Effects of long-chain alkyl substituents on the protolytic reactions of naphthols

Solntsev, Kyril M.; Al-Ainain, Sami Abou; Il’ichev, Yuri V.; Kuz’min, M. G.

doi:10.1016/j.jphotochem.2005.01.021

Cited by 9 publications

(11 citation statements)

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“…It is known that I R*OH / I R*O − ∼ 1/( k d τ′), where k d is the proton dissociation rate during ESPT and τ′ is average lifetime of the indirectly excited R*O – . 38 The higher ratio I R*OH / I R*O − in apo-CatchER than holo-CatchER indicated the larger population of R*O – remained in the excited state with the additional calcium. Therefore, the calcium binding shifts the acid–base equilibrium of the CatchER Cro in the ground state toward the anion.…”

Section: Resultsmentioning

confidence: 99%

Effect of Ca²⁺ on the Steady-State and Time-Resolved Emission Properties of the Genetically Encoded Fluorescent Sensor CatchER

et al. 2014

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We previously designed a calcium sensor CatchER (a GFP-based Calcium sensor for detecting high concentrations in the high calcium concentration environment such as ER) with a capability for monitoring calcium ion responses in various types of cells. Calcium binding to CatchER induces the ratiometric changes in the absorption spectra, as well as an increase in fluorescence emission at 510 nm upon excitation at both 395 and 488 nm. Here, we have applied the combination of the steady-state and time-resolved optical methods and Hydrogen/Deuterium isotope exchange to understand the origin of such calcium-induced optical property changes of CatchER. We first demonstrated that calcium binding results in a 44% mean fluorescence lifetime increase of the indirectly excited anionic chromophore. Thus, CatchER is the first protein-based calcium indicator with the single fluorescent moiety to show the direct correlation between the lifetime and calcium binding. Calcium exhibits a strong inhibition on the excited-state proton transfer nonadiabatic geminate recombination in protic (vs deuteric) medium. Analysis of CatchER crystal structures and the MD simulations reveal the proton transfer mechanism in which the disrupted proton migration path in CatchER is rescued by calcium binding. Our finding provides important insights for a strategy to design calcium sensors and suggests that CatchER could be a useful probe for FLIM imaging of calcium in situ.

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Section: Resultsmentioning

confidence: 99%

Effect of Ca²⁺ on the Steady-State and Time-Resolved Emission Properties of the Genetically Encoded Fluorescent Sensor CatchER

et al. 2014

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“…Given that the acid dissociation constant, p K a *, of the OH group of hydroxyarenes in the excited state can decrease by several orders of magnitude compared to the ground state molecule, − , experiments were carried out to estimate this value for donor 1 . Substituents on naphthols influence the degree of photoacidity .…”

Section: Results and Discussionmentioning

confidence: 99%

Mechanistic Insights into Rapid Generation of Nitroxyl from a Photocaged N-Hydroxysulfonamide Incorporating the (6-Hydroxynaphthalen-2-yl)methyl Chromophore

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Zhou

et al. 2021

J. Org. Chem.

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HNO is a highly reactive molecule that shows promise in treating heart failure. Molecules that rapidly release HNO with precise spatial and temporal control are needed to investigate the biology of this signaling molecule. (Hydroxynaphthalen-2-yl)methylphotocaged N-hydroxysulfonamides are a new class of photoactive HNO generators. Recently, it was shown that a (6-hydroxynaphthalen-2-yl)methyl (6,2-HNM)-photocaged derivative of N-hydroxysulfonamide incorporating the trifluoromethanesulfonamidoxy group (1) quantitatively generates HNO. Mechanistic studies have now been carried out on this system and reveal that the ground state protonation state plays a key role in whether concerted heterolytic C−O/N−S bond cleavage to release HNO occurs versus undesired O−N bond cleavage. N-Deprotonation of 1 can be achieved by adding an aqueous buffer or a carboxylate salt to an aprotic solvent. Evidence is presented for C−O/N−S bond heterolysis occurring directly from the singlet excited state of the N-deprotonated parent molecule on the picosecond time scale, using femtosecond time-resolved transient absorption spectroscopy, to give a carbocation and 1 NO − . This is consistent with the observation of significant fluorescence quenching when HNO is generated. The carbocation intermediate reacts rapidly with nucleophiles including water, MeOH, or even (H)NO in the absence of a molecule that reacts rapidly with (H)NO to give an oxime.

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“…(12.13) (or Eq. (12.15)) in the case of selfquenching [49][50][51][52][53]58]) have demonstrated the general microscopic validity of K * a , even in a most demanding situation where the excited state is rapidly quenched back to the ground state.…”

Section: Evidence For the General Validity Of The Förster Cycle Based...mentioning

confidence: 94%

“…(12.15)) in the case of selfquenching [49][50][51][52][53]58]) have demonstrated the general microscopic validity of K * a , even in a most demanding situation where the excited state is rapidly quenched back to the ground state. s 0 and s¢ 0 are the fluorescence lifetime of the photoacid and photobase, respectively, in the absence of proton transfer.…”

Section: Evidence For the General Validity Of The Förster Cycle Basedmentioning

confidence: 95%

“…A further step to establish the validity of the K * a has been undertaken by Pines and Fleming [49] and was extended by Pines et al [50,51] and by Solntsev et al [52,53]. These authors have shown that the concept of an excited-state equilibrium constant holds in the more kinetically demanding (and more general) situation of proton quenching in parallel to reversible geminate rocombination.…”

Section: Evidence For the General Validity Of The Förster Cycle Based...mentioning

confidence: 99%

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Solvent Assisted Photoacidity

Pines

2006

Hydrogen‐Transfer Reactions

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Effects of long-chain alkyl substituents on the protolytic reactions of naphthols

Cited by 9 publications

References 103 publications

Effect of Ca²⁺ on the Steady-State and Time-Resolved Emission Properties of the Genetically Encoded Fluorescent Sensor CatchER

Effect of Ca²⁺ on the Steady-State and Time-Resolved Emission Properties of the Genetically Encoded Fluorescent Sensor CatchER

Mechanistic Insights into Rapid Generation of Nitroxyl from a Photocaged N-Hydroxysulfonamide Incorporating the (6-Hydroxynaphthalen-2-yl)methyl Chromophore

Solvent Assisted Photoacidity

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Effects of long-chain alkyl substituents on the protolytic reactions of naphthols

Cited by 9 publications

References 103 publications

Effect of Ca2+ on the Steady-State and Time-Resolved Emission Properties of the Genetically Encoded Fluorescent Sensor CatchER

Effect of Ca2+ on the Steady-State and Time-Resolved Emission Properties of the Genetically Encoded Fluorescent Sensor CatchER

Mechanistic Insights into Rapid Generation of Nitroxyl from a Photocaged N-Hydroxysulfonamide Incorporating the (6-Hydroxynaphthalen-2-yl)methyl Chromophore

Solvent Assisted Photoacidity

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Product

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Effect of Ca²⁺ on the Steady-State and Time-Resolved Emission Properties of the Genetically Encoded Fluorescent Sensor CatchER

Effect of Ca²⁺ on the Steady-State and Time-Resolved Emission Properties of the Genetically Encoded Fluorescent Sensor CatchER