On the derivation of Hamilton's equations

Dedicated to Walter Noll     

Transition metal complexes with bidentate ligands spanning trans-positions. Part XIV. Some complexes of 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene with platinum (0) and their reactivities

The ligand 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene ( 1 ) has been used to prepare complexes of the type [PtL( 1 )] (L ? C₂H₄, CH₂?CH? CO₂Me, PhC?CPh, MeC?CMe, MeO₂CC?CCO₂Me, (i-Pr)O₂CC?CCO₂(i-Pr), Ph₃P and CO). It is shown that these complexes are less labile than the corresponding species [PtL(Ph₃P)₂]. The preparation of complexes trans-[PtX(R)(1)] by oxidative addition of RX (RX ? PhCH₂Br and Mel) to [Pt(C₂H₄)(1)] is described. The isolation of [PtO₂(CH₃)₂CO(1)] is also reported.     

ENHANCED RESPONSE TO DAUNOMYCIN OF NORMAL, TUMOR AND METASTATIC CELL LINES via DRUG PHOTO ACTIVATION

Abstract— We have compared the cytotoxicity of daunomycin in vitro to highly differentiated normal epithelial cells (Fisher rat thyroid cells, FRTL-5) and to two neoplastic cell lines, a thyroid carcinoma (TK-6) and its lung metastasis (MPTK-6). Whereas the cell lines are equally sensitive to the drug in the dark, if irradiated during incubation with daunomycin (86 J/cm² at 488 nm), they become more and differently sensitive. Namely, the drug doses producing 50% mortality decrease by factors of about 22, 28 and 16 for FRTL-5, TK-6 and MPTK-6 cell lines, respectively. This result correlates with differences in drug uptake and resistance observed in the normal and neoplastic cell lines.     

Binding of Co(II) and Cu(II) cations to chemically modified wool fibres: an IR investigation

Wool fibres were modified by treatment with tannic acid (TA) solution or by acylation with ethylenediaminetetraacetic (EDTA) dianhydride. The unmodified and modified fibres were subsequently treated with Cu²⁺ and Co²⁺ solutions, at alkaline pH, and analysed by Attenuated Total Reflectance, ATR/IR spectroscopy to evaluate the changes induced in the structure of the fibre by metal binding. The spectral changes were correlated to metal adsorption results obtained by Inductive Coupled Plasma-Atomic Emission Spectrometry (ICP-AES).

The IR results were discussed in relation to our previous findings on the metal binding mode of Bombyx mori and Tussah silk fibres; the changes observed in the spectra were explained by considering the different affinity of the fibres for the modifying reagent and the amount of the metal absorbed. More relevant spectral changes were observed upon Cu²⁺ complexation rather than Co²⁺ complexation, according to the metal absorption results. The most relevant changes were observed for the EDTA-modified wool sample treated with Cu²⁺, according to the higher affinity of wool for EDTA. The IR spectra were quantitatively evaluated by the intensity ratio between the Amide I and Amide II bands (I_AmideI/I_AmideII) and its trend as a function of metal absorption was reported.

The present investigation demonstrated that the interaction between fibre and metal and the subsequent fibre modification depend on the chemical nature of the fibre, the metal cation and the modifying reagent.     

Promoting laccase activity towards non-phenolic substrates: a mechanistic investigation with some laccase-mediator systems

The oxidation of benzyl alcohols with the enzyme laccase, under mediation by appropriate mediator compounds, yields carbonylic products, whereas laccase can not oxidise these non-phenolic substrates directly. The oxidation step is performed by the oxidised form of the mediator (Med(ox)), generated on its interaction with laccase. The Med(ox) can follow either an electron transfer (ET) or a radical hydrogen atom transfer (HAT) route of oxidation of the substrates. Experimental evidence is reported that enables unambiguous assessment of the occurrence of either one the oxidation routes with each of the investigated mediators, namely, ABTS, HBT, HPI and VLA. Support to the conclusions is provided by (i) investigating the intermolecular selectivity of oxidation with appropriate substrates, (ii) attempting Hammett correlations for the oxidation of a series of 4-X-substituted benzyl alcohols, (iii) measuring the kinetic isotope effect, (iv) investigating the product pattern with suitable probe precursors. Based on these points, a HAT mechanism results to be followed by the laccase-HBT, laccase-HPI and laccase-VLA systems, whereas an ET route appears feasible in the case of the laccase-ABTS system.     

Separation of sigma and pi energies

This work presents an all-electron density functional theory implementation of the separation of sigma and pi energies. On the basis of the separation of the electronic density, rho, into sigma and pi parts, an ansatz for the separation of the exchange-correlation energy is proposed. The behavior of the sigma and pi energy parts in benzene is investigated under different distortions. The effect of local and nonlocal functionals on the separation of the exchange-correlation energy is studied, too.     

Gaussian density-functional study for small neutral (Al n ), positive (Al n + ) and negative (Al n − ) aluminium clusters (n=2–5)

The structures and properties of Al _n , Al _n ⁺ , Al _n ^– (n=1,5) clusters have been investigated by using the Linear Combination of Gaussian Type Orbitals (LCGTO) method, considering Local (LSD) and Non Local (NLSD) Spin Density Approximations and employing a Model Core Potential (MCP) that allows the explicit treatment of 3s ² 3p ¹ valence electrons. For each system different geometrical structures and electronic states have been considered. For Al₃, Al ₃ ⁺ , Al ₃ ^– the most stable geometry proved to be the equilateral triangle (D _3h ). Al₄ and Al ₄ ⁺ prefer the rhombus (D _2h ) structure, while the corresponding anion prefers the square (D _4h ) one. The trapezoidal form (C _2v ) is the most stable isomer for Al₅, Al ₅ ⁺ and Al ₅ ^– clusters. The analysis of vibrational frequencies shows that these structures are minima in the potential energy surface. The binding energies (D _e), the adiabatic ionization potentials (IP) and electron affinities (EA), the chemical potentials or absolute hardnesses () and electronegativities () have been computed. Results are in good agreement with the available experimental data and the previous high level theoretical computations.     

Multifunctional cadmium single source precursor for the selective deposition of CdO or CdS by a solution route

We report on the interesting properties of a novel single precursor, Cd(tta)2 x tmeda (Htta = 2-thenoyl-trifluoroacetone, tmeda = N,N,N',N'-tetramethylethylenediamine), ideally suited for the selective and reproducible fabrication of pure quality films of CdS or CdO through a simple solution process.