Etude des copolymeres (ethylene-hexene-1) par resonance magnetique nucleaire du proton et du carbone 13

Ethylene 1-hexene copolymers obtained by catalytic polymerization have been examined by ¹H and ¹³C NMR. Copolymer compositions have been determined by ¹H NMR and i.r. and the sequence distributions for 1-hexene by ¹³C NMR. Variations of the copolymer microstructure have been related to the experimental conditions for copolymerization.     

Synthesis,Spectroscopic Studies,and In Vitro Antifungal Activity of Organosilicon(IV) and Organotin(IV) Complexes of 4-Amino-5-mercapto-3-methyl-S-triazole Schiff Bases

The Schiff bases derived from condensation of s-triazole with heterocyclic aldehydes and their 1:1 and 1:2 complexes have been synthesized. These complexes have been characterized by elemental analyses, molar conductance and spectroscopic studies, including UV, IR, ¹H, ¹³C, ²⁹Si, and ¹¹⁹Sn NMR spectroscopy. On the basis of these studies, the resulting complexes have been proposed to have trigonal bipyramidal and octahedral geometries. The biological activity of these complexes against various fungi has been investigated.     

Synthesis,crystal structures and competitive complexation property of a family of calix-crown hybrid molecules and their application in extraction of potassium from bittern

A family of calix-crown hybrid molecules containing calix[4]arene and crown-5/6, either at lower rim or at both upper and lower rims, have been synthesised, characterised and their competitive complexation property towards alkali and alkaline earth metal ions in aqueous media have been investigated. The competitive metal ion extraction study, carried out with equimolar mixture of Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺ and Sr²⁺ in aqueous media, revealed that the amount of K⁺ extracted is remarkably high compared to other metal ions. Complexation with K⁺ has been investigated by ¹H NMR, association constants and thermodynamic parameters have been determined by isothermal calorimetric study. The molecular structures of one of the receptors and two of the K⁺ complexes have been established by single crystal X-ray study. One of the receptors formed bimetallic complex and it exhibited interesting polymeric network structure with bridged picrate anion. These receptors have been applied for extraction of metal ions from bittern.     

Antimicorbial effects of newly synthesized organotin(IV) and organolead(IV) derivatives

Triorganotin(IV) and triorganolead(IV) derivatives of the types Me₃Sn(SCZ) and Ph₃Pb(SCZ) (where SCZ^? is the anion of a semicarbanzone ligand) have been synthesized by substitution reactions of trimethyltin chloride and triphenyl-lead chloride with semicarbazones derived from heterocyclic ketones. The resulting complexes have been characterized by elemental analyses, molecualr weight determinations and conductivity measurements. The mode of bonding has been established on the basis of infrared and ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopic studies. Some respresentative complexes have also been evaluated for their antimicrobial effects on different species of pathogenic fungi and bacteria; the results of these investigations have been reported in the present paper.     

Restricted rotations and stereodynamics of aziridine-2-methanol derivatives

‘Gear-like’ rotations of simple C-C bonds have been observed in some aziridine methanol derivatives. These restricted rotations have been studied by dynamic and multinuclear magnetic resonance experiments, and the barrier for rotations of Csp³-Csp³ and Csp³-Csp² bonds have been calculated. The role of an intramolecular hydrogen bond on the stereodynamics has also been demonstrated.     

True coincidence summing corrections in point and extended sources

The true coincidence summing (TCS) effect on the full energy peak (FEP) efficiency calibration of an HPGe detector has been studied as a function of sample-to-detector distance using multi-gamma sources. Analytical method has been used to calculate coincidence correction factors for ¹⁵²Eu, ¹³³Ba, ¹³⁴Cs and ⁶⁰Co for point and extended source geometry at close sample-to-detector distance. Peak and total efficiencies required for this method have been obtained by using MCNP code by using the optimized detector geometry. The correction factors have also been obtained experimentally. The analytical and the experimental correction factors have been found to match within 1–5%. The method has been applied to obtain the activity of the radionuclides (¹⁰⁶Ru, ¹²⁵Sb, ¹³⁴Cs and ¹⁴⁴Ce) present in a fission product sample.     

β-Diketonates of Cyclopalladated Arylazonaphthalenes: Synthesis, Characterization and Redox Activity

The synthesis of monomeric mixed species of the type [PdLK] (L = cyclopalladated arylazonaphthalenes) have been achieved by splitting the halogeno-bridge in [Pd₂L₂Cl₂] by β-diketones (HK). The compounds have been characterized on the basis of spectral (IR, UV–VIS, FAB mass, ¹H and ¹³C{¹H}NMR) and elemental analysis data. Some of the [PdLK] cyclometallates occur as isomeric mixtures whose composition have been established by ¹H-NMR data. Electron transfer properties of the cyclopalladates in DMF have been thoroughly examined using cyclic voltammetry.     

