Electrochemical Diselenation of BODIPY Fluorophores for Bioimaging Applications and Sensitization of 1 O2.

We report a rapid, efficient, and scope-extensive approach for the late-stage electrochemical diselenation of BODIPYs. Photophysical analyses reveal red-shifted absorption - corroborated by TD-DFT and DLPNO-STEOM-CCSD computations - and color-tunable emission with large Stokes shifts in the selenium-containing derivatives compared to their precursors. In addition, due to the presence of the heavy Se atoms, competitive ISC generates triplet states which sensitize 1 O2 and display phosphorescence in PMMA films at RT and in a frozen glass matrix at 77 K. Importantly, the selenium-containing BODIPYs demonstrate the ability to selectively stain lipid droplets, exhibiting distinct fluorescence in both green and red channels. This work highlights the potential of electrochemistry as an efficient method for synthesizing unique emission-tunable fluorophores with broad-ranging applications in bioimaging and related fields.

Electrochemical Diselenation of BODIPY Fluorophores for Bioimaging Applications and Sensitization of 1 O2.

Invited for the cover of this issue are the groups of Holger Braunschweig at the Julius-Maximilians-Universität Würzburg, Germany and Eufrânio N. da Silva Júnior at the Universidade Federal de Minas Gerais, UFMG, Brazil. The image depicts the electrochemical synthesis of selenium-containing BODIPY molecules with lightning symbolizing the electrifying synthetic process, while the surrounding elemental chaos hints at the red-shifted absorption and emission and the transformative photophysical properties of these new compounds. Read the full text of the article at 10.1002/chem.202303883.

Unveiling a Strategy for Ring Opening of Epoxides: Synthesis of 2-Hydroxyindolinylidenes Using α-Ester Sulfoxonium Ylides.

The untapped potential of α-carbonyl sulfoxonium ylides in epoxide ring-opening reactions has been a notable gap in current research, with such reactivity predominantly associated with the highly reactive dimethylsulfoxonium methylide. This study introduces an innovative approach wherein an epoxide indole, formed in situ from 2-hydroxyindoline-3-triethylammonium bromide, undergoes reaction with α-ester sulfoxonium ylides. The outcome is the efficient synthesis of a range of 2-hydroxyindolin-3-ylidenes, demonstrating favorable yields (41-81%) and Z/E ratios from 4:1 to those of exclusive Z isomers. Additionally, the photophysical properties of the synthesized indolinylidenes are explored, along with their derivatization using various nucleophiles under acid catalysis.