Fluorescence Characteristics and Inclusion of ICT Fluorescent Probe in Organized Assemblies

The inclusion behavior of an intramolecular charge transfer (ICT) fluorescent probe namely; 2-[3-(4-dimethylamino-phenyl)-allylidene]-tetralone (DMAPT) in organized assemblies of aqueous micellar, α- and β-cyclodextrins (CDs) and bovine serum albumin (BSA) pockets have been studied using steady-state absorption and fluorescence spectroscopy. The fluorescence characteristics (energy and intensity) of DMAPT are highly sensitive to the properties of the medium. The ICT maximum is strongly blue-shifted with a great enhancement of the fluorescence intensity upon addition of different surfactants, confirming the solubilization of DMAPT in the hydrophobic micellar assembly. In addition, the fluorescence of DMAPT is more sensitive to the nature and concentration of the added CDs. In α- or β-CD solutions, the fluorescence intensity increases strongly (by 6 and 23 orders of magnitude, respectively). Upon encapsulation in the CD cavity, the molecular flexibility decreases due to the geometrical restrictions of the CD nanocavity which decreases the non radiative transition via the free rotation around the single and/or double bonds of the butadiene bridge. This was supported by finding that the fluorescence quantum yield of DMAPT increases with increasing the viscosity of the medium. The binding constants of DMAPT with micelles, α- and β-CD solutions have been calculated and were found to be highly dependent on the nature of the used surfactants or CDs. The thermodynamic parameters have been also determined and the difference in magnitude between the formed α- and β-CD-DMAPT inclusion complexes is discussed on the basis of the cavity size. Finally, the binding constant of DMAPT with bovine serum albumin was calculated, indicating the relative stability of the DMAPT-BSA complex. The energy transfer distance between BSA as a donor and DMAPT as an acceptor was obtained following the fluorescence quenching of BSA by DMAPT, via resonance mechanism as a quencher.     

Construction and performance characterization of screen printed and carbon paste ion selective electrodes for potentiometric determination of naphazoline hydrochloride in pharmaceutical preparations

This paper describes the development of screen-printed (SPE) and carbon paste (CPE) sensors for the rapid and sensitive quantification of naphazoline hydrochloride (NPZ) in pharmaceutical formulations. This work compares the electroactivity of conventional carbon paste and screen-printed carbon paste electrodes towards potentiometric titration of NPZ. The repeatability and accuracy of measurements performed in the analysis of these pharmaceutical matrices using new screen printed sensors were evaluated. The influence of the electrode composition, conditioning time of the electrode and pH of the test solution, on the electrode performance were investigated. The drug electrode showed Nernstain responses in the concentration range from 1 × 10(-6) to 1 × 10(-2) mol L(-1) with slopes of 57.5 ± 1.3 and 55.9 ± 1.6 mV per decade for SPE and CPE, respectively, and was found to be very precise and usable within the pH range 3-8. These sensors exhibited a fast response time (about 3 s for both SPE and CPE, respectively), a low detection limit (3.5 × 10(-6) and 1.5 × 10(-6) M for SPE and CPE, respectively), a long lifetime (3 and 2 months for SPE and CPE, respectively) and good stability. The selectivity of the electrode toward a large number of inorganic cations, sugars and amino acids was tested. It was applied to potentiometric determination of NPZ in pure state and pharmaceutical preparation under batch conditions. The percentage recovery values for the assay of NPZ in tablets (relative standard deviations ≤0.3% for n = 4) were compared well with those obtained by the official method.     

Synthesis and biological evaluation of 5-substituted benzo[b]thiophene derivatives as anti-inflammatory agents

Abstract  5-Aminobenzo[b]thiophene-2-carboxylic acid was converted to the corresponding 5-(2-chloroacetamido)benzo[b]thiophene-2-carboxylic acid by reaction with chloroacetyl chloride. This acetamido product was treated with different alkyl, cycloalkyl, aryl, and heterocyclic amines to afford a series of C5-substituted benzo[b]thiophenes. These compounds were found to possess potent anti-inflammatory activity. Graphical abstract        

Synthesis and anti-arrhythmic activity of some piperidine-based 1,3-thiazole, 1,3,4-thiadiazole, and 1,3-thiazolo[2,3-c]-1,2,4-triazole derivatives

Abstract  The reaction of 1-[4-(piperidin-1-yl)benzylidene]thiosemicarbazide with hydrazonoyl chlorides afforded 1,3-thiazole derivatives. Cyclization of two compounds of the latter 1,3-thiazole by means of bromine in the presence of sodium acetate at room temperature gave 1,3-thiazolo[2,3-c]-1,2,4-triazole derivatives. The reaction of 2-cyano-3-(4-piperidin-1-ylphenyl)prop-2-enethioamide with hydrazonoyl chlorides under reflux in ethanol in the presence of triethylamine yielded 1,3-thiazoles. Treatment of 3-oxo-3-(piperidin-1-yl)propanenitrile with phenyl isothiocyanate in DMF, in the presence of KOH, at ambient temperature, resulted in the formation of 3-anilino-3-mercapto-2-(piperidin-1-ylcarbonyl)acrylonitrile which was reacted with hydrazonoyl chlorides to yield the corresponding 1,3,4-thiadiazole derivatives. Some of the newly synthesized compounds had significant anti-arrhythmic activity. Graphical Abstract