- Palladium(II) complexes with highly basic imidazolin-2-imines and their reactivity toward small bio-molecules
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A series of novel Pd(ii) complexes with chelating mono(imidazolin-2-imine) and bis(imidazolin-2-imine) ligands were synthesized. The crystal structures of [Pd(DMEAImiPr)Cl2] and [Pd(DPENImiPr)Cl2] were determined by X-ray diffraction analysis. The reactivity of the six Pd(ii) complexes, namely, [Pd(en)Cl2], [Pd(EAImiPr)Cl2], [Pd(DMEAImiPr)Cl2], [Pd(DPENImiPr)Cl2], [Pd(BLiPr)Cl2] and [Pd(DACH(ImiPr)2)Cl2], were investigated. Spectrophotometric acid-base titrations were performed to determine the pKa values of the coordinated water molecules in [Pd(en)(H2O)2]2+, [Pd(EAImiPr)(H2O)2]2+, [Pd(DMEAImiPr)(H2O)2]2+, [Pd(DPENImiPr)(H2O)2]2+, [Pd(BLiPr)(H2O)2]2+ and [Pd(DACH(ImiPr)2)(H2O)2]2+. The substitution of the chloride ligands in these complexes by TU, l-Met, l-His and Gly was studied under pseudo-first-order conditions as a function of the nucleophile concentration and temperature using stopped-flow techniques; the sulfur-donor nucleophiles have shown better reactivity than nitrogen-donor nucleophiles. The obtained results indicate that there is a clear correlation between the nature of the imidazolin-2-imine ligands and the acid-base characteristics and reactivity of the resulting Pd(ii) complexes; the order of reactivity of the investigated Pd(ii) complexes is: [Pd(en)Cl2] > [Pd(EAImiPr)Cl2] > [Pd(DMEAImiPr)Cl2] > [Pd(DPENImiPr)Cl2] > [Pd(BLiPr)Cl2] > [Pd(DACH(ImiPr)2)Cl2]. The solubility measurements revealed good solubility of the studied imidazolin-2-imine complexes in water, despite the fact that these Pd(ii) complexes are neutral complexes. Based on the performed studies, three unusual features of the novel imidazolin-2-imine Pd(ii) complexes are observed, that is, good solubility in water, very low reactivity and high pKa values. The coordination geometries around the palladium atoms are distorted square-planar; the [Pd(DMEAImiPr)Cl2] complex displays Pd-N distances of 2.013(2) and 2.076(2) ?, while the [Pd(DPENImiPr)Cl2] complex displays similar Pd-N distances of 2.034(4) and 2.038(3) ?. The studied systems are of interest because little is known about the substitution behavior of imidazolin-2-imine Pd(ii) complexes with bio-molecules under physiological conditions.
- Bogojeski, Jovana,Volbeda, Jeroen,Freytag, Matthias,Tamm, Matthias,Bugar?i?, ?ivadin D.
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- Hydrolytic species of the ion cis-diaqua(ethylenediamine) palladium (II) complex and of cis-dichloro (ethylenediamine) palladium (II): Fitting its equilibrium models in aqueous media with or without chloride ion
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Thermodynamic data for equilibria involved in the overall hydrolytic process of the cis-[Pd(en) (H2O)2]2+ complex in the presence or absence of chloride ion are reported. All expected hydrolytic species are taken into account to calculate their formation constants and to fit the equilibrium model. The formation constants (log βpqr) of aqua and/or hydroxo complexes were obtained from E(H+) data of alkalimetric titrations of cis-[Pd(en)(H2O)2] (ClO4)2 solutions. The log βpqr values of chloro-containing complexes were obtained from E(H+) and E(Cl-) data pairs, taking into account the above log β data as fixed values. All formation constants were fitted by SUPERQUAD calculations: log βpqr for cis-aqua-hydroxo (pqr= 10-1, -6.68 (10)), di-μ-hydroxo (20-2, -7.758(4)), cis-dihydroxo (10-2, -14.523(4)), cis-dichloro (120, 5.24(1)), cis-chloro-aqua (110, 3.18(1)) and cis-chloro-hydroxo (11-1, -3.75(4)) species for I=0.15 mol dm-3 in NaClO4 and t=37°C. This constant set allows good simulation of experimental titration curves and is used to obtain a variety of species distribution diagrams.
