Band 234, Heft 11-12

We present a femtosecond pump-probe UV-Vis broadband transient absorption spectroscopy study of two styryl-substituted BODIPY chromophores with different position of the substituent. The α -substituted isomer shows typical BODIPY-type spectral features, such as sharp absorption and emission bands, a small Stokes shift and an excited-state lifetime in the 4 ns range, which only weakly depends on the solvent. In contrast, β -styryl-BODIPY features much broader steady-state absorption and emission spectra and a larger Stokes shift, particularly in polar solvents. Transient absorption spectroscopy including a complete global kinetic analysis reports a substantial decrease in S 1 lifetime to 300 ps for polar solvents upon change from α - to β -substitution. In the case of the α -isomer, TD-DFT calculations identify a typical “cyanine-type” electron rearrangement upon S 0 → S 1 excitation accompanied by a slight reduction in dipole moment. In contrast, the same transition in the β -isomer shows strong intramolecular charge transfer (ICT) character involving a substantial increase in dipole moment. Assuming a simple energy-gap-law argument, the accelerated nonradiative decay of the β -isomer in polar solvents may be linked to the decrease of the S 1 (ICT)-S 0 energy difference. BODIPY dyes with a conjugated substituent in β -position therefore suffer a substantial loss in fluorescence brightness in polar environments compared with their α -substituted counterparts. This might limit their applicability in fluorescence imaging.

In the current research, we observed numerous suggestions are promoting the use of bio-based epoxy resins, replacing the petroleum-based products like Diglycidyl ether of bisphenol A type epoxy resin DGEBA. With the passage of time, the impending challenges include preparation of environmentally-friendly epoxy with minimum toxic side effect and improved properties. Therefore, we describe a very useful method for preparing new silicone-bridged dimethyl siloxane monomers in high quantity, derived from naturally occurring eugenol. By putting the methyl siloxane, computed with different chain lengths into their molecular backbone. Such epoxy monomers have different molecular structure with high purity. This dimethyl siloxane epoxy, with lower viscosity than commercial DGEBA epoxy, has superior thermal properties, which were evaluated using differential scanning calorimetry DSC. Modification of CMS increases the hydrophilicity. Bio-based epoxy (self-prepared) resin improved adhesive properties, with the help of modified CMS. This study presents a very easy and effective chemical modification to enhance interfacial adhesion composites with superior properties.

The benzoic acid solubility in aqueous phase and in various aqueous mixtures of methanol, ethanol and 2-propanol was determined at temperatures ranging from 303 to 333 K by an analytical technique. The results showed that the solubility of the acid in alcohols-water binary mixtures is high as compared to pure aqueous phase. The addition of alcohols to water favors the dissolution of benzoic acid which increases further with the increase in alcohols content of water within the investigated temperature range. The benzoic acid solubility in water alone and aqueous mixtures of the selected alcohols was in the order of; 2-propanol in water > ethanol in water > methanol in water > pure water. It is also observed that within the investigated temperature range, the acid solubility increases with rise in temperature in both the aqueous phase and alcohols-water binary solvents. The logarithm of the mole fraction of the acid’s solubility also showed a linear trend against the temperature. The experimental results obtained in the current study were compared with the reported literature for the studied acid and other organic acids in various solvents and showing a good agreement. The study will have implications in the processes involving separation, crystallization and pharmaceutical formulation in various industries.

Plant based materials are considered to have broad applications in the remediation of toxic materials. In this report, we present an environmental friendly and economic Cicer arietinum , named as (CP) supported for the synthesis of Ni nanoparticles (NPs) designated as Ni@CP. The in situ Ni@CP NPs were obtained using aqueous medium in the presence of sodium borohydride (NaBH 4 ) as a reducing agent. The prepared catalysts were applied for the hydrogenation/degradation of p -nitrophenol (PNP), o -nitrophenol (ONP), and 2,4-dinitrophenol (DNP), as well as congo red (CR), methyl orange (MO), methylene blue (MB) and rhodamine B (RB) dyes. The amount of total metal ions adsorbed onto the CP was evaluated by flame atomic absorption spectroscopy. The Ni@CP catalyst was characterized through PXRD, FTIR, FESEM and EDX analyses.

