Synthesis and characterization of new mesomorphic octakis(alkylthio)-substituted lead phthalocyanines and their films

The syntheses of new octakis (alkylthio)-substituted phthalocyanines of Pb(II) (1a and 2a) are described. These compounds are very soluble in most common organic solvents. They have been fully characterized using elemental analysis, NMR, infrared and UV–Vis spectroscopy. The mesogenic properties of these new materials were studied by differential scanning calorimetry and optical microscopy. These phthalocyanine derivatives are liquid at room temperature and form columnar-hexagonal (Col_h) mesophases below −10 °C. It has been indicated that the addition of methylene bridges to the phthalocyanine (Pc) core increases the clearing point temperatures. Also, the coordination of Pb²⁺ with the phthalocyanine core decreases the clearing point temperatures and the liquid crystal phase transition temperatures. Thin films of octakis(alkylthio)-substituted Pb(II) phthalocyanines 1a and 2a were prepared by the method of spin-coating. To obtain films with an ordered structure the film of 1a was slowly cooled from room temperature down to −10 °C. Sandwich structures of the form Au/PbPc(1a)/Au were prepared for the investigation of their electrical properties. It was shown that a slowly cooled Au/PbPc(1a)/Au structure demonstrates repeatable and stable electrical switching behaviour for applied bias voltages between −1 V and +1 V.     

Image reversal for direct electron beam patterning of protein coated surfaces

Electron beam lithography (EBL) is used to create surfaces with protein patterns, which are characterized by immunofluorescence and atomic force microscopies. Both negative and positive image processes are realized by electron beam irradiation of proteins absorbed on a silicon surface, where image reversal is achieved by selectively binding a second species of protein to the electron beam exposed areas on the first protein layer. Biofunctionality at the cellular level was established by culturing cortical cells on patterned lines of fibronectin adsorbed on a bovine serum albumin background for 7 days in culture.     

A set of highly water-soluble tetraethyleneglycol-substituted Zn(II) phthalocyanines: synthesis, photochemical and photophysical properties, interaction with plasma proteins and in vitro phototoxicity

Three Zn(II) phthalocyanines substituted by hydroxyl-terminated tetraethylene glycol chains have been synthesized. In order to evaluate the potential of these highly water-soluble phthalocyanines as type II-photosensitisers for photodynamic therapy, their structure-activity relationship was assessed by determining relevant photophysical and photochemical properties, such as their aggregation behaviour in aqueous buffers, their fluorescence properties and their efficiency with regard to the generation of singlet oxygen. In addition, evidence for a negligible interaction with plasma proteins in undiluted human plasma was obtained using a recently developed bioanalytical method and compared with the fluorescence quenching approach. These results combined with in vitro data regarding the phototoxicity of these phthalocyanines against HT-29 cancer cells provide evidence for the relevance of the non-peripherally substituted derivative for further in vivo investigations.     

An evaluation of coal fly ash as an adsorbent for the removal of methylene blue from aqueous solutions: kinetic and thermodynamic studies

Abstract

In this study the effect of the dose and particle size of the adsorbent, initial dye concentration, initial pH, contact time and temperature were investigated for the removal of by means of fly ash (FA) methylene blue (MB) from an aqueous solution. The FA dose was found to be 2.0?g and the under 270 mesh sized particles were found to be effective particles for adsorption. The adsorption process reached its maximum value at 0.5?mg/L dye concentration and attained equilibrium within 10?minutes. The adsorption isotherm was found to follow the Langmuir model. The estimated adsorption free energy (ΔG^o), enthalpy change (ΔH^o), and entropy change (ΔS^o) for the adsorption process were ?37.77?kJ mol^?1, ?13.44?kJ mol^?1 and 122 J mol^?1 K^?1 respectively at 298 K. The maximum adsorption capacity is 0,12?mg g^?1 at 298 K and 0,07?mg g^?1 at 398 K. The adsorption process was exothermic, feasible and spontaneous. The positive value of ΔS^o shows the affinity of FA for MB while the low value of ΔG^o suggests a physical adsorption process.