New possibilities in isotope correlation analysis of spent nuclear fuel

Isotopic correlation analysis is believed to make possible quick and accurate determinations of nuclear fuel parameters for reactor operation, reprocessing, fuel management and nuclear safeguards. Correlation dependencies have been found between ratios of fission products on the one hand and isotope ratios of the heavy elements on the other hand. The use of the¹⁵⁴Eu/¹⁵⁵Eu ratio in correlation analysis was proposed by SMULEK. The scope of useful applications of this isotopic ratio has been further investigated. A quick and time-saving method to measure the¹⁵⁴Eu/¹⁵⁵Eu ratio has been elaborated. The atomic ratios have been found by internal calibration using the computer programme ABSINT. Beside this the atomic ratios of¹⁵⁴Eu/¹⁵⁵Eu as a function of nuclear fuel burn-up have been calculated using the computer programme ISOTOP. The correlation between the¹⁵⁴Eu/¹⁵⁵Eu ratio and nuclear fuel burn-up is best approximated by a quadratic function. Up to a burn-up of 1% fima a linear function can be used.     

Thorium series disequilibrium and geochemical processes in estuarine sediments of Mandovi river

The measurements of natural radioactivity due to thorium isotopes have been carried out in estuarine sediments of Mandovi river (Goa). The geochemical behaviour of these sediments has been studied by leaching the samples with 5 % ethylenediaminetetraacetic acid at pH 3.0 in order to investigate the processes occurring on the surface of the sediment particles and the distribution of natural thorium in estuarine sediments. The²²⁸Th/²³²Th activity ratios have been found to be in the range of 2.00 to 2.12. This anomaly between²³²Th and²²⁸Th has been attributed to the preferential leaching of²²⁸Ra by water flowing over these sediments. The activities of²²⁸Ra on the surface labile layers of the sediments have also been determined. The²³⁰Th/²³²Th activity ratios have been found to be in the range of 0.94 to 1.04. These ratios are mainly dependent on the precipitation action of²³⁰Th on adjacent sediments.     

New sulfonate-containing network polymers based on immobilized <Emphasis Type="Italic">cis</Emphasis>-metacyclophane-3,5,10,12,17,19,24,26-octols

Polymeric metacyclophaneoctol-based sulfonic acids have been synthesized, and their ion-exchange properties have been studied. New polymeric sulfonic acids have been obtained through the sulfonation of network polymers based on immobilized cis-metacyclophane-3,5,10,12,17,19,24,26-octols. The structure of the polymers has been investigated by means of IR spectroscopy, potentiometric titration, and elemental analysis. The polymers thus obtained possess a high ion-exchange capacity with respect to Na⁺, Cu²⁺, [Pd(NH₃)₄]²⁺, and In³⁺ cations in a wide pH range. Selectivity coefficients of Na⁺-H⁺, Cu²⁺-H⁺, and In³⁺-H⁺ ion exchange have been estimated.     

Laser Spectroscopy on the MgH A2Π - X2Σ+ Band System

The A²Π - X²Σ⁺ electronic transition of MgH has been studied by the laser excitation spectroscopy. Some new transitions have been observed for the first time. Rotational parameters of the X and A state have been derived and compared with other experimental values.     

13C?1H coupling constants in 9, 10-dihydroanthracene

The ¹H and ¹³C NMR spectra of 9,10-dihydroanthracene have been obtained at 2.1 and 9.4 T using selective decoupling of the methylene protons. Complete spectral analyses of the experimental spectra have provided the chemical shifts and coupling constants. The ¹³C? ¹H coupling constants in 9, 10-dihydroanthracene and biphenylene have been well accounted for by MNDO theoretical calculations of the molecular geometries and bond orders in these compounds.     

Determination of the methyl group rotation energy barrier in some substituted tricyclo [3.1.0.02,6]hexanes by carbon-13 spinlattice relaxation

The resonances in the ¹³C NMR spectra of 1,2,5,6-tetramethyl-3,4-dimethylenetricyclo[3.1.0.0^2,6]hexane and the corresponding enone and dione have been assigned. The rotation energy barriers of the methyl groups have been determined from ¹³C spin-lattice relaxation time measurements; barriers of 6.7–10.9 kJ mol^?1 have been found. Since X-ray data have shown that the skeleton bonds are bent away from the CCH₃ axis by angles of over 120°, only minor interactions occur between adjacent methyl groups. Therefore, these barriers are mainly governed by interactions with the CC skeleton bonds.     

