Radical CH Arylation of the BODIPY Core with Aryldiazonium Salts: Synthesis of Highly Fluorescent Red‐Shifted Dyes

Abstract

We describe herein the first radical C À Harylation of BODIPY dyes.T his novel,g eneral, one-step synthetic procedure uses ferrocene to generate aryl radical species from aryldiazonium salts and allows the straightforwardsynthesis of brightly fluorescent (F > 0.85) 3,5-diarylated and 3-monoarylated boron dipyrrins in up to 86 %yield for abroad range of aryl substituents.Inthis way,new and complex dyes with redshifted spectra can be easily prepared.

A versatile synthetic approach to design tailor-made push-pull chromophores with intriguing and tunable photophysical signatures

“…In other words, the BODIPY core behaves better as electron acceptor rather than donor. Therefore, the amine group greatly favors the formation of an ICT state, as observed previously in related push-pull chromophores bearing the said 3-amine and ED or EW groups at 8-position [6,24]. Nevertheless, it should be emphasized the main role of the 8-functionalization in the activation of the ICT, since the direct linkage of 3-amine to an alkylated BODIPY yielded high fluorescence efficiencies, without sign of ICT formation [20].…”

“…However, the fact that all of them displayed interesting photophysical properties, including bathochromic shift, warranted the study of further transformations on both the meso-position and the 3-aryl substituent. According to the observations made by Dehaen [6], the reaction also failed when an electron-rich amine was used. The arylation reaction was also attempted on BODIPY 1b (ec.…”

“…There are just a few methods reported in the literature that describe the C-H activation of BODIPYs. For example, Burgess introduced an electron-withdrawing vinyl group at the 2-position by treating 2-unsubstituted BODIPY dyes with activated double-bonds, a Pd(II) catalyst, and an oxidant [5], whereas Dehaen and co-workers described both a radical C-H arylation of BODIPYs with aryldiazonium salts [6], and a radical C-H alkylation of the same dyes with potassium trifluoroborates [7] (Scheme 1). Building upon Dehaen´s results, we envisioned the C-H arylation of 1a and 1b in order to functionalize the 3-and 1-positions respectively.…”

Enhanced Hypsochromic Shifts, Quantum Yield, and π–π Interactions in a meso,β-Heteroaryl-Fused BODIPY

“…BODIPY 4 was prepared in two steps from perhalogenated BODIPY 1 , 13 via a substitution reaction followed by a Pd(0)-catalyzed intramolecular cyclization. There are several advantages to our strategy: (1) 8-aryloxy (and alkoxy) substituted BODIPYs typically display high quantum yields; 14 (2) the 8-phenoxy group allows the formation of a 6-membered fused ring; (3) the 1,7-bromo groups are more reactive than hydrogens, 6, 9i, 15 particularly under Pd(0)-catalyzed reaction conditions; and (4) the presence of halogen groups at the pyrrolic positions allows for further functionalization of the BODIPY. BODIPY 4 features a planar backbone as evidenced by X-ray crystallography, strong π-π stacking, high quantum yields, and unusually large hypsochromic shifts in its absorption and emission spectra.…”

Oxidative C-H/C-H Coupling of Dipyrromethanes with Azines by TiO2-Based Photocatalytic System. Synthesis of New BODIPY Dyes and Their Photophysical and Electrochemical Properties

“…A more atom-economical method of incorporating functional groups into the BODIPY nucleus at positions 3,5 is an oxidative substitution of α-hydrogen by fragments of C-, N-nucleophiles [ 38 ]. In addition, examples of radical C-H arylation/heteroarylation of BODIPY dyes using aryldiazonium salts are known [ 39 , 40 ], ferrocene is used to generate aryl radical species in these transformations.…”