Photocatalytic hydrogen evolution over cyanine-sensitized Ag/TiO2.

Sensitization of TiO2 by dyes such as cyanine and their derivatives is used as a technique to improve potency for the production of hydrogen gas as an alternative green fuel. These dyes shift the spectrum of TiO2 from the UV region to the visible region, enabling it to harvest as much sunlight as possible. Herein, four different derivatives of cyanine (labelled C1, C2, C3, and C4) were prepared and doped in Ag/TiO2 via the impregnation method. The properties of the prepared photocatalysts were studied by XRD, SEM-EDS, FTIR, and UV-visible spectroscopy. The sensitized photocatalysts exhibited a similar morphology, nanoscale particle size, and good absorbance in the visible region. The rate constant for the photocatalytic activity of Ag/TiO2 showed a great enhancement for hydrogen evolution after sensitization from 0.088 to 0.33 µmol min-1. Doping of the C2 derivative in Ag/TiO2 promoted the photocatalytic and sonophotocatalytic rates of H2 production by 7.5 and 9 times, respectively. Also, the amount of photocatalyst had a significant effect on the photocatalytic activity of the sensitized Ag/TiO2, where 0.14 g was the optimum dose, giving the maximum yield at both the initial rate and 300 min. One of the important factors causing the efficiency to reach high levels is the inhibition of photogenerated electron/hole recombination. This was achieved by adding a small quantity of methanol, which increased the rate by 9 times. The stability of the prepared photocatalysts was tested, which gave good results even after their 5th use. All the results confirmed that the sensitization of metal oxides is a promising solution in industry to produce clean energy (H2) in high quantities over highly stable photocatalysts.

Synergetic effects of Cu/TiO2 sensitized with different cyanine dyes on hydrogen evolution.

The production of hydrogen as an alternative fuel is a major challenge for developed countries. To achieve this, photocatalysis is a promising method, which depends mainly on a renewable energy source, namely, the sun. Many derivatives of cyanine-sensitized Cu/TiO2 were prepared and characterized by XRD, SEM-EDS, TEM, BET surface area and UV-vis spectrophotometry and their photocatalytic activity was studied. The study of hydrogen production over the sensitized photocatalysts confirmed the significant role of the dyes in the enhancement of hydrogen production. Dye molecules harness light radiation to produce strong oxidizing species, such as hydroxyl radicals, which in turn form hydrogen molecules. Combining sonolysis with photocatalysis processes proved that ultrasound waves inhibit the agglomeration of particles and maintain their surface area. This synergetic process increased the efficiency of hydrogen production by 7 times using photocatalysis only.

Synthesis of some novel dimethine, bis-dimethine cyanine dyes and octacosamethine cyanine dyes endowed with promising biological potency against (HepG2), (Hela), (MCF-7), (MIA), (SN12C) and (H358) cell lines.

Successfully, one step two component synthesis of dimethine cyanine dyes, bis-dimethine cyanine dyes and icosamethine cyanine dyes 2-10via reaction of pyridinium salt 1 with some different aldehydes hope to obtain these compounds with enhanced biological potency as antitumor agents against spontaneous liver (HepG2), cervical (Hela), breast (MCF-7), pancreas (MIA), kidney (SN12C) and lung (H358). The impact of substituted drugs on the tumor cells was reflected by means of structure activity relationship (SAR). Among these dyes, icosamethine cyanine dye 8 recorded an excellent activity toward all the tested cell lines. The newly destined drugs were identified and emphasized by spectroscopy and elemental analyses.

Recent trends in smart and flexible three-dimensional cross-linked polymers: synthesis of chitosan-ZnO nanocomposite hydrogels for insulin drug delivery.

One set of major challenges and significant progress is attributed to the discovery of novel pharmaceuticals from the exoskeleton of marine crustacean wastes to minimize the environmental pollutants. In this strategy, high molecular weight chitosan was subsequently used in the synthesis of smart three-dimensional cross-linked network polymers. Super absorbent chitosan-ZnO nanocomposite hydrogels were synthesized via a terminated diisocyanate compound, a chitosan sample (NH2/NCO), and ZnO nanoparticles in different concentrations (1-7%). The discovered intelligent drugs were confirmed by spectral analyses such as FTIR, XRD, DLS, TGA and morphological analyses such as AFM, SEM, and TEM. The unique physical properties of chitosan-ZnO nanocomposite hydrogels towards environmental stimuli and the porosity of their structures have gained particular interest in fluorescence isothiocyanate-labeled insulin-loaded hydrogel nanocomposites for in vivo drug delivery into the rat nasal cavity. Confocal laser scanning microscopy (CLSM) was used to prove the absorption enhancement of fluorescein isothiocyanate (FITC)-labeled insulin-loaded hydrogels in the rat nasal cavity by this formulation. The formulation of hydrogels apparently decreased the blood glucose concentration (50-65% of initial blood glucose concentration) for at least 4-5.5 h after administration, and no apparent cytotoxicity was found after administration.

Synthesis and pharmacological screening of novel meso-substituted porphyrin analogs.

A novel series of mesotetrakis[aryl]-21H,23H-porphyrin derivatives 2a-j was synthesized from the condensation of aldehyde derivatives 1a-j with pyrrole in the presence of p-toluenesulfonic acid. The synthesized porphyrins were considered as a model to study the free radical-induced damage of biological membranes and the protective effects of these porphyrins. It was found that these compounds effectively inhibit the free radical-induced oxidative hemolysis of red blood cells. Compounds 2c and 2d which bear a sulfur atom, a nitro group, and a chlorine atom exhibited markedly higher antihemolysis activity than the other analogous. Compounds 2a, 2c, 2d, and 2j showed the highest protection activity against DNA damage induced by the bleomycin-iron complex. Compounds 2d, 2f, 2i, and 2j were proved to exhibit antioxidative activity.

Synthesis and molluscicidal activity of some new thiophene, thiadiazole and pyrazole derivatives.

The base-catalyzed reaction of benzoyl acetone 1 with phenyl isothiocyanate yields the non-isolable intermediate 2. Treatment of 2 with dilute HCl afforded the corresponding thiocarbamoyl derivative 3. Reaction of the intermediate 2 with phenacyl bromide, ethyl bromoacetate, chloroacetonitrile, chloroacetyl chloride, bromodiethyl malonate and chloroacetone afforded the corresponding thiophene derivatives 5, 8, 15 and 17. The thiocarbamoyl derivative 3 reacts with arylazophenacyl bromide and/or hydrazine hydrate to afford the corresponding thiadiazole and pyrazole derivatives 20a-c and 22, respectively. These new synthesized compounds show generally a moderate molluscicidal activity to Biomphalaria alexandrina snails.