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PubMed2000

Intraligand charge transfer in the Pd(II) oxinate complex Pd(qol)2. Site-selective emission, excitation, and optically detected magnetic resonance.

The first spectroscopic investigation of Pd(qol)2 (qol- = 8-quinolinolato-N,O = oxinate) dissolved in an n-octane matrix (Shpol'skii matrix) is reported. Application of several spectroscopic methods at liquid helium temperatures (typically, T = 1.2 K), such as site-selective and highly resolved luminescence and excitation spectroscopy, time-resolved emission spectroscopy, optically detected magnetic resonance, microwave recovery, phosphorescence microwave double-resonance, and magnetic fields, allows us to characterize the lowest excited electronic states in detail. In accord with previous assignments for the related Pt(qol)2 it is shown that these lowest states represent-intraligand charge-transfer states, namely, 1ILCT and 3ILCT. The electronic origin of the 1ILCT state lies at 20,617 cm(-1) (site A). It exhibits a nearly homogeneous line width with a half-width of about 80 cm(-1) (fwhm), which corresponds to a lifetime of tau(1ILCT) approximately equals 2 x 10(-13) s. This value is even shorter than that found for Pt(qol)2, presumably due to intersystem crossings and relaxations to dd* states. The electronic origin of the 3ILCT state lies at 16 090 cm(-1) (site A), and its zero-field splittings (zfs) into three sublevels are 2E = 2356 MHz (0.0785 cm(-1)) and D - E = 5241 MHz (0.175 cm(-1)). The emission decay times of the three sublevels are determined as tauI = 90 +/- 30 ms, tau(II) = 180 +/- 10 mus, and tau(II) = 80 +/- 10 mus. (Slightly different values are found for a second site B at 16,167 cm(-1).) From the small values of zfs and the long emission decay times it is concluded that metal-d or MLCT admixtures to 3ILCT are very small. This result clearly reflects the ligand-centered character of the transition. The assignment as an ILCT transition is supported by the occurrence of relatively strong vibrational satellites of Pd-N and Pd-O character in highly resolved emission spectra. Although the transition is ascribed to a charge-transfer process, the geometry changes between the ground state and 3ILCT are very small. The results found for Pd(qol)2 are compared to those of companion studies of Pt(qol)2 and Pt(qtl)2 (qtl- = 8-quinolinethiolato-N,S).

Journal Article↗

PubMed2001

CO oxidation on Pd(100) and Pd(111): a comparative study of reaction pathways and reactivity at low and medium coverages.

We have performed density functional theory calculations with the generalized gradient approximation to investigate CO oxidation on a close-packed transition metal surface, Pd(111), and a more open surface, Pd(100), aiming to shed light on surface structure effects on reaction pathways and reactivity, an important issue in catalysis. Reaction pathways on both surfaces at two different coverages have been studied. It is found that the reaction pathways on both surfaces possess crucial common features despite the fact that they have different surface symmetries. Having determined reaction barriers in these systems, we find that the reaction on Pd(111) is strongly coverage dependent. Surface coverages, however, have little effect on the reaction on Pd(100). Calculations also reveal that the low coverage reactions are structure sensitive while the medium coverage reactions are not. Detailed discussions on these results are given.

Journal Article↗

PubMed2006

Changes in coordination of sterically demanding hybrid imidazolylphosphine ligands on Pd(0) and Pd(II).

Low-coordinate organometallic complexes are important in structure and catalysis, and hemilability or secondary interactions such as hydrogen bonding enabled by hybrid ligands are receiving increasing attention. To study the factors controlling these phenomena, three new imidazol-2-ylphosphine ligands, L, were made. In these ligands, the bulk around P and the hindrance at the basic and potentially coordinating imidazole N-3 were varied. Remarkably, L(2)Pd(0) complexes 3a-c were shown to be two-coordinate, 12-electron species, despite the availability of imidazole N-3 to enter into eta(2)-P,N chelation. In oxidative additions of C-X bonds to the Pd(0) complexes, reaction rates and products could be controlled by the nature of the C and X groups and the R groups on the phosphine. Most significantly, whereas 4c-PhI and 4c-MeOTf from 3c are normal trans-bis(phosphine)Pd(R)(X) species, 5a-PhI, 5a-PhBr, and 5b-PhI from 3a and 3b were shown by X-ray diffraction to be a monomeric species with a single eta(2)-P,N-chelating phosphine. From 3a and methyl triflate, an ionic complex [6a-Me](+)[OTf](-) with one chelating and one nonchelating phosphine was formed, with temperature-dependent windshield-wiper exchange of the two, showing hemilability. Thus, large phosphine substituents (R = tert-butyl rather than isopropyl) favor chelation. The chelate Pd-imidazole N-3 bond is longer when the heterocyclic nitrogen is hindered by an adjacent tert-butyl group at C-4 (comparing 5a-PhI and 5b-PhI). Finally, whereas in [8b-Ph](+)[OTf](-) from 5b-PhI and isopropylamine, the amine coordinates without chelate opening or hydrogen bonding, in [10c-Me](+)[OTf](-) made from 4c-MeOTf and isopropylamine, the amine is not only coordinated at N but also donates a hydrogen bond to each phosphine imidazol-2-yl substituent.