This study focuses on application of advanced oxidation (Photo-Fenton) processes to decolorize Basic Turquise Blue (BTB) X-GB 250% and Basic Blue (BB) X-GRRL 250% dyes. The percent decolorization was studied in terms of effect of variation in intensity of UV light at optimum conditions of all the parameters (pH = 3.0, H 2 O 2 = 4.8 mM, FeSO 4 = 1.6 mM, temperature = 50 °C, time = 80 min for BTB X-GB, and pH = 5.0, H 2 O 2 = 5.6 mM, FeSO 4 = 2.0 mM, temperature = 40 °C, time = 60 min for BB X-GRRL). Maximum decolorization was obtained at maximum intensity (15660 counts/min) of UV light as 96.17% for BTB X-GB and 88.48% for BB X-GRRL. First order, 2 nd order and BMG kinetic models were used to analyze the data obtained for intensity of UV light. BMG model gives us the higher values of correlation coefficients for all data of both the dyes. The results have shown that Photo-Fenton oxidation process is the beneficial and effective for oxidation treatment of waste water effluents containing dyes as main pollutants.

The WO 3 thin films have been synthesized on to the glass substrates by a simple and easy spin coating method at different deposition cycles and their sensor responses towards various concentrations of NO 2 gas were investigated. The WO 3 films were spin coated at a spinning rate of 2500–3000 rpm for 5, 10 and 15 deposition cycles, respectively. Then the films were annealed at 400 °C for 1 h in a furnace. The structural, morphological, optical and electrical properties of WO 3 films were studied by different characterization techniques such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), FT-RAMAN Spectroscopy and electrical resistivity measurements by laboratory made two probe method respectively. It reveals a spherical grain – like morphology with a pure monoclinic phase of WO 3 . The FT-RAMAN spectra also confirm the pure monoclinic phase of WO 3 . The WO 3 -10 film sensor exhibits maximum gas sensitivity 21.93 and 102.4% to 5 and 100 ppm NO 2 at 200 °C, respectively. The WO 3 -10 thin film sensors is highly sensitive and selective to NO 2 over other gases.

The adsorption action of polyethylene oxide (PEO) on copper surface in 3.5 wt.% NaCl solution was tested using electrochemical frequency modulation (EFM), atomic absorption spectrometry (AAS), UV- visible spectrometry and the morphology of copper surface was investigated by attenuated total reflectance spectroscopy (ATR-FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques. Results obtained show that PEO is effective in preventing the corrosion of copper in NaCl solution. The adsorption of PEO onto copper surface was found to follow Langmuir isotherm model. ATR-FTIR, SEM and EDX spectroscopy techniques confirmed the adsorption of protective film of PEO on copper surface. Further, quantum chemical calculations were in agreement with inhibition efficiency (% I ) of PEO that were obtained experimentally.

The experimental values of density, ρ and speed of sound, u of doxycycline hyclate drug (0.002–0.014) mol kg −1 in water and (0.1, 0.2 and 0.4) mol kg −1 of aqueous galactitol solutions at temperatures T = (303.15, 308.15 and 313.15) K and at atmospheric pressure have been reported in the present communication. From the experimental values, various derived parameters such as apparent molar volume ( Φ V ), apparent molar isentropic compression ( Φ K ), limiting apparent molar volume (Φvo$\phi_{\text{v}}^{\text{o}}$), limiting apparent molar isentropic compression (ΦKo$\phi_{\text{K}}^{\text{o}}$), limiting apparent molar volume of transfer (ΔΦVO$\phi_{\text{V}}^{\text{O}}$), limiting apparent molar isentropic compression of transfer (ΔΦKO$\phi_{\text{K}}^{\text{O}}$), limiting apparent molar expansibility (ΦEo$\phi_{\text{E}}^{\text{o}}$), thermal expansion coefficient (α) and acoustic parameters like isentropic compressibility (κS)$({{\kappa}_{\text{S}}})$, intermolecular free length (L f ), and specific acoustic impedance (Z) were calculated. The structure-making behaviour of DH in aqueous galactitol solution was determined on the basis of Hepler’s Equation i.e. on the basis of sign of (d2ΦVOdT2)P${\left({\frac{{{{\text{d}}^{2}}\phi_{\text{V}}^{\text{O}}}}{{{\text{d}}{{\text{T}}^{2}}}}}\right)_{\text{P}}}$. The various derived parameters were utilised to interpret the molecular interactions i.e. solute–solute and solute–solvent existing in the studied system.