Reduction of nitroaromatics with poly(vinylpyridine) complexes of palladium(II) and platinum(II)

Palladium(II) and platinum(II) anchored to 2- and 4-vinylpyridine polymers of different molecular weights were used for the dihydrogen reduction of various nitroaromatics and benzaldehyde in ethanol at 50°C. Palladium(II) complexes were far more effective than their platinum(II) analogues and the activity decreased with increasing molecular weights of the polymers. The nitroaromatics were selectively and almost completely reduced to the corresponding anilines. During reduction, the orange palladium(II) complexes changed to voluminous green precipitates, which could be used repeatedly and preserved for a long time without any loss of activity. A rate equation of the type: rate = K[Cat] [H₂] has been derived and a reduction mechanism has been proposed on the basis of experimental results and kinetic data.     

Reactions with Proteins of Three Novel Anticancer Platinum(II) Complexes Bearing N-Heterocyclic Ligands

Three novel platinum(II) complexes bearing N-heterocyclic ligands, i.e., Pt2c, Pt-IV and Pt-VIII, were previously prepared and characterized. They manifested promising in vitro anticancer properties associated with non-conventional modes of action. To gain further mechanistic insight, we have explored here the reactions of these Pt compounds with a few model proteins, i.e., hen egg white lysozyme (HEWL), bovine pancreatic ribonuclease (RNase A), horse heart cytochrome c (Cyt-c) and human serum albumin (HSA), primarily through ESI MS analysis. Characteristic and variegate patterns of reactivity were highlighted in the various cases that appear to depend both on the nature of the Pt complex and of the interacting protein. The protein-bound Pt fragments were identified. In the case of the complex Pt2c, the adducts formed upon reaction with HEWL and RNase A were further characterized by solving the respective crystal structures: this allowed us to determine the exact location of the various Pt binding sites. The implications of the obtained results are discussed in relation to the possible mechanisms of action of these innovative anticancer Pt complexes.     

Methods for correction of selectivity of N-(2-sulfoethyl)chitosan-based materials towards platinum(IV) and palladium(II) ions

In this paper, we report methods for correction of selectivity of sorbents based on N-(2-sulfoethyl)chitosan towards platinum(IV) and palladium(II) in HCl solutions. The common method for correction of selectivity of the sorbents is variation of their modification degree with complexing groups. An increase in the degree of sulfoethylation of the chitosan leads to the significant increase in selectivity of sorption of palladium(II) over platinum(IV). Application of the N-(2-sulfoethyl)chitosan with the highest degree of sulfoethylation allows for selective separation palladium(II) from platinum(IV) (рН = 5.0). Palladium is quantitatively desorbed from the surface of the N-(2-sulfoethyl)chitosans by 3.5 mol/dm³ solution of HCl.     

Preparation of ordered macroporous platinum and palladium powders

Ordered macroporous platinum and palladium metal powders were prepared with a combination of silica template and hydrogen reduction methods. The effects of species of metal precursor and calcination of silica templates on the structure of final metal powders were investigated. Precursor of platinum or palladium was infiltrated into closely packed silica templates prepared from tetraethyl orthosilicate and vacuum dried at room temperature following hydrogen reduction to obtain metal–silica complexes. After the removal of the silica templates from the complexes by hydrofluoric acid treatment, metal powders were obtained. Ordered macroporous platinum and palladium powders were obtained by using hydrogen hexachloroplatinate (IV) hexahydrate with uncalcined silica template and palladium (II) chloride with calcined templates, respectively. Composition analyses indicated that silica templates were completely removed from the ordered metal powder. Sizes of the voids in the ordered macroporous metal powders were controlled in the range of 240–520 nm corresponding to those of the silica spheres used.     

Determination of cobalt(II), nickel(II) and palladium(II) Ions via fabric phase sorptive extraction in combination with high-performance liquid chromatography-UV detection

A method for the determination of Co(II), Ni(II) and Pd(II) in aqueous samples by fabric phase sorptive extraction-high-performance liquid chromatography-UV detection (FPSE-HPLC-UV) is developed. A preconcentration step was necessary due to the trace level concentrations of these elements in aqueous samples. Sol-gel polytetrahydrofuran nanocomposite was selected as the sorbent. All major FPSE parameters were optimized. The limit of detection for Co(II), Ni(II) and Pd(II) morpholino dithiocarbamate complexes were found at much lower concentration level compared with earlier reported data with excellent reproducibility. The new FPSE-HPLC-UV method can be used for routine determination of these metal species in various aqueous environmental samples and in different alloys.     