Journal Article↗

PubMed2002

Resolution of Pd catalyst with tropos biphenylphosphine (BIPHEP) ligand by DM-DABN: asymmetric catalysis by an enantiopure BIPHEP-Pd complex.

[reaction: see text] The racemic Pd complex with the chirally flexible (tropos) biphenylphosphine (BIPHEP) ligand can be resolved with enantiopure 3,3'-dimethyl-2,2'-diamino-1,1'-binaphthyl (DM-DABN) as a resolving agent at room temperature. The enantiopure BIPHEP-Pd complex is obtained from complexation with enantiopure DABN followed by tropo-inversion into the single BIPHEP-Pd diastereomer at 80 degrees C and protonation at 0 degrees C. The enantiopure BIPHEP-Pd complex can be used as an efficient Lewis acid catalyst for the Diels-Alder reaction at room temperature to give high enantioselectivity (82% ee, 60%).

Journal Article↗

PubMed2003

Magnetic anisotropy of transition-metal interfaces from a local perspective: reorientation transitions and spin-canted phases in Pd capped Co films on Pd(111).

Layer-resolved self-consistent electronic calculations of magnetic anisotropy energy (MAE) provide new insight to the off-plane magnetization observed in Pd capped Co films on Pd(111). We demonstrate that the transition from perpendicular to in-plane phases with increasing film thickness involves an intermediate spin-canted phase. The interfaces responsible for the stability of the off-plane easy axes are characterized microscopically. A local analysis of the MAEs reveals an unexpected internal magnetic structure of the Co-Pd interfaces in which the magnetic moments and spin-orbit interactions at the Pd atoms play a crucial role.

Journal Article↗

PubMed1993

In vitro activities of meropenem, PD 127391, PD 131628, ceftazidime, chloramphenicol, co-trimoxazole, and ciprofloxacin against Pseudomonas cepacia.

In a study of 110 Pseudomonas cepacia isolates from patients without cystic fibrosis, the in vitro potencies of three new compounds, meropenem, PD 127391, and PD 131628, were comparable to those of ceftazidime and ciprofloxacin and exceeded those of chloramphenicol and co-trimoxazole. The MICs of ceftazidime, ciprofloxacin, meropenem, and the PD compounds for 90% of strains tested were < or = 4 micrograms/ml, whereas they were 32 micrograms/ml for chloramphenicol and co-trimoxazole. Data for 20 isolates from patients with cystic fibrosis indicated that the isolates were less susceptible to all seven antibiotics tested, with the most active compounds being meropenem and PD 127391.

Anti-Bacterial Agents↗

PubMed1993

In vitro antibacterial activities of PD 138312 and PD 140248, new fluoronaphthyridines with outstanding gram-positive potency.

PD 138312 and PD 140248 are new quinolones with high in vitro activities against a wide spectrum of bacterial species, notably including gram-positive isolates. The respective MICs (in micrograms per milliliter) of PD 138312 and PD 140248 capable of inhibiting > or = 90% of the strains were < or = 0.06 and < or = 0.06 for oxacillin-susceptible and -resistant staphylococci, streptococci (including Streptococcus pyogenes, S. agalactiae, S. pneumoniae, and viridans group streptococci), Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae; 0.125 and 0.03 for Legionella pneumophila; 0.25 and 0.125 for Listeria monocytogenes; 0.25 and 0.25 for Enterococcus faecalis; 0.5 and 0.06 for anaerobic gram-positive cocci; 0.5 and 0.25 for Acinetobacter spp.; 0.5 and 0.5 for members of the family Enterobacteriaceae (excluding Serratia marcescens); 2 and 0.5 for Bacteroides fragilis; 2 and 2 for Serratia marcescens and ciprofloxacin-resistant staphylococci; and 8 and 4 for Pseudomonas aeruginosa.

