Salvatore Occhipinti

Guest-induced capsular assembly of calix[5]arenes

Abstract Novel dimeric capsules are generated from the non-covalent assembly of cone calix[5]arenes and alkyldiammonium ions [H 3 N-(CH 2 ) n -NH 3 ] 2+ featuring an appropriate length of the spacer joining the two charged end groups. 1 H NMR spectroscopy and electrospray ionisation mass spectrometry provide evidence that in the capsule a single ditopic guest holds together a pair of calix[5]arene units, which are oriented rim-to-rim to form a closed cavity encapsulating the shape-complementary dication.

Recognition and binding of paraquat dichloride by cyclodextrin/calix[6]pyrrole binary host systems

The synergic effect of paired anion and cation receptors in the recognition of organic salts is demonstrated by the combined action of acylated cyclodextrins and calix[6]pyrrole in the solubilisation and complexation of paraquat dichloride in organic solvents, and its extraction from water solution into dichloromethane.

Adsorption isotherms on cotton of direct sky blue FF from aqueous ethanolic solutions

Abstract Adsorption isotherms at 80° Cfor Direct Sky Blue FF (C.I. Direct Blue 1) on cotton in the presence of variable amounts of NaCl (2, 10, 15 and 50 g litre−1) and ethanol (v/v) (0, 5, 10, 20, 30, 40, 50, 60%) were measured. The Langmuir equation has been used to describe the equilibrium except for the measurements obtained at 15 g litre−1 of NaCl and 50 % and 60 % of ethanol, and at 50 g litre−1 of NaCl and 20 % of ethanol for which the distribution law was followed. The saturation values increased markedly with the salt concentration. The concentration of ethanol influenced the adsorption in two ways; one was a depressing action and the other an accelerating action. The increasing concentration of ethanol decreased the degree of association of the dye and the adsorption was Langmuir type; at 15glitre−1 ofNaCl and 50% and 60% ofethanol,and 50 g litre −1 of NaCl and 20% of ethanol the degree of association of the dye increased and the adsorption was distribution type.

Kinetics of Hydrolysis of Dichlorotriazinyl Reactive Azo Dyes

The rate of hydrolysis of some dichlorotriazinyl reactive azo dyes is measured where the triazinyl-ring is attached to a derivative of H-acid in the buffer solutions over the range 25-35°C. The rate constants obtained at constant pH are pseudo-first-order, but they are dependent on the concentration of hydroxyl ion. This dependence of the hydrolysis constants on the hydroxyl ion concentration is explained, supposing that, as the pH of the dye solution increases, ionization of the phenolic hydroxyl group at the 8-positioh in the naphthalene ring occurs to give a less reactive ionized form.

Donnan Approach to Equilibrium Sorption: Influence of Electrolytes on Dyeing of Dralon X-100 with CI Basic Blue 3

We have investigated the effects of various electrolytes at different concentrations . on dyeing equilibria of CI basic blue 3 with Dralon X-100, interpreting the data with the Donnan approach. We have tried to separate the contribution of the cations and anions in the electrolytes. The results indicate that both cations and anions have independent effects on dye sorption. With increasing salt concentration, the dye sorp tion decreases, but with sodium and ammonium sulphate, an unusual increase of dye sorption occurs at salt concentrations up to 0.5 mol/l.

THE MASS SPECTRA OF SOME THIOPHENE 2- AND 3-CARBOXANILIDES

Abstract Mass spectra of some substituted thiophene-2-carboxanilides and thiophene-3-carboxanilides at 70 eV are reported. Primary main degradation reaction of these compounds occurs by cleavage of the amide bond, followed by CO elimination. The substituent effects on mass spectra are related by the Hammett equation. The plots of log Z/Z0 for substituted thiophene-3-carboxanilides against [sgrave] (r = 0.972; ρ = 0.486) and [sgrave]+ (r = 0.905; ρ = 0.346) are linear. The plot for 3-substituted thiophene-2-carboxanilides against [sgrave] give poor linearity (r = 0.797); ρ = −0.098).

THE MASS SPECTRA OF SOME SUBSTITUTED THIOPHENE-2-CARBOXYLIC ACIDS

Abstract The mass spectra of some 3-, 4-, and 5-substituted thiophene-2-carboxylic acids at 70 eV are reported. The majority of isomeric 5-and 3-substituted compounds can be differentiated by mass spectrometry. In 3-methyl-, 3-methoxy, 3-thiomethyl-, 3-methylsulphinyl-, 3-formyl-thiophene-2-carboxylic acids the fragmentation is influenced by an “ortho-effect” which activates the H2O elimination.

THE MASS SPECTRA OF SOME (E)- AND (Z)-α-(PHENYL)-β-(2-THIENYL) ACRYLAMIDES

Abstract Mass spectra of some (E)- and (Z)-α-(4-X-phenyl)-β-(2-thienyl) acrylamides at 70 eV are reported. The stereoisomeric compounds do not show significant differences. The mass spectra show a four centre reaction scheme with NH2 migration to the β-carbon atom and subsequent fission of Cα[sbnd]Cβ bond.

The protonation of some 5-substituted thiophen-2-carboxamides

The protonation behaviour at 25 °C in aqueous sulphuric acid solution of some 5-X-thiophen-2-carboxamides (X = CH3O, CH3, H, Cl, Br, I, and NO2) has been investigated by u.v. spectrophotometry. pKBH+ Values were calculated by HA, Bunnett–Olsen, and Cox–Yates methods from experimental absorption curves and by the method of multivariate analysis to separate the effect of protonation from that of the medium. Hammett treatment of the data show a value of σα– s of 0.63 ± 0.13 indicating that the sulphur atom acts as an electron withdrawing substituent. A plot of pKBH+ against σ is linear and the slope (ρ– 1.16) is greater than that of the corresponding benzamides (ρ– 0.956) indicating that the thiophen nucleus is more efficient than the benzene ring in relaying the electronic effects of substituents to the reaction centre.

1 H nuclear magnetic resonance spectra of some 3- and 5-substituted thiophen-2-carboxamides

The 1H n.m.r. spectra of some 3- and 5-substituted thiophen-2-carboxamides in CDCl3 are reported. 3-Substituted thiophen-2-carboxamides show intramolecular hydrogen bonding between the N–H proton and the 3-substituent and also an intermolecular hydrogen bond, except for the 3-methyl derivative, which exhibits only intermolecular hydrogen bonding. 5-Substituted thiophen-2-carboxamides exhibit intermolecular hydrogen bonding. The chemical shifts for the 4-protons of 3-substituted thiophen-2-carboxamides correlate with σp(r= 0.962; ρ= 1.39). Correlation for the 4-protons of the 5-substituted amides is poor.The activation energies of rotation of the 3-substituted amides are higher than those of the corresponding 5-substituted derivatives. For 5-substituted amides the activation energies of rotation depend on the electronic nature of the substituents, and ΔG(Tc)/σp+ shows a linear relationship (r= 0.954; ρ= 1.77).