BODIPY Dyes Bearing Multibranched Fluorinated Chains: Synthesis, Structural, and Spectroscopic Studies

Abstract

A small series of boron‐dipyrromethene (BODIPY) dyes, characterized by the presence of multibranched fluorinated residues, were designed and synthesized. The dyes differ in both the position (para‐perfluoroalkoxy‐substituted phenyl ring or boron functionalization) and number of magnetically equivalent fluorine atoms (27 or 54 fluorine atoms per molecule). Photophysical and crystallographic characterization of the synthesized BODIPYs was carried out to evaluate the effect of the presence of highly fluorinated moieties on the optical and morphological properties of such compounds.

Synthesis and Applications of Selected Fluorine-Containing Fluorophores

“…Martinez Espinoza et al studied the synthesis and effects of branched fluorinated chains off a BODIPY scaffold [ 21 ]. The synthetic design focused on the fluorinated chain placement in two different positions.…”

“…The other placement was a substitution of fluorine atoms at the boron center with alkoxy groups containing the fluorinated chain as seen in compounds 4 and 5 ( Figure 3 ) [ 21 ]. In these dyes, an iodination step occurs to add iodine atoms to the BODIPY core to promote singlet oxygen generation.…”

“…Molecules 2021, 26, x 5 of 37 Scheme 1. BODIPY with multi-branched fluorinated chains on meso phenyl [21]. Scheme 1.…”

“…Fluorophores in the visible range optical window show peak absorption and emission values within 400 nm and 600 nm. Compounds such as derivatives of boron-dipyrromethene (BODIPY), rhodamine, and fluorescein typically demonstrate signal wavelengths around 500 nm and 600 nm; however, it is more favorable to see these signals closer to 700 nm to improve biological applications [ 17 , 18 , 19 , 20 , 21 ]. For this reason, recent studies described further in the text demonstrate the applications of adding fluorine-based substituents and phenyl rings to the chemical designs, thus resulting in greater absorption and fluorescence wavelengths.…”

Halogen‐Bonded BODIPY Frameworks with Tunable Optical Features**

“…However, the design of efficient supramolecular architectures with highly complex structures, such as BODIPY, presents a great challenge and requires comprehensive knowledge of noncovalent interactions. Recently, a few studies have reported observation of the XB interaction in their BODIPY structures [28–31] …”