A generalized reversal model for the solvatochromism of merocyanines

Rezende, Marcos Caroli

doi:10.1002/poc.3565

Cited by 24 publications

(19 citation statements)

References 30 publications

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“…These traces were scaled considering the absorption at the excitation wavelength for a direct comparison of the intensities and were acquired in the linear region of the intensity vs absorbance relation of the instrument. [29] This behaviour is typical of cyanine dyes where the ground state has a larger dipole than the excited state. The same trend was observed for BNIR ( Figure S6).…”

Section: Steady State Spectroscopymentioning

confidence: 93%

Bichromophoric Sensors for Ratiometric Measurements of Molecular Microenvironments through the Interplay of Charge Transfer and Energy Transfer Channels

2018

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A new molecular architecture was designed to amplify the sensitivity of bichromophoric probes, in which two sequential kinetic competitions of photophysical channels were used to define the emission yield of the lower energy chromophore. Additionally, the emission from both chromophores can be used for ratiometric measurements, which are concentration independent. Two sensors were synthesized to demonstrate the concept, coupling a boron-dipyrromethene (BODIPY) dye and a cyanine dye. Both the energy transfer from the BODIPY to the cyanine and the cyanine radiative channel compete with a charge transfer state formation, giving the cyanine emission intensity a twofold dependence on polarity. This was confirmed with steady state and time-resolved spectroscopies. Also, the large spectral gap between the two emissions (approx. 280 nm) makes the ratiometric measurements crosstalk-free. The use of the sensors in live cells was demonstrated through the staining and imaging of SK-LU-1 lung cells under normal and apoptotic conditions.[a] A.Changes in the microenvironment of these molecules will affect the kinetics of the last process, and thus, the yields of the three competing processes. The molecules that underwent the RET process will then have the excitation localized in the second chromophore. The polarity-dependent formation of the CT state in the second chromophore will compete with its locally excited emission. This double dependence on the polarity of the medium gives these systems an enhanced sensitivity to different solvent or cell environments.Two prototype molecules were synthesized to demonstrate these design principles (see Figure 1). This was achieved by coupling the commercially available IR780 cyanine with a BODIPY dye trough a bridge formed by an ether bond and two different aromatic moieties: a phenyl group (BBIR) or a naphthyl group (BNIR). The aromatic moieties were selected to analyse the effect of changing the electron donor in the formation of the CT states and the sensitivity of the sensors while maintaining the distances between the energy transfer donor and the acceptor. The precursor cyanine IR780 was chosen due to its optical properties and because it can be easily functionalized at the meso position. Additionally, the IR780 cyanine has been widely used as a near-IR fluorescent probe due to its low toxicity and facile uptake by cells and tissues. [22,23] The water-2 3 4 5 6 7 8

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Section: Steady State Spectroscopymentioning

confidence: 93%

Bichromophoric Sensors for Ratiometric Measurements of Molecular Microenvironments through the Interplay of Charge Transfer and Energy Transfer Channels

2018

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“…We have recently proposed a generalized reversal model for the interpretation of the behavior of solvatochromic dyes, as an alternative to the cyanine‐limit model . Starting from the observation that the environment changes the solvatochromic strength of a dye, it is postulated that a minimum value of the transition energy should always exist for any merocyanine, as a consequence of the hyperbolic dependence of E T on S .…”

Section: Introductionmentioning

confidence: 99%

“…This polarity value is frequently “virtual”: if an extended polarity scale is employed, it occurs beyond the limits of the range of experimental solvent polarities, leading to the particular cases of a positive or a negative solvatochromism. “Real” reversal is verified only when this minimum occurs at some point within the range of experimental solvent polarities …”

Section: Introductionmentioning

confidence: 99%

“…We have recently proposed ag eneralized reversal model for the interpretationo ft he behavior of solvatochromic dyes, as an alternative to the cyanine-limit model. [9] Startingf rom the observation that the environmentc hanges the solvatochromic strength of ad ye, it is postulated that am inimum value of the transition energy should alwayse xist for any merocyanine, as a consequence of the hyperbolic dependence of E T on S. This minimum value is ap oint of solvatochromic reversal and thus all merocyanines should exhibit reverseo ri nverted solvatochromic behavior at some polarityv alue. This polarity value is frequently "virtual":i fa ne xtended polarity scale is employed, it occurs beyond the limits of the range of experimental solvent polarities, leadingt ot he particular cases of ap ositive or a negatives olvatochromism.…”

