Photophysics of 3,5-diphenoxy substituted BODIPY dyes in solution

Solvatochromic Sensitivity of BODIPY Probes: A New Tool for Selecting Fluorophores and Polarity Mapping

This research work is devoted to collecting a high-quality dataset of BODIPYs in a series of 10-30 solvents. In total, 115 individual compounds in 71 solvents are represented by 1698 arrays of the spectral and photophysical properties of the fluorophore. Each dye for a series of solvents is characterized by a calculated value of solvatochromic sensitivity according to a semiempirical approach applied to a series of solvents. The whole dataset is classified into 6 and 24 clusters of solvatochromic sensitivity, from high negative to high positive solvatochromism. The results of the analysis are visualized by the polarity mapping plots depicting, in terms of wavenumbers, the absorption versus emission, stokes shift versus - (absorption maxima + emission maxima), and quantum yield versus stokes shift. An analysis of the clusters combining several dyes in an individual series of solvents shows that dyes of a high solvatochromic sensitivity demonstrate regular behaviour of the corresponding plots suitable for polarity and viscosity mapping. The fluorophores collected in this study represent a high quality dataset of pattern dyes for analytical and bioanalytical applications. The developed tools could be applied for the analysis of the applicability domain of the fluorescent sensors.

Cascades of energy and electron transfer in a panchromatic absorber

The investigation of molecular model systems is fundamental towards a deeper understanding of key photochemical steps in natural photosynthesis. Herein, we report an entirely non-covalent triad consisting of boron dipyrromethene (BDP), porphyrin (ZnP), and fullerene (C60). Non-covalent binding motifs such as an amidinium-carboxylate salt bridge as well as axial pyridyl-metal coordination offer substantial electronic coupling and establish efficient pathways for photoactivated energy and electron transfer processes along a well-tuned gradient. Experimental findings from steady-state and time-resolved spectroscopic assays, as well as (spectro-)electrochemical measurements corroborate the formation of BDP|ZnP|C60 in solution, on one hand, and significant communication in the excited states, on the other hand. BDP acts as an energy harvesting antenna towards ZnP, which eventually undergoes charge separation with C60 by electron transfer from ZnP to C60. Notably, full spectral deconvolution of the transient species was achieved, supporting the successful self-assembly as well as giving a clear view onto the occurring photophysical processes and their spectral footprints upon photoexcitation.

New insights into quantifying the solvatochromism of BODIPY based fluorescent probes

A simple semiempiric phenomenological approach is developed for quantifying the solvent effect on the absorption and emission properties of BODIPYs. It is based on a new rule describing the linear relationship between the difference (Stokes shift) and the sum (double Gibbs free energy of electron transfer) for absorption and emission wavenumbers derived from a combination of solvent functions of Liptay theory. This rule is correspondent to changes of dipole moments in the ground and excited states. High reliability and advantages of the developed approach in comparison with traditional methods of the analysis of the solvatochromism based on Dimroth-Reichard and Lippert-Mataga solvent scales are illustrated for selected BODIPYs exhibiting positive, negative, and near-zero solvatochromism.

Bay-Substituted Thiaza[5]helicenes: Synthesis and Implications on Structural and Spectroscopic Properties

A series of bay-substituted thiaza[5]helicenes was synthesized to investigate the effect of different substituents on the properties of these helicenes. These thiaza[5]helicenes with different substituents were prepared in a straightforward manner through indole- and benzo[b]thiophene synthesis, palladium-catalyzed Suzuki coupling, oxidative cyclization, and functional group interconversion reactions. We investigated the impact of these different bay area substituents compared to the unsubstituted thiaza[5]helicene on the structural parameters and studied the steady-state electronic spectroscopy of these thiaza[5]helicenes in toluene and acetonitrile. We found that different functional groups influence the solid state structure and spectroscopic properties, but a single substituent in the bay area of a thiaza[5]helicene was not enough to prevent enantiomerization at room temperature.

