Physico-Chemical Studies on the Interaction of Surface Active Substances at the Dropping Mercury Electrode in Pulsating Field

The tensammetric measurements indicated an appreciable interaction of o-cresol with piperidine as well as with triethanolamine in aqueous media. The sharp discontinuities in the mixtures of o-cresol + piperidine and o-cresol + triethanolamine at the mole ratio 3:1 for o-cresol to amine are observed by tensammetric, conductommetric and high frequency measurements. The shift of peak potential as well as increase in the magnitude of peak of the mixture have been utilized in determining the composition of the complexes by tensammetric measurements. The nature of formation of such complexes has been predicted. The nature of such interactions have been investigated by infra-red studies. The molar ratio of phenol to amine (piperidine and triethanolamine) are also estimated to be 3:1.     

Kinetic study of the oxidation of isobutyraldehyde by aqueous chlorine

The kinetics of oxidation of isobutyraldehyde with aqueous chlorine has been investigated in 11.6 vol. % aqueous acetic acid. The reaction is first order with respect to both substrate and chlorine. Molecular chlorine is the principal oxidant. The influence of various factors, e.g. ionic strength, inorganic salts, D₂O and temperature on the initial rate has been studied. The activation parameters have been calculated and a possible mechanism is suggested.

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11,6% . , . . ( , , D₂O) . .

     

The use of ion-molecule reactions in the mass spectrometric location of double bonds

A method for the location of the positions of carbon-carbon double bonds using high pressure mass spectrometry is proposed. A known olefinic molecular ion reacts with a second, unknown olefin to form a four-centre complex, which fragments with retention of the structural identity of methylene and substituted methylene groups to eliminate a new olefin molecule and to form an unsaturated ion from which the position of the double bond in the unknown olefin can be inferred. Vinyl methyl ether proved to be a convenient reagent gas and its molecular ion undergoes the required reaction with several classes of olefinic compound. Conjugated dienes and unsaturated compounds containing electronegative groups do not undergo this reaction.     

Synthesis and binding studies of new bis-calix[4]arenes containing aromatic and heteroaromatic units

A series of new bis-calix[4]arenes containing different aromatic and heteroaromatic moieties have been synthesized. The complexing behavior of these bis-calix[4]arenes have been studied towards different metal ions and it has been found that these bis-calix[4]arenes bind silver ions selectively over other metal ions. The complexation has been studied by liquid-liquid extraction and by NMR and IR spectroscopy.     

Investigation of the reactions of fluorinated isatins and N-acetylisatins with thiocarbohydrazide: Synthesis of a novel spiro system: 2-oxo-1′,2′,4′,5′-tetrahydrospiro[3H-indole-3,3′-1,2,4,5-tetrazine]-6′-thione

A novel system 2-oxo-1′,2′,4′,5′-tetrahydrospiro[3H-indole-3,3′-1,2,4,5-tetrazine]-6′-thione has been synthesized by the treatment of fluorinated isatins with thiocarbohydrazide in aqueous ethanolic medium. Under exactly similar conditions, N-acetylisatin gave exclusively thiocarbohydrazone. The spiro product, on treatment with acetic acid, gave fluorinated isoindigo. Characterization of these products have been done by elemental analyses, ir, pmr and mass spectral studies.     

4-t-Butylphenoxo complexes of oxovanadium(V)

Summary Complexes of composition [VOCl₂(OC₆H₄Bu-t-4)] (1) and [VOCl(OC₆H₄Bu-t-4)₂] (2) have been synthesized by the reaction of VOCl₃ with equimolar and bimolar amounts, respectively, of 4-t-BuC₆H₄OSiMe₃ in CCl₄ and characterized by physio-chemical techniques. The complexes react with -hydroxyaldehydes and ketones such as 2-hydroxybenzaldehyde (salicylaldehyde, salH), and 2-hydroxy-2-phenylacetophenone (benzoin, benzH), 2-hydroxyacetophenone (hapH) and also with the potassium salt of p-chlorobenzohydroxamic acid (KBHACl) in 11 and 12 molar ratios, to yield five- and six-coordinate complexes.     

On the long-lived transient absorption observed in nanosecond laser photolysis studies of two polymethine cyanine dyes

It is shown that the long-lived transient absorption which is observed when solutions of cryptocyanine and DDI (1, 1′-diethyl-2, 2′-dicarbocyanine iodide) in methanol and other alcohols are exposed to nanosecond ruby laser pulses arises from a photoproduct whose formation requires consecutive absorption of two photons.     

Lipid-protein interactions in the membrane: studies with model peptides

We have used fluorescence quenching of tryptophan-containing trans-membrane peptides by bromine-containing phospholipids to study the specificity of peptide-lipid interactions. We have synthesized peptides Ac-K2GLm WLnK2A-amide where m = 7 and n = 9 (L16) and m = 10 and n = 12 (L22). Binding constants of L22 for dioleoylphosphatidylserine [di(C18 : 1)PS] or dioleoylphosphatidic acid [di(C18 : 1)PA] relative to dieoleoylphosphatidylcholine [di(C18 : 1)PC] were close to 1. However, for L16, whilst the bulk of the di(C18 : 1)PA molecules bound with a binding constant relative to di(C18 : 1)PC close to 1, a small number of di(C18 : 1)PA molecules bound much more strongly. Assuming just one high affinity binding site on L16 for anionic lipid, the affinity of the site for di(C18 : 1)PS was calculated to be ca. 8 times that for di (C18 : 1)PC. The relative binding constant was little affected by ionic strength and close contact between the anionic headgroup of di(C18 : 1)PS and a lysine residue on the peptide was suggested. The relative binding constant for di(C18 : 1)PS at this high affinity site was less than for di(C18 : 1)PA. Cholesterol interacts with L22 with an affinity about 0.7 of that of di(C18 : 1)PC. The structure of the peptide itself is important. The peptide Ac-KKGYL6WL8YKKA-amide (Y2L14) incorporated into bilayers of dinervonylphosphatidylcholine [di(C24 : 1)PC] whereas L16 did not incorporate into this lipid. It is suggested that thinning of a lipid bilayer around a peptide to give optimal hydrophobic matching is less energetically unfavourable when a Tyr residue is located in the lipid/water interfacial region.     

Remote Raman and fluorescence studies of mineral samples

In the present study, we investigated remote laser-induced fluorescence (LIF), at a distance of 4.8 m, of a variety of natural minerals and rocks, and Hawaiian Ti (Cordyline terminalis) plant leaves. These minerals included calcite cleavage, calcite onex and calcite travertine, gypsum, fluorapatite, Dover flint and chalk, chalcedony and nephelene syenite, and rubies containing rock. Pulsed laser excitation of the samples at 355 and 266 nm often resulted in strong fluorescence. The LIF bands in the violet-blue region at approximately 413 and approximately 437 nm were observed only in the spectrum of calcite cleavage. The green LIF bands with band maxima in the narrow range of approximately 501-504 nm were observed in the spectra of all the minerals with the exception of the nephelene syenite and ruby rocks. The LIF red bands were observed in the range approximately 685-711 nm in all samples. Excitation with 532 nm wavelength laser gave broad but relatively low fluorescence background in the low-frequency region of the Raman spectra of these minerals. One microsecond signal gating was effective in removing nearly all background fluorescence (with peak at approximately 610 nm) from calcite cleavage Raman spectra, indicating that the fluorescence was probably from long-lifetime inorganic phosphorescence.