Engineering Gram Selectivity of Mixed‐Charge Gold Nanoparticles by Tuning the Balance of Surface Charges

Nanoparticles covered with ligand shells comprising both positively and negatively charged ligands exhibit Gram‐selective antibacterial action controlled by a single experimental parameter, namely the proportion of [+] and [?] ligands tethered onto these particles. Gram selectivity is attributed to the interplay between polyvalent electrostatic and non‐covalent interactions that work in unison to disrupt the bacterial cell wall. The [+/?] nanoparticles are effective in low doses, are non‐toxic to mammalian cells, and are tolerated well in mice. These results constitute the first example of rational engineering of Gram selectivity at the (macro)molecular level.     

Oxidation of Bromide by Tert‐Butyl Hypochlorite

The kinetics of the oxidation reaction of bromide by tert‐butyl hypochlorite (^tBuOCl) was studied at 25°C, ionic strength 0.5 M, and under isolation conditions. A stopped‐flow spectrophotometer was employed for monitoring the reactions. Kinetic studies show that the reaction is first order with respect to [Br^?] and [^tBuOCl]. Linear dependences of the proton concentration, in perchloric acid medium, and the buffer solution concentration were found on the rate constant. The activation parameters were calculated using the Arrhenius and Eyring equations from the kinetic studies performed to analyze the influence of temperature on the rate constant. The results are consistent with a reaction mechanism of general acid catalysis. The catalytic constants were obtained for the oxidation of bromide by tert‐butyl hypochlorite. The slope obtained for the Brönsted relationship was 0.36.     

The effects of magnesium and aluminium ions’ additions on the kinetics of titanium dioxide structural transformation

Catalytic fast pyrolysis analysis of miscanthus over HZSM-5, La/ZSM-5, and Ca/ZSM-5 was performed using pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). The characteristics of the catalysts used in this study were analyzed using XRD, SEM, Pyridine IR, ICP, and N₂ adsorption. The catalytic performance of the three catalysts was evaluated in terms of deoxygenation. Py–GC/MS results show that with increasing temperature, pyrolysis vapor yield first increased and then decreased. This may be due to secondary cracking at higher temperatures, which produced more gas products. Moreover, hydrocarbon content increased with rising temperature. The optimum temperature was found to be 600 °C, which resulted in the greatest liquid yield. All three catalysts increased pyrolysis vapor yield by about 30 %. Moreover, the hydrocarbon content of miscanthus increased from 6 to 39 %, 46, and 44 %, respectively, when HZSM-5, La/ZSM-5, and Ca/ZSM-5 were applied. In conclusion, the three catalysts were effective for deoxygenation of pyrolysis vapor yield. Considering both economic and catalytic upgrading effect, Ca/ZSM-5 may be the best catalyst.     

Fluorescent Nitric Oxide Photodonors Based on BODIPY and Rhodamine Antennae

Two novel NO photodonors (NOPDs) based on BODIPY and Rhodamine antennae activatable with the highly biocompatible green light are reported. Both NOPDs exhibit considerable fluorescence emission and release NO with remarkable quantum efficiencies. The combination of the photoreleasing and emissive performance for both compounds is superior to those exhibited by other NOPDs based on similar light-harvesting centres, making them very intriguing for image-guided phototherapeutic applications. Preliminary biological data prove their easy visualization in cell environment due to the intense green and orange-red fluorescence and their photodynamic action on cancer cells due to the NO photo-liberated.     

Dual Photoredox/Nickel‐Catalyzed Three‐Component Carbofunctionalization of Alkenes

The potential of merging photoredox and nickel catalysis to perform multicomponent alkene difunctionalizations under visible‐light irradiation is demonstrated here. Secondary and tertiary alkyl groups, as well as sulfonyl moieties can be added to the terminal position of the double bond with simultaneous arylation of the internal carbon atom in a single step under mild reaction conditions. The process, devoid of stoichiometric additives, benefits from the use of bench‐stable and easy‐to‐handle reagents, is operationally simple, and tolerates a wide variety of functional groups.