Anti-Infective Agents↗

PubMed2003

PD and the future: the role of PD in the overall management of ESRD.

Given the epidemic growth of ESRD and the high costs of dialysis therapy, there is an urgent need to define the optimal dialysis modality distribution. The factors influencing dialysis modality distribution are complex and not well understood. Based on survey results that have assessed the attitudes of nephrologists in Canada, the USA and the UK, it appears that there is underutilization of both peritoneal dialysis (PD) and home hemodialysis (HD) in these countries. Nephrologists have a positive attitude towards home therapies, and do not appear to be biased against PD. A planned approach to dialysis initiation, with active promotion of PD and home HD as the initial dialysis modality for suitable patients, would be expected to revive usage of home PD and allow for the emergence of daily home HD as a significant and exciting new modality.

Global Health↗

PubMed2006

PD membrane: biological responses to different PD fluids.

In chronic peritoneal dialysis (PD) alterations of both membrane structure and function occur with time on treatment, but also in relation to frequency and severity of infectious complications. In addition, therapy-associated factors such as the dialysis fluid bioincompatibility are important determinants for the longevity of the peritoneum as the dialysis membrane. Evidence available to date suggests that the elimination of glucose degradation products from multi-chambered PD solutions is particularly important to improve peritoneal cell function as well as to reduce protein glycation and peritoneal advanced glycation end products deposition. Results from recent prospective randomized studies suggest that chronic treatment with these novel PD fluids may indeed lead to a significant improvement of clinical outcomes in chronic PD patients.

Biological Transport↗

PubMed2005

Preparation and catalytic activity of Au-Pd, Au-Pt, and Pt-Pd binary metal dendrimer nanocomposites.

Catalytic activity of Au-Pt, Au-Pd, and Pt-Pd dendrimer nanocomposites for reduction of p-nitrophenol was investigated in water. The bimetallic dendrimer nanocomposites were prepared by simultaneous reduction with sodium borohydride in the presence of poly(amidoamine) (PAMAM) dendrimers with amine and carboxyl terminal groups. Average diameters of the obtained particles were 2-4 nm by transmission electron microscopy. From UV-vis spectroscopy, it was found that the particles were not mixtures of monometallic particles but binary ones. X-ray photoelectron spectroscopy showed that formation of binary composite particles prevents palladium atoms from oxidation. The Au-Pd and Pt-Pd binary particles exhibited higher catalytic activity than monometallic ones. On the other hand, catalytic activity of Au-Pt binary particle was comparable to that of platinum nanoparticles.

Borohydrides↗

PubMed2002

Hemodialysis (HD) versus peritoneal dialysis (PD): latent overhydration in PD patients?

Data on the difference in fluid status between hemodialysis (HD) and peritoneal dialysis (PD) patients are scarce. Bio-electrical impedance analysis (BIA) is able to detect total body water (TBW) and its distribution in intracellular (ICW) and extracellular water (ECW). Echographic determination of the diameter of the inferior caval vein (VCD) provides information about the intravascular space (IVS). Nineteen PD-patients and 20 HD-patients in stable clinical condition were studied. In HD-patients a significant decrease in VCD, mean arterial pressure (MAP), TBW and ECW was noted due to ultrafiltration. Both ratios of VCD to ICW/ECW and of VCD to ECW/TBW decreased. No significant differences were found in these variables between PD-patients and HD-patients before HD. In both patient groups the measured variables pointed towards overhydration and the increased ratios both of VCD to ICW/ECW and VCD to ECW/TBW towards the storage of surplus of fluid in the intravascular space. It can be concluded that both PD-patients and HD-patients before HD have a surplus of fluid in the extracellular compartment, predominantly stored in the intravascular space.

Body Fluid Compartments↗

PubMed1992

[Intracomplex alkylation of octanucleotide pd(TGTTTGGC) by a 5'-(4-N-methyl-N-(2-chloroethyl)-amino)benzylphosphamide derivative of heptanucleotide pd(CCAAACA). Preparation of a covalent adduct and study of its spatial structure in an aqueous solution by two-dimensional (1)H-NMR spectroscopy].

