Eco-friendly heteropoly acid supported on natural clay for the synthesis of calix[4]resorcinarene derivatives

The catalytic activity of green catalyst heteropoly-11-tungsto-1-vanadophosphoric acid, H4[PVW11O40] (HPV) supported on activated natural clay (HPVAC)  has been tested towards the synthesis of calix[4]resorcinarene under solvent-free condition. It is a one-pot multi-component condensation reaction of four moles of aromatic aldehydes with four moles of resorcinol. The advantages of the protocol, solvent-free heterogeneous reaction condition, simple workup procedure, short reaction time, high yield of products and reusability of the catalyst make this method to declare as green approach for synthesis of calix[4]resorcinarene

Eco-friendly heteropoly acid supported on natural clay for the synthesis of calix[4]resorcinarene derivatives

185-191The catalytic activity of green catalyst heteropoly-11-tungsto-1-vanadophosphoric acid, H4[PVW11O40] (HPV) supported on activated natural clay (HPVAC)  has been tested towards the synthesis of calix[4]resorcinarene under solvent-free condition. It is a one-pot multi-component condensation reaction of four moles of aromatic aldehydes with four moles of resorcinol. The advantages of the protocol, solvent-free heterogeneous reaction condition, simple workup procedure, short reaction time, high yield of products and reusability of the catalyst make this method to declare as green approach for synthesis of calix[4]resorcinarene

Nanostructured AgBr loaded TiO2: An efficient sunlight active photocatalyst for degradation of Reactive Red 120

The AgBr loaded TiO2 catalyst was prepared by a feasible approach with AgBr and tetraisopropyl orthotitanate and characterized by BET surface area measurement, diffuse reflectance spectra (DRS), scanning electron microscope (SEM), energy dispersive spectra (EDS), X-ray diffraction (XRD), transmission electron microscope (TEM) and atomic force microscope (AFM) analysis. The results of characterization reveal that AgBr loaded TiO2 has a nanostructure. Formation of the nanostructure in AgBr loaded TiO2 results in substantial shifting of the absorption edge of TiO2 to red and enhancement of visible light absorption. Electrochemical impedance spectroscopy measurements reveal that AgBr loaded TiO2 has a higher photoconductivity than prepared TiO2 due to higher separation efficiency of electron-hole pairs. Cyclic voltammetric studies reveal enhanced conductivity in AgBr loaded TiO2, which causes an increase in its photocatalytic activity. AgBr loaded TiO2 exhibited a higher photocatalytic activity than TiO2-P25 and prepared TiO2 in the photodegradation of Reactive Red 120 (RR 120)

Dual fluorescence of 2-phenoxyaniline

818-8242-Phenoxyaniline (2POA) shows a dual fluorescence in hydrogen bonding solvents. The increase in Stokes shift with increase in polarity is much more for longer wavelength abnormal fluorescence band (FA) than for shorter wavelength fluorescence band (FN). It is found that FA band arises only due to bulk properties of solvent and not due to complex formation. A mechanism involving twisted intramolecular charge transfer (TICT) state is proposed for the dual fluorescence of 2POA. pHstudies indicate that the stretched sigmoid curve obtained for the neutral-monocation equilibrium is due to overlap of proton induced fluorescence quenching and monocation formation curves

Photocatalytic synthesis of 2-methylquinolines with TiO2 Wackherr and Home Prepared TiO2 – A comparative study

A comparative study was carried out on the efficiency of titanium dioxide specimens Wackherr TiO2, prepared TiO2 and Aeroxide P25 toward the photocatalytic synthesis of pharmaceutically important 2-methylquinolines. TiO2 Wackherr induced significantly faster conversion of nitrobenzene to 2-methylquinoline than Aeroxide P25 when high photocatalyst loadings and high substrate concentrations were used. Photocatalytic synthesis of 2-methylquinolines from substituted nitrobenzenes and anilines show that the product yield is not significantly influenced by the substituents. Low cost TiO2 Wackherr is more useful when high photocatalyst loading is required at high substrate concentration

Electron transfer fluorescence quenching of napthalenediols by metal ions

915-919Fluorescence quenching of four naphthalenediols (1,5-; 1,7-; 2,7-; 2,3-NDs) by transition metal ions (Cu2+, Co2+, Ni2+, Mn2+, Zn2+, Pb2+) has been investigated in 95% water-ethanol mixture. The dynamic quenching is appreciable with all metal ions except Pb2+. Cupric ion (Cu2+) is found to be an efficient quencher with all naphthalenediols and the sensitivity of 1,7-ND fluorescence is much higher than other naphthalenediols. The quenching rate constants (kq) have been analyzed for various possible mechanisms. A good correlation of log kq values with the reduction potentials of metal ions reveals the electron transfer quenching mechanism via a non-emissive exciplex with electron transfer from excited fluorophore to the metal ions. The anomalous behavior of 1,7-ND is explained by its point group symmetry and polarity

Synthesis and characterization of gadolinium tungstate doped zinc oxide photocatalyst

50-56Fabrication of 5 wt% Gd2WO6 doped ZnO via template-free hydrothermal process and its photocatalytic activity against azo dyes, rhodamine-B (Rh–B) and trypan blue (TB) in UV-A light irradiation are reported. The as-prepared Gd2WO6 doped ZnO has been characterised by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and, diffused reflectance and photoluminescence spectroscopy. The XRD pattern indicates the distinct diffraction peaks for wurtzite ZnO and body-centered monoclinic structure of Gd2WO6 with good crystallinity. EDS analysis reveals the homogeneous distribution of Gd, Zn, W and O in the prepared catalyst. The results suggests that rare earth tungstate, Gd2WO6 doping on ZnO has great influence on the photocatalytic activity under UV-A light. Gd2WO6-ZnO possesses high reusability without appreciable loss of catalytic activity up to four runs