Rational Design of Boradiazaindacene (BODIPY)‐Based Functional Molecules

Abstract

Three boradiazaindacene (BODIPY) dyes with different-coloured (greenish-yellow, orange and red) fluorescence and good Stokes shifts were synthesised starting from the greenish-yellow BODIPY dye PM546. The high Stokes shifts of the dyes are due to the release of the steric strain in their excited states relative to that in the highly twisted ground states. One of these compounds might be a useful water-soluble fluorophore, whereas the other two are promising H(+) sensors.

Construction of the carbon–chalcogen (S, Se, Te) bond at the 2,6-positions of BODIPY via Stille cross-coupling reaction

“…The lowest coefficients in the LUMO at the 2,6-positions of BODIPY 15 hamper nucleophilic substitution which is normally used for installation of heteroatom-containing substituents. Therefore, BODIPY derivatives substituted with chalcogen atoms at the 2,6-positions, such as ethers, 16 amines, 17 or thioethers, 18,19 are rare. We recently reported on the synthesis of several 3-chalcogen substituted BODIPYs, which exhibit intersystem crossing (ISC) quantum yields comparable to those of iodo-analogues.…”

Synthesis and Characterization of Some BODIPY‐based Substituted Salicylaldimine Schiff Bases

“…This could be due to distortion in the planar BODIPY core due to weak H–F hydrogen bonding as observed in X‐ray crystallography. Distortion in the pyrrole ring brought out by bulky substitutes (e.g., tert ‐butyl) is known to result in large Stokes shift (30–38 nm) . The quantum yield for 4c (Table ) is highest among other compounds, which may be due to higher mixing of orbitals as distortion may be higher in the planar BODIPY core as compared with other compounds.…”

Further investigation on the nitration of BODIPY with cupric nitrate: crystal structures of 4,4-difluoro-1,3,5,7,8-pentamethyl-2-nitro-4-bora-3a,4a-diaza-s-indacene, 4,4-difluoro-3-nitro-8-phenyl-4-bora-3a,4a-diaza-s-indacene, and 3-chloro-6-ethyl-5,7,8-trimethyl-2-nitro-4,4-diphenyl-4-bora-3a,4a-diaza-s-indacene

“…In order to broaden its utilities, the discovery of reactions to introduce functional group into BODIPY has attracted significant interest. Among these, installation of nitro groups into BODIPY core represents a useful approach to functionalize BODIPY (Ulrich et al, 2012;Esnal et al, 2013;Gupta et al, 2013). In this respect, while BODIPY fluorophores with nitro ISSN 2056-9890 groups are poorly fluorescent, their fluorescence is usually restored upon reduction of nitro to amine (Yang et al, 2014;Yang et al, 2017).…”