Quenching of the excited singlet state of acridine and 10-methylacridinium cation by thio-organic compounds in aqueous solution

Pędziński, Tomasz; Marciniak, Bronisław; Hug, Gordon L.

doi:10.1016/s1010-6030(02)00028-x

Cited by 45 publications

(49 citation statements)

References 31 publications

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“…where A obs is the observed absorbance at any pH, and A [14,18,21] The corresponding excitedstate (S 1 ) acidity constant, pK a *, was also estimated (using the Fçrster cycle method, see Method M1 in the Supporting Information) and is also found to be 10.1 AE 0.15, in good agreement with the reported value. [18] The significant increase in pK a * is a clear indication that the acridine molecule in the excited state becomes a stronger proton acceptor than in the ground state.…”

Section: Absorption Properties In the Presence Of P-sulfonatocalix[6]supporting

confidence: 79%

“…In contrast, the Ac form (at pH 8.5) displayed a gradual decrease in the fluorescence intensity with the addition of SCX6, without any change in the maximum fluorescence at 430 nm [18] (Figure 3 B). This is in contrast to the general observations made using other macrocycles such as cyclodextrins (CDs) and cucurbiturils, for which the altered (less polar) microenvironment inside the macrocyclic host cavities and/or a spatial confinement limits alternative nonradiative pathways.…”

Section: Fluorescence Properties In the Presence Of P-sulfonatocalix[mentioning

confidence: 94%

“…[18,21] Under alkaline conditions (pH > 7), the neutral Ac form dominates, retaining the strong absorption peak at approximately 355 nm but with a diminished shoulder band at approximately 380 nm. [18,21] To account for this protolytic change and to estimate the pK a of acridine, the changes in the absorption spectra of the dye as a function of the pH of the solution were measured; the results are shown in Figure S1 of the Supporting Information. The pH-dependent absorbance changes at 355 nm (see Figure 5 B) were fitted according to Equation (1): [24] A obs ¼ A…”

Section: Absorption Properties In the Presence Of P-sulfonatocalix[6]mentioning

confidence: 99%

“…[18] The significant increase in pK a * is a clear indication that the acridine molecule in the excited state becomes a stronger proton acceptor than in the ground state.…”

Section: Absorption Properties In the Presence Of P-sulfonatocalix[6]mentioning

confidence: 99%

“…[16,17] Recently, Sedlacek et al have demonstrated pH-controlled activation of polymer-conjugated acridine-based anticancer drugs in cancer cells. [17] This was possible because acridine exists in water in two prototropic forms (pK a % 5.3), [14,18] one being neutral (Ac) and the second being protonated (AcH + , cf. Figure 1).…”

Section: Introductionmentioning

confidence: 99%

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Molecular‐Recognition‐Assisted pK_a Shifts and Metal‐Ion‐Induced Fluorescence Regeneration in p‐Sulfonatocalix[6]arene‐Encapsulated Acridine

et al. 2014

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The host-guest interactions of cationic (AcH(+) ) and neutral (Ac) forms of the dye acridine with the macrocyclic host p-sulfonatocalix[6]arene (SCX6) were investigated by using ground-state absorption, steady-state and time-resolved fluorescence, and NMR measurements. The cationic form undergoes significant complexation with SCX6 (Keq =2.5×10(4) M(-1) ), causing a sharp decrease in the fluorescence intensity and severe quenching in the excited-state lifetime of the dye. The strong binding of the AcH(+) form of the dye with SCX6 is attributed to ion-ion interactions involving the sulfonato groups (SO3 (-) ) of SCX6 and the positively charged AcH(+) at pH of approximately 4.3. Whereas, the neutral Ac form of the dye undergoes weak complexation with SCX6 (Keq =0.9×10(3) M(-1) ) and the binding constant is lowered by one order of magnitude compared with that of the SCX6-AcH(+) system. The strong affinity of SCX6 to the protonated form leads to a large upward pKa shift (≈2 units) in the dye. In contrast, strong emission quenching upon SCX6 interaction and the regeneration of fluorescence intensity of the dye in the presence of Gd(3+) through competitive binding have also been demonstrated.

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Section: Absorption Properties In the Presence Of P-sulfonatocalix[6]supporting

confidence: 79%

Section: Fluorescence Properties In the Presence Of P-sulfonatocalix[mentioning

confidence: 94%

Section: Absorption Properties In the Presence Of P-sulfonatocalix[6]mentioning

confidence: 99%

“…[18] The significant increase in pK a * is a clear indication that the acridine molecule in the excited state becomes a stronger proton acceptor than in the ground state.…”

Section: Absorption Properties In the Presence Of P-sulfonatocalix[6]mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Molecular‐Recognition‐Assisted pK_a Shifts and Metal‐Ion‐Induced Fluorescence Regeneration in p‐Sulfonatocalix[6]arene‐Encapsulated Acridine

et al. 2014

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Recognition of Free Tryptophan in Water by Synthetic Pseudopeptides: Fluorescence and Thermodynamic Studies

