehensively investigated by pore-structure, X-ray absorption fine structure, and in situ CO adsorption Fourier transform infrared analyses. The results demonstrated that the framework comprises different coordination geometries of Co (tetrahedral) and Pd (square planar) ions connected by the benzimidazolate ligand. Notably, the inherently nonporous, 2D Co-ZIF structure was transformed into a hierarchical porous structure, and the PdCo-ZIFs exhibited a significantly increased concentration of defects and distorted Co sites. Based on these results, the catalytic performances of the synthesized ZIFs in the cycloaddition of CO2 to epoxides were evaluated under a cocatalyst and solvent-free conditions. The PdCo-ZIFs exhibited significantly higher catalytic activity (maximum turnover frequency, TOF = 2501 h-1) than Co-ZIF (TOF = 65 h-1) and Pd-ZIF (no activity), which revealed that the undercoordinated Co sites with distorted structure are the active sites rather than the incorporated Pd ions. This study provides a facile one-pot method for synthesizing bimetallic ZIFs with mixed-coordination modes, hierarchical porous structures, and modified defect concentrations, which would expand the library of structurally diverse bimetallic ZIFs toward various applications.

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.

Hydrogen bond-directed coordination of phosphine-amino-alcohol (P,N,OH) ligands: Stereochemical considerations and catalytic studies

Novel phosphine-aminoalcohol type chiral ligands of the chemical formula Ph2PCH(CH3)CH2CH(CH3)NHCH(R)CH2OH (1a: (R,R)-(S), R = CH3, 1b: (S,S)-(S), R = CH3, 1c: (S,S), R = H) have been synthesized in two simple steps using cyclic sulfates. The coordination behavior of 1a-c having stereochemically labile nitrogen donor to square planar Pd(II) center was investigated by X-ray crystallography, 1D and 2D NMR methods and by DFT calculations. In the solid state of complex [Pd(1a)Cl2] an intramolecular hydrogen bond could be observed between the OH-moiety and one of the Cl co-ligands, while intermolecular hydrogen bonds were detected in the case of [Pd(1b)Cl2] between the same functionalities. In the dichloromethane solution of the complexes the hydrogen bond was identified as a crucial factor in determining ring conformation and nitrogen configuration. Ligand 1a coordinated stereoselectively to the metal in [Pd(1a)Cl2] leading to a complex having a single conformationally rigid six-membered chelate and a configurationally fixed N-donor. In contrast, coordination of ligands 1b-c resulted in the formation of a mixture of isomers with different chelate conformation and nitrogen configuration. The ligands were utilized in Pd-catalyzed asymmetric allylic alkylation where high enantioselectivities (ees up to 96 %) and activities could be obtained.

Direct Enantioselective Addition of Alkynes to Imines by a Highly Efficient Palladacycle Catalyst.

Enantiopure propargylic amines are highly valuable synthetic building blocks. Much effort has been devoted to develop methods for their preparation. The arguably most important strategy is the 1,2‐addition of alkynes to imines. Despite remarkable progress, the known methods using Zn and Cu catalysts suffer from the need for high catalyst loadings, typically ranging from 2–60 mol % for neutral aldimine substrates. Here we report a planar chiral Pd complex acting as very efficient catalyst for direct asymmetric alkyne additions to imines, requiring very low catalyst loadings. Turnover numbers of up to 8700 were accomplished. Our investigation suggests that a Pd‐acetylide complex is generated as a catalytically relevant intermediate by the aid of an acac ligand acting as internal catalytic base. It is shown that the catalyst is quite stable under the reaction conditions and that product inhibition is not an issue. A total of 39 examples is shown which all yielded almost enantiopure products.

Direkte enantioselektive Addition von Alkinen an Imine unter Verwendung eines hocheffizienten Palladacyclus als Katalysator

