Synthese eines funktionalen Aluminiumalkinids,Me3C‐C≡C‐AlBr2, und dessen Reaktionen mit der sperrigen Lithiumverbindung LiCH(SiMe3)2

Synthesis of a Functional Aluminium Alkynide, Me₃C‐C≡C‐AlBr₂, and its Reactions with the Bulky Lithium Compound LiCH(SiMe₃)₂ Treatment of aluminium tribromide with the lithium alkynide (Li)C≡C‐CMe₃ afforded the aluminium alkynide Me₃C‐C≡C‐AlBr₂ ( 1 ) in an almost quantitative yield. 1 crystallizes with trimeric formula units possessing Al₃C₃ heterocycles and the anionic carbon atoms of the alkynido groups in the bridging positions. A dynamic equilibrium was determined in solution which probably comprises trimeric and dimeric formula units. Reaction of 1 with one equivalent of LiCH(SiMe₃)₂ yielded the compound [Me₃C‐C≡C‐Al(Br)‐CH(SiMe₃)₂]₂ ( 2 ), which is a dimer via Al‐C‐Al bridges. Two equivalents of the lithium compound gave a mixture of four main‐products, which could be identified as 2 , Li[Me₃C‐C≡C‐Al{CH(SiMe₃)₂}₃] ( 3 ), Me₃C‐C≡C‐Al[CH(SiMe₃)₂]₂ ( 4 ), and Al[CH(SiMe₃)₂]₃. The lithium atom of 3 is coordinated by the C≡C triple bond and an inner carbon atom of one bis(trimethylsilyl)methyl group. Further interactions were observed to C‐H bonds of methyl groups.     

Electrocatalytical Application of Platinum Nanoparticles Supported on Reduced Graphene Oxide in PEM Fuel Cell: Effect of Reducing Agents of Dimethlyformamide or Hydrazine Hydrate on the Properties

Two kinds of reduced graphene oxide (rGO) were synthesized with the reducing agents of either dimethylformamide (DMF) or hydrazine hydrate (HYD). The decoration of platinum nanoparticles (Pt NPs) over these materials was provided by microwave irradiation (MWI) method. Detailed physical and electrochemical measurements were carried out. Based on the electrochemical results of both catalysts, it is not surprising the achievement of higher electrochemical active surface area (ECSA), higher oxygen reduction reaction (ORR) activity, higher electron transfer number, lower charge transfer resistance and higher fuel cell performance with the Pt/rGO (DMF) catalyst which surpasses Pt/rGO (HYD) in many ways.     

A new biflavonoid from Solanum dulcamara L. and investigation of anti-hyperglycaemic activity of its fruit extract

A new biflavone, 6,2′,3″,5″,4?-pentahydroxy-3,7″-biflavone, has been isolated from the fruits of Solanum dulcamara L., in addition to two known compounds, β-sitosterol and stigmasterol. Their structures were established on the basis of UV, IR, 1D, 2D NMR and HR-ESI-MS spectroscopic methods. The anti-hyperglycaemic effect of S. dulcamara was investigated using diabetic rats. The anti-hyperglycaemic activity of the fruit extract of S. dulcamara was presented for the first time in this study.     

Synthesis and characterization of new cyclotriphosphazene compounds

In the present study, spiro (1a), dispiro (1b, 2, 3), per-substituted spermine-bridged (6–9) and dispiroansa spermine (10) derivatives of cyclotriphosphazene have been synthesized. The structures of the novel compounds (1b, 6–10) have been characterized by elemental analysis, FTIR, mass spectrometry, ¹H and ³¹P NMR spectroscopy. The molecular structures of 1b, 2, 8, and 10 were determined by single crystal X-ray crystallography. In order to investigate the anti-tumour properties of the newly synthesized cyclotriphosphazene derivatives, in vitro cytotoxic activity test (MTT assay) has been performed using HT-29 (human colon adenocarcinoma) and Hep2 (human epidermoid larynx carcinoma) cell lines. The result of the MTT assay showed that while compound 1a has cytotoxic effect on both Hep2 and HT-29 cell lines, compound 3 has only cytotoxic effect towards the Hep 2 cells.     

Synthesis and Characterization of Novel Methacrylate Monomers Having Pendant Oxime Esters and Their Copolymerization with Styrene

New methacrylate monomers, 2‐{[(diphenylmethylene)amino]oxy}‐2‐oxoethyl methacrylate (DPOMA) and 2‐{[(1‐phenylethylidene)ami no]oxy}‐2‐oxoethyl methacrylate (MMOMA) were prepared by reaction of sodium methacrylate with diphenylmethanone O‐(2‐chloroacetyl) oxime and 1‐phenylethanone O‐(2‐chloroacetyl) oxime, respectively. They were obtained from a reaction of chloroacetyl chloride with benzophenone oxime or acetophenone oxime. The free‐radical‐initiated copolymerization of (DPOMA) and (MMOMA) with styrene (St) were carried out in 1,4‐dioxane solution at 65°C using 2,2‐azobisisobutyronitrile (AIBN) as an initiator with different monomer‐to‐monomer ratios in the feed. The monomers and copolymers were characterized by FTIR, ¹H‐ and ¹³C‐NMR spectral studies. The copolymer compositions were evaluated by nitrogen content in polymers. The reactivity ratios of the monomers were determined by the application of Fineman–Ross and Kelen–Tüdös methods. The molecular weights (M¯_w and M¯_n) and polydispersity index of the polymers were determined by using gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of St in the copolymers. The activation energies of the thermal degradation of the polymers were calculated with the MHRK method. Glass transition temperatures of the copolymers were found to decrease with an increase in the mole fraction of DPOMA or MMOMA in the copolymers. The antibacterial and antifungal effects of the monomers and polymers were also investigated on various bacteria and fungi. The photochemical properties of the polymers were investigated by UV and FTIR spectra.     

