Spectral and Electrochemical Sensing Studies of Unsymmetrical Schiff Bases having Enhanced Antifungal Activity

Novel unsymmetrical Schiff bases comprising azomethine spin-off having ferrocene moiety at one end and simple aromatic component attached imine at other end, capable of sensing multiple metal ions have been synthesized. The MLCT charge transfer band in UV-Visible studies upon coordination with metal ions with receptors is recorded particularly for Cu2+ ions. The observed ΔEp values with change in scan rate for metal free and metal added receptor solution suggest quasi-reversible process. Agar well diffusion method and molecular docking studies reveals that the synthesized compounds inhibit more efficiently fungi rather than bacteria, which hampers the progress of microbial research, as the available antifungal agents are minimal compared to antibacterial counterpart.

Mechanism of Base-Catalyzed Halogen Dance Reactions and the Role of Bromo-Bridged Transition States

Base-catalyzed halogen dance reaction, has puzzled chemists ever since, to come up with new ideas regarding the mechanism of this beautiful chemical transformation. Series of fast metal-halogen exchanges are among the most recent mechanisms. Using DFT-Cam-B3LYP/ land2dz computations and focused on Halogen Dance (HD) reactions of bromobenzene derivatives, new bromo-bridged Transition States (TS) are proposed. These are then used to lay out 8 possible isomerization and 18 possible disproportionation paths. Mechanistic pathways were then analyzed based on TS’s energy and protonation/deprotonation steps to find the most suitable pathways. Overall pattern of these mechanisms draws for the first-time a cascade-like pattern for base-catalyzed halogen dance in its entirety. The present work shed light on a dynamic domino mechanism which dominates the realm of nonaqueous strongly basic medium reactions. Trends like these may well be a shared feature in base digestion of wood for its precious poly aromatic component like lignin.

Effect of rapeseed oil aromatisation with marjoram on the content of volatile fraction and antioxidant properties

The aim of the paper was to study how the process of aromatisation with marjoram affected the composition of volatile fraction and antioxidant properties of rapeseed oil. Different methods of aromatisation were used: direct addition of marjoram essential oil, classical macerations of marjoram herb, and maceration assisted with ultrasound or microwave. The dominant aromatic component in the volatile fraction was γ-terpinene with concentration in the range from 3.15 μg/mL (microwave assisted maceration) to 8.82 μg/mL (classic maceration with shaking). The content of this compound in the mixture of rapeseed oil with essential oil was 152.09 μg/mL. The sample aromatized by the direct addition of essential oil contained the highest amount of volatile substances but simultaneously it had the lowest antioxidant activity.

Review: dry hopping in brewing

Dry hopping defined as the addition of hops or hops-products at the cold stage of the brewing process. The practice of dry hopping is currently used in many American styles of beer (IPA, APA, Imperial Stout), Belgian (Ali and Tripoli), traditional British (IPA, Extra Special Bitter), as well as other styles of beer with a developed aromatic component. The main volatile bitter and aromatic components of hops include terpenes (myrcene, humulene and betacarotene), which are characterized by “herbaceous” aroma. There are also linalool and geraniol, which give floral and fruity notes. Terpineol and pinene are making a resinous character. Currently developed special technology, the introduction of hops and the appropriate equipment for dry hopping: flower hops; hop suspension; hop pellets; semi-automatic methods. Dry hopping carried out to increase the “hoppy” aroma of beer and found application due to the increased popularity of small brewing in the world. Since dry hopping performed at relatively low temperatures thermal decomposition and volatilization of aromatic compounds is significantly reduced. This results in a higher concentration of these compounds in the finished product. The source of the aromatic properties of the beer is the polyphenols. In the process of dry hopping about 80-90% of polyphenols extracted during the first 12 hours. Flavan-3-ols increases perceived bitterness and astringency. Monomers and oligomers of flavan-3-ol play a role in the stability of taste, colloidal stability and foam resistance of the drink, have antiradical and antioxidant properties.

Investigation of Different Phenolic Resins and their Behavior during Pyrolysis to Form SiC/C-Composites

Specific phenolic resin samples have been developed as the carbon precursor for SiC/C composites. Liquid phenolic resins suitable for fiber-infiltration in the resin transfer moulding (RTM) process are synthesized by using versatile combination of the aromatic component (phenol, naphthalen-2-ol) with various formaldehyde equivalents such as methanal, 1,3,5,7tetraazatricyclo [3.3.1.13,7] decane (urotropine), and 1,3,5-trioxane, under different reaction conditions. Room temperature liquid resoles (RTLR) are obtained by using an excess of the formaldehyde component over phenol (≥2) under basic conditions. Upon heating RTLR can form a crosslinked network even without addition of a hardening reagent. In addition, novolacs are synthesized under acidic conditions using a phenol/formaldehyde ratio ≥1. Nitrogen-containing resins contain nitrogen due to reaction of phenol with urotropine. Novolacs and nitrogen-containing resins are solids at room temperature and not self-curing. To infiltrate these both resins into SiC fibers in the RTM process, they are dissolved in 2furanmethanol (furfuryl alcohol FA) and urotropine which is added as curing-agent. Both, the molecular weight and the amount of the dissolved phenolic resin have an influence on the viscosity and the carbon yield after pyrolysis which is important for this application. The aim was to create different phenolic resins for the fabrication in the RTM process and to characterize the carbon after pyrolysis with respect to the structure and porosity as these are key parameters to generate a stoichiometric SiC matrix by LSI.

Raman Spectrometry Study on the Composite of Bamboo Charcoal Pottery

In this paper a confocal micro-raman spectrometer was used to study the characteristic change of bamboo charcoal pottery(BCP) during its formation from bamboo-charcoal and clay.The effect of carbonization temperature on the carbon bonds and corresponding modes of vibration was detailedly discussed through analysising raman spectrum of the samples.The results showed that the raman spectra of the samples assumes a typical saddle and have no sharp peak, which belong to the typical spectra of carbon material containing amorphous graphite.BCP was mainly pyrolyzed to aromatic substances at low temperature carbonization stage(less than 973K),but didn't form complete graphite crystallite.At low temperature it is pyrolyzed to generate aromatic component, while at 1073K, it becomes hexagonal planar network aggregate composed of sp3 hybridized C atoms, in this case is shows the structure of microcrystalline graphite.With the rise of baking temperature（973K～1373K）, the valne of R representing disorder began to reduce and the value of La standing for the diameter of microlite started to increase which approves that higher temperature is benefit for the growth of amorphous and the enhancement of graphitizing degree.But BCP was also typical non-graphitizable carbon when heat treatment temperature increased to 1373K.