- Tercero-Moreno,Matilla-Hernandez,Gonzalez-Garcia,Niclos-Gutierrez
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- The metal-binding sites of glycose phosphates
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In aqueous solution, the reducing sugar phosphates d-arabinose 5-phosphate, d-ribose 5-phosphate, d-fructose 1,6-bisphosphate, d-fructose 6-phosphate, d-glucose 6-phosphate and d-mannose 6-phosphate provide metal-binding sites at their glycose core on rea
- Gilg, Kathrin,Mayer, Tobias,Ghaschghaie, Natascha,Kluefers, Peter
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- Amine-bridged binuclear complexes involving [Pd(ethylenediamine)(H2O)2]2+, 4,4'-bipiperidine and DNA constituents
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The complex formation equilibria in the reaction of [Pd(en)(H2O)2]2+ with 4,4'-bipiperidine (Bip) and DNA constituents such as inosine, inosine-5'-monophosphate, uracil, uridine, thymine, and thymidine were investigated at
- Khalaf Alla, Perihan A.,Shoukry, Mohamed M.,Van Eldik, Rudi
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- Antimicrobial, antioxidant and DNA-binding studies of palladium(II) complexes with different chelate ligands containing nitrogen donor atoms
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The antimicrobial and antioxidant activities, as well as the DNA-binding of four square-planar Pd(II) complexes, [Pd(terpy)Cl]+ (C1), [Pd(en)Cl2] (C2), [Pd(DMEAImi Pr)Cl2] (C3) and [Pd(dach)Cl2] (C4) (terpy = 2,2′:6′,2′′--terpyridine, en = ethylenediamine, dach = trans-1,2-diaminocyclohexane and DMEAImi Pr = N2-((1,3-dihydro-1,3-diisopropyl-4,5-dimethyl)-2H-imidazol-2-ylidene)-N1,N1-dimethyl-1,2-ethanediamine are reported. The antimicrobial activities of the Pd(II) complexes with the appropriate ligands were tested using the microdilution method against 18 strains of microorganisms, whereby the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC) were determined. The antibiofilm activity of [Pd(terpy)Cl]+ and the corresponding ligand were determined on a formed biofilm. The intensity of antimicrobial activity varied depending on the type of microorganism and the tested compound. The C1 complex with the corresponding ligand demonstrated significantly greater overall antimicrobial activity than C2, C3 and C4. The antibacterial activity of the C1 complex was better than its antifungal activity that was overall greater than that of the positive control, fluconazole. The greatest sensitivity for C1 and L1 was with Penicillium italicum (MIC -1) among the fungi, and with Proteus mirabilis ATCC 12453 (MIC = 0.98 μg mL-1) among the tested bacteria. The tested compounds show low and moderate antibiofilm activity. The complexes showed weak antioxidant properties when tested using the DPPH (1,1-diphenyl-2--picrylhydrazyl) method. The interaction of the metal complexes C1–C4 with calf thymus DNA (CT-DNA) was further examined by absorption (UV–Vis) and emission spectral studies (EthBr displacement studies). Overall, the investigated complexes exhibited good DNA interaction ability.
- Rakovi?, Ivana R.,Radojevi?, Ivana D.,Mladenovi?, Katarina G.,Popovska Jovi?i?, Biljana D.,Petrovi?, Sara,?anovi?, Petar P.,?omi?, Ljiljana R.,?anovi?, Predrag S.,Bogojeski, Jovana V.
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p. 1229 - 1242
(2019/01/03)
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- A chiroptical molecular sensor for ferrocene
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A homochiral, square-shaped, D2 symmetrical nanosized metal-linked macrocycle is able to form stable complexes with ferrocene in polar solvents, with detection achieved by means of multiple outputs (optical/chiroptical spectroscopies and cyclic voltammetry). Selective sensing using chiroptical spectroscopy in the presence of interfering analytes is demonstrated.