AbstractEnantiomerenreine Propargylamine sind sehr wertvolle Synthesebausteine. Große Anstrengungen wurden bereits unternommen, um Verfahren zu ihrer Herstellung zu entwickeln. Als vermutlich wichtigste Synthesestrategie ist die 1,2‐Addition von Alkinen an Imine zu nennen. Trotz aussichtsreicher Fortschritte sind für die bekannten Verfahren unter Verwendung von Zn‐ und Cu‐Katalysatoren hohe Katalysatorladungen, die typischerweise im Bereich von 2–60 mol % für neutrale Aldiminsubstrate liegen, notwendig. Wir entwickelten einen planar‐chiralen Pd‐Komplex, welcher als hocheffizienter Katalysator für die direkte asymmetrische Alkin‐Addition an Imine dient und sehr geringe Katalysatorladungen ermöglicht. Umsatzzahlen von bis zu 8700 wurden erreicht. Unsere Untersuchungen legen nahe, dass mit Hilfe eines acac‐Liganden, der als interne katalytische Base fungiert, ein Pd‐Acetylid‐Komplex als katalytisch relevantes Intermediat erzeugt wird. Weiterhin konnten wir zeigen, dass der Katalysator unter den Reaktionsbedingungen weitgehend stabil ist und keine Produktinhibierung auftritt. Insgesamt sind 39 Beispiele aufgeführt, die alle nahezu enantiomerenreine Produkte ergaben.

Tuning the location of Pd on HY zeolite by a dual-solvent method for efficient deep hydrogenation saturation of naphthalene

Tuning the location of metal on the support is of great importance for catalyst performance optimization, which is hardly realized by the traditional impregnation method. Herein, a dual-solvent method using dichloromethane and water has been developed for the preparation of Pd/HY catalysts via evaporation-induced aggregation of Pd(OAc)2. The state and location of Pd nanoparticles on HY can be effectively tuned by the water content in the dual-solvent system. Due to the filling of partial micropore channels by certain amount of water, hydrophobic Pd(OAc)2 is selectively deposited on the un-occupied surface of HY, which is verified by the changes in textural and acid properties of the Pd/HY catalysts. FT-IR spectra illustrate the reconstruction of tridimensional Pd3(CH3COO)6 trimer in solution to the planar bidentate Pd(II) acetate species on HY surface, which guarantees the stable loading of active Pd nanoparticles on HY. Pd nanoparticles selectively loaded around the junctions of micropores and mesopores of HY zeolite by moderate amount of water have been demonstrated to be highly active for the deep hydrogenation saturation of naphthalene. Due to the selective locating of Pd nanoparticles in the properly open space of HY, the B acid sites are well maintained and efficiently utilized for the enhanced anchoring of Pd nanoparticles and facilitated diffusion of the reactants. Therefore, the optimum Pd/HY catalyst possesses highly dispersed and electron-deficient Pd nanoparticles, and exhibited superior performance of hydrogenation saturation. The dual-solvent strategy can be applied to other zeolite systems to selectively loading of Pd nanoparticles for various catalytic applications.

Planar narrowband Tamm plasmon-based hot-electron photodetectors with double distributed Bragg reflectors

Hot-electron photodetectors (HE PDs) are attracting a great deal of attention from plasmonic community. Many efficient HE PDs with various plasmonic nanostructures have been demonstrated, but their preparations usually rely on complicated and costly fabrication techniques. Planar HE PDs are viewed as potential candidates of cost-effective and large-area applications, but they likely fail in the simultaneous achievement of outstanding optical absorption and hot-electron collection. To reconcile the contradiction between optical and electrical requirements, herein, we propose a planar HE PD based on optical Tamm plasmons (TPs) consisted of an ultrathin gold film (10 nm) sandwiched between two distributed Bragg reflectors (DBRs). Simulated results show that strong optical absorption (>0.95) in the ultrathin Au film is realized. Electrical calculations show that the predicted peak photo-responsivity of proposed HE PD with double DBRs is over two times larger than that of conventional single-DBR HE PD. Moreover, the planar dual-DBR HE PDs exhibit a narrowband photodetection functionality and sustained performance under oblique incidences. The optical nature associated with TP resonance is elaborated.

Luminescent Pd(II) Complexes with Tridentate − Aryl‐pyridine‐(benzo)thiazole Ligands

