A facile synthesis of benzo[b][1,4]thiazepine derivatives by palladium acetate catalyzed reaction

The preparation of steroid/nonsteroid fused benzo[b][1,4]thiazepines and 2-arylsubstituted benzo[b][1,4]thiazepines is described from Pd(OAc)₂ catalyzed reaction of steroidal/nonsteroidal β-halovinyl aldehydes and 2-aminothiophenols in DMF under heating condition.     

Nelumbo nucifera leaves as source of water-repellent wax: Extraction through polar and non-polar organic solvents

Nelumbo nucifera leaves are rich source of natural wax possessing super-hydrophobic properties. It provides protection to them from ecological turbulences and climatic wear and tear. In this study, various experiments have been conducted to observe the yield of extraction and the determination of various functional groups, which are present in natural wax, derived from Nelumbo nucifera leaves. The natural wax has been extracted from lotus leaves through non-polar (hexane) and polar (ethanol) solvent via different extraction methods. The superhydrophobic wax has been successfully extracted with hexane. Whereas, ethanol did not extract the water-repellent wax of lotus leaf. Considering the cumulative amount, i.e. (desired + undesired), the maceration shows the extraction of 2.9% (%w/w, through hexane) and 10.2% (%w/w, through ethanol), while it was found 2.5% (%w/w, cycle period 15 min) and 9.0% (%w/w, cycle period 26 min) respectively, in case of Soxhlet extraction technique. For this specific case of natural wax recovery from biomass (lotus leaf), the maceration (traditional method) resulted a little bit superior extraction yield in comparison to the Soxhlet extraction method for extraction of crude wax. In the case of non-polar solvent (hexane), an extraction yield of 1.97% (%w/w) through maceration method was observed while in the case of non-polar solvent (ethanol), an extraction yield of 1.62% (%w/w) through Soxhlet extraction was observed. The TLC analysis on both types of extracts was performed. For the detection of various hydrocarbon chains in the crude wax extracts, FTIR was also performed. Topography of wax surface and wax-coated waterproof fabric was compared through SEM.     

Metal Complexes of Singly,Doubly and Triply Linked Porphyrins and Corroles: An Insight into the Physicochemical Properties

Metal complexes of multi-porphyrins and multi-corroles are unique systems that display a host of extremely interesting properties. Availability of free meso and β positions allow formation of different types of directly linked bis-porphyrins giving rise to intriguing optical and electronic properties. While the fields of metalloporphyrin and corroles monomer have seen exponential growth in the last decades, the chemistry of metal complexes of bis-porphyrins and bis-corroles remain rather underexplored. Therefore, the impact of covalent linkages on the optical, electronic, (spectro)electrochemical, magnetic and electrocatalytic activities of metal complexes of bis-porphyrins and -corroles has been summarized in this review article. This article shows that despite the (still) somewhat difficult synthetic access to these molecules, their extremely exciting properties do make a strong case for pursuing research on these classes of compounds.     

Density of near-extreme events

We provide a quantitative analysis of the phenomenon of crowding of near-extreme events by computing exactly the density of states (DOS) near the maximum of a set of independent and identically distributed random variables. We show that the mean DOS converges to three different limiting forms depending on whether the tail of the distribution of the random variables decays slower than pure exponential, faster than pure exponential, or as a pure exponential function. We argue that some of these results would remain valid even for certain correlated cases and verify it for power-law correlated stationary Gaussian sequences. Satisfactory agreement is found between the near-maximum crowding in the summer temperature reconstruction data of western Siberia and the theoretical prediction.     

Aromatic Superhalogens

No organic molecules with electron affinities near or above those of halogens are known. We show for the first time that aromaticity rules can be used to design molecules with electron affinities far exceeding those of halogen atoms either by tailoring the ligands of cyclopentadienyl or by multiple benzoannulations of cyclopentadienyl in conjunction with the substitution of CH groups with isoelectronic N atoms. Results based on density functional theory revealed that the electron affinities of some of these organic molecules can reach as high as 5.59 eV, thus opening the door to new class of superhalogens that contain neither a metal nor a halogen atom.     

