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Picric Acid (picric + acid)
Selected AbstractsSupramolecular order following binding of the dichroic birefringent sulfonic dye Ponceau SS to collagen fibersBIOPOLYMERS, Issue 3 2005B. C. Vidal Abstract The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggregates of the sulfonic azo-dye Ponceau SS and of dye complexed with chicken tendon collagen fibers were investigated in order to assess their polarizing properties and similarity to liquid crystals. In some experiments, the staining was preceded by treatment with picric acid. Crystalline fibrous aggregates of the dye had a negative LD, and their electronic transitions were oriented perpendicular to the filamentary structures. The binding of Ponceau SS molecules to the collagen fibers altered the LD signal, with variations in the fiber orientation affecting the resulting dichroic ratios. The long axis of the rod-like dye molecule was assumed to be bound in register, parallel to the collagen fiber. Picric acid did not affect the oriented binding of the azo dye to collagen fibers. There were differences in the optical anisotropy of Ponceau SS-stained tendons from 21-day-old and 41-day-old chickens, indicating that Ponceau SS was able to distinguish between different ordered states of macromolecular aggregation in chicken tendon collagen fibers. In the presence of dichroic rod-like azo-dye molecules such as Ponceau SS, collagen also formed structures with a much higher degree of orientation. The presence of LD in the Ponceau SS-collagen complex even in unpolarized light indicated that this complex can act as a polarizer. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 121,128, 2005 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Directly Heated Bismuth Film Electrodes Based on Gold MicrowiresELECTROANALYSIS, Issue 13 2010Martin Jacobsen Abstract As a nontoxic substitute for mercury electrodes, bismuth electrodes attained a lot of attention during the last years. In this report we describe for the first time the preparation of two different directly heatable bismuth-modified microwire electrodes. We characterized the electrochemical behaviour using cyclic voltammetry in acetate buffer and alkaline tartrate solution. The bismuth electrodes show a significantly wider potential window compared with bare gold wires. In the presence of picric acid as one example for the detection of explosives, the bismuth electrodes deliver higher signals. By applying heat during the measurements, the signals can be enhanced further. We used the temperature pulse amperometry (TPA) technique to improve the electrochemical response at the different types of electrodes. In this preliminary study, we were able to detect 3,ppm traces of picric acid. [source] Molecular "Glass" Blowing: From Carbon Nanotubes to Carbon Nanobulbs ,ADVANCED MATERIALS, Issue 5 2004P. Zhu Molecular-scale "glass" blowing of multi-wall carbon nanotubes into nanobulbs (see Figure) is achieved in a unique tube growth environment generated by the explosive decomposition of picric acid. Results indicate that carbon nanotubes have remarkable thermoplasticity and structural fluidity during their generation, and can be engineered into various shaped micro-vessels or devices. [source] Band gaps and the possible effect on impact sensitivity for some nitro aromatic explosive materialsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 7 2009Hong Zhang Abstract The first principle density functional theory method SIESTA has been used to compute the band gap of several polynitroaromatic explosives, such as TATB, DATB, TNT, and picric acid. In these systems, the weakest bond is the one between an NO2 group and the aromatic ring. The bond dissociation energy (BDE) alone cannot predicate the relative sensitivity to impact of these four systems correctly. It was found that their relative impact sensitivity could be explained by considering the BDE and the band gap value of the crystal state together. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Spectrophotometric determination of the transition system for interactions involving model hydrogen bonds in acetonitrileJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 4 2002Józef Mago Abstract The bonds formed by interactions of picric acid (HA) with each of 12 (un)substituted pyridines (B) in acetonitrile (AN) were studied by UV,vis spectrophotometry to determine the corresponding to the transition system. The choice of both model system and experimental technique enabled the effect of heteroconjugation to be observed and the effects of formation of two theoretically possible homoconjugates (AHA, and BHB+) to be eliminated. The relationship between the wavelength at the absorbance maximum (,max) for 10,4,M solutions of complexes of picric acid with (un)substituted pyridines in acetonitrile and was found to have a sigmoidal shape with an inflection point at of ca ,0.3. On the basis of this relationship and UV,vis spectra, the picric acid,3-acetylpyridine system was recognized as that being the nearest to the transition system. The fact that the transition was lower than zero has been explained by the remarkable effect of species having the average structures A,···+HB on the established ,max values. The general results of this work and our previous results based on IR and 1H NMR studies, and also the lack of any experimental counterexamples, indicate that the zero value of constitutes a fundamental basis for predicting which one, among the given family of protonic hetero systems, is the most likely to show transitional properties in acetonitrile. Finally, it is postulated that the protonic hetero systems which are the most likely to show transitional properties in a given solvent S are those for which is close to zero, the eventual shift arising from peculiarity of the technique applied. Copyright © 2002 John Wiley & Sons, Ltd. [source] Control of polyaniline