Phenol/phenolate-dependent on/off switching of the luminescence of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes

Gareis, Thomas; Huber, Christian; Wolfbeis, Otto S.; Daub, Joerg

doi:10.1039/a703536e

Cited by 102 publications

(85 citation statements)

References 12 publications

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“…As previous work on 3 b has shown, [85] these properties can be readily exploited for pH sensing. The transference of the knowledge obtained here to meso-phenol-substituted derivatives [76] is expected to offer similar modes of tuning for indicators for the basic pH range.…”

Section: Resultsmentioning

confidence: 94%

“…pH-Dependent absorption and fluorescence spectroscopy of 1 d: As outlined in the Introduction, the meso position is in many cases the position of choice for the integration of an analyte-or a stimuli-responsive group, and since the late 1990s [65,76] many such BODIPY dyes have been developed. [4] However, as we have seen in the previous sections, the degree of twisting around the interannular C meso À C phenyl bond, the degree of conformational confinement and the conjugation in the BODIPY core are decisive parameters for the spectroscopic manifestation of the interaction of the fragments.…”

Section: Molecular Orbitals and Transitionsmentioning

confidence: 99%

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

Wang

Descalzo

Shen

et al. 2010

Chemistry A European J

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A new series of boron-dipyrromethene (BDP, BODIPY) dyes with dihydronaphthalene units fused to the beta-pyrrole positions (1a-d, 2) has been synthesised and spectroscopically investigated. All the dyes, except pH-responsive 1d in polar solvents, display intense emission between 550-700 nm. Compounds 1a and 1b with a hydrogen atom and a methyl group in the meso position of the BODIPY core show spectroscopic properties that are similar to those of rhodamine 101, thus rendering them potent alternatives to the positively charged rhodamine dyes as stains and labels for less polar environments or for the dyeing of latex beads. Compound 1d, which carries an electron-donating 4-(dimethylamino)phenyl group in the meso position, shows dual fluorescence in solvents more polar than dibutyl ether and can act as a pH-responsive "light-up" probe for acidic pH. Correlation of the pK(a) data of 1d and several other meso-(4-dimethylanilino)-substituted BODIPY derivatives allowed us to draw conclusions on the influence of steric crowding at the meso position on the acidity of the aniline nitrogen atom. Preparation and investigation of 2, which carries a nitrogen instead of a carbon as the meso-bridgehead atom, suggests that the rules of colour tuning of BODIPYs as established so far have to be reassessed; for all the reported couples of meso-C- and meso-N-substituted BODIPYs, the exchange leads to pronounced redshifts of the spectra and reduced fluorescence quantum yields. For 2, when compared with 1a, the opposite is found: negligible spectral shifts and enhanced fluorescence. Additional X-ray crystallographic analysis of 1a and quantum chemical modelling of the title and related compounds employing density functional theory granted further insight into the features of such sterically crowded chromophores.

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Section: Resultsmentioning

confidence: 94%

Section: Molecular Orbitals and Transitionsmentioning

confidence: 99%

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

Wang

Descalzo

Shen

et al. 2010

Chemistry A European J

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“…Likewise, fluorescent pH indicators based on difluoroboron dipyrromethene in which a proton signaling subunit connected to the meso position is uncoupled from the fluorophore are never ratiometric. [6][7][8][9][10] An essential design principle for a ratiometric, fluorescent pH signaling system is to have conjugation between the pH-(i.e., H + -) sensitive subunit and the fluorophore. Figure 1) was synthesized in 51 % yield by condensation of 8-(4-carbomethoxyphenyl)-4,4-difluoro-1,3,5,7-tetramethyl-3a,4a-diaza-4-bora-s-indacene (III) with 1H-imidazole-4-carbaldehyde (IV) with acetic acid/piperidine as catalyst (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

“…[6,7] These on/off pH indicators showed photoinduced electron transfer (PET) from the twisted and conjugatively uncoupled phenolate to the BODIPY subunit, causing fluorescence quenching at high pH. 8-(4'-Hydroxyphenyl)-substituted BODIPY derivatives [6] sense the alkaline pH range, while the tetrahydroxylated calix [4]arene derivative [7] is sensitive in the near-neutral pH range. An on/off 8-(4'-dimethylaminophenyl)-substituted BODIPY indicator has been reported for the acidic pH range.…”

Section: Introductionmentioning

confidence: 98%

Rational Design, Synthesis, and Spectroscopic and Photophysical Properties of a Visible‐Light‐Excitable, Ratiometric, Fluorescent Near‐Neutral pH Indicator Based on BODIPY

