Synthesis of 2,3,4,5-tetranitropyrrole

Dealkylation of 1-tert-butyl-2,3,4-trinitropyrrole in boiling trifluroacetic acid gave 2,3,4-trinitropyrrole, the structure of which was confirmed by X-ray crystallography. Treatment of this trinitropyrrole with nitric acid/oleum briefly at 60° gave 2,3,4,5-tetranitropyrrole.     

Heterogeneous activation of oxone using Co3O4

This study explores the potential of heterogeneous activation of Oxone (peroxymonosulfate) in water using cobalt oxides. Two commercially available cobalt oxides, CoO and Co3O4 (CoO.Co2O3) were tested for the activation of peroxymonosulfate and the consequent oxidation of 2,4-dichlorophenol (2,4-DCP) via a sulfate radical mechanism. Both systems, CoO/Oxone and Co3O4/Oxone, were tested at acidic and neutral pH and compared with the homogeneous Co(NO3)2/Oxone. The activity of these systems was evaluated on the basis of the induced transformation of 2,4-DCP as well as the dissolution of cobalt occurred after 2 h of reaction. It was observed that only Co3O4 activates peroxymonosulfate heterogeneously, with its heterogeneity being more pronounced at neutral pH. Both CoO and Co2O3 contained in Co3O4 might be responsible for the observed heterogeneity, and the relative mechanisms are further discussed here. To our knowledge, this is perhaps the first study that documents the heterogeneous activation of peroxymonosulfate with cobalt, the best-known catalyst-activator for this inorganic peroxide.     

PHEOPHORBIDE a-INDUCED PHOTO-OXIDATION OF CYTOCHROME c: IMPLICATION FOR PHOTODYNAMIC THERAPY

Pheophorbide a-induced photo-oxidation, in vitro, of cytochrome c oxidase and cytochrome c results in irreversible modifications to both protein components. Photo-oxidation of cytochrome c, as exhibited by change in its heme oxidation state, displays exponential kinetics and is detected with a lag period. Both the photo-induced inactivation of the enzyme, and destruction of the substrate ability of cytochrome c occur as complex multi-process events. Under similar experimental conditions, the loss of the substrate capability of cytochrome c develops approximately three times faster than inactivation of the enzyme. The slight lag in the photo-oxidation of cytochrome c is due to pheophorbide a-induced superoxide production. However, the relative amount of photo-oxidant produced is considerably more effective than the cytochrome c reducing capacity of the superoxide. Neither hydroxyl radical nor hydrogen peroxide are involved in the photo-oxidation of the heme function. The possibilities of heme oxidation by a singlet oxygen mediated pathway or direct electron abstraction involving the heme or apoprotein are not excluded. It is proposed that a multi-site oxidation of numerous reduced energy cofactors within cells may augment collateral enzyme inactivation in maximizing photosensitizer-induced cytotoxicity. Accordingly, amphipathic photosensitizers, capable of accessing both lipid and aqueous compartments containing reduced cofactors, may be more effective agents for photodynamic therapy than those which exhibit a high specificity of subcellular localization.     

A modified bischler-napieralski reaction. Synthesis of 2,3,4,9- tetrahydro-1H-pyrido[3,4-B]indole derivatives and their base-catalyzed transformation to N-acetyl-N-[2-[1 -acetyl-2-[1 -(acetyloxy)-1-propenyl]- 1H-indol-3-yl]ethyl]acetamides

The treatment of N-[2-(1H-indol-3-yl)ethyl]alkanamide, 1 (1), with phosphorus oxychloride under controlled conditions gave l-alkyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-ol, 2 . The reaction of 2 with acetic anhydride or with methyl isocyanate at room temperature resulted in the formation of amido carbinol 3 and urea carbinol 7, respectively. The former was transformed into amido ester 4 by boiling acetic anhydride. When the reaction of 3 with acetic anhydride was carried out in the presence of excess triethylamine at 105°, C-N bond cleavage of the tetrahydropyridine ring took place with concurrent bis(N-acetylation) to give the enol ester derivative 5 . The structures of all compounds are consistent with chemical and spectral evidence.     