AbstractCyclometalated Pd(II) complexes generally show inferior luminescence properties compared with their Pt(II) analogues. The established approach employing tridentate cyclometalating ligands has allowed us to create a series of square planar Pd(II) complexes [Pd( )X] from their protoligands H (2‐(6‐phenylpyridin‐2‐yl)thiazoles and ‐benzothiazoles; coligands X=Cl, Br, I) with extensive variations at the Carene group (phenyl, naphthyl, fluorenyl), the central Npyridine (pyridine, 4‐phenylpyridine, 3,5‐di‐tert‐butyl‐4‐phenylpyridine), and the peripheral Nthiazole (thiazole, benzothiazole) to probe for structural factors that might enhance efficient luminescence. Long‐wavelength bands at 400–500 nm were assigned to transitions into mixed ligand‐centred/metal‐to‐ligand charge transfer (MLCT) states based on time‐dependent (TD)DFT calculations. The MLCT contributions are rather low, in agreement with relatively long lifetimes and high photoluminescence quantum yields of up to 0.79 recorded in frozen glassy solvent matrices at 77 K along with emission bands showing pronounced vibrational progressions and peaking at about 520 nm. No photoluminescence was observed at 298 K in solution. Variation of the ligand allowed to shift the experimental absorption energies from about 2.4 to 2.7 eV, in good agreement with the electrochemical band gaps (2.58 to 2.81 eV). The theoretical absorption and emission spectra excellently reproduced the experimental trends.

Crystal structures of 9-[bis-(benzyl-sulfan-yl)meth-yl]anthracene and of cyclo-dodeca-kis-(μ2-phenyl-methane-thiol-ato-κ2 S:S)hexa-palladium(6 Pd-Pd)-anthracene-9,10-dione (1/1).

The first title compound, C29H24S2, L1, represents an example of an anthracene-based functionalized di-thio-ether, which may be useful as a potential chelating or terminal ligand for coordination chemistry. This di-thio-acetal L1 crystallizes in the monoclinic space group P21/c. The phenyl rings of the benzyl groups and that of the anthracene unit form dihedral angles of 49.21 (4) and 58.79 (5)° and the crystal structure displays short C-H⋯π contacts. Surprisingly, when attempting to coordinate L1 to [PdCl2(PhCN)2], instead of the targeted chelate complex [PdCl2(κ2-L1)], a cleavage reaction leads to the formation of the centrosymmetric hexa-nuclear cyclic cluster of composition [Pd6(μ2-SCH2Ph)12] Pd6, or [Pd6(C7H7S)12]·C14H8O2. This tiara-shaped hexa-mer crystallizing in the triclinic space group P consists of six approximately square planar Pd(II)S4 centers, which are inter-connected through twelve μ2-bridging benzyl thiol-ate groups. The Pd⋯Pd contacts range from 3.0892 (2) to 3.1609 (2) Å and can be considered as weakly bonding. The unit cell of Pd6 contains also a co-crystallized anthracene-9,10-dione mol-ecule.

Carbazolyl-bis(triazole) and Carbazolyl-bis(tetrazole) Complexes of Palladium(II) and Platinum(II)

The synthesis of several carbazole-bis(triazole) (CzTrR ) and carbazole-bis(tetrazole) (CzTR ) ligands (5a–d and 6a–d, respectively, where R=Me (a), i –Pr (b), Bz (c) and CH2-2,4,6-C6H2Me3 (d)) is reported. Reaction of these ligands with PdCl2 in refluxing acetonitrile affords the complete series of square planar complexes, Pd(CzTrR)Cl (7a–d) and Pd(CzTR)Cl (8a–d). The analogous platinum complexes are prepared by deprotonation of ligand carbazole nitrogen under nitrogen followed by reaction with Pt(COD)Cl2 to give Pt(CzTrR)Cl (9b, 9d) and Pt(CzTR)Cl (10b, 10d). The X-ray structure of several ligands (5b, 5c, 6c) and their metal complexes (8b, 8d, 9b) are reported. Complexes 7–10d were examined by cyclic voltammetry and DFT calculations to shed light on their electronic structures. The Pd and Pt complexes of the same ligand (CzTr: 7d, 9d; CzT: 8d, 10d) showed very similar oxidation potentials suggesting the lowest oxidation is ligand based. In contrast, oxidations of the tetrazole complexes 7d and 9d were notably more difficult than the triazole complexes 8d and 10d. Both of these observations are supported by DFT calculations that indicate the HOMO is essentially carbazole π-bonding in character.

Synthesis, Study, and Application of Pd(II) Hydrazone Complexes as the Emissive Components of Single-Layer Light-Emitting Electrochemical Cells.