Vinyl polymerization of norbornene with bis(imino)pyridyl nickel(II) complexes

A series of different steric hindrance nickel(II) complexes 1 – 6 bearing 2,6‐bis(imino)pyridine ligands have been synthesized and characterized. The molecular structures of the complexes 3 – 5 were determined by X‐ray diffraction analysis. The coordination geometry around the nickel center of the complexes is either square pyramid for complexes 3 and 4 or trigonal bipyramid for complex 5 . All of the nickel complexes exhibit high catalytic activity for norbornene polymerization in the presence of MAO, although low activity for ethylene oligomerization and polymerization. The effects of the Al/Ni ratio, halogen, monomer concentration, temperature, and reaction time on activity of catalyst for norbornene polymerization and polymer microstructure were investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of tridentate phenoxy‐imine ligand [N,N,O] nickel(II) and palladium(II) complexes and their catalytic behaviors in vinyl polymerization of norbornene

In this study, new complexes LNiCl( 1 ), LNiBr( 2 ), LNiI( 3 ), and LPdCl( 4 ) (L = 4,6‐di‐tert‐butyl‐2‐(N‐(quinolin‐8‐yl)iminomethyl)phenolato) have been synthesized and characterized. X‐ray diffraction studies on Complexes 1 and 4 revealed that N, N, O, and halogen atoms coordinated to metal, with a nearly square planar geometries in all cases. All these complexes are robust and exhibit high activities for the addition polymerization of norbornene (NB) with methylaluminoxane as cocatalyst [up to 47.62 kg PNB(mmol of Ni)^?1h^?1] and also lead to various activities and molecular weights of polynorbornenes under different reaction conditions. It is noteworthy that Complexes 1 and 4 show better activity under higher reaction temperature of 80°C. However, Complex 2 showed lower activity, and Complex 3 was found nearly inert toward NB polymerization, probably, because of thermal instability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Transition metal complexes with Girard reagent-based ligands, Part I: Synthesis and crystal structure of the first cobalt(III) complexes with Schiff base derivative of Girard reagent

A new ligand, pyridoxilidene Girard-T hydrazone, [H₃L]Cl₂ · 2H₂O, and its octahedral cobalt(III) complexes [Co(HL)(NO₂)₃] · H₂O (1) and [Co(HL)₂](PF₆)₃ (2) were synthesized. The X-ray analysis of (1) showed that the complex has a mer-octahedral configuration formed by coordination of the tridentate ONO neutral Schiff-base molecule and three monodentate N-bonded NO₂ groups. Hydrogen bonds and intermolecular interactions for this complex are discussed. Complex (2) also has a mer-octahedral configuration. The ligand and complexes were characterized by elemental analysis, conductometric and magnetochemical measurements, IR and UV–Visible, ¹H and ¹³C NMR spectra.     

Effect of Substitution of [Pd(PPh3)4] by Related Compounds as Catalysts in Reactions of Organic Syntheses

The effect of substitution of [Pd(PPh₃)₄], which is unstable in air, by complexes of the type [MCl₂L₂] (M = Pd, Pt; L = AsPh₃, SbPh₃), [PdL₄](L = PPh₃, AsPh₃, SbPh₃) and [NiX₂(PPh₃)₂] on the syntheses of thioethers, acetylenes and ketones is described.     

Synthesis, in vitro cytotoxicity, and interaction with DNA of platinum(II) complexes with N-monocycloalkyl derivatives of 1R,2R-diaminocyclohexane as carrier ligands

A series of platinum(II) complexes with N-monocyclopentyl/cyclohexyl derivatives of 1R,2R-diaminocyclohexane as carrier ligands and dicarboxylate anions as leaving groups were synthesized and characterized. All complexes were characterized by elemental analysis, IR, (1)H NMR, and (13)C NMR spectroscopy, as well as ESIMS. The in vitro antiproliferative activities were tested by MTT assay against four human cancer cell lines; breast carcinoma (MCF-7) and colon cancer (HCT-116) cells were particularly sensitive, especially to complexes 1f (IC(50) =9.81 and 1.49 μM) and 2f (IC(50) =4.59 and 0.36 μM). Flow cytometry indicated that representative compounds exert cytotoxicity toward MCF-7 and HCT-116 cells through induction of apoptosis and blockage of cell-cycle progression in the S phase, similar to cisplatin. The interaction between the platinum(II) complexes and pET22b plasmid DNA was observed by agarose gel electrophoresis, revealing that complex 2f has the capacity to distort plasmid DNA in a manner distinct from that of oxaliplatin.     