Development of combinatorial chemistry methods for coatings: high-throughput adhesion evaluation and scale-up of combinatorial leads

Coupling of combinatorial chemistry methods with high-throughput (HT) performance testing and measurements of resulting properties has provided a powerful set of tools for the 10-fold accelerated discovery of new high-performance coating materials for automotive applications. Our approach replaces labor-intensive steps with automated systems for evaluation of adhesion of 8 x 6 arrays of coating elements that are discretely deposited on a single 9 x 12 cm plastic substrate. Performance of coatings is evaluated with respect to their resistance to adhesion loss, because this parameter is one of the primary considerations in end-use automotive applications. Our HT adhesion evaluation provides previously unavailable capabilities of high speed and reproducibility of testing by using a robotic automation, an expanded range of types of tested coatings by using the coating tagging strategy, and an improved quantitation by using high signal-to-noise automatic imaging. Upon testing, the coatings undergo changes that are impossible to quantitatively predict using existing knowledge. Using our HT methodology, we have developed several coatings leads. These HT screening results for the best coating compositions have been validated on the traditional scales of coating formulation and adhesion loss testing. These validation results have confirmed the superb performance of combinatorially developed coatings over conventional coatings on the traditional scale.     

Electron-capture negative ionization calibrants for magnetic sector mass spectrometers

Fomblin [poly(perfluoropropylene oxide)], PFK (perfluorokerosene) and FC-43 (perfluorotributylamine) are investigated as mass calibrants in electron-capture negative ionization mass spectrometry on a magnetic sector hybrod mass spectrometer. This work provides exact negative ion mass tables of these three calibrants obtained using high-resolution peak matching of representative ions of the calibrants against ions of known mass. The suitability of these calibrants for full data system control in the negative ionization mode is demonstrated for the techniques of high-resolution scanning, selected ion recording and calibration of the quadrupole sector of a hybrid instrument.     

Sesquiterpenoids—27: X-ray crystallographic analysis of istanbulin-B,A 1-oxo-eremophilenolide

The stereochemistry of istanbulin-B has been defined by X-ray crystal-structure analysis. Rings A and B are transfused, with the Me groups at C(4) and C(5) cis. The α,β-unsaturated,γ -lactone ring is essentially planar. Crystals of istanbulin-B are orthorhombic, space group P2₁2₁,2₁, with a = 6.729(2), b = 13.447(3), c = 14.721(3)Â,and Z = 4. The crystal structure was determined by direct phasing and the atomic parameters were subsequently adjusted by least-squares calculations that converged at R 38% over 1179 diffractometer |F_a| values     

Organometallic chemistry : V. Protonation of acylferrocenes under stable ion conditions in fso3h-so2c1f solution

Protonation of acylferrocenes (FeCOR) in FSO₃H-SO₂CIF(SO₂) solution was studied by PMR spectroscopy. The site of protonation is found to be at the carbonyl oxygen atom. Temperature dependent PMR spectra of protonated acylferrocenes FeCROH⁺ (R = CH₃, C₂H₅, C₆H₅, OCH₃) were observed indicating intermolecular hydrogen exchange with the acid solvent system. In addition the PMR spectra of acylferrocenes in FSO₃ H-SO₂ CIF(SO₂) were found to be dependent upon the acid concentration.     

Criticality and phase transitions in ionic fluids

Recent experimental investigations of criticality and phase separation in ionic fluids have revealed behavior of great theoretical interest. In seeking to understand the experiments, some of which appear to exhibit argonlike criticality and some of which exhibit classical (mean-field) criticality, a convenient starting point is the restricted primitive model (RPM) of symmetrically charged hard spheres, all of equal diameter , each sphere bearing a positive or negative charge of magnitudeq. There is overall charge neutrality, so that the expected number densities of the anions and cations are equal, ₊= _-. Studies of RPM charge-charge and density-density correlation functions indicate that the fluctuation-suppressing mechanism that yields mean-field critical behavior in nonionic systems with long-range interparticle potentials is not operative in the RPM. On the basis of plausible assumptions, Ising-like behavior is instead expected. The above work is summarized. New work of Zhang and the author is outlined, showing that when one loses the RPM symmetry (through, e.g., different valence, diameter, or dipole moment of anions and cations) a strong coupling between charge-charge and density-density correlation ensues. The way in which this can be expected to give rise to mean-field or mean-field-like behavior is noted. Other new observations concern the mean-field analogy found by Høye and the author between the parameter 2/(d–2) (d is the dimensionality) in that model and the monomer number in high polymers, with respect to the coexistence-curve shape dependence on those parameters.     

Relativistic quarks bound with a one-body tensor potential

A dipole fit to electromagnetic form factors is used to determine a quark density in the nucleon. A radial tensor potential is used to bind the quarks into states of goodJ, J _z, and parity. The tensor potential radial component is taken to satisfy the equationT = T ₀, whereT ₀ is a parameter of the model. This linear divergence equation can be simultaneously solved with the Dirac equation for the bound quark wave functions. A self-consistent solution is possible where the mass density used as the source for the binding potential is the same as that determined from the solution for the quark wave functions.