For the first time, square planar Pd(II) complexes of hydrazone ligands have been investigated as the emissive components of light-emitting electrochemical cells (LECs). The neutral transition metal complex, [Pd(L1)2]·2CH3OH (1), (HL1 = (E)-N'-(phenyl(pyridin-2-yl)methylene)isonicotinhydrazide), was prepared and structurally characterized. Complex 1 displays quasireversible redox properties and is emissive at room temperature in solution with a λmax of 590 nm. As a result, it was subsequently employed as the emissive material of a single-layer LEC with configuration FTO/1/Ga/In, where studies reveal that it has a yellow color with CIE(x, y) = (0.33, 0.55), a luminance of 134 cd cm-2, and a turn-on voltage of 3.5 V. Protonation of the pendant pyridine nitrogen atoms of L1 afforded a second ionic complex [Pd(L1H)2](ClO4)2 (2) which is also emissive at room temperature with a λmax of 611 nm, resulting in an orange LEC with CIE(x, y) = (0.43, 0.53). The presence of mobile anions and cations in the second inorganic transition metal complex resulted in more efficient charge injection and transport which significantly improved the luminance and turn-on voltage of the device to 188.6 cd cm-2 and 3 V, respectively. This study establishes Pd(II) hydrazone complexes as a new class of materials whose emissive properties can be chemically tuned and provides proof-of-concept for their use in LECs, opening up exciting new avenues for potential applications in the field of solid state lighting.

Selective Mesitylene Oxidative Coupling Reaction by Metastructured Electrocatalyst Comprised of Carbonaceous Scaffold Coated with Pd Derived from Zeolitic Imidazole Framework

Electrocatalysis plays a vital role in industrial processes like electrohydrodimerization of acrylonitrile, anodic substitution and addition, electrolytic oxidative/reductive coupling and electrolysis of heterocyclic compounds. Electrocatalysts with suitable size and shape selectivity for reactants, reactant intermediates and products increase their selectivity. Zeolites are the most common vehicles for size-/shape-selective heterogeneous catalysts, but their lack of electronic conductivity vitiates their use in electrocatalysis. In this context, we explore the effectiveness of carbon derived from the zeolitic imidazole framework (ZIF), which possesses both electronic conductivity and structural selectivity for electrocatalytic oxidative coupling of mesitylene to bimesityl. Co-ZIF synthesized by facile solvothermal method was heated in an inert atmosphere and acid-leached to remove Co in order to generate C-based structured material. Further, Pd acting as a catalyst was deposited inside the pore walls of the obtained C scaffold by electroless deposition to derive pore sizes ranging between the molecular size of the particular product. Controlling the pore size of metastructured electrocatalyst at ~ 16 A allows only bimesityl formation, and restricts any larger sized by-product. Metastructured electrocatalyst showed ~ 18 times higher selective conversion for the desired bimesityl production than the planar Pd film electrocatalyst, demonstrating the potential of the proposed approach.

Low-dimensional compounds containing bioactive ligands. Part XIII: Square planar anti-cancer Pd(II) complexes with halogenderivatives of 8-quinolinol and dimethylamine

Four new Pd(II) complexes with halogenderivatives of 8-quinolinol (HXQ) were prepared: [PdCl(NH(CH3)2)(CQ)] (1), [PdCl(NH(CH3)2)(dClQ)] (2), [PdCl(NH(CH3)2)(dBrQ)] (3) and [PdCl(NH(CH3)2)(BrQ)] (4), where HCQ is 5-chloro-7-iodo-8-quinolinol, HdClQ is 5,7-dichloro-8-quinolinol, HdBrQ is 5,7-dibromo-8-quinolinol and HBrQ is 7-bromo-8-quinolinol. The infrared spectroscopy confirmed the presence of XQ moiety in all complexes as well as dimethylamine ligands resulting from the decomposition of DMF used as solvent. Subsequent X-ray structural analysis confirmed that XQ ligands are chelate bind to Pd(II) atom through oxygen and nitrogen atoms, the dimethylamine molecules are attached via nitrogen atom, wherein the nitrogen atoms of XQ and of dimethylamine are in trans-positions. The fourth coordination place is occupied by chloride ligand, suggesting a square planar configuration of the central Pd(II) atom. The structures are stabilized by both H-bonds and π-π interactions while observing the formation of 2D or 3D structures. 1H and 13C NMR spectra of 1–4 confirmed their stability in dimethylsulfoxide. The radical scavenging experiments revealed relatively low antioxidant properties with 1 being the most potent antioxidant among prepared complexes. In vitro antiproliferative properties of the newly prepared complexes were studied on adenocarcinomic human alveolar basal epithelial cells A549, human colon cancer cell line HCT116, human breast cancer cell line MDA-MB-231 and their selectivity was studied on non-cancerous mouse mesenchymal stem cells MSCs. All the prepared complexes were toxic to the tumor cells and the higher cytotoxicity was induced by complex 1 against A549 cells at very low concentrations which would provide new potential antitumor drug that deserves much more attention in lung cancer research.