A straightforward synthesis of phenyl boronic acid (PBA) containing BODIPY dyes: new functional and modular fluorescent tools for the tethering of the glycan domain of antibodies

We report here on the efficient and straightforward synthesis of a series of modular and functional PBA-BODIPY dyes 1–4. They are an outstanding example of the efficient merge of the versatility of the 3,5-dichloro-BODIPY derivatives and the receptor-like ability of the PBA moiety. The potential bioanalytical applicability of these tools was assessed by measuring the binding to glycan chains of antibodies by a Quartz Crystal Microbalance (QCM).

PBA-BODIPY dyes as functional and modular fluorescent probes for the tethering of the glycan domain of mAbs.

Fast and Selective Two-Stage Ratiometric Fluorescent Probes for Imaging of Glutathione in Living Cells

Two fluorescent, m-nitrophenol-substituted difluoroboron dipyrromethene dyes have been designed by nucleophilic substitution reaction of 3,5-dichloro-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY). Nonsymmetric and symmetric probes, that is. BODIPY 1 (with one nitrophenol group at the position 3) and BODIPY 2 (with two nitrophenol groups at the positions 3 and 5) were applied to ratiometric fluorescent glutathione detection. The detection is based on the two-step nucleophilic aromatic substitution of the nitrophenol groups of the probes by glutathione in buffer solution containing CTAB. In the first stage, probe 1 showed ratiometric fluorescent color change from green (λ_em = 530 nm) to yellow (λ_em = 561 nm) because of monosubstitution with glutathione (I_561nm/I_530nm). Addition of excess glutathione caused the second stage of ratiometric fluorescent color change from yellow to reddish orange (λ_em = 596 nm, I_596nm/I_561nm) due to disubstitution with glutathione. Therefore, different concentration ranges of glutathione (from less to excess) could be rapidly detected by the two-stage ratiometric fluorescent probe 1 in 5 min. While, probe 2 shows single-stage ratiometric fluorescent detection to GSH (from green to reddish orange, I_596nm/I_535nm). Probes 1 and 2 exhibit excellent properties with sensitive, specific colorimetric response and ratiometric fluorescent response to glutathione over other sulfur nucleophiles. Application to cellular ratiometric fluorescence imaging indicated that the probes were highly responsive to intracellular glutathione.

Halogenated boron-dipyrromethenes: synthesis, properties and applications

Synthesis and properties of halogenated boron-dipyrromethenes and their applications in developing various BODIPY systems are described in this review.

Unprecedented one-pot sequential thiolate substitutions under mild conditions leading to a red emissive BODIPY dye 3,5,8-tris(PhS)-BODIPY

Phenylthiol performs a thiol exchange with 8-MeS-BODIPY and activates/substitutes the 3,5 positions forming a tri-thiolated BODIPY.

Synthesis and photochemical properties of BODIPY-functionalized silica nanoparticles for imaging Cu2+ in living cells

A highly selective copper(ii) sensor based on BODIPY-functionalized silica nanoparticles, BODIPY–DPA@SN, is designed and synthesized.

Structural modification strategies for the rational design of red/NIR region BODIPYs

The structure–property relationships of red/NIR region BODIPY dyes is analyzed, so that trends in their photophysical properties can be readily compared.

Fluorescent indicators based on BODIPY

This critical review covers the advances made using the 4-bora-3a,4a-diaza-s-indacene (BODIPY) scaffold as a fluorophore in the design, synthesis and application of fluorescent indicators for pH, metal ions, anions, biomolecules, reactive oxygen species, reactive nitrogen species, redox potential, chemical reactions and various physical phenomena. The sections of the review describing the criteria for rational design of fluorescent indicators and the mathematical expressions for analyzing spectrophotometric and fluorometric titrations are applicable to all fluorescent probes (206 references).

Synthesis, spectroscopic properties and protein labeling of water soluble 3,5-disubstituted boron dipyrromethenes

Sulfur-containing 3,5-disubstituted boron dipyrromethene (Bodipy) fluorescent probes with improved water solubility were synthesized. A dicarboxylic acid derivative that can be excited by the 543 nm HeNe laser line is very soluble in aqueous solution and retains high fluorescence quantum yield of the unionizable parent molecule. Conversion of the dicarboxylic acid to the succimidyl or sulfosuccinimidyl diester produces molecules capable of labeling proteins with a bright and stable fluorescence signal.