Covalent adduct--the product of intracomplex alkylation at N-3-position of dC-8-nucleoside residue of target octanucleotide pd[TGTTTGGC] was completely synthesized by means of 4-[N-methyl-N-(2-chloroethyl)amino]benzyl-5'-phosphamido derivative of heptanucleotide pd[CCAAACA]. Its melting temperature was shown to be 70 degrees C. Tm did not depend on covalent adduct concentration and was by 40 degrees C higher than that for unmodified duplex pd[TGTTTGGC].pd[CCAAACA] at concentration of 0.5 x 10(-4) M. The spatial structure of the covalent adduct in aqueous solution was investigated by two-dimensional 3H-NMR spectroscopy. The assignment of oligonucleotide protons as well as protons of a modifying group was carried out using COSY, COSY-DQF and NOESY experiments. Conformational analysis of proton-proton coupling constants for H1', H2'a, H2'b and H3' protons showed the sugar residues to be in 2'-endo conformation. Analysis of NOE connectivities observed between the protons of the alkylating group and oligonucleotide protons yielded conclusion, regarding the 4-[N-methyl-N-(2-chloroethyl)amino]benzylamido 5'-residue being localized in the region of the lacked nucleoside residue of the heptanucleotide chain about 5 A apart from the dC-1 residue and from cytosine base of the alkylated dC-8 residue.

Alkylation↗

PubMed1981

[Studies on Au-Ag-Pd-Cu alloys. (Part 3) Effects of additional elements to Au-Ag-Pd-Cu alloys (author's transl)].

In the previous papers, the author pointed out that alloys containing 30 wt% Au, 15-25 wt% Pd and Cu were more favourable for Au-Ag-Pd-Cu quarternary dental alloys. In this paper, the experiments were carried out to find the effects of additional elements and so, Pt, Ir, Os, W, Mo, Cr, Mn, Co, Zn, In, Sn and Si were added to 30 wt% Au-30 wt% Ag-20 wt% Pd-20 wt% Cu alloys ranging 0.1 wt% to 2.0 wt% respectively. Then, tensile strength, elongation, hardness, corrosion resistivity and porosity ratio were tested on these specimen. Results were as follows. 1) The addition of 0.2 wt% Ir, 0.2 wt% Os and 1.0 wt% Co were comparatively effective for the fineness of grain sizes, elongation and tensile strength. 2) The addition of 0.2 wt% W, 1.0 wt% Mo and 0.2 wt% Si showed respectively bad effect for porosities or mechanical properties. 3) The addition of 1.0 wt% Cr, 2.0 wt% Mn, 1.0 wt% Co, 2.0 wt% Zn and 2.0 wt% In were good for the decrease of porosities respectively and showed that the porosity ratio was lower than 0.2%. 4) The additions of 2.0 wt% Zn-1.0 wt% Pt-0.5 wt% Co to Au-Ag-Pd-Cu alloy was especially good and showed 80 kg/mm2 of tensile strength, 5.1% of elongation, 249 of Vicker's hardness number and 0.4% of porosity ratio.

Copper↗

PubMed2026

A novel neoadjuvant immunotherapy confers improved overall survival in oral cancer patients with low tumor PD-L1 expression The IT-MATTERS Clinical trial - Prognostic role of tumor PD-L1 expression.

OBJECTIVE: Five-year overall survival (OS) remains < 50% for patients with resectable, locally advanced (LA) primary oral squamous cell carcinoma (OSCC) and soft palate, receiving current standard of care (SOC). The aim of our study was to examine neoadjuvant Leukocyte Interleukin Injection (LI) with CIZ (intravenous low dose cyclophosphamide, indomethacin and zinc multivitamins) effect on OS, in low-risk (LR) OSCC patients. PATIENTS AND METHODS: In a randomized, controlled Phase 3 trial, treatment-naïve locally advanced patients, with stage III/IVa OSCC and soft-palate cancer, had surgical tumor samples assessed for pre-defined thresholds of PD-L1 tumor proportion score (TPS). OS was analyzed using proportional hazard models for LI + CIZ + SOC vs SOC, in the intention-to-treat (ITT) population. RESULTS: OS was superior in low risk (LR) patients receiving LI + CIZ + SOC compared to SOC; OS advantage hazard ratio (HR) 0.64, p = 0.0569 (without selecting for N0, PD-L1 TPS < 10%), and the Kaplan-Meier (K-M) lifetable achieved significance (log rank p = 0.0340) favoring LI + CIZ + SOC vs SOC. Applying the selection criteria (cN0 and TPS < 10%) to ITT, OS reached HR 0.34p = 0.0012, Kaplan-Meier log rank p = 0.0015. The ITT LR cohort (cN0 and TPS < 10%) achieved a HR 0.26 (p = 0.0023), Kaplan-Meier log rank p = 0.0013, supported by progression free survival (PFS) HR 0.43, p = 0.0178, Kaplan-Meier log rank p = 0.0431, with 32% absolute survival advantage over control at 60 months. CONCLUSIONS: Significant OS prolongation was observed in ITT population for LI + CIZ + SOC vs SOC, in LR and in ITT LR cN0, PD-L1TPS < 10% cohort having locally advanced squamous cell carcinoma tumors in oral cavity/soft-palate. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT01265849; EudraCT (Identifier: 2010-019952-35).

