Positioning a Carbon–Fluorine Bond over the π Cloud of an Aromatic Ring: A Different Type of Arene Activation

It is known that the fluoro group has only a small effect on the rates of electrophilic aromatic substitutions. Imagine instead a carbon–fluorine (C?F) bond positioned tightly over the π cloud of an aryl ring—such an orthogonal, noncovalent arrangement could instead stabilize a positively charged arene intermediate or transition state, giving rise to novel electrophilic aromatic substitution chemistry. Herein, we report the synthesis and study of molecule 1 , containing a rigid C?F???Ar interaction that plays a prominent role in both its reaction chemistry and spectroscopy. For example, we established that the C?F???Ar interaction can bring about a >1500 fold increase in the relative rate of an aromatic nitration reaction, affording functionalization on the activated ring exclusively. Overall, these results establish fluoro as a through‐space directing/activating group that complements the traditional role of fluorine as a slightly deactivating aryl substituent in nitrations.     

Neuroprotective Ability of Apocynin Loaded Nanoparticles (APO-NPs) as NADPH Oxidase (NOX)-Mediated ROS Modulator for Hydrogen Peroxide-Induced Oxidative Neuronal Injuries

Apocynin (APO) is a known multi-enzymatic complexed compound, employed as a viable NADPH oxidase (NOX) inhibitor, extensively used in both traditional and modern-day therapeutic strategies to combat neuronal disorders. However, its therapeutic efficacy is limited by lower solubility and lesser bioavailability; thus, a suitable nanocarrier system to overcome such limitations is needed. The present study is designed to fabricate APO-loaded polymeric nanoparticles (APO-NPs) to enhance its therapeutic efficacy and sustainability in the biological system. The optimized APO NPs in the study exhibited 103.6 ± 6.8 nm and −13.7 ± 0.43 mV of particle size and zeta potential, respectively, along with further confirmation by TEM. In addition, the antioxidant (AO) abilities quantified by DPPH and nitric oxide scavenging assays exhibited comparatively higher AO potential of APO-NPs than APO alone. An in-vitro release profile displayed a linear diffusion pattern of zero order kinetics for APO from the NPs, followed by its cytotoxicity evaluation on the PC12 cell line, which revealed minimal toxicity with higher cell viability, even after treatment with a stress inducer (H₂O₂). The stability of APO-NPs after six months showed minimal AO decline in comparison to APO only, indicating that the designed nano-formulation enhanced therapeutic efficacy for modulating NOX-mediated ROS generation.     

Biotinylation of aminopyridine-based macrocycles and metallomacrocycles and inclusion of biotinylated iron(II) complex in avidin

A simple methodology for single-site conjugation of macrocycles and metallomacrocycles with biotin is presented. This method has been used to conjugate a redox-active macrocyclic complex and embed it into avidin. The resulting biotin-metal complex-avidin adduct exhibits peroxidase activity as shown by the oxidation of ABTS and pyrogallol with H₂O₂.     

An evaluation of the emission profile for two-wheelers at a traffic junction

Two-wheeler vehicles are an important mode of transportation in developing countries.However,the emissions from two-wheeler vehicles are significant.Urban two-wheeler vehicles with gasoline-fueled engines produce NO,and particulate matter emissions that affect urban air quality.During traffic light stops and programmed stops,for instance,pollutants are emitted and are dangerous to human health.In this experimental study,two-wheeler vehicles with different makes,technologies and engine capacities were tested for exhaust emissions including gravimetric and online measurements at different engine speeds and a no load condition at a si mutated traffic junction.Gravimetric measurements were performed by collecting the particulate mass(at two engine speeds:1500 and 2500 rpm) from a diluted engine-out exhaust on quartz filter paper.Next,these collected particulates were used to determine the presence of metals,as well as the benzene soluble organic fraction(BSOF).The total particulate mass,BSOF and trace elements were slightly higher at a higher engine speed(2500 rpm).Online measurements were performed by sampling the engine exhaust(at four engine speeds:1500.2000,2500,and 3000 rpm)and using online instruments to determine the particle number and size distribution,the particle-bound polyaromatic hydrocarbons(PAHs),the gaseous emissions and the smoke opacity.Engines with higher cubic capacity emitted a higher concentration of nano-particles.The particle-bound PAH concentration increased as the engine speed increased,but this concentration was notably low for the highest engine speed tested(3000 rpm).The regulated gaseous emissions increased as the engine speed increased for all vehicles.     

Emission profiling of diesel and gasoline cars at a city traffic junction

In congested urban roads,cars must stop at intersections because of city traffic lights.As a result,pedestrians and traffic police personnel are exposed to pollutants emanating from the tailpipe of various vehicles at such city traffic junctions.In this study,various gasoline- and diesel-fueled cars complying with different emission standards were tested for their emissions in simulated city traffic junction conditions.The engine exhaust from these cars was subjected to physicochemical characterization at different engine speeds under no-load conditions.These engine conditions were chosen because the cars idle at different engine speeds at a city traffic junction.Gravimetric and real-time measurements were performed for the tailpipe exhaust sampled from these vehicles.Exhaust particles were collected on 47 mm diameter quartz filter papers and subjected to gravimetric analysis for determining the total particulate mass(TPM)and trace metals while the engines were operated at two different engine idling speeds,1500 rpm(representing low idling) and 2500 rpm(representing high idling).At similar engine operating conditions,TPM and trace metals were lower for the exhaust from gasoline engines compared to the exhaust from diesel engines.Real-time measurements were performed for particle-bound poly-aromatic hydrocarbons(PAHs),particle number and size distribution,regulated gaseous emissions and smoke opacity of the exhaust at four different engine speeds,1500,2000,2500,and 3000 rpm.Particle-bound PAHs showed a decreasing trend for the vehicles that complied with stricter vehicular emission standards.Higher particle peak number concentrations were observed for diesel exhausts compared to the results for gasoline exhaust.Regulated gaseous emissions were also compared.     

Development of sulfonic acid–functionalized tetraethyl orthosilicate derivative cross-linked with sulfonated PEEK membranes for fuel cell applications

Journal of Solid State Electrochemistry - A novel technique for improving the characteristics of proton exchange membranes (PEMs) for fuel cell applications has been proposed, which combines...     

Correction to: Evaluation of background radiation level and excess lifetime cancer risk in Doon valley,Garhwal Himalaya

Journal of Radioanalytical and Nuclear Chemistry -     

Explaining the Advantageous Impact of Tertiary versus Secondary Nitrogen Center on the Activity of PNP-Pincer Co(I)-Complexes for Catalytic Hydrogenation of CO2

Pincer ligated coordination complexes of base metals have shown remarkable catalytic activity for hydrogenation/dehydrogenation of CO₂. The recently reported MeN[CH₂CH₂(ⁱPr₂)]₂Co(I)PNP-pincer complex was shown to exhibit substantially higher catalytic activity in comparison to the corresponding catalyst, HN[CH₂CH₂(ⁱPr₂)]₂Co(I)PNP, bearing a secondary nitrogen center on the pincer ligand. Here, we computationally investigate the mechanisms for hydrogenation of CO₂ to formate catalyzed by these two Co-PNP complexes to explain how such a small structural difference could have a sizable impact on their catalytic activity. Plausible hydrogenation routes were examined in details and our findings provide solid support for the experimental observations. Our results reveal that such trends in catalytic activity could be explained from the lower activation barrier for the hydride transfer step upon changing the pincer nitrogen center from secondary to tertiary.