- Agnes, Marco,Nitti, Andrea,Vander Griend, Douglas A.,Dondi, Daniele,Merli, Daniele,Pasini, Dario
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supporting information
p. 11492 - 11495
(2016/10/03)
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- Synthesis, Characterization, and Cytotoxicity of Palladium(II) Complexes with Diimine/Diamine and N-Carbonyl-L-Phenylalanine Dianion
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Six palladium(II) complexes, [Pd(bipy)(Bzphe-N,O)] (I-a), [Pd(bipy)(p-Mbzphe-N,O)]·2H2O (I-b), [Pd(bipy)(p-Nbzphe-N,O)]·2H2O (I-c), [Pd(phen)(Bmined by X-ray diffraction. The cytotoxicity test indicates that the complexes exert cytot
- Wang, Li-Wei,Liu, Si-Yuan,Wang, Jin-Jie,Peng, Wen,Li, Sheng-Hui,Zhou, Guo-Qiang,Qin, Xin-Ying,Wang, Shu-Xiang,Zhang, Jin-Chao
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p. 1049 - 1056
(2015/03/18)
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- Synthesis, characterization, and cytotoxicity of platinum(II)/palladium(II) complexes with 4-toluenesulfonyl-L-amino acid dianion and diimine/diamine
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Eight new platinum(II)/palladium(II) complexes with 4-toluenesulfonyl-L- amino acid dianion and diimine/diamine ligands, [Pd(en)(Tsile)]·H 2O (1), [Pd(bipy)(Tsile)] (2), [Pd(bipy)(Tsthr)]·0.5H 2O (3), [Pd(phen)(Tsile)]·0.5H2O (4), [Pd(phen)(Tsthr)]·H2O (5), [Pd(bqu)(Tsthr)]·1.5H 2O (6), [Pt(en)(Tsser)] (7), and [Pt(en)(Tsphe)]·H 2O (8), have been synthesized and characterized by elemental analyses, 1H NMR and mass spectrometry. The crystal structure of 7 has been determined by X-ray diffraction. Cytotoxicities were tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and sulforhodamine B assays. The complexes exert cytotoxicity against HL-60, Bel-7402, BGC-823, and KB cell lines with 4 having the best cytotoxicity against HL-60, Bel-7402, and BGC-823 cell lines; the compounds are less cytotoxic than cisplatin.
- Li, Luwei,Zhang, Jinchao,Ma, Lili,Zhang, Zhilei,Wang, Shuxiang,Li, Shenghui,Zhou, Guoqiang
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p. 638 - 649
(2013/05/22)
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- Pd complexes with trans-chelating ligands composed of two pyridyl groups and rigid π-conjugated backbone
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1,2-Bis(2-pyridylethynyl)benzene derivatives, having two pyridyl groups and π-conjugated backbone, were prepared from the 1:2 Sonogashira reaction of 1,2-diiodobenzene with 2-alkynyl pyridines. The obtained ligands react with the palladium(II) complexes such as [PdCl2(cod)] and [PdCl 2(MeCN)2] to form the complexes with the ligands coordinated in a trans-chelating bidentate mode. The ligand obtained from 1,3-diiodobenzene and 2-alkynyl pyridine bridges two Pd(II) centers, yielding a dipalladium complex. A dichloropalladium complex with the trans-chelating ligand, containing two methoxy groups in the central arylene group, promotes coupling of phenyl lithium and of phenyl acetylene to yield the respective homo-coupling products. The ligand displacement reactions of {bis(2-pyridylethynyl)benzene}palladium(II) complex with phosphine and dinitrogen ligands, such as PPh3, dppe, dppb, en, tmeda, bpy and phen, takes place smoothly to release the trans-chelating ligand.
- Jung, Miso,Suzaki, Yuji,Saito, Takashi,Shimada, Kyoichi,Osakada, Kohtaro
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p. 168 - 174
(2012/08/28)
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- Synthesis, characterization and cytotoxic activity of palladium (II) dithiocarbamate complexes with α,ω-diamines
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The polymeric [PdCl(dithiocarbamate)]n complexes, in which the ligand ion is dimethyldithiocarbamate (DMDT), pyrrolidine dithiocarbamate (PyDT, (CH2)4NCS2-) and sarcosine ethyl ester dithiocarbamate (ESDT, EtO2CCH2N(CH 3)CS2-), have been reacted with chelating diamines, like ethylenediamine (en) or 1,3-diaminopropane (dap) and long chain diamines, like 1,4-diaminobutane (dab) or 1,7-diaminoheptane (dah). The reaction products depend on either diamine chain length or molar ratio. By operating at PdCl(dithiocarbamate)/diamine molar ratio 1:1 chelating diamines yielded the ionic [Pd(dithiocarbamate)(diamine)]Cl species (diamine = en or dap), whereas with long chain diamines species of the type [Pd(dithiocarbamate)(diamine)] nCln (diamine = dab or dah) were obtained, in which each Pd(dithiocarbamate)+ unit binds to the NH2 group of two different molecules, in a network of bridging diamines. At molar ratio 1:0.5, the long chain diamines yielded the binuclear [Pd2Cl 2(dithiocarbamate)2(diamine)] complexes (diamine = dab or dah), whereas exchange reactions take place generally in the presence of en or dap. The reaction trend is described on the basis of IR and proton NMR spectra. The new dithiocarbamate complexes were preliminarily tested for their cytotoxicity on human cancer cells.