Martí‐Centelles

Izquierdo

Burguete

et al. 2014

Chemistry A European J

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Pseudopeptidic receptors containing an acridine unit have been prepared and their fluorescence response to a series of amino acids was measured in water. Free amino acids, not protected either at the C or the N terminus, were used for this purpose. The prepared receptors display a selective response to tryptophan (Trp) versus the other assayed amino acids under acidic conditions. The macrocyclic nature of the receptor is important as the fluorescence quenching is higher for the macrocyclic compound than for the related open‐chain receptor. Notably, under the experimental acidic conditions used, both the receptor and guest are fully protonated and positively charged; thus, the experimental results suggest the formation of supramolecular species that contain two positively charged organic molecular components in proximity stabilized through aromatic–aromatic interactions and a complex set of cation‐anion‐cation interactions. The selectivity towards Trp seems to be based on the existence of a strong association between the indole ring of the monocharged amino acid and the acridinium fragment of the triprotonated form of the receptor, which is established to be assisted by the interaction of the cationic moieties with hydrogen sulfate anions.

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Influence of 2′‐Deoxy Sugar Moiety on Excited‐State Protonation Equilibrium of Adenine and Adenosine with Acridine inside SDS Micelles: A Time‐Resolved Study with Quantum Chemical Calculations

2012

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The protonation dynamics of the DNA base adenine (Ade) and its nucleoside 2'-deoxyadenosine (d-Ade) are investigated by monitoring the deprotonation kinetics of an N-heterocyclic DNA intercalator, acridine (Acr), in the confined environment of sodium dodecyl sulfate (SDS) micelles. Protonation of acridine (AcrH(+)) occurs at the hydrophilic interface and this species remains in dynamic equilibrium with its deprotonated counterpart (Acr) inside the hydrophobic core of SDS micelles. Quenching of the fluorescence of AcrH(+)* at 478 nm is observed after addition of Ade and d-Ade with Stern-Volmer constant (K(SV)) 298 and 75 M(-1), respectively, with a concomitant increment in Acr* at 425 nm. Time-resolved fluorescence studies reveal quenching in the lifetime of AcrH(+)*. The relative amplitude of AcrH(+)* decreases from 0.97 to 0.51 and 0.97 to 0.89 with equimolar addition of Ade and d-Ade, respectively. These observations are explained by excited-state proton transfer (ESPT) from AcrH(+)* to the bases. The reduced K(SV) value and negligible change in the relative amplitudes of AcrH(+)* with d-Ade infer that ESPT is hindered substantially by the presence of a 2'-deoxy sugar unit. Transient time-resolved absorption spectra of Acr reflect that Ade reduces the absorbance of (3)AcrH(+)*; however, d-Ade keeps it unaltered for more than a time delay of 2 μs. The optimized geometries calculated by quantum chemical methods reflect deprotonation of AcrH(+)* with protonation at the N1 position of Ade, while it remains protonated with d-Ade. The hindered ESPT between AcrH(+)* and d-Ade singles out the significance of the 2'-deoxy sugar moiety in controlling the deprotonation kinetics.

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Quenching of the excited singlet state of acridine and 10-methylacridinium cation by thio-organic compounds in aqueous solution

Cited by 45 publications

References 31 publications

Molecular‐Recognition‐Assisted pK_a Shifts and Metal‐Ion‐Induced Fluorescence Regeneration in p‐Sulfonatocalix[6]arene‐Encapsulated Acridine

Molecular‐Recognition‐Assisted pK_a Shifts and Metal‐Ion‐Induced Fluorescence Regeneration in p‐Sulfonatocalix[6]arene‐Encapsulated Acridine

Recognition of Free Tryptophan in Water by Synthetic Pseudopeptides: Fluorescence and Thermodynamic Studies

Influence of 2′‐Deoxy Sugar Moiety on Excited‐State Protonation Equilibrium of Adenine and Adenosine with Acridine inside SDS Micelles: A Time‐Resolved Study with Quantum Chemical Calculations

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Quenching of the excited singlet state of acridine and 10-methylacridinium cation by thio-organic compounds in aqueous solution

Cited by 45 publications

References 31 publications

Molecular‐Recognition‐Assisted pKa Shifts and Metal‐Ion‐Induced Fluorescence Regeneration in p‐Sulfonatocalix[6]arene‐Encapsulated Acridine

Molecular‐Recognition‐Assisted pKa Shifts and Metal‐Ion‐Induced Fluorescence Regeneration in p‐Sulfonatocalix[6]arene‐Encapsulated Acridine

Recognition of Free Tryptophan in Water by Synthetic Pseudopeptides: Fluorescence and Thermodynamic Studies

Influence of 2′‐Deoxy Sugar Moiety on Excited‐State Protonation Equilibrium of Adenine and Adenosine with Acridine inside SDS Micelles: A Time‐Resolved Study with Quantum Chemical Calculations

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Molecular‐Recognition‐Assisted pK_a Shifts and Metal‐Ion‐Induced Fluorescence Regeneration in p‐Sulfonatocalix[6]arene‐Encapsulated Acridine

Molecular‐Recognition‐Assisted pK_a Shifts and Metal‐Ion‐Induced Fluorescence Regeneration in p‐Sulfonatocalix[6]arene‐Encapsulated Acridine