Section: Introductionmentioning

confidence: 99%

“…"Real" reversal is verifiedo nly when this minimum occurs at some point within the range of experimental solvent polarities. [9] The emphasis put on the solvatochromic reversal of merocyaninesn aturallys timulates research on new dyes that exhibit ac lear inverted behavior in solvents of mediump olarity. We have been interested in ap articularf amily of dyeso fg eneral structure 5 (Scheme 2), [10,11] with ap henolate donor conjugated with ap olynitroaryl acceptorm oiety,w hich,b esides being readily accessible, satisfy the above requirement and also the need for good solvent sensitivity.…”

Section: Introductionmentioning

confidence: 99%

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Reverse Solvatochromism of Imine Dyes Comprised of 5‐Nitrofuran‐2‐yl or 5‐Nitrothiophen‐2‐yl as Electron Acceptor and Phenolate as Electron Donor

Melo

Nicoleti

Rezende

et al. 2018

Chemistry A European J

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Eight compounds with phenols as electron-donating groups and 5-nitrothiophen-2-yl or 5-nitrofuran-2-yl acceptor moieties in their molecular structures were synthesized. The crystalline structures of six compounds were obtained. Their corresponding phenolate dyes were studied in 29 solvents and the data showed that in all cases a reverse solvatochromism occurred. The results are explained in terms of the ability of the medium to stabilize the electronic ground and excited states of the probes to different extents. The frontier molecular orbitals were analyzed for the protonated and deprotonated forms of the compounds. The calculated geometries are in agreement with the X-ray structures determined for the compounds and it was verified that after their deprotonation an increase in the electron delocalization occurs. Radial distribution functions were calculated for the dyes in water and n-hexane to analyze different solvation patterns resulting from the interaction of the solvents with the dyes. Data obtained by using the Catalán multiparameter equation revealed that the medium acidity is responsible for hypsochromic shifts, whereas the solvent basicity, polarizability, and dipolarity contributed to bathochromic shifts of the solvatochromic band of these dyes. Two model "hybrid cyanine" dyes were used in the design of simple experiments to demonstrate that the solvatochromic behavior of these dyes in solution can be tuned with careful consideration of the properties of the medium.

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N-Methylpyridinium-4-phenolates: Generation of a Betaine Dye Library Bearing Different Spacer Units and Their Solvatochromism

Reißig

Domínguez

2016

ChemistrySelect

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A library of thirteen N-methylpyridinium-4-phenolate betaine dyes was synthesized from 4-(4-methoxyphenyl)pyridines in a three step procedure involving N-methylation, a subsequent Odemethylation, and a final deprotonation. Their general structure comprised an electron-donating phenolate group and an electron-accepting 2,6-disubstituted-N-methylpyridinium moiety, connected either directly, or by a carbon-carbon double or triple bond. Their UV-Vis spectroscopic behavior exhibits a borderline inverted solvatochromism in a wide range of solvents with different polarities, changing from bathochromic to hypsochromic shifts with the increase of the solvent polarity. Inserting a double-or a triple-bond spacer between the donor and acceptor rings had the effect of increasing the solvatochromic sensitivity of the resulting dyes.

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A generalized reversal model for the solvatochromism of merocyanines

Cited by 24 publications

References 30 publications

Bichromophoric Sensors for Ratiometric Measurements of Molecular Microenvironments through the Interplay of Charge Transfer and Energy Transfer Channels

Bichromophoric Sensors for Ratiometric Measurements of Molecular Microenvironments through the Interplay of Charge Transfer and Energy Transfer Channels

Reverse Solvatochromism of Imine Dyes Comprised of 5‐Nitrofuran‐2‐yl or 5‐Nitrothiophen‐2‐yl as Electron Acceptor and Phenolate as Electron Donor

N-Methylpyridinium-4-phenolates: Generation of a Betaine Dye Library Bearing Different Spacer Units and Their Solvatochromism

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