Micro-synthesis and electron ionization mass spectral analysis of O-alkyl N,N-dialkylphosphoramidocyanidates

This communication describes microsynthesis and GC/MS analysis of O-alkyl N,N-dialkylphosphoramidocyanidates (ADAPCs), which are analogues of chemical warfare agent, Tabun. The study was undertaken with a view to develop spectral data base of ADAPCs for verification purpose of Chemical Weapons Convention (CWC). Reported microsynthetic approach has advantages over traditional synthesis in terms of efficiency, synthetic waste, and exposure to toxic chemicals. GC/MS analysis of variety of these compounds (ADAPCs) was performed. Based on the obtained mass spectra of structurally diverse ADAPCs, the fragmentation routes are proposed, which explains most of the characteristic ions.     

Phosphorus containing polymers. Part 5. Polyazoxyphosphonate

A new polyazoxyphosphonate was synthesized by reaction of 4-4-dihydroxyazoxybenzene and dichlorophenyl phospine oxide by interfacial polycondensation using a phase transfer catalyst. The polymer was characterized and the results obtained by various analytical techniques indicate that it is mostly amorphous, low molecular weight and soluble in organic solvents such as DMF, DMAC, NMP, etc. The high char residue (40%) and limiting oxygen index indicate flame retardancy of the polymer which is due to phosphorus. Thermal stability of this polymer is moderate. TheT _g appears to be at 152°C.     

Electrical conductivity of thermally degraded poly(vinyl chloride)–polyacrylonitrile blends

Finely powdered blends of poly(vinyl chloride) (PVC) and polyacrylonitrile (PAN) have been thermally degraded at 275°C for 24 h in an inert atmosphere to effect complete de-hydrochlorination of PVC to a conjugated polyene structure and simultaneous internal polymerization of nitrile groups in PAN to a conjugated polyimine sequence. The room temperature d.c. conductivity of the degraded blends showed clear synergistic behavior. A maximum conductivity has been observed with a blend of 60 PAN/40 PVC which is about 4 orders of magnitude over the linearly weighted average conductivity of the individual degraded homopolymers. The results have been interpreted in terms of a possible donor-acceptor interaction between the degraded homopolymers leading to mutual doping and, hence, an enhanced electrical conductivity. © 1995 John Wiley & Sons, Inc.     

Synthesis, characterization, physicochemical, and photophysical studies of redox switchable NIR dye derived from a ruthenium-dioxolene-porphyrin system

Newly synthesized semi-quinone derivatives of the ruthenium polypyridyl, covalently linked to a porphyrin core, show very high epsilon values (59,000-83,500 M(-1)cm(-1)) for the absorption band in the near infrared (NIR) region of the spectrum. Further, complexes 1-4 show an interesting reversible electrochromic behavior as a function of the redox state of the coordinated dioxolene functionality, and a switching phenomenon between bleaching and the restoration of the NIR peak could be achieved electrochemically. Thus, complexes 1-4 could be ideal candidate materials for NIR-active electrochromic devices. Ultrafast studies on 1 and its mononuclear components, 5-(3,4-dihydroxyphenyl)-10,15,20-triphenyl-21H,23H-porphyrin (H2L1) and Ru(bpy)2(bsq)+, reveal that there is no electron or energy transfer from the porphyrin to the Ru(bpy)2sq+ (bpy is 2,2'-bipyridine and sq is the deprotonated species of a substituted semi-quinone fragment) fragment or vice versa in 1. The observed decrease in the luminescence quantum yield for 1 compared to that of H2L1 can be ascribed to the increased nonradiative pathway due to higher vibronic coupling because of the direct linkage of the metal center to the porphyrin moiety.     

Studies in some new initiator systems for vinyl polymerization. IV. Amino acids as the reducing component

Amino acids have been found to form good redox initiator systems with halogens (Cl₂ and Br₂), KBrO₃, KMnO₄, and Fe(NH₄)(SO₄)₂. The three systems, viz., glycine–Cl₂, taurine–Cl₂, and sulfamic acid–Cl₂ incorporate amine, carboxy (or sulfoxy), chlorine, and hydroxy endgroups in the resulting polymers, the monomer investigated being mainly methyl methacrylate. On the basis of endgroup results it is suggested that initiation through amino acid radical, chlorine radical and also through some hydroxyl radicals takes place. The probable termination mechanism is discussed.     

Quantitative treatment of the dye partition method of analysis of surfactants and of ionic groups in high polymers

A quantitative treatment of the extraction of ionic dyes from aqueous solutions into organic solvents of low dielectric constant by surfactants or polymers with ionic groups having a charge opposite to that of the dye ion, is presented. The assumption is made that the extracted species are ion-paired in the organic phase. Based on this, a graphical extrapolation method is suggested for the quantitative estimation of ionic groups in polymers. Theoretically, the method should yield quantitative results irrespective of polymer chain length and character. This method of analysis does not require any calibration data.     

TDPAD measurements of magnetic hyperfine field for <Superscript>132</Superscript>Ba in ferromagnetic Ni

The magnetic hyperfine field of Ba in ferromagnetic Ni has been measured by time differential perturbed angular distribution technique using the 13 ns 10⁺ isomeric state in ¹³²Ba as probe which was populated in the reaction ¹²C(¹²⁴Sn, 4n) ¹³²Ba at beam energy of 60 MeV. The hyperfine field extracted from the observed Larmor precession frequency comes out to be ?84(5) kG. Our experimental results show good agreement with theoretical calculations performed within local density approximation of the density functional theory. The hyperfine field data presented here would be useful towards accurate determination of g-factor in other high spin states in Ba isotopes.     

A new model system for diffusion NMR studies of concentrated monodisperse and bidisperse colloids

A method to prepare monodisperse and simultaneously NMR-visible and fluorescent colloidal particles is described, and a systematic approach to obtain spectrally resolved diffusion coefficient for every component in a monodisperse colloidal suspension is presented. We also prepared bidisperse colloidal suspensions, where each colloid component has a distinct NMR spectral signature, and obtained the diffusion coefficients of both colloid species simultaneously in concentrated colloidal suspensions, with volume fractions between 20 and 50%. The colloidal model system developed in this work enables the study of colloidal phase behavior in binary mixtures for different number and size ratios.     

Angular momentum population in fragmentation reactions

Using a relativistic transport model followed by a statistical sequential binary emission model, the population of metastable high-spin isomeric states are studied in relativistic projectile fragmentation reactions. The initial angular momentum distribution are generated from hole excitations. We find that the angular momentum distribution of the excited prefragments are considerably broadened due to light particle evaporation. The model reproduces the experimentally measured population of relatively low-lying states and underpredicts states with high angular momentum I?17?$I?17?$. We propose that coupling the spin of the excited and hole states in the prefragment will give a better understanding of the data.