conductivity and contact angles by partial protonationPOLYMER INTERNATIONAL, Issue 1 2008Natalia V Blinova Abstract Many studies require a specific value of conductivity when investigating conducting polymers. The conductivity of polyaniline can efficiently be controlled by partial protonation of the polyaniline base. Although this is a simple task in principle, practical guidelines are missing. In the present study, the changes in the conductivity of polyaniline base after immersion in aqueous solutions of various acids are reported. Polyaniline base has been reprotonated in aqueous solutions of picric, camphorsulfonic and phosphoric acids. The conductivity of partially reprotonated polyaniline varied between 10,9 and 100 S cm,1. The relation between the pH of a phosphoric acid solution, which was in equilibrium with polyaniline, and the conductivity , is pH = 0.77 , 0.64 log(, [S cm,1]). The wettability, i.e. water contact angles, can similarly be set by partial protonation to between 78° for polyaniline base and 44° for polyaniline reprotonated in 1 mol L,1 phosphoric acid. In solutions of picric acid, the transition from the non-conducting to the conducting state occurs over a narrow range of acid concentrations, and the tuning of conductivity is consequently difficult. Phosphoric acid is well suited for the control of conductivity of polyaniline because of the moderate dependence of the conductivity on the acid concentration or pH. Copyright © 2007 Society of Chemical Industry [source] Two-dimensional networks in 2-methylanilinium picrate and 2,5-dichloroanilinium picrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Gao-Xiang Meng Both the title molecular adducts of 2-methylaniline or 2,5-dichloroaniline with picric acid are 1:1 organic salts, namely 2-methylanilinium picrate, C7H10N+·C6H2N3O7,, (I), and 2,5-dichloroanilinium picrate, C6H6Cl2N+·C6H2N3O7,, (II). In both structures, the phenoxide O atoms accept two N,H hydrogen bonds in a bifurcated acceptor fashion, which link the component ions by N,H...O hydrogen bonds into continuous two-dimensional zigzag layers, running parallel to the (100) plane in (I) and the (010) plane in (II). A ,,, interaction is observed between symmetry-related anilinium cations in (I), while in (II), Cl...Onitro and Cl...Cl interactions are observed. This study indicates that a substitution on aniline can exert a pivotal influence on the construction of its supramolecular structure. [source] Spectroscopic studies of charge transfer complexes of meso -tetra- p -tolylporphyrin and its zinc complex with some aromatic nitro acceptors in different organic solventsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 11 2007Mohamed E. El-Zaria Abstract The charge transfer complex (CTC) formation of 5,10,15,20-tetra(p -tolyl)porphyrin (TTP) and zinc 5,10,15,20-tetra(p -tolyl)porphyrin with some aromatic nitro acceptors such as 2,4,6-trinitrophenol (picric acid), 3,5-dinitrosalicylic acid, 3,5-dinitrobenzoic acid (DNB) and 2,4-dinitrophenol (DNP) was studied spectrophotometrically in different organic solvents at different temperatures. The spectrophotometric titration, Job's and straight line methods indicated the formation of 1:1 CTCs. The values of the equilibrium constant (KCT) and molar extinction coefficient (,CT) were calculated for each complex. The ionization potential of the donors and the dissociation energy of the charge transfer excited state for the CTC in different solvents was also determined and was found to be constant. The spectroscopic and thermodynamic properties were observed to be sensitive to the electron affinity of the acceptors and the nature of the solvent. No CT band was observed between Zn-TTP as donor and DNP or DNB as acceptors in various organic solvents at different temperature. Bimolecular reactions between singlet excited TTP (1TTP*) and the acceptors were investigated in solvents with various polarities. A new emission band was observed. The fluorescence intensity of the donor band decreased with increasing the concentration of the acceptor accompanied by an increase in the intensity of the new emission. The new emission of the CTCs can be interpreted as a CT excited complex (exciplex). Copyright © 2007 John Wiley & Sons, Ltd. [source] Supramolecular order following binding of the dichroic birefringent sulfonic dye Ponceau SS to collagen fibersBIOPOLYMERS, Issue 3 2005B. C. Vidal Abstract The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggregates of the sulfonic azo-dye Ponceau SS and of dye complexed with chicken tendon collagen fibers were investigated in order to assess their polarizing properties and similarity to liquid crystals. In some experiments, the staining was preceded by treatment with picric acid. Crystalline fibrous aggregates of the dye had a negative LD, and their electronic transitions were oriented perpendicular to the filamentary structures. The binding of Ponceau SS molecules to the collagen fibers altered the LD signal, with variations in the fiber orientation affecting the resulting dichroic ratios. The long axis of the rod-like dye molecule was assumed to be bound in register, parallel to the collagen fiber. Picric acid did not affect the oriented binding of the azo dye to collagen fibers. There were differences in the optical anisotropy of Ponceau SS-stained tendons from 21-day-old and 41-day-old chickens, indicating that Ponceau SS was able to distinguish between different ordered states of macromolecular aggregation in chicken tendon collagen fibers. In the presence of dichroic rod-like azo-dye molecules such as Ponceau SS, collagen also formed structures with a much higher degree of orientation. The presence of LD in the Ponceau SS-collagen complex even in unpolarized light indicated that this complex can act as a polarizer. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 121,128, 2005 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] | |||||||||||||