Nonradiative Decay Channels for a Structurally-Distorted, Monostrapped BODIPY Derivative

Sirbu, Dumitru; Karlsson, Joshua; Harriman, Anthony

doi:10.1021/acs.jpca.8b07840

Cited by 8 publications

(10 citation statements)

References 88 publications

(147 reference statements)

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“…Our TD-DFT calculations demonstrated that modulation of the dihedral angle between the IFC and the DCM units decreases the oscillator strength of S 1 excitations, leading to a considerable decrease in S 1 fluorescence emissions. The oscillator strength of both excitations drops by 30% as the dihedral angle is tuned from 180° to 150°, which indicates that the S 1 excitation energy is likely to be quenched through the other nonradiative decay pathways via structural distortion. , Enhancing the rigidity of the chromophore structure through a conformational lock at the C 49 HC 51 H bond increases the fluorescence quantum yield, − which might be useful in terms of designing highly specific anti-Kasha-based dual-emission fluorophores for bioimaging applications.…”

mentioning

confidence: 99%

Tracking Ultrafast Structural Dynamics in a Dual-Emission Anti-Kasha-Active Fluorophore Using Femtosecond Stimulated Raman Spectroscopy

Wei

et al. 2021

J. Phys. Chem. Lett.

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The anti-Kasha process provides the possibility of using high-energy excited states to develop novel applications. Our previous research (Nature communications, 2020, 11, 793) has demonstrated a dual-emission anti-Kasha-active fluorophore for bioimaging application, which exhibits near-infrared emissions from the S 1 state and visible anti-Kasha emissions from the S 2 state. Here, we applied tunable blue-side femtosecond stimulated Raman spectroscopy (FSRS) and transient absorption spectroscopy, assisted by quantum calculations, to reveal the anti-Kasha dual emission mechanism, in which the emergence of two fluorescing states is due to the retardation of internal conversion from the S 2 state to the S 1 state. It has been demonstrated that the facts of anti-Kasha high-energy emission are commonly attributed to a large energy gap between the two excited states, leading to a decrease in the internal conversion rate due to a poor Franck−Condon factor. In this study, analysis of the calculation and FSRS experimental results provide us further insight into the dual-emission anti-Kasha mechanism, where the observation of hydrogen out-of-plane Raman modes from FSRS suggested that, in addition to the energy-gap law, the initial photoinduced molecular conformational change plays a key role in influencing the rate of internal conversion.

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mentioning

confidence: 99%

Tracking Ultrafast Structural Dynamics in a Dual-Emission Anti-Kasha-Active Fluorophore Using Femtosecond Stimulated Raman Spectroscopy

Wei

et al. 2021

J. Phys. Chem. Lett.

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“…A non‐rigid reaction chain profile, starting from PI 200 and converting to AF‐647 via rotation around the connecting C 13 ‐C 14 ‐C 15 ‐N 16 dihedral angle (Figure S51), establishes that the two structures are interconverted simply by rotating one of the indole terminals (Scheme c). The calculated rotational barrier for this transformation is 11.5 kJ mol −1 ; and as a note, each geometry along the chain was fully optimized.…”

Section: Computational Studiesmentioning

confidence: 82%

“…[119] A water reservoir was used with the PCM model. [120] An on-rigid chain calculation was performed [98] to transform between any two optimized geometries, with structure optimization at each point along the trajectory.These calculations provide the basis for the ro-tational barriers mentioned in the text. The calculations were made only at the ground-state level.…”

Section: Methodsmentioning

confidence: 99%

Photo‐isomerization of the Cyanine Dye Alexa‐Fluor 647 (AF‐647) in the Context of dSTORM Super‐Resolution Microscopy

Karlsson

Laude

Hall

et al. 2019

Chemistry A European J

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Cyanine dyes, as used in super‐resolution fluorescence microscopy, undergo light‐induced “blinking”, enabling localization of fluorophores with spatial resolution beyond the optical diffraction limit. Despite a plethora of studies, the molecular origins of this blinking are not well understood. Here, we examine the photophysical properties of a bio‐conjugate cyanine dye (AF‐647), used extensively in dSTORM imaging. In the absence of a potent sacrificial reductant, light‐induced electron transfer and intermediates formed via the metastable, triplet excited state are considered unlikely to play a significant role in the blinking events. Instead, it is found that, under conditions appropriate to dSTORM microscopy, AF‐647 undergoes reversible photo‐induced isomerization to at least two long‐lived dark species. These photo‐isomers are characterized spectroscopically and their interconversion probed by computational means. The first‐formed isomer is light sensitive and transforms to a longer‐lived species in modest yield that could be involved in dSTORM related blinking. Permanent photobleaching of AF‐647 occurs with very low quantum yield and is partially suppressed by the anaerobic redox buffer.

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“…This indicates that nonradiative decay channels are still active at room temperature for the α crystal, suggesting a residual activity of large-scale motions, 20 , 29 , 30 , 39 − 42 aggregation effects, 21 , 29 , 43 or heat dissipation by crystal phonons. 44 , 45 …”

Section: Resultsmentioning

confidence: 99%

Highly Emissive Biological Bilirubin Molecules: Shedding New Light on the Phototherapy Scheme

et al. 2021

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Bilirubin (BR) is the main end-product of the hemoglobin catabolism. For decades, its photophysics has been mainly discussed in terms of ultrafast deactivation of the excited state in solution, where, indeed, BR shows a very low green emission quantum yield (EQY), 0.03%, resulting from an efficient nonradiative isomerization process. Herein, we present, for the first time, unique and exceptional photophysical properties of solid-state BR, which amend by changing the type of crystal, from a closely packed α crystal to an amorphous loosely packed β crystal. BR α crystals show a very bright red emission with an EQY of ca. 24%, whereas β crystals present, in addition, a low green EQY of ca. 0.5%. By combining density functional theory (DFT) calculations and time-resolved emission spectroscopy, we trace back this dual emission to the presence of two types of BR molecules in the crystal: a “stiff” monomer, M1, distorted by particularly strong internal H-bonds and a “floppy” monomer, M2, having a structure close to that of BR in solution. We assign the red strong emission of BR crystals to M1 present in both the α and β crystals, while the low green emission, only present in the amorphous (β) crystal, is interpreted as M2 emission. Efficient energy-transfer processes from M2 to M1 in the closely packed α crystal are invoked to explain the absence of the green component in its emission spectrum. Interestingly, these unique photophysical properties of BR remain in polar solvents such as water. Based on these unprecedented findings, we propose a new model for the phototherapy scheme of BR inside the human body and highlight the usefulness of BR as a strong biological fluorescent probe.

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Nonradiative Decay Channels for a Structurally-Distorted, Monostrapped BODIPY Derivative

Cited by 8 publications

References 88 publications

Tracking Ultrafast Structural Dynamics in a Dual-Emission Anti-Kasha-Active Fluorophore Using Femtosecond Stimulated Raman Spectroscopy

Tracking Ultrafast Structural Dynamics in a Dual-Emission Anti-Kasha-Active Fluorophore Using Femtosecond Stimulated Raman Spectroscopy

Photo‐isomerization of the Cyanine Dye Alexa‐Fluor 647 (AF‐647) in the Context of dSTORM Super‐Resolution Microscopy

Highly Emissive Biological Bilirubin Molecules: Shedding New Light on the Phototherapy Scheme

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