Charge-transfer mediated J-aggregation in red emitting ultra-small-single-benzenic -fluorophore crystals.

Red emission in crystals has been observed with an ultra-small-single-benzenic -fluorophore () with a molecular weight (MW) of only 197 Da, bettering the literature report of fluorophores with the lowest MW = 252 Da. Supramolecular extensive hydrogen-bonding and J-aggregate type centrosymmetric discrete-dimers or a 1D chain of s led to red emission ( = 610-636 nm) in crystals. Unlike in the solution phase showing one absorption band, in thin films and in crystals the transition from the S state to both the S state and S state becomes feasible.

Gold-catalyzed fluorination of alkynes/allenes: mechanistic explanations and reaction scope.

Since the beginning of this century, there has been a great deal of research on homogeneous gold-catalyzed alkyne fluorination due to the precious values of fluorinated scaffolds in many bioactive natural products, drugs, and agrochemicals. This area of research, which originally took advantage of gold's mild Lewis acidity and tendency to form π-complexes with alkynes, has gained new momentum after Sadighi's discovery in 2007 of Au-catalyzed hydrofluorination of internal alkynes. The methods have enabled direct access to valuable fluoroalkanes, fluoroalkenes, α-fluorocarbonyls, and fluorinated carbo- and hetero-cycles in one pot from readily available alkyne precursors.

Progress of Photoantibiotics in Overcoming Antibiotic Resistance.

Antibiotic resistance has emerged as a global public health crisis in the 21 century, leading to treatment failures. To address this issue, the medical and pharmaceutical sectors are confronted with two challenges: i) finding potent new antimicrobial agents that would work against resistant-pathogens, and ii) developing conceptually new or unconventional strategies by which a particular antibiotic would remain effective persistently. Photopharmacology with the aid of reversibly controllable light-active antibiotics that we call "photoantibiotics" shows great promise to meet the second challenge, which has inspired many research laboratories worldwide to align their research in inventing or developing such antibiotics.

Direct Asymmetric Synthesis of α-Aminoimines from 1,2-Bis-N-Sulfinylimines by Using Allyl Boronic Acids.

A unique direct asymmetric synthesis of α-aminoimines is realized, through rapid and exclusive mono-allylation of chiral bis-N-sulfinylimines using allylboronic acids. The highly selective allylation was possible as electrophilic imine functional group in the product α-aminoimines remained unreactive towards allyl boronic acid nucleophiles. Notably, by varying the geometry and chiral auxiliary, all four isomers of the α-aminoimines were accessed from readily available precursors.

Spectator Exciton Effects in Nanocrystals III: Unveiling the Stimulated Emission Cross Section in Quantum Confined CsPbBr Nanocrystals.

Quantifying stimulated emission in semiconductor nanocrystals (NCs) remains challenging due to masking of its effects on pump-probe spectra by excited state absorption and ground state bleaching signals. The absence of this defining photophysical parameter in turn impedes assignment of band edge electronic structure in many of these important fluorophores. Here we employ a generally applicable 3-pulse ultrafast spectroscopic method coined the "Spectator Exciton" (SX) approach to measure stimulated-emission efficiency in quantum confined inorganic perovskite CsPbBr NCs, the band edge electronic structure of which is the subject of lively ongoing debate.