2,859 publications from this institution
The title Schiff base compound, C(16)H(14)N(2)O(2), has been synthesized by the reaction of 5-amino-3,4-dimethyl-isoxazole and 2-hydr-oxy-1-naphthaldehyde. The dihedral angle between the isoxazole ring and the napthyl ring system is 3.29 (7)°. The mol-ecule adopts an E configuration about the central C=N double bond. Intra-molecular O-H⋯N hydrogen bonding generates an S(6) ring motif. In the crystal structure, π-π inter-actions are observed involving the isoxazole ring and the substituted benzene ring of the naphthyl unit, with centroid-centroid distances of 3.5200 (10) Å.
Metal-organic frameworks (MOFs) having a large surface area and porosity as well as a high density of transition metals are increasingly used as heterogeneous catalysts for organic reactions. However, one of the main limitations of various MOFs has been their lack of structural stability that led to an assumption that MOFs are unstable materials, particularly in water or polar solvents. However, since a few years ago the hydrothermal stability of several MOFs such as MIL-101(Cr), MIL-53(Al) and ZIF-8 has been demonstrated and, hence, they can be used as solid catalysts in the aqueous phase. The present review is aimed at showing that there are a sufficiently large number of reports proving that certain MOFs can be used as reusable catalysts in water as the solvent. The use of water as the solvent has considerable advantages from the environmental point of view and affordability. Water can be the solvent of choice for hydrolytic processes, but MOFs have been reported as catalysts in water even for esterifications and C-C couplings. Considering that the synthesis of new MOFs is an active area of research and the flexibility in the selection of transition metals and organic linkers, these materials can be prepared with the required hydrophilicity/hydrophobicity to adapt specifically for catalysis in aqueous phase.
Chitosan-bounded copper (chitosan-Cu) was introduced for green synthesis of novel ferrocenated spiropyrrolidine hybrids, namely 3'-(4-.bromobenzoyl)-5'-(4-hydroxybenzyl)-4'-ferrocenylspiro[indoline-3,2'-pyrrolidin]-2-one and 3'-(4-bromobenzoyl)-4'-ferrocenylspiro[indoline-3,2'-pyrrolidin]-2-one, in good yield. A one-pot three-component 1,3-dipolar cycloaddition reaction was employed for the formation of spiropyrrolidines from 1-(4-bromophenyl)-ferrocene-prop-2-en-1-one and azomethine ylides, which were developed in situ from tyrosine, glycine, and isatin, respectively. Various spectroscopic methods were used to establish the structures of spiropyrrolidines, and a single crystal X-ray diffraction study of a spiropyrrolidine provided additional confirmation. The crystallographic study revealed that compound <b>3a</b> has one independent molecule in its unit cell, which is correlated with Hirshfeld surface analysis, and describes intramolecular contacts adversely. The highly yielded products in green conditions were determined for their antibacterial significance and were found to have good activity against Gram-positive and Gram-negative bacterial strains.
In the title compound, C(18)H(20)O(4)S, the thio-phene and benzene rings are oriented at a dihedral angle of 10.83 (11)°. The central chain makes dihedral angles of 1.86 (13) and 9.25 (12)° with the benzene and thio-phene rings, respectively. In the crystal, mol-ecules are linked through weak inter-molecular C-H⋯O inter-actions. π-π inter-actions are also observed between the benzene rings with a centroid-centroid distance of 3.6832 (12) Å. The slippage between the benzene rings is 0.956 Å.
Purpose The purpose of this paper is to investigate the effect of annealing on photochromic performance of (E)‐dicyclopropylmethylene‐(2, 5‐dimethyl‐3‐furylethylid‐ene)‐succinicanhydride doped in polyacrylic acid thin film. Design/methodology/approach (E)‐dicyclopropylmethylene‐(2,5‐dimethyl‐3‐furyl‐ethylidene)‐succinic‐anhydride (DMDFS‐E) fulgide doped in polyacrylic acid thin films was prepared. DMDFS‐E fulgide doped in polyacrylic acid thin films was heated at various annealing temperatures. Photocoloration, photobleaching and photochemical fatigue resistance for the desired DMDFS‐E fulgide doped in polyacrylic acid thin films were studied. Findings Upon irradiation with UV light (366 nm), fulgide DMDFS‐E undergoes a conrotatory ring closure to the pinkish colored closed form C (523 nm). The later color was switched back to the original color when the films were irradiated with white light. The kinetics of photocoloration and photobleaching processes were followed spectrophotometrically by monitoring the absorbance of the ring closed product DMDFS‐C at its λmax of 523 nm. The first‐order plots of photocoloration reaction showed distinct linear line at different temperatures. The slope of these first‐order lines corresponding to the rate constants k. It was found that for photocoloration reaction, the rate constant of the photocoloration reaction was slower than the photobleaching reaction and both reactions decrease with increasing the annealing temperatures. It was found that there was almost improvement of photochemical fatigue resistance of fulgide DMDFS‐E doped in polyacrylic acid thin film at several of the annealing temperatures. Originality/value The results obtained in this work showed that the photochromic properties of DMDFS fulgide E were improved upon annealing the film at 100°C. Therefore, it would be recommended for improvement to apply fulgides as annealed polymer films.
In this paper we report a nano concentration of ruthenium(III) used as a homogenous catalyst for the oxidation of thiamine (THM) by chloramine T(CAT) alongwith its mechanistic pathway, spectrophotometrically.Such studies are greatly helpful in gaining an insight into the interaction of metal ions through the study of the mechanistic pathway of THM in redox reactions. The reaction followed a pseudo first-order rate constant throughout the variation of CAT in the oxidation of THM. It was observed that the first-order kinetics with respect to [Ru(III)], [THM] and [H+].It is clear from the experiential values of rate constant increase with increased concentration of each reactant. The investigators, thus, concluded that the variations of [p-toluene sulphonamide, PTS] and halide ions have an insignificant effect on the reaction rate. Protonated CAT, TsNHCl, and chloro complex of Ru(III), [RuCl5(H2O)]2−, have been suggested as the reactive species in acidic medium. The stochiometry of the reaction is 1:1 in the presence of catalyst. The two main products, 4-amino-2-methyl-4,5-dihydropyrimidine-5-carbaldehyde and 2-(4-methyl-1,3-thiazol-5-yl)ethanol and 2-(4-methyl-1,3-thiazol-5-yl)ethanol were separated, and identified by column chromatography, TLC and FT-IR. Consequently, the interaction between the complex species and THM is supported kinetic orders of reaction by spectrophotometric verification, positive entropy of activation and the first-order rate constant increased with the decrease in the dielectric constant and increase ionic strength of the medium. The reaction constants involved in the mechanism were computed and the overall activation parameters were evaluated which lend support to the proposed mechanism.
