Red/Near‐infrared Boron–Dipyrromethene Dyes as Strongly Emitting Fluorophores

Abstract

We present an overview of the state of the art in long-wavelength boron-dipyrromethene (BODIPY) fluorophores, focusing on strategies to shift the absorption and emission bands into the red/near-infrared (NIR) range of the spectrum. This report also discusses chemical modifications of the chromophoric core to obtain analyte-responsive fluorophores, including examples of pH and metal ion indicators. Finally, we present a new series of phenanthrene-fused BODIPY dyes, emitting with high efficiency in the red/NIR region of the spectrum, as well as discussing potential applications thereof as probes.

Single-cell and subcellular pharmacokinetic imaging allows insight into drug action in vivo

“…Fifth, the model enables in vivo synergy and distribution to be determined by using combinations of differently tagged drugs. BODIPY fluorochromes in particular have a relatively small footprint and can be synthesized in a variety of excitation/emission ranges 46 . Finally, due to advances in optics and objectives 47 , and through the use of newer immobilization and gating techniques, it has recently become possible to study drug distribution directly in orthotopic cancers without the use of window chambers.…”

Dihydronaphthalene‐Fused Boron–Dipyrromethene (BODIPY) Dyes: Insight into the Electronic and Conformational Tuning Modes of BODIPY Fluorophores

“…Simple, alkyl-substituted dipyrrin BODIPYs, however, display absorption and emission bands with maxima only in the region of 480-540 nm so that today considerable effort is being made to shift the optical properties to the red. [5,[14][15][16][17][18] Several strategies have been reported to be successful such as the introduction of aryl substituents in the 3,5-and/or 1,7-positions of the BODIPY core (like in compounds 4, [19] 5, [20] 6, [21] 7, [22] 8 [23] and 9; [24] Scheme 2) or electron acceptors in the meso position, [25][26][27] aromatic ring fusion, [28][29][30] extension of the electronic p system by styryl substitution [31][32][33][34][35][36][37][38] or aza-substitution of the meso-carbon atom (like in compounds 7 and 9; Scheme 2).…”

Functionalization of 3,5,8-Trichlorinated BODIPY Dyes

“…1−4 BODIPY dyes have advantages compared with other fluorophores, including large molar absorption coefficients and high fluorescence quantum yields, redox active, relatively high thermal and photochemical stability, and easy functionalization that enables the tuning of their properties, such as absorption/emission wavelengths, charge-transfer, and amphiphilicity. 5−7 Due in part to their relatively low molecular weight, BODIPYs and their conjugates usually show good permeability across the membranes of living cells, making them suitable for biological and medical applications. 4−10 …”

“…These methods include, but are not limited to, electrophilic and nucleophilic substitutions, palladium-catalyzed cross-couplings, aromatic ring fusion, and Knoevenagel condensations. 5−7 Among these, aromatic ring fusion 7,11,12 and cross-coupling reactions 13−16 are particularly useful for inducing bathochromic shifts of the BODIPY optical transitions via extension of π-conjugation, while substitution reactions 17−21 are often used to modify the molecular amphiphilicity upon introduction of heteroatom-based groups, and for bioconjugations. Halogenated BODIPYs are particularly versatile substrates for functionalization purposes via both cross-coupling and nucleophilic substitution reactions, and all halogens (fluoride, chloride, bromide, and iodide) have been introduced into the pyrrolic positions of BODIPY (or a dipyrromethane or pyrrole precursor), mainly using electrophilic substitution.…”