Investigations on the Synthesis, Reactivity, and Properties of Perfluoro‐α‐Benzo‐Fused BOPHY Fluorophores

Abstract

The synthesis and reactivity of 3,8‐dibromo‐dodecafluoro‐benzo‐fused BOPHY 2 are reported, via SNAr with O‐, N‐ S‐ and C‐nucleophiles, and in Pd(0)‐catalyzed cross‐coupling reactions (Suzuki and Stille). The resulting perfluoro‐BOPHY derivatives were investigated for their reactivity in the presence of various nucleophiles. BOPHY 3 displays reversible color change and fluorescence quenching in the presence of bases (Et3N, DBU), whereas BOPHY 7 reacts preferentially at the α‐pyrrolic positions, and BOPHY 8 undergoes regioselective fluorine substitution in the presence of thiols. The structural and electronic features of the fluorinated BOPHYs were studied by TD‐DFT computations. In addition, their spectroscopic and cellular properties were investigated; BOPHY 10 shows the most red‐shifted absorption/emission (λmax 659/699 nm) and 7 the highest fluorescence (Φf=0.95), while all compounds studied showed low cytotoxicity toward human HEp2 cells and were efficiently internalized.

Solid-State Emissive meso-Aryl/Alkyl-Substituted and Heteroatom-Mixed BOPPY Dyes: Syntheses, Structures, Physicochemical, Redox Properties, and Computational Analysis

“…Various substituents have been realized, such as aryl/alkyl groups attached at the meso -position, N-inserted the pyridine segment, and the Cl atom in the pyridine segment replaced by heteroatom substitution (Figures and S1–S9 and Tables S1 and S2). Similar to the previously reported bisBF 2 complexes, − the BOPPYs exhibit almost planar frameworks, although slightly distorted conformations were observed with a dihedral angle of 6.1° defined by the pyridine unit and the BOPPY core. Similar with the reported BOAPY , and BOPPY, , the coordinated B–N distances on the same boron atom are slightly different, further supporting the unsymmetrical structure.…”

“…Recently, bisBF 2 chromophores such as BOPHY, − BOBPY, BOIMPY, , BOAPY, , and BOPPY , (Figure ) have attracted significant attention due to their exceptional properties and low LUMO energy levels, making them a promising platform for various applications. Among them, the BOPPY fluorophore stands out due to its unsymmetrical, rigid, and fluorescent properties.…”

Aromatic-Ring-Fused BOPPY Fluorophores: Synthesis, Spectral, Redox Properties, and Bioimaging Application

“…For more than three decades, boron dipyrromethene (BODIPY) dyes, as one of the most successful fluorophores, have been intensively investigated, due to their simple synthesis strategy, easy modification, high stability, and tunable photophysical properties. − The success of BODIPY dyes has inspired investigations into similar skeletal analogue systems, such as Boranil, , aza-BODIPY fluorophore, − and so forth. Recently, bis­(BF 2 ) chromophores containing N–B–N or N–B–O bridges such as BOPHY, − BOIMPY, − BOAPY, and BOPAHY have received much attention, which usually have excellent photostability and exhibit a low LUMO energy level due to the two anchored electron-deficient BF 2 groups (Figure ). Among these, the potential applications of the BOPHY chromophore (Figure ) as a novel platform were immediately established, and its derivatives have been quickly used in a wide array of promising diverse fields from bioimaging and energy-transfer cascades to solar cells and so on.…”

“…We notice that the π-sufficient aromatic-ring fusions are efficient methods to achieve bathochromic shifts. Inspired by the studies successfully demonstrated in the BODIPYs and BOPHYs, − ,− herein, we report the synthesis, photophysical properties, redox properties, and cellular applications of a series of α-benzo-fused BOPPYs with 6,6,6,5,6,5,6-pentacyclic rings and β-benzothiophene-fused BOPPYs with 5,6,5,6,5,6-hexacyclic rings, as illustrated in Figure . The fusion of α-benzo and β-benzothiophene efficiently extended the π-conjugated system of the BOPPY core; meanwhile, the chlorine atom in the pyridine segment of the chromophore could provide a convenient method for further postfunctionalization such as nucleophilic substitution reactions and metal-catalyzed coupling reactions.…”

Synthesis and Regioselective Functionalization of Tetrafluorobenzo-[α]-Fused BOPYPY Dyes

“…The electron-withdrawing fluorine atoms in these molecules further stabilize this type of chromophore relative to the currently known compounds . In addition to improving stability, advantages of introducing a tetrafluorobenzo-fused unit in the chromophore include (1) extending the chromophore π-system leading to longer wavelength absorptions and emissions, (2) allowing direct attachment of molecules via nucleophilic substitutions of one or more fluorine atoms, (3) allowing for F-radiolabeling for dual fluorescence and MRI imaging, and (4) improving solubility. , In addition, a Stille coupling reaction was investigated on the α-bromo-BOPYPY derivative 2 , demonstrating the versatility of regioselective functionalization of this type of chromophore.…”