Effect of LiClO4 Salt on Dielectric Properties of Acrylonitrile-Methyl Methacrylate and Acrylonitrile-Isobutyl Methacrylate Copolymers

Poly(acrylonitrile-co-isobutyl methacrylate), PAN-co-PIBMA, and poly(acrylonitrile-co-methyl methacrylate), PAN-co-MMA copolymers are synthesized by emulsion polymerization. The structural characterization is done by FTIR and ¹H-NMR spectroscopy and thermal analyses are performed by thermogravimetric analysis (TGA). After various amounts of LiClO₄ salt loading into copolymer films, the dielectric properties of these films at different temperatures and frequencies are determined. The effects of different methacrylate groups and salt content on the dielectric properties of copolymers are investigated. It is found that the dielectric constant increases systematically with increasing MMA and IBMA content in the copolymer. The samples with higher salt content show higher ac-conductivities.     

Development of Lactose Biosensor Based on β‐Galactosidase and Glucose Oxidase Immobilized into Gelatin

In this article, we describe the preparation of a new lactose biosensor based on electrode coating with β‐galactosidase and glucose oxidase immobilized gelatin. For this purpose, β‐galactosidase and glucose oxidase enzymes were immobilized onto gelatin by crosslinking with glutaraldehyde. Properties of the immobilized β‐galactosidase and glucose oxidase enzymes electrode have been studied. The effects of glutaraldehyde concentration, temperature and pH variations and reusability were among the subjects analyzed. Lactose biosensors were subjected to continuous repeated use in order to observe reusability and shelf life; where standard lactose and milk samples were used as substrate solutions. Continuous reuse experiments showed that most of the lactose biosensors activities were retained even after the 10th use in a period of 30 days.     

Colour contribution to children's wayfinding in school environments

The purpose of this study was to explore the contribution of colour to children's wayfinding ability in school environments and to examine the differences between colours in terms of their remembrance and usability in route learning process. The experiment was conducted with three different sample groups for each of three experiment sets differentiated by their colour arrangement. The participants totalled 100 primary school children aged seven and eight years old. The study was conducted in four phases. In the first phase, the participants were tested for familiarity with the experiment site and also for colour vision deficiencies by using Ishihara's tests for colour-blindness. In the second phase, they were escorted on the experiment route by the tester one by one, from one starting point to one end point and were asked to lead the tester to the end point by the same route. In the third phase, they were asked to describe verbally the route. In the final phase, they were asked to remember the specific colours at their correct locations. It was found that colour has a significant effect on children's wayfinding performances in school environments. However, there were no differences between different colours in terms of their remembrances in route finding tasks. In addition, the correct identifications of specific colours and landmarks were dependent on their specific locations. Contrary to the literature, gender differences were not found to be significant in the accuracy of route learning performances.     

Preparation of rapid (chain-stopped) alkyds by incorporation of gum rosin and investigation of coating properties

In this study, the synthesis, characterization, and properties of a short oil length chain–stopped(rapid) alkyd resin is investigated. Gum rosin modified alkyd resin (RA-GR) was prepared using soybean oil, phthalic anhydride, glycerin and gum rosin acid. An alkyd modified with benzoic acid (RA-BA) was also prepared for comparison. FTIR analyses and GPC measurements of the alkyds were used for characterization. Other properties such as the viscosity, acid value, and solid content of the final resins were determined. Separately, the synthesized resins were used in paint formulations without any changes in other parameters such as filler, airdrying agents, solvents, etc. Paints were applied to metal and glass surfaces and the effect of gum rosin was investigated by looking at touch and hard drying times, adhesion to metals and gloss changes. Compared to the benzoic acid modified resin (RA-BA), gum rosin modified resin (RA-GR) exhibited remarkable positive effects on the paint with a better adhesion to the metals, and short drying times without any loses in the glosses.     

A Robust,Precious‐Metal‐Free Dye‐Sensitized Photoanode for Water Oxidation: A Nanosecond‐Long Excited‐State Lifetime through a Prussian Blue Analogue

Herein, we establish a simple synthetic strategy affording a heterogeneous, precious metal‐free, dye‐sensitized photoelectrode for water oxidation, which incorporates a Prussian blue (PB) structure for the sensitization of TiO₂ and water oxidation catalysis. Our approach involves the use of a Fe(CN)₅ bridging group not only as a cyanide precursor for the formation of a PB‐type structure but also as an electron shuttle between an organic chromophore and the catalytic center. The resulting hetero‐functional PB‐modified TiO₂ electrode demonstrates a low‐cost and easy‐to‐construct photoanode, which exhibits favorable electron transfers with a remarkable excited state lifetime on the order of nanoseconds and an extended light absorption capacity of up to 500 nm. Our approach paves the way for a new family of precious metal‐free robust dye‐sensitized photoelectrodes for water oxidation, in which a variety of common organic chromophores can be employed in conjunction with CoFe PB structures.