BOIMPYs: Rapid Access to a Family of Red‐Emissive Fluorophores and NIR Dyes

Abstract

A fundamental, highly fluorescent, and easily accessible scaffold derived from the BODIPY core is reported. The use of benzimidazole as a bridging ligand at the meso position enables the binding of two BF units to provide sufficient rigidity and enhanced electron-withdrawing strength. Absorption and emission events thus take place in the red (λ≈600 nm); the fluorescence quantum yields can reach unity (0.96) and show little dependence on solvent polarity. The synthetic route was shortened to two steps starting from commercially available precursors while the preparation is modular and tolerates various pyrrole and benzimidazole moieties. Fluoride replacement by propynyl groups, various halogenations, as well as Knoevenagel-type condensations were applied to extend the versatility of these new photostable fluorophores, which we termed BOIMPYs.

Direct Transformation of Esters into Heterocyclic Fluorophores

“…[12] Whereas acridinium salts 4a-d already indicated efficient formation of the desired product, the mesityl-substituted diaminoacridinium catalyst 4e gave complete conversion after 3h(entry 5, 86 %y ield). [14,15] Thecorresponding 1,5-bifunctional organomagnesium reagents were expeditiously synthesized in three steps by heteroatom-bridge formation, double bromination, and dimagnesiation (Schemes S2 and S3). Thet etramethyldiaminoacridinium salts 4a-f therefore complement the carbazolyl dicyanobenzene organophotoredox catalysts recently reported by Zhang and co-workers for dual catalysis with nickel.…”

Gb3 Glycosphingolipids with Fluorescent Oligoene Fatty Acids: Synthesis and Phase Behavior in Model Membranes

“…Chemical synthesis of Gb 3 glycosphingolipids enabled us to access two glycoconjugates, 1 and 2 , differing in their fatty acid part (Scheme ). In order not to alter the membrane structure and dynamics to a major extent, we did not consider fatty acids with embedded polar and/or bulky fluorescent moieties, such as NBD, pyrene, boron‐dipyrromethene (BODIPY), boron complexes of iminopyrrolide ligands (BOIMPY), or benzothiadiazole, but prepared fatty acids consisting of pentaene and hexaene moieties either at the terminus or in the middle of the acyl chain . Their slim shape and hydrophobic scaffold should only disturb the membrane integrity to a minor extent .…”

BOIMPY: Fluorescent Boron Complexes with Tunable and Environment‐Responsive Light‐Emitting Properties

“…In order to take full advantage of such structure‐dependent and environment‐sensitive light‐emitting properties, the BOIMPY motif was engineered into a bioprobe, which is localized selectively at LDs to allow for live‐cell imaging without affecting cell viability. By exploiting: 1) high modularity in synthesis, 2) optical tuning by covalent/conformational modification, and 3) peripheral functionalization for delivery, our future efforts will be directed toward applications of BOIMPY fluorophores in biological imaging, chemical sensing, and molecular switching …”