- Montagner, Diego,Marzano, Cristina,Gandin, Valentina
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p. 574 - 580
(2011/11/06)
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- Selective hydrolysis of the unactivated peptide bond in N-acetylated L-histidylglycine catalyzed by various palladium(II) complexes: Dependence of the hydrolysis rate on the steric bulk of the catalyst
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Hydrolytic reactions between various palladium(II) complexes of the type cis-[Pd(L)(H2O)2]2+ in which L is a chelating diamine (ethylenediamine, en; 1,2-propylenediamine, 1,2-pn; N-methylethylenediamine, Meen; isobutylenediamine, ibn and N,N,N',N'-tetramethylethylenediamine, Me4en) or S,N-coordinated amino acid (S-methyl L-cysteine, MeS-L-HCys and L-methionine, L-HMet) and N-acetylated L-histidylglycine (MeCO-His-Gly), were studied by 1H NMR spectroscopy. The reactions were carried out in the pH range 2.0-2.5 and at 60°C. In all these reactions, a palladium(II) complex bound to a histidine residue effects the regioselective cleavage of the amide bond involving the carboxylic group of histidine. We found that the rate of hydrolysis decreases as the steric bulk of the palladium(II) complex increases (en > 1,2-pn > Meen > MeS-L-HCys > ibn > L-HMet > Me4en). The observed rates of hydrolytic reaction are discussed in terms of steric hindrance of the chelating diamine or sulfur-containing amino acid on the palladium(II) complexes. This study is an important step in the development of new palladium(II) complexes as artificial metallopeptidases. (C) 2000 Elsevier Science Ltd.
- Djuran, Milo? I,Milinkovi?, Sne?ana U
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p. 959 - 963
(2008/10/08)
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- Kinetic study of the interaction of aquated palladium (II) complexes with purine 5′-nucleoside monophosphates and ribose 5′-monophosphate in aqueous solution. Effects of steric hindrance and phosphate-induced reactivity
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The complex formation reactions of a series of complexes of the type Pd(R4en)(H2O)22+ (R4en = N-substituted ethylenediamine, R = H, Me, Et) with ribose, adenosine, inosine, and guanosine 5′-monophosphate were investigated as a function of monophosphate concentration and temperature in the pH range 4-5. In all cases the complex formation with 5′-XMP (X = R, A, I, G) occurs in two consecutive steps for which the pseudo-first-order rate constants fit the equation kobs = ka + kb[XMP]. The experiments with ribose monophosphate revealed complex formation rate constants significantly smaller than those reported before for inosine, but larger than those found for adenosine. This trend is also observed for the nucleoside monophosphates for which the rate constants follow the sequence AMP a significant transition state stabilization effect by the monophosphate group during the complex formation reactions. The systematic variation of the substituents on the en ligand decreases the formation rate constant by as much as 3 orders of magnitude in going from the unsubstituted (R = H) to the most sterically hindered species (R = Et). The complex formation reactions all proceed according to an associative substitution mechanism and are accompanied by significantly negative ΔS? values. The results are discussed in reference to data available for the corresponding nucleosides and structural information on the final reaction products reported in the literature.
- Hohmann, Heribert,Hellquist, Bj?rn,Van Eldik, Rudi
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p. 1090 - 1095
(2008/10/08)
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- Palladiu(II,IV) Mixed-valence Complexes of 1,2-Diaminoethane, 1,3-Diaminopropane, and Diethylenetriamine: Syntheses, Electronic, Infrared, Raman, and Resonance Raman Spectra and X-Ray Studies
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The syntheses of the neutral, linear-chain mixed-valence complexes 2>4>, 2>4>, 2>4>, and a mixed-valence complex of empirical formula Pd2(en)2Br3Cl3, where en=1,2-diaminoethane and tn=1,3-diaminopropane, are reported, together with their electronic, infrared, Raman, and resonance Raman spectra.In addition, the synthesis and spectroscopic properties of the first palladium complex of the +1 charge type, 3>Br2, where dien=diethylenetriamine, is reported.The electronic spectra of the complexes are characterised by intense, broad intervalence bands which decrease in wavenumber in the order Cl > Br.The resonance Raman spectra show overtone progressions (v1ν1) in the axial X-PdIV-X symmetric stretching mode (ν1), which lies at ca. 260 cm-1 for X=Cl and at ca. 145 cm-1 for X=Br, and combination tones v1ν1 + νn, where νn is the ν(Pd-X) equatorial stretching mode, or ν2, νasym(X-PdIV-X), the antisymmetric chain-stretching mode.The excitation profiles of the ν1 and 2ν1 bands of the neutral chain complexes do not reach maxima even with excitation of the lowest available wavenumber (12510 cm-1).These complexes appear to be more delocalised than those of the +2 charge type.Powder diffraction data indicate that Pd2(en)2Br3Cl3 and 2>4> are isostructural and belong to space group Ama2.
- Clark, Robin J. H.,Croud, Vincent B.,Kurmoo, Mohamedally
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p. 815 - 820
(2007/10/02)
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