2,859 publications from this institution
Abstract The interaction of an anionic textile dye, acid red 151 (AR), with a cationic surfactant, cetyltrimethylammonium bromide (CTAB), in aqueous electrolyte medium (e.g., KCl, NaCl) and in H 2 O + ethanol medium was observed using the conductometric method. Two critical micelle concentrations ( CMC ) were found for the AR + CTAB system in water and H 2 O + ethanol medium, but only one CMC was detected for AR + CTAB in salt+H 2 O media and for pure CTAB in all solutions. The change in CMC behavior of CTAB in the presence of AR indicates the occurrence of strong interaction between AR and CTAB. The extent of solubility increases with an increase of temperature, which disfavors micellization. The CMC values in NaCl solution are comparatively lower than those found in KCl solution, which signifies that the micelle formation is more favorable in attendance of NaCl. In aqueous ethanol solution, two CMC values were also observed for AR + CTAB that are higher than those obtained in water. The free energy of micellization ( ) was negative, which illustrates a thermodynamically spontaneous micellization process. The values of enthalpy ( ) and entropy ( ) of micellization show that the process was entirely entropically driven at a lower temperature; but, enthalpic events are favored at elevated temperature in electrolyte medium, whereas both enthalpy and entropy are reduced in attendance of ethanol. In aqueous medium, the thermodynamic parameters signify the presence of electrostatic interaction between AR and CTAB at higher temperatures, while the hydrophobic interaction is the main driving force at a lower temperature. A linear expression of as a function of demonstrates enthalpy‐entropy compensation over the experimental conditions employed in this study.
Purpose To evaluate the photo, thermo, piezo and solvatochromism of new bis‐imidazole derived from three isomers of chlorobenzaldehyde. Design/methodology/approach The synthesis of the three new bis‐imidazoles was accomplished using modified procedure of the previously reported method, by dissolving the imidazol derivative and cooling in ice bath, and adding potassium ferricyanide drop wise. The compounds were used evaluate the effects of the position of the substitutions on the aromatic ring, on the photo, thermo and piezochromic properties. Findings New bis‐imidazole derived from 2‐chloro, 3‐chloro and 4‐chloro phenyl have been synthesised and their photochromic properties upon irradiation with ultraviolet light were studies in different solvents. The photochromic properties and performance were affected remarkably upon changing the solvent. Also, the thermochromic properties upon heating in different solvents were studied. The dimers showed piezochromism on grinding. Practical implications The method reported for the synthesis is simple. The new compounds showed photochromic, thermochromic, piezochromic, and solvatochromic making them potential candidates for many applications such as sensors, optical data storage and heat sensitive materials. Originality/value The method for preparation was modified and improved. The materials prepared were new compounds.
The sp(3)-hybridized methine C atom in the title compound, C(19)H(18)O(5), lies out of the mean plane of the remaining 13 atoms of the naphthopyran fused-ring system by 0.571 (1) Å, and its H atom occupies a pseudo-equatorial site.
We have prepared calcined Ag2O nanoparticles (NPs) by a wet-chemical method using reducing agents in alkaline medium. The NPs were characterized by UV/vis., FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Energy-dispersive X-ray spectroscopy, and Field-Emission Scanning Electron Microscopy (FESEM) etc. NPs were embedded onto μ-chips to fabricate a sensor with a fast response towards aprepitant (APPT) in phosphate buffer phase. The fabricated APPT sensor on NPs/μ-chips also exhibits higher sensitivity, low-sample volume, reliable, reproducibility, easy integration, long-term stability, and enhanced electrochemical responses. The calibration plot is linear (r2 = 0.9852) over the large APPT concentration ranges (2.2 nM to 4.1 μM). The sensitivity and detection limit is calculated as ~2.732 μAcm-2μM’1 and ~0.29 nM (SNR of 3) respectively. Here, it is also discussed the possible potential uses of the NPs in terms of APPT sensing, which could also be employed for the determination of biochemicals in quality control of formulation.
Cu<sub>3</sub>(BTC)<sub>2</sub> (BTC: 1,3,5-benzenetricarboxylate) as a heterogeneous catalyst in the presence of cesium carbonate as a base is reported for the borylation of α,β-conjugated enones by bis(pinacolato)diboron (B<sub>2</sub>pin<sub>2</sub>). According to the hot-filtration test, Cu<sub>3</sub>(BTC)<sub>2</sub> is acting as a heterogeneous catalyst. Further, Cu<sub>3</sub>(BTC)<sub>2</sub> exhibits a wide substrate scope and can be reused in consecutive runs, maintaining a crystal structure as evidenced by powder X-ray diffraction (XRD). A suitable mechanism is also proposed for this transformation using Cu<sub>3</sub>(BTC)<sub>2</sub> as catalyst.