Synthesis and Spectroscopic and Cellular Properties of Near-IR [a]Phenanthrene-Fused 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacenes

Abstract

A new synthetic method to build aryl-fused 4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPYs) is reported. The intramolecular cyclization step was completed in a short time (1-2 h) and in high yields (>90%), due to the intrinsic rigid structural conformation of the precursor BODIPY and the high reactivity of its 1,7-bromo groups. The [a]phenanthrene-fused BODIPYs 4a-c were characterized by NMR spectroscopy, HRMS, DFT calculations, and, in the case of 4a, by X-ray crystallography. Spectroscopic studies show that 4a-c strongly absorb and emit in the NIR spectral region, in the range 642-701 nm. In addition, BODIPYs 4b and 4c exhibit no toxicity in the light or dark in HEp2 cells and accumulate intracellularly in a time-dependent manner, mainly in the cell endoplasmic reticulum. These results suggest the potential use of [a]phenanthrene-fused BODIPYs as NIR bioimaging probes.

A Simple Central Seven‐Membered BOPYIN: Synthesis, Structural, Spectroscopic Properties, and Cellular Imaging Application

“…All BOPYINs showeds light solvatochromism in the fluorescence spectra (for l em and F f values, see Figures S8-S11a nd Ta ble S5). Based on the Lipperte-Mataga equation [14] (Equation S1), the differenceb etween the dipole moment of the first excited singlet and ground state can be estimated from the slope of ap lot versus orientation polarizability (Df). The Lippert-Matagap lot for BOPYIN-3 was linear ( Figure S1, BOPYIN-3:R 2 = 0.88) with positives lope, which suggests that the dipole moment of BOPYIN-3 in the first excited singlet state is larger than that in the ground state.…”

Highly Efficient Deep‐Red‐ to Near‐Infrared‐Absorbing and Emissive Benzo/Naphtho[b]furan‐Fused Boron Dipyrromethene (BODIPY)

“…4,4-Difluoro-4-borata-3a,4a-diaza-s-indacene, abbreviated as BODIPY, is a popular family of dyes characterized by flexible chemical modifications, tunable absorption/emission band, good photo-stability and high fluorescent efficiency. [13][14][15][16][17][18] Such fused BODIPYs are generally obtained via complex reaction for aryl-fused pyrrole precursors and/or inter-/intra-molecular ring closure, which usually sacrifices the overall yields of the final BODIPYs. [8] Amongst all these methods, aromatic fusion is a promising strategy for the development of high quality emitters, because the extra rigidity provided by the aromatic fusion structure can enhance the thermal/photo-stability and suppress the non-radiative decay routes via the bond vibration and/or rotation.…”

“…One the other hand, interaction between photons and electrons that is the principle mechanism in all these applications, high stability and low photo-bleaching effect are required. [13][14][15][16][17][18] Such fused BODIPYs are generally obtained via complex reaction for aryl-fused pyrrole precursors and/or inter-/intra-molecular ring closure, which usually sacrifices the overall yields of the final BODIPYs. [6,7] Since the typical photo-active region of a BODIPY chromophore is from 450 to 550 nm, several approaches have been realized to achieve deep-red and NIR absorbing/emitting BODIPYs: (1) introduce "push-pull" strategy by introducing electron donating/withdrawing groups; (2) replace meso-carbon atom by a nitrogen atom to obtain aza-BODIPY; (3) extend the p conjugation system by fusing the dipyrromethene core with aryl moieties.…”

“…[8] Amongst all these methods, aromatic fusion is a promising strategy for the development of high quality emitters, because the extra rigidity provided by the aromatic fusion structure can enhance the thermal/photo-stability and suppress the non-radiative decay routes via the bond vibration and/or rotation. [13][14][15][16][17][18] Such fused BODIPYs are generally obtained via complex reaction for aryl-fused pyrrole precursors and/or inter-/intra-molecular ring closure, which usually sacrifices the overall yields of the final BODIPYs. [13][14][15][16][17][18] Such fused BODIPYs are generally obtained via complex reaction for aryl-fused pyrrole precursors and/or inter-/intra-molecular ring closure, which usually sacrifices the overall yields of the final BODIPYs.…”

Synthesis of 6,6′‐Bis(O‐4‐arylethynylbenzoyl)‐α,α‐Trehaloses and Their Utilization as Fluorescent Probes for Cellular Imaging

“…Thus, the aromatic compounds having large π‐conjugation can be used for the chemical sensors by using their highly fluorescent character . Moreover, Vicente and co‐workers recently reported the synthesis and spectroscopic and cellular properties of aryl‐fused 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐ s ‐indacenes (BODIPYs) . In this paper, they reported that [ α ]phenanthrene‐fused BODIPYs strongly absorb and emit in a near‐IR region (641–701 nm), and can be applied to bio‐imaging agents in human HEp2 cells.…”