Polymerization of methyl methacrylate catalyzed by mono-/bis-salicylaldiminato nickel(II) complexes and methylaluminoxane

Two types of salicylaldiminato-based nickel complexes, mono-ligated Ni(II) complexes ([O-C₆H₄-o- C(H)=N-Ar]Ni(PPh₃)(Ph) (5), [O-(3,5-Br₂)C₆H₂-o-C(H)=N-Ar]Ni(PPh₃)(Ph) (6), [O-(3-t-Bu)C₆H₃-o-C(H)=N-Ar]Ni(PPh₃)(Ph) (7)) and bis-ligated Ni(II) complexes ([O-(3,5-Br₂)C₆H₂-o-C(H)=N-Ar]₂Ni (8), [O-(3,5-Br₂)C₆H₂-o-C(H)=N-2-C₆H₄(PhO)]₂Ni (9), Ar=2,6-C₆H₃(i-Pr)₂) were synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), mass spectrography (MS) and elemental analysis (EA). In the presence of methylaluminoxane (MAO) as cocatalyst, all the nickel complexes exhibited high activities for the polymerization of methyl methacrylate (MMA) and syndiotactic-rich poly(methyl methacrylate) (PMMA) was obtained. The complexes with less bulky substituents on salicylaldiminato framework possessed higher activities, while with the same salicylaldiminato, the mono-ligated nickel complexes showed higher catalytic activity than bis-ligated ones.     

Enantioselective hydroformylation of olefins catalyzed by rhodium(I) complexes of chiral phosphine–phosphite ligands

Using Rh(I) complexes of chiral phosphine–phosphites, hydroformylation of such a variety of olefins as aryl–substituted, alkyl–substituted, and heteroatom–substituted ones proceeded in high enantioselectivity. A trigonal bipyramidal RhH(CO)₂(phosphine–phosphite) complex is suggested as the active species, in which the hydride and the phosphite moiety are located at the apical positions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Polymers containing metal chelate units. I. Immobilized mono- and binuclear chelates of nickel(II) and cobalt(II)

A number of polymer carriers with chelating groups such as diketones, diacylamines, and enaminoketones has been synthesized. The immobilized mono- and binuclear chelates have been prepared by the interaction of these polymeric ligands with nickel(II) and cobalt(II) acetates in alcohol. Spectral and magnetic data confirm the tetrahedral structure of the cobalt complexes and octahedral structure of the nickel complexes. The catalytic properties of the immobilized complexes in ethylene dimerization and butadiene polymerization have been investigated.     

Dinuclear alkylamine platinum(II) complexes of [1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II): influence of endocytosis and copper and organic cation transport systems on cellular uptake

Various possible pathways for the uptake of cationic alkylamine platinum(II) complexes into the MCF-7 breast cancer cells were studied with di[meso-1,2-bis(4-fluorophenyl)ethylenediamine]di[sulfinylbis(methane)-S][mu-1,6-diaminohexaneN:N']diplatinum(II) disulfate (m-4F-PtDMSO-DAH) as an example. It was demonstrated that m-4F-PtDMSO-DAH competed neither for the copper transporter nor the organic cation transporters (OCT and OATP). Instead, adsorptive endocytosis by macropinocytosis played an essential role. Inhibitors of this processes such as amiloride, N-ethyl-N-isopropylamiloride (EIPA), wortmannin, and cytochalasin D decreased the intracellular uptake of m-4F-PtDMSO-DAH dramatically. These results support the understanding of the pharmacological behavior of this promising drug family, which showed no cross resistance with cisplatin.     

Piperazine Functionalized Resins for Au(III), Pt(IV), and Pd(II) Sorption

The result of synthesis of anion exchangers bearing piperazine functionalities is presented in this paper. A series of new ion exchange resins was synthesized by modification of VBC/DVB copolymer with 1(2-aminoethyl)piperazine (resin 1P), 1-amino-4-methylpiperazine (resin 2P), and 1-methylpiperazine (resin 3P). Adsorption studies of gold, platinum, and palladium were conducted with batch and dynamic method from multicomponent solutions containing AuCl₄^?, PtCl₆^2?, and PdCl₄^2? in the concentration range 10 mg/dm³ to 919 mg/dm³. The resins revealed excellent sorption ability towards these metals. The greatest total sorption capacities were determined as 331 mg/g Au for 2P resin, 405 mg/g Pt for 3P resin, and 150 mg/g Pd for 1P resin. The examined 3P resin showed the best total sorption capacity 796 mg/g. Affinity studies were also conducted. The examined resin 1P revealed the greatest affinity to platinum and palladium (lgK 4.5-5) whereas resin 2P revealed the best affinity to gold where lgK were ca. 4.9.     