Synthesis,structural and conformational study of 6-hydroxy (or acyloxy) derivatives of the 1,3-dimethyl-1,3-diazoniatricyclo[3.3.1.13–7]decane system

1,3-Dimethyl-1,3-diazoniatricyclo[3.3.1.1^3–7]decan-6-ol, and his p-chlorobenzoxy and diphenylacetoxy derivatives have been synthesized and studied by ¹H and ¹³C nmr spectroscopy. The crystal structure of the alcohol 2a has been determined by X-ray diffraction. Each ring of the adamantane cage system is a nearly perfect chair. From the ¹H and ¹³C nmr data, several stereoelectronic effects have been deduced.     

Electron transfer oxidation kinetics of Na2[Mo2O4EDTA] by S2O82− ion in dilute acid medium

Na₂(Mo₂^vO₄EDTA).4H₂O crystals have been prepared in pure form. Kinetics for the oxidation of the compound by S₂O₈²⁻ have been studied spectrophotometrically in dilute sulphuric acid medium. The effects of hydrogen ion concentration, metal ion concentration, S₂O₈²⁻ ion concentration, and temperature on the process have been studied. Rate equations have been derived to explain the experimental observations. On the basis of the observations, suitable mechanisms have been suggested. The kinetic parameters E^*, ΔH^≠, and ΔS^≠ of the process have also been determined. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 269–274, 1997     

Extraction of cesium from water into nitrobenzene using hydrogen dicarbollylcobaltate in the presence of p-nonylphenylnonaethylene glycol

The extraction of cesium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of Slovafol 909 (p-nonylphenylnonaethylene glycol, L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL₂ ⁺, CsL⁺ and CsL₂ ⁺ are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Views on quality tests of radiopharmaceuticals

The quality tests of radionuclides produced from generators (⁹⁹Mo→^99mTc,¹¹³Sn→^113mIn) have been reviewed. The quality controls of radiopharmaceuticals derived from these radionuclides and prepared with the help of ready-for-use reagents assembled in kits have been presented. The possibility of new tests regarding sterility (by means of a radiometric method) and detection of endotoxin (based on gelification of limulus amoebocyte lysate) have been suggested.     

Synthèse de la désamino1-Orn8-vasopressine,de la désamino1-Phe2-Orn8-vasopressine,de la désamino1-Ile3-Orn8-vasopressine (= désamino1-Orn8-oxytocine) et de la désamino1-Phe2-Ile3-Orn8-vasopressine (= désamino1 -Phe2-Orn8-oxytocine)

Four analogues of the vasopressins have been synthesised: Deamino¹-Orn⁸-vasopressin, Deamino¹-Phe²-Orn⁸-vasopressin, Deamino¹-Ile³-Orn⁸-vasopressin (= Deamino¹-Orn⁸-oxytocin) and Deamino¹-Phe²-Ile³-Orn⁸-vasopressin (= Deamino¹-Phe²-Orn⁸-oxytocin). The two former have been prepared by condensation of tripeptide azides with an hexapeptide. The two latter have been obtained from the hexapeptide by the recurring method, using active trichlorophenyl esters.     

13C NMR spectroscopy of natural substances: IV—13C NMR studies of trachylobane diterpenes: Complete carbon assignment

The diterpene trachylobane and a series of derivatives have been completely analysed by FT ¹³C NMR spectroscopy. All ¹³C frequencies for trachylobanol have been unambiguously assigned by experimental techniques, i.e. by proton single-frequency selective decoupling and shift reagent experiments. Shift calculations have been performed for the parent compound by using known methods. The results are discussed in comparison with the experimental data. Satisfactory agreement between predicted and experimental values has been obtained.     

Solid State NMR Characterisation of Encapsulated Molecules in Mesoporous Silica

Ibuprofen molecules have been encapsulated in mesoporous MCM-41 type-silica functionalised or not by amino groups. They have been characterised by ¹³C and ¹H solid state NMR spectroscopy. The ¹³C MAS single pulse or cross polarization NMR spectra, as well as the ¹H MAS NMR spectra demonstrate an extremely high mobility of the ibuprofen molecules when the matrix is not functionalised. On the contrary, when the silica matrix is functionalized by amino groups, the ¹³C NMR response shows less mobility suggesting the existence of interactions between the amino groups and the carboxylic groups. Benzoic acid as well as benzamide have also been encapsulated and their NMR responses compared to that of ibuprofen.