Nickel‐Catalyzed α‐Carbonylalkylarylation of Vinylarenes: Expedient Access to γ,γ‐Diarylcarbonyl and Aryltetralone Derivatives

We report a Ni‐catalyzed regioselective α‐carbonylalkylarylation of vinylarenes with α‐halocarbonyl compounds and arylzinc reagents. The reaction works with primary, secondary, and tertiary α‐halocarbonyl molecules, and electronically varied arylzinc reagents. The reaction generates γ,γ‐diarylcarbonyl derivatives with α‐secondary, tertiary, and quaternary carbon centers. The products can be readily converted to aryltetralones, including a precursor to Zoloft, an antidepressant drug.     

Alteration in Cross Diffusivities Governs the Nature and Dynamics of Spatiotemporal Pattern Formation

Realizing spatiotemporal patterns out of a chemical reaction diffusion system remains an experimental challenge owing to the difficulty in overcoming the stringent condition of diffusion driven instability. Herein, by considering the spatially extended Gray-Scott model system, we have investigated how the cross diffusivities of the reactants involved influence the nature and dynamics of spatiotemporal patterns. Our study unravels that in absence of diffusion driven instability, spatially inhomogeneous patterns can be obtained for the Gray-Scott model system, and unstable time dependent patterns can be stabilized just by adjusting cross diffusivities of the reactants. Interestingly, the effect of cross diffusion in presence of the diffusion driven instability can differentially alter the speed of pattern formation, and potentially modify the nature of the spatiotemporal patterns obtained under different parametric conditions. Experimental verification of our findings may allow us to observe spatiotemporal patterns beyond the regime of classical Turing instability.     

Antibacterial Activity of Alpinia galanga (L) Willd Crude Extracts

Methanol, acetone and diethyl ether extracts of Alpinia galanga have been evaluated against pathogens viz. Bacillus subtilis MTCC 2391, Enterobacter aerogene, Enterobacter cloacae, Enterococcus faecalis, Escherichia coli MTCC 1563, Klebsiella pneumoniae, Pseudomonas aeruginosa MTCC 6642, Salmonella typhimurium, Staphylococcus aureus and Streptococcus epidermis using Agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of all the extracts were determined using the macrodilution method. Methanol extracts have shown excellent activity towards all the pathogens with MIC and MBC values ranging from 0.04–1.28 mg/ml and 0.08–2.56 mg/ml, respectively. The GC–MS analysis of methanol extracts have yielded compounds like 5-hydroxymethyl furfural (59.9%), benzyl alcohol (57.6%), 1,8 cineole (15.65%), methylcinnamate (9.4%), 3-phenyl-2-butanone (8.5%) and 1,2 benzenedicarboxylic acid (8.9%), which could be responsible for its broad spectrum activity. So, A. galanga can be quite resourceful for the development of new generation drugs.     

Catalyst electronic polarizability and enantiomeric excess in asymmetric hydrogenation

In the classical rhodium-diphosphine complexes-catalyzed asymmetric hydrogenation of enamide substrates, examination on the role of catalyst electronic polarizability in the origin of enantioselectivity reveals its linear free energy relationship with the product enantiomeric ratio that is much more pronounced than analogous correlation with steric effect in the same systems. From a conceptually novel scenario, this work suggests that the often-overlooked chiral catalyst local polarizability property may function as a controlling force in enantioselection thus has important implication in rational catalyst design.     

Complexification of three potential models — II

A new kind of $ \mathcal{P}\mathcal{T} $ \mathcal{P}\mathcal{T} and non-$ \mathcal{P}\mathcal{T} $ \mathcal{P}\mathcal{T} -symmetric complex potentials are constructed from a group theoretical viewpoint of the sl(2,C) potential algebras. The real eigenvalues and the corresponding regular eigenfunctions are also obtained. The results are compared with the ones obtained before.