Synthesis and cytotoxicity of enantiomerically pure [1,2-diamino-1-(4-fluorophenyl)-3-methylbutane]platinum(II) complexes

A series of leaving group derivatives of enantiomerically pure [1,2-diamino-1-(4-fluorophenyl)-3-methylbutane]platinum(II) complexes were synthesized and tested for cytotoxicity. The enantiomeric purity was determined by 1H NMR spectroscopy on the final diamines after derivation with (1R)-myrtenal. For coordination to platinum, the diamines were reacted with K2PtI4. The treatment of diiodoplatinum(II) complexes (4F-Ph/iProp-PtI2) with Ag2SO4 resulted in the sulfatoplatinum(II) complexes (4F-Ph/iProp-PtSO4), which can be easily transformed to dichloroplatinum(II) complexes (4F-Ph/iProp-PtCl2) with 2 n HCl. The importance of the leaving groups and the configuration at the diamine ligand on the antiproliferative effects was evaluated on the hormone-dependent MCF-7 and the hormone-independent MDA-MB 231 breast cancer cell lines as well as the LNCaP/FGC prostate cancer cell line. (R,R)-4F-Ph/iProp-PtCl2 was identified as the most active platinum(II) complex. The 3-methyl group increased antiproliferative effects relative to the [1,2-diamino-1-(4-fluorophenyl)butane]platinum(II) complexes described in an earlier study.     

Synthesis, structural characterization, and pro-apoptotic activity of 1-indanone thiosemicarbazone platinum(II) and palladium(II) complexes: potential as antileukemic agents

In the search for alternative chemotherapeutic strategies against leukemia, various 1‐indanone thiosemicarbazones, as well as eight novel platinum(II) and palladium(II) complexes, with the formula [MCl₂(HL)] and [M(HL)(L)]Cl, derived from two 1‐indanone thiosemicarbazones were synthesized and tested for antiproliferative activity against the human leukemia U937 cell line. The crystal structure of [Pt(HL1)(L1)]Cl^.2M eOH, where L1=1‐indanone thiosemicarbazone, was solved by X‐ray diffraction. Free thiosemicarbazone ligands showed no antiproliferative effect, but the corresponding platinum(II) and palladium(II) complexes inhibited cell proliferation and induced apoptosis. Platinum(II) complexes also displayed selective apoptotic activity in U937 cells but not in peripheral blood monocytes or the human hepatocellular carcinoma HepG2 cell line used to screen for potential hepatotoxicity. Present findings show that, in U937 cells, 1‐indanone thiosemicarbazones coordinated to palladium(II) were more cytotoxic than those complexed with platinum(II), although the latter were found to be more selective for leukemic cells suggesting that they are promising compounds with potential therapeutic application against hematological malignancies.     

The structures and decomposition products of palladium(II) and platinum(II) terpyridine phenoxide complexes

A series of complexes of formula [Pd(OR)(terpy)]BF₄ and [Pt(OR)(terpy)]BF₄ (ROH=a substituted phenol; terpy=2,2^′:6^′,2^″-terpyridine) have been prepared by reaction of [M(OH)(terpy)]BF₄ (M=Pd, Pt) with ROH. One Pd(II) and one Pt(II) complex in this series have been structurally characterised. These compounds are very acid sensitive; decomposition products resulting from recrystallisation of two of these compounds from MeNO₂ or MeCN have been crystallographically characterised.     

Synthesis, Characterization and Thermal Studies of Zn(II), Cd(II) and Hg(II) Complexes of N-Methyl-N-Phenyldithiocarbamate: The Single Crystal Structure of [(C(6)H(5))(CH(3))NCS(2)](4)Hg(2)

Zn(II), Cd(II) and Hg(II) complexes of N-methyl-N-phenyl dithiocarbamate have been synthesized and characterized by elemental analysis and spectral studies (IR, (1)H and (13)C-NMR). The single crystal X-ray structure of the mercury complex revealed that the complex contains a Hg centre with a distorted tetrahedral coordination sphere in which the dinuclear Hg complex resides on a crystallographic inversion centre and each Hg atom is coordinated to four S atoms from the dithiocarbamate moiety. One dithiocarbamate ligand acts as chelating ligand while the other acts as chelating bridging ligand between two Hg atoms, resulting in a dinuclear eight-member ring. The course of the thermal degradation of the complexes has been investigated using thermogravimetric and differential thermal analyses techniques. Thermogravimetric analysis of the complexes show a single weight loss to give MS (M = Zn, Cd, Hg) indicating that they might be useful as single source precursors for the synthesis of MS nanoparticles and thin films.     

2-甲基咪唑-4,5-二羧酸镍配合物的合成及其晶体结构

以配体2-甲基咪唑-4,5-二羧酸与氯化镍反应,合成出了一个新的配合物[Ni(HMIDC-)]2(H2O)2]n;采用单晶X射线衍射方法测定了配合物的晶体结构。结果表明,所合成的配合物属正交晶系,pbca空间群,晶胞参数a=0.683 74 nm,b=1.388 13 nm,c=1.655 19 nm,V=1 570.97 nm3,Z=4,Dc=1.831 g/cm3,F(000)=1 000.0,GOF=1.304。镍原子与两个不同配体H2MIDC中的咪唑上的氮原子、羧基氧原子以及水分子配位,且形成了六配位八面体构型。配合物由分子间氢键构筑成了三维超分子氢键网络结构。