Acidic Condensation of BODIPYs with Aldehydes: A Quick and Versatile Route to Alkenyl‐BODIPYs and C(sp³)‐Connected DYEmers

Abstract

The condensation of aldehydes with BODIPY (boron dipyrrin) luminophores was investigated. Formaldehyde can be used to connect two BODIPYs at each of the three pyrrolic C positions (α-, β-, and β'-positions) in a quick and highly selective manner, yielding new DYEmers (di- and oligomeric BODIPY derivatives) with varied photophysical properties. Benzaldehydes form DYEmers only at the β- and the β'-positions. For aliphatic aldehydes the DYEmer formation competes with the elimination of water from a proposed alcohol intermediate, leading to the formation of α- and β-alkenyl-BODIPYs. 2-Phenylacetaldehyde and similar precursors exclusively yield elimination products. These acid-mediated transformations are valuable alternatives to the well-established, base-promoted Knoevenagel condensation protocol that is typically employed in the preparation of BODIPYs with near infrared (NIR)-shifted absorptions.

Ultrafast Resonance Energy Transfer in Ethylene-Bridged BODIPY Heterooligomers: From Frenkel to Förster Coupling Limit

“…BODIPY motifs, which are predominantly known for serving as powerful fluorescent tags and sensing platforms in life sciences, − also entered the field of supramolecular chemistry and profit from a toolbox of versatile postfunctionalizations. − While a range of different conjugation modes was introduced, most of them suffer from either a conformational space that is too restricted (methylene tether) , or detrimental π-overlap (direct sp 2 –sp 2 , , alkynyl , ) to enable defined alignments. However, such alignments would be necessary to achieve narrowed absorption/emission profiles as consequence of J-aggregation with delocalized excitons.…”

One‐Pot Preparation of Non‐Symmetric meso‐Aryl‐BODIPYs: Functional Derivatives with Unusual Reactivity

“…The formation of BODIPY DYEmers also gains from the use of non‐symmetric BODIPY precursors as losses due to the formation of higher oligomers or macrocycles can be avoided . Two such DYEmers, the directly linked α,α‐DYEmer 18 and the methylene‐bridged compound 19 , were prepared from 1 by using the newly established methods of oxidative coupling and acidic condensation with formaldehyde, respectively (Scheme ). Both compounds form as stable and intensely fluorescing dyes in acceptable yields of 48 and 70 %, respectively.…”

Rational Design and Biological Application of Hybrid Fluorophores

“…( 1) BODIPY oligomerization of non-conjugated hybrid fluorophores. Broring et al developed a series of BODIPY dimers and tetramers 228-236 in 2016 [141] (Figure 16 and Table 13).…”

“…Broring et al . developed a series of BODIPY dimers and tetramers 228 – 236 in 2016 [141] (Figure 16 and Table 13). Compared to the BODIPY monomers, these dimers have excellent molar extinction coefficients and fluorescence quantum yields, except for 232 and 233 , but their absorption and emission wavelengths are not significantly lengthened.…”