Boens

Qin

Baruah

et al. 2011

Chemistry A European J

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A visible-light-excitable, ratiometric, brightly fluorescent pH indicator for measurements in the pH range 5-7 has been designed and synthesized by conjugatively linking the BODIPY fluorophore at the 3-position to the pH-sensitive ligand imidazole through an ethenyl bridge. The probe is available as cell membrane permeable methyl ester 8-(4-carbomethoxyphenyl)-4,4-difluoro-3-[2-(1H-imidazol-4-yl)ethenyl]-1,5,7-trimethyl-3a,4a-diaza-4-bora-s-indacene (I) and corresponding water-soluble sodium carboxylate, sodium 8-(4-carboxylatophenyl)-4,4-difluoro-3-[2-(1H-imidazol-4-yl)ethenyl]-1,5,7-trimethyl-3a,4a-diaza-4-bora-s-indacene (II). The fluorescence quantum yield Φ(f) of ester I is very high (0.8-1.0) in the organic solvents tested. The fluorescence lifetime (ca. 4 ns) of I in organic solvents with varying polarity/polarizability (from cyclohexane to acetonitrile) is independent of the solvent with a fluorescence rate constant k(f) of 2.4×10(8) s(-1). Probe I is readily loaded in the cytosol of live cells, where its high fluorescence intensity remains nearly constant over an extended time period. Water-soluble indicator II exhibits two acid-base equilibria in aqueous solution, characterized by pK(a) values of 6.0 and 12.6. The Φ(f) value of II in aqueous solution is high: 0.6 for the cationic and anionic forms of the imidazole ligand, and 0.8 for neutral imidazole. On protonation-deprotonation in the near-neutral pH range, UV/Vis absorption and fluorescence spectral shifts along with isosbestic and pseudo-isoemissive points are observed. This dual-excitation and dual-emission pH indicator emits intense green-yellow fluorescence at lower pH and intense orange fluorescence at higher pH. The influence of ionic strength and buffer concentration on the absorbance and steady-state fluorescence of II has also been investigated. The apparent pK(a) of the near-neutral acid-base equilibrium determined by spectrophotometric and fluorometric titration is nearly independent of the added buffer and salt concentration. In aqueous solution in the absence of buffer and in the pH range 5.20-7.45, dual exponential fluorescence decays are obtained with decay time τ(1)=4.3 ns for the cationic and τ(2)=3.3 ns for the neutral form of II. The excited-state proton exchange of II at near-neutral pH becomes reversible on addition of phosphate (H(2)PO(4)(-)/HPO(4)(2-)) buffer, and a pH-dependent change of the fluorescence decay times is induced. Global compartmental analysis of fluorescence decay traces collected as a function of pH and phosphate buffer concentration was used to recover values of the deactivation rate constants of the excited cationic (k(01)=2.4×10(8) s(-1)) and neutral (k(02)=3.0×10(8) s(-1)) forms of II.

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“…These chemosensors are generally chromogenic and/or fluorescent probes, which efficiently change their photophysical properties in the presence of anions. Among numerous fluorophores, BODIPY dyes possess excellent photophysical properties and applications in the areas of anion sensors, metal probes, and pH indicators [14][15][16][17][18][19][20] . This versatile utility is due to the capacity to substitute the many positions of the BODIPY core in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

A Bodipy-Phenol-Based Sensor for Selectively Recognizing Three Basic Anions

Wei

Xie

2015

J. Chil. Chem. Soc.

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A novel BODIPY-based anion sensor 1 bearing di-tert-butyl phenol unit was designed and prepared. In the presence of three basic anions F -, AcO -or H 2 PO 4 -, 1 exhibited two novel partially overlapped red-shift absorption bands at 718 nm and 757 nm, respectively. The formation of allotropic structures, after deprotonation of phenol OH, is responsible for these two emerging bands. Fluorescence quenching was also observed due to intramolecular charge transfer (ICT) from phenolate to BODIPY core. As results revealed, the anion affinity mainly depended on the acidity of binding site OH and the basicity of the target anion. Moreover, two bulky tert-butyl groups cannot effectively exclude the approach of large anions to phenol OH, but can facilitate the formation of allotropic resonance structures.

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Phenol/phenolate-dependent on/off switching of the luminescence of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes

Cited by 102 publications

References 12 publications

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

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

Rational Design, Synthesis, and Spectroscopic and Photophysical Properties of a Visible‐Light‐Excitable, Ratiometric, Fluorescent Near‐Neutral pH Indicator Based on BODIPY

A Bodipy-Phenol-Based Sensor for Selectively Recognizing Three Basic Anions

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