Palladium (II) Complexes Containing 2-Phenylpyridine Derivatives: Synthesis, Molecular Structures, and Catalytic Activity for Suzuki–Miyaura Cross-Coupling Reactions

The preparation and characterization of a series of new 2-phenylpyridine derivative ligands consisting of 2-(R) pyridine (R = mesityl (L1), 2,6-dimethylphenyl (L2), o-tolyl (L3), m-tolyl (L4), p-tolyl (L5), o-methoxyphenyl (L6), and p-methoxyphenyl (L7)) and their Pd complexes [PdCl2L2] (L1–L7) is investigated using a combination of X-ray diffraction spectroscopy, GC-MS, and NMR. The crystal structures show that the Pd complexes adopt a square planar geometry, and the monodentate ligand is coordinated through the N donor of the pyridine ring to the Pd atom. The catalytic activities of the synthesized complexes are investigated. The square planar Pd complex trans-[(2-mesitylpy)2PdCl2)] shows a high efficiency in promoting Suzuki-Miyaura cross coupling in an aqueous solvent under aerobic conditions.

Anti‐hepatocellular carcinoma, antioxidant, anti‐inflammation and antimicrobial investigation of some novel first and second transition metal complexes

New coordination compounds of some selected metal ions from the first and second transition metals series with a Schiff base were synthesized and characterized. The Schiff base is derived from 4‐Aminoantipyrine and 3‐(hydroxyimino) butan‐2‐one. The compounds were characterized by different analysis tools like; elemental analysis, mass spectra, Fourier transform infrared (FTIR) as well as electronic spectra, magnetic measurements, molar conductance and thermal analysis technique. All complexes were formed with 1:1 (metal: ligand) stoichiometry except Mn (II) where 1:2 (Mn: ligand) is formed. Schiff base ligand interacted as a tridentate ligand by using the nitrogen atoms of the imine and the oximato groups and the carbonyl oxygen atom as donor groups with all studied metal ions except copper (II) and manganese (II) where the carbonyl oxygen is not shared in the coordination. These complexes show various physicochemical properties. X‐ray powder diffraction shows different crystal systems; Cd (II) complex: hexagonal, Cu (II) complex: orthorhombic; and [Ni (II), Mn (II), Rh (III) & Pd (II)] complexes: monoclinic.All compounds showed potent cytotoxicity against the growth of human liver cancer cell lines. The square planar Pd (II) complex was more active than those of octahedral geometries of all other synthesized complexes. Cd (II) complex has the highest microbial growth inhibition than the rest of the prepared complexes. The docking active sites interactions were evaluated using the selected proteins EGFR tyrosine kinase and protein crystal structure of GlcN‐O‐P synthase. in vitro antioxidant assay revealed potent free radical scavenging activity of the three synthesized Cu (II), Pd (II) and Rh (III) complexes that exceeded the standard ascorbic acid. Pd (II) complex shows the most significant inhibition denaturation percent.

Heteroleptic palladium(II) complexes of dipyrrin-1,9-dione supported by intramolecular hydrogen bonding

The dipyrrin-1,9-dione framework, which is characteristic of the propentdyopent pigments deriving from heme metabolism, coordinates metal ions as monoanionic bidentate donors. The resulting analogs of dipyrrinato complexes undergo reversible ligand-based reductions, thus showcasing the ability of the dipyrrindione scaffold to act as an electron reservoir. Herein we report the synthesis and characterization of three heteroleptic palladium complexes of the redox-active dipyrrindione ligand. Primary amines were chosen as additional ligands so as to assemble complexes of planar geometries with complementary interligand hydrogen-bonding. Full chemical characterization confirms the hydrogen bonding interactions between the primary amine ligands and the acceptor carbonyl groups on the dipyrrolic ligand. The resulting heteroleptic compounds display reversible one-electron reduction events that are centered on the dipyrrindione ligand as revealed by voltammetry and spectroelectrochemistry data. Within these planar Pd(II) complexes, the propentdyopent motif therefore combines reversible ligand-based redox chemistry with interligand hydrogen bonding in the primary coordination sphere of the metal center.