Effet faraday en solution et strobilisme: La technique des solvants equi-polarisables

The magneto-optical behaviour of some strobilic compounds in solution in different solvents is described. The strobilic character vanishes when the electric polarisabilities of solute and solvent are equal, and in such cases the magnetic properties of the strobilic compounds are independent of concentration. An “equi-polarisable solvents” technique is proposed.     

Raman studies on anticancer inorganic ring–dna interactions: Part 1. HexaziridmocyclotriphosphazeneN3P3(NC2H4)6

A Raman investigation of hexaziridinocyclotriphosphazene3D?NA interactions in vitro suggests that the alkylating sites on DNA for this powerful antitumour agent are the N(7) and NH₂ positions of adenine.     

Analyse conformationnelle théorique du biaziridyle

The semi-empirical CNDO and INDO methods are applied to a theoretical conformational analysis of biaziridyl. In agreement with infrared and electron diffraction data, this molecule is found to be in its s-trans conformation. The origins of such a conformation are discussed in terms of Fourier developments. The prediction that some alterations of angles occur when going from the s-trans to the s-cis form, arises from these calculations.     

A new approach for the characterization of insoluble amphiphilic copolymers based on their emulsifying properties

The purpose of the present study was to propose a new approach for the characterization of insoluble amphiphilic copolymers using their emulsifying properties. The capacity of four newly-synthesized block copolymers to stabilize a model emulsion formed by mixing equal volumes of water and ethyl acetate was investigated. The copolymers were composed of dextran or heparin and poly(isobutylcyanoacrylate) and were obtained either by anionic or by radical polymerization of isobutylcyanoacrylate in emulsion, initiated on dextran or heparin. A quantitative analysis of the stability of the emulsion obtained with the different copolymers was evaluated using a Turbiscan MA 2000. The results suggested that this approach provides a new methodology for investigating emulsifying properties of polymers that are insoluble in pure solvents, allowing quantitative comparisons to be made between them.     

Über die NH3-“rocking”-schwinguno in amminmetall komplexen

A magneto-optical investigation of dialkyl derivatives of zinc, cadmium and mercury (in the liquid state, at 20 °C) leads to the conclusion that there is a lack of linearity in such molecules, the largest deviations being observed in the case of the mercury compounds. This shows that the inconsistency of the alteration of any chemical or physical property which is classically observed in the group IIB, is in fact due to mercury and not to cadmium as was often assumed in the literature.     

Spectrofluorometric and spectrophotometric investigations of cyclophosphazene-DNA complexes

A series of cyclophosphazene—DNA matrices is investigated by UV spectrophotometry and by spectrofluorometry (using EtdBr (ethidium bromide) as a probe) in order to gain information about the structural modifications of DNA due to the different possible modes of interaction and thus to attempt to explain the origin of their antitumour properties. There is no direct relationship between antitumour activity and fluorescence decrease (and/or the hyper-bathochromic UV shift, when observed) suggesting that targets other than DNA must be looked at to explain the real mode of action of cyclophosphazenes as antitumour agents.     

Une extension de la méthode CNDO/2 à l'étude des complexes d'éléments de transition

The previously proposed extension of the CNDO/2 formalism is used for investigating the electronic structure of Cr(CO)₆ and Fe(CO)₅. Thus, the ordering and the eigen values of molecular energy levels agree well with results provided byab initio calculations and photoelectron spectroscopy. The formal charge on metal is found to be in any case positive, as in Ni(CO)₄ and Ni(PF₃)₄. Moreover, the validity of our parametrization is supported by the pretty agreement which exists between energy levels distribution and electronic structure provided by our technique and Veillard'sab initio results for Ni(CN) ₄ ^2? . The parameters for the (Cr, Fe, Ni) set are now available and will allow to study large series of complexes in order to interpret their physical and chemical behaviour.     

Electron diffraction study and CNDO/2 calculations on the complex of aluminium trichloride with ammonia,Cl3Al.NH3

The molecular geometry of the complex of aluminium trichloride with ammonia, Cl₃Al.NH₃, has been studied by electron diffraction. The most important internuclear distances in terms of r_a parameters are as follows: r(Al-Cl) = 2.100±0.005 Å, r(Al-N) = 1.996±0.019 Å, r(Cl·Cl) = 3.569±0.011 Å and r(Cl·N) = 3.165±0.012 Å. The Cl-Al-Cl bond angle in terms of an approximate r_a structure is 116.9°. The assumptions of a staggered model in the structure analysis was justified by CNDO/2 calculations. The experimental data indicate strong linkage between the donor and acceptor parts. The flat pyramidal average configuration of the AlCl₃ part of the complex suggests planar equilibrium structure for free AlCl₃. Variations in the bond configurations of the donor and acceptor parts, as compared with those of the respective free molecules, are discussed.     

Determination of scission, crosslinking and branching parameters of electron beam irradiated methacrylate-acrylamide copolymer

The aim of this work was to investigate the impact of electron beam irradiation at different dose rates on the molecular structure of linear methacrylate-acrylamide copolymer. In the first part, the radiation chemical yields of scission (G_s) and crosslinking (G_x) have been determined after irradiation for various initial molecular weights CL1 (40?000 g/mol), CL2 (90?000 g/mol) and CL3 (425?000 g/mol). Based on this calculation, solvent (ethanol) was found to increase the impact of irradiation especially at low concentration of copolymer. In the second part, the presence of branching in samples before and after e-beam irradiation was explored, and branching calculation was performed.