Humans↗

PubMed2003

Molecular design of DABNTf as a highly efficient resolving reagent for racemic Pd complex with Tropos biphenylphosphine (BIPHEP) ligand: circular dichroism (CD) spectra of enantiopure BIPHEP-Pd complex.

The racemic Pd complexes with chirally flexible (tropos) biphenylphosphine (BIPHEP) ligands can be resolved but transformed into the enantio- and diastereo-pure complex. The enantiopure metal complex of BIPHEP ligand is thus obtained through enantiomer-selective complexation of a racemic BIPHEP-Pd complex with enantiopure 1,1'-binaphthyl-2,2'-di(triflyl)amide, DABNTf. The differential CD spectra of the enantiopure BIPHEP-Pd complex is also reported.

Journal Article↗

PubMed1977

Parallel occurrence of oxidant-sensitivity and decreased inhibition by NADPH in G-6-PD Lublin and G-6-PD Poxnań.

In two studied variants of G-6-PD without chronic hemolysis in probands, sensitivity of enzymes to inhibition by NADPH was decreased. Ki for NADPH was 28 micronM in Gd Lublin and 19 micronM in Gd Poznań. Susceptibility to the oxidant-induced hemolysis was described in probands, as well as in patients hemizygous for two other variants of G-6-PD with increased Ki for NADPH. It is suggested that in these cases, the oxidant-induced hemolysis is aggravated by their inability to counteract the drop in NADPH concentration with an increase in G-6-PD activity.

Adolescent↗

PubMed1998

Pervanadate-triggered MAP kinase activation and cell proliferation are not sensitive to PD 98059. Evidence for stimulus-dependent differential PD 98059 inhibition mechanism.

A tight and stable complex with corresponding protein kinases and phosphatases establishes coupling between activators and inactivators. One such example is emerging from the studies of the Ras-dependent MAP kinase cascade signaling pathway. Pervanadate, a potent inhibitor of protein tyrosine phosphatase, stimulates MAP kinase and elicits cell proliferation in cultured mouse fibroblasts which is insensitive to PD 98059, the major inhibitor of upstream MEK, whereas serum- or TPA-triggered proliferation is sensitive to PD 98059. It is suggested that imbalanced coordination between protein kinase and protein phosphatase determines the cellular responses such as cell proliferation. The PD 98059-insensitive cell proliferation upon protein tyrosine phosphatase inhibition is attributed to a MEK bypass pathway.

Animals↗

PubMed1999

Kinetic and Mechanistic Aspects of Sulfur Recovery from Pd(2)I(2)(&mgr;-S)(&mgr;-dpm)(2) Using I(2) and Structures of Pd(II) Complexes with the Chelated Monosulfide of dpm.

The Pd(2)X(2)(&mgr;-S)(dpm)(2) complexes (2) (X = I, Br) react with halogens to yield PdX(2)(dpm) (3) and elemental sulfur. Kinetic and mechanistic studies on the X = I system in CHCl(3) reveal that the reaction proceeds via addition of I(2) to give Pd(2)I(4)(dpm)(2) (4c), which then undergoes unimolecular decomposition to generate PdI(2)(dpm) (3c); the liberated sulfur concatenates to form elemental S(8). The addition reaction is in the stopped-flow time regime and is first-order in both 2c and I(2), with DeltaH() = 32 +/- 1 kJ mol(-)(1) and DeltaS() = -91 +/- 3 J K(-)(1) mol(-)(1). The slower decomposition reaction of 4c is first order in 4c, with DeltaH() = 80 +/-1 kJ mol(-)(1) and DeltaS() = -26 +/- 3 J K(-)(1) mol(-)(1). Byproduct PdX(2)(dpm(S)) (5) [dpm(S) = Ph(2)PCH(2)P(S)Ph(2)] also forms under some conditions via reaction of 3 with an S(n)() species (n < 8). Complexes 5 (X = Cl (a), Br (b), I (c)) were also synthesized directly, and the structure of the 5c species, as well as of [Pd(dpm(S))(2)]Cl(2), were determined by X-ray analyses that reveal the envelope configuration of the five-membered chelate ring.

Journal Article↗