Dual Fluorescence through Kasha’s Rule Breaking: An Unconventional Photomechanism for Intracellular Probe Design

Brancato, Giuseppe; Signore, Giovanni; Neyroz, Paolo; Polli, Dario; Cerullo, Giulio; Abbandonato, Gerardo; Nucara, Luca; Barone, Vincenzo; Beltram, Fabio; Bizzarri, Ranieri

doi:10.1021/acs.jpcb.5b01119

Cited by 80 publications

(74 citation statements)

References 48 publications

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“…3). Clearly, the excitation-dependent emission in DCM-IFC (open form) is not in agreement with Kasha's rule 36 and warranted further investigation.…”

Section: Revealing the Anti-kasha Properties Of Open-form Dcm-ifcmentioning

confidence: 86%

De novo strategy with engineering anti-Kasha/Kasha fluorophores enables reliable ratiometric quantification of biomolecules

et al. 2020

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Fluorescence-based technologies have revolutionized in vivo monitoring of biomolecules. However, significant technical hurdles in both probe chemistry and complex cellular environments have limited the accuracy of quantifying these biomolecules. Herein, we report a generalizable engineering strategy for dual-emission anti-Kasha-active fluorophores, which combine an integrated fluorescein with chromene (IFC) building block with donor-π-acceptor structural modification. These fluorophores exhibit an invariant near-infrared Kasha emission from the S 1 state, while their anti-Kasha emission from the S 2 state at around 520 nm can be finely regulated via a spirolactone open/closed switch. We introduce bio-recognition moieties to IFC structures, and demonstrate ratiometric quantification of cysteine and glutathione in living cells and animals, using the ratio (S 2 /S 1) with the S 1 emission as a reliable internal reference signal. This de novo strategy of tuning anti-Kasha-active properties expands the in vivo ratiometric quantification toolbox for highly accurate analysis in both basic life science research and clinical applications.

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“…3). Clearly, the excitation-dependent emission in DCM-IFC (open form) is not in agreement with Kasha's rule 36 and warranted further investigation.…”

Section: Revealing the Anti-kasha Properties Of Open-form Dcm-ifcmentioning

confidence: 86%

De novo strategy with engineering anti-Kasha/Kasha fluorophores enables reliable ratiometric quantification of biomolecules

et al. 2020

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“…2,3 No guidelines exist to design molecules possessing dual fluorescence as the phenomenon can arise from fairly different molecular species. In most cases 4 dual fluorescence is not formally in violation of Kasha's rule as fluorescence does occur from the lowest excited state of a particular conformation; if the fluorophore undergoes a structural rearrangement on the excited state surface this may lead to two excited state minima and two fluorescence bands.…”

Section: Introductionmentioning

confidence: 99%

Solvent-dependent dual fluorescence of the push–pull system 2-diethylamino-7-nitrofluorene

Larsen

Stephansen

Alarousu

et al. 2018

Phys. Chem. Chem. Phys.

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The solvent-dependent excited state behavior of the molecular push-pull system 2-diethylamino-7-nitrofluorene has been explored using femtosecond transient absorption spectroscopy in combination with density functional theory calculations. Several excited state minima have been identified computationally, all possessing significant intramolecular charge transfer character. The experimentally observed dual fluorescence is suggested to arise from a planar excited state minimum and another minimum reached by twisting of the aryl-nitrogen bond of the amino group. The majority of the excited state population, however, undergo non-radiative transitions and potential excited state deactivation pathways are assessed in the computational investigation. A third excited state conformer, characterized by twisting around the aryl-nitrogen bond of the nitro group, is reasoned to be responsible for the majority of the non-radiative decays and a crossing between the excited state and ground state is localized. Additionally, ultrafast intersystem crossing is observed in the apolar solvent cyclohexane and rationalized to occur via an El-Sayed assisted transition from one of the identified excited state minima. The solvent thus determines more than just the fluorescence lifetime and shapes the potential energy landscape, thereby dictating the available excited state pathways.

