Gas chromatographic subsystem for fast on-line concentration profile measurements for advanced distillation column control

An automated gas chromatographic subsystem for the provision of fast and reliable concentration profile data for distillation column control is presented. The subsystem consists of a gas chromatograph, equipment for sample conditioning and a PC/AT compatible computer communicating with the supervisory process computer. A fast separation time is obtained through the use of a liquid chromatographic packing material and a high pressure drop across the column. Preliminary results show separation times below 10 s for the water-methanol-isopropanol system. Peak areas are quantified by use of parameter estimation in the frequency domain, a method that does not demand complete peak separation.     

Synthesis,characterization, and photophysical properties of paraben substituted cyclotriphosphazenes with hydrophilic side groups

Abstract

In this study, five new paraben substituted cyclotriphosphazene compounds containing hydrophilic glycol groups were successfully synthesized. All synthesized cyclotriphosphazene compounds 1-10 were fully characterized via general spectroscopic techniques such as ¹H, ³¹P NMR and MALDI-TOF mass spectrometry. In addition, the investigations of the UV-vis absorption and fluorescence emission properties of the 1-10 carried out via absorption and fluorescence spectroscopies in different solvents. The absorbance bands of the all synthesized compounds 1-10 were observed at about 230–300?nm in all solvents studied. Furthermore, the highest fluorescence emission intensity of the compounds 1-10 was observed in tetrahydrofuran at about 312?nm and the lowest emission intensity was observed in chloroform. The synthesized molecules can be used as custom designed molecules to investigate the DNA binding properties in automatic biosensor device in our laboratories, since they carry hydrophilic glycol units for water solubility and paraben derivatives for DNA effecting properties.     

Bingel–Hirsch Addition of Diethyl Bromomalonate to Ion-Encapsulated Fullerenes M@C60 (M=Ø, Li+, Na+, K+, Mg2+, Ca2+, and Cl−)

In the last 30 years, fullerene-based materials have become popular building blocks for devices with a broad range of applications. Among fullerene derivatives, endohedral metallofullerenes (EMFs, M@C_x) have been widely studied owing to their unique properties and reactivity. For real applications, fullerenes and EMFs must be exohedrally functionalized. It has been shown that encapsulated metal cations facilitate the Diels–Alder reaction in fullerenes. Herein, the Bingel–Hirsch (BH) addition of ethyl bromomalonate over a series of ion-encapsulated M@C₆₀ (M=Ø, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, and Cl⁻; Ø@C₆₀ stands for C₆₀ without any endohedral metal) is quantum mechanically explored to analyze the effect of these ions on the BH addition. The results show that the incarcerated ion has a very important effect on the kinetics and thermodynamics of this reaction. Among the systems studied, K⁺@C₆₀ is the one that leads to the fastest BH reaction, whereas the slowest reaction is given by Cl⁻@C₆₀.     

The synthesis and electrochemical behaviour of carbazole-substituted phthalocyanines

The syntheses of new cobalt and zinc phthalocyanine complexes containing carbazole (Cz) substituents at the peripheral positions are reported (CzCoPc and CzZnPc). The reaction of Cz with 4-iodophthalonitrile in the presence of a catalytic amount of copper(I) oxide and potassium carbonate led to the formation of 4-(9H-carbazol-9-yl) phthalonitrile. Furthermore, by heating the dinitrile and anhydrous metal salts (CoCl₂, Zn(CH₃COO)₂) at 160 °C in n-hexanol in the presence of DBU, the phthalocyanines were obtained. They were characterised by ¹H NMR, FT-IR, UV-Vis and MS spectroscopic data. Aggregation behaviours of Pcs were investigated in THF. Electrochemical redox behaviour of CzCoPc was investigated by cyclic voltammetry depending on the potential range, and the oxidation and reduction products were followed by UV-Visible absorption measurements. Polymerisation of CzCoPc was carried out by potentiodynamic methods on glassy carbon electrode, and the catalytic activity of resulting polymer (P[CzCoPc]) was tested comparatively with polycarbazole (PCz)-coated electrode for dopamine and better response was obtained for P[CzCoPc] modified electrode.     

Luster decoration of ceramics: mechanisms of metallic luster formation

Luster is a metallic decoration produced since early Islamic times (9th century AD in Iraq). Different studies have shown that medieval lusters are a metal-glass nanocomposite (metal nanoparticles embodied in a silica glassy matrix) obtained from the reaction of a copper and/or silver containing paint with a glaze. The mechanisms of formation of these metallic-like layers are investigated by laboratory reproductions of Medieval luster. Copper and silver lusters are obtained based on different thermal paths and atmospheres, and by using different glaze compositions. The ionic exchange between Cu⁺ and Ag⁺ ions from the luster paint with Na⁺ and K⁺ of the glaze, is demonstrated in either oxidizing or inert atmospheres and at firing temperatures between 500 °C and 600 °C. The reduction of copper and silver to their metallic state is obtained by introducing a reducing gas afterwards. The lusters are non-metallic red ruby copper or green with brown spots silver when developed over alkaline glazes, while they appear coppery and golden metallic when developed over mixed alkaline-lead glazes. SR-XRD, optical absorption and microprobe chemical analysis of the lusters indicate that the total amount of copper and silver, and the nature and size of the nanoparticles, are similar in both cases. Further work is needed to clarify the origin of these differences. PACS 81.05.Pj; 81.07.b; 81.16.Be; 78.67.Bf; 42.50.Fx     

Tailoring the NIR-II Photoluminescence of Single Thiolated Au25 Nanoclusters by Selective Binding to Proteins**

Atomically precise gold nanoclusters are a fascinating class of nanomaterials that exhibit molecule-like properties and have outstanding photoluminescence (PL). Their ultrasmall size, molecular chemistry, and biocompatibility make them extremely appealing for selective biomolecule labeling in investigations of biological mechanisms at the cellular and anatomical levels. In this work, we report a simple route to incorporate a preformed Au₂₅ nanocluster into a model bovine serum albumin (BSA) protein. A new approach combining small-angle X-ray scattering and molecular modeling provides a clear localization of a single Au₂₅ within the protein to a cysteine residue on the gold nanocluster surface. Attaching Au₂₅ to BSA strikingly modifies the PL properties with enhancement and a redshift in the second near-infrared (NIR-II) window. This study paves the way to conrol the design of selective sensitive probes in biomolecules through a ligand-based strategy to enable the optical detection of biomolecules in a cellular environment by live imaging.