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“…Other theories postulate formation of compound concentration-induced excimer systems [43, 44], various types of acid-base reactions in the investigated system, or very frequent formation of excited-state tautomeric systems [45, 46]. The anti-Kasha mechanism of the dual fluorescence effect postulated in 2015 in the Journal of Physical Chemistry B by Brancato et al should also be mentioned [47]. However, as suggested by the research results presented in this paper, none of these mechanisms seems to be successful in elucidation of the observed effects and molecular mechanisms involved in the spectroscopic changes.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Studies of Fluorescence Effects in Bioactive 4-(5-Heptyl-1,3,4-Thiadiazol-2-yl)Benzene-1,3-Diol and 4-(5-Methyl-1,3,4-Thiadiazol-2-yl)Benzene-1,3-Diol Molecules Induced by pH Changes in Aqueous Solutions

et al. 2017

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This paper presents the results of stationary fluorescence spectroscopy and time-resolved spectroscopy analyses of two 1,3,4-thiadiazole analogues, i.e. 4-(5-methyl-1,3,4-thiadiazol-2-yl)benzene-1,3-diol (C1) and 4-(5-heptyl-1,3,4-thiadiazol-2-yl)benzene-1,3-diol (C7) in an aqueous medium containing different concentrations of hydrogen ions. An interesting dual florescence effect was observed when both compounds were dissolved in aqueous solutions at pH below 7 for C1 and 7.5 for C7. In turn, for C1 and C7 dissolved in water at pH higher than the physiological value (mentioned above), single fluorescence was only noted. Based on previous results of investigations of the selected 1,3,4-thiadiazole compounds, it was noted that the presented effects were associated with both conformational changes in the analysed molecules and charge transfer (CT) effects, which were influenced by the aggregation factor. However, in the case of C1 and C7, the dual fluorescence effects were visible in a higher energetic region (different than that observed in the 1,3,4-thiadiazoles studied previously). Measurements of the fluorescence lifetimes in a medium characterised by different concentrations of hydrogen ions revealed clear lengthening of the excited-state lifetime in a pH range at which dual fluorescence effects can be observed. An important finding of the investigations presented in this article is the fact that the spectroscopic effects observed not only are interesting from the cognitive point of view but also can help in development of an appropriate theoretical model of molecular interactions responsible for the dual fluorescence effects in the analysed 1,3,4-thiadiazoles. Furthermore, the study will clarify a broad range of biological and pharmaceutical applications of these compounds, which are more frequently used in clinical therapies. Graphical AbstractUpper left corner – C7 molecule at high pH, right upper corner - fluorescence emission spectrum for C7 dissolved in H2O at high pH (7–12) - single fluorescence. Bottom left corner – C7 molecule at low pH (1–7), lower right corner - fluorescence emission spectrum for C7 dissolved in water at low pH – two fluorescence emissions. The circles indicate the group related to dissociation of molecules at low and high pH and the additional long circles indicate C1 or a molecule with a shorter acyl chain. Electronic supplementary materialThe online version of this article (doi:10.1007/s10895-017-2053-y) contains supplementary material, which is available to authorized users.

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Dual Fluorescence through Kasha’s Rule Breaking: An Unconventional Photomechanism for Intracellular Probe Design

Cited by 80 publications

References 48 publications

De novo strategy with engineering anti-Kasha/Kasha fluorophores enables reliable ratiometric quantification of biomolecules

De novo strategy with engineering anti-Kasha/Kasha fluorophores enables reliable ratiometric quantification of biomolecules

Solvent-dependent dual fluorescence of the push–pull system 2-diethylamino-7-nitrofluorene

Spectroscopic Studies of Fluorescence Effects in Bioactive 4-(5-Heptyl-1,3,4-Thiadiazol-2-yl)Benzene-1,3-Diol and 4-(5-Methyl-1,3,4-Thiadiazol-2-yl)Benzene-1,3-Diol Molecules Induced by pH Changes in Aqueous Solutions

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