Pteridine-based fluorescent pH sensors designed for physiological applications

Saleh, Na’il; Graham, John; Afaneh, Akef T.; Al‐Soud, Yaseen A.; Schreckenbach, Georg; Esmadi, Fatima T.

doi:10.1016/j.jphotochem.2012.08.002

Cited by 13 publications

(10 citation statements)

References 56 publications

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“…[39,78] The only firmly established example of phototautomerism among pteridines is that of lumazine [79] (2,4-dihydroxypteridine), the detailed mechanism of which is still under dispute, [80][81][82] but nevertheless finds many analytical applications. [83] This phototautomerism is somewhat analogous to that observed in the alloxazine system. [84,85] It should be also recalled that nucleoside analogs capable of intramolecular ESPT were developed and applied to the modified DNA studies.…”

Section: Related Systemssupporting

confidence: 58%

Excited-State Proton Transfer and Phototautomerism in Nucleobase and Nucleoside Analogs: A Mini-Review

Wierzchowski¹

2014

Nucleosides, Nucleotides and Nucleic Acids

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Intermolecular excited-state proton transfer (ESPT) has been observed in several fluorescent nucleobase and/or nucleoside analogs. In the present work, some new examples of ESPT in this class of compounds are presented together with a brief recapitulation of the previously published data. The nucleobases, nucleosides, and their analogs contain many basic and acidic centers and therefore their ESPT behavior may be complex. To interpret the complex data, it is usually necessary to determine the microscopic pK* values for each (or most) of the possible ESPT centers. Typical approach to solve this problem is by analysis of the alkyl derivatives, in which the possibility of the ESPT is reduced. Of particular interest are examples of "phototautomerization via the cation," observed in several systems, which in the neutral media do not undergo ESPT. Protonation of the molecule in the ground state facilitates the two-step phototautomerism in several systems, including formycin A and 2-amino-8-azadenine. Fluorescence of the nucleobase and nucleoside analogs undergoing ESPT is usually solvent-, isotope-, and buffer-ion sensitive, and in some systems the ESPT can be promoted by environmental factors, e.g., the presence of buffer ions. This sensitivity to the microenvironment parameters makes the ESPT systems potentially useful for biological applications.

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Section: Related Systemssupporting

confidence: 58%

Excited-State Proton Transfer and Phototautomerism in Nucleobase and Nucleoside Analogs: A Mini-Review

Wierzchowski¹

2014

Nucleosides, Nucleotides and Nucleic Acids

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“…The first equilibrium of Eqn must take place at such an acidic pH that it has not been detected in the study of the pH dependence (0 to 14 pH range) of the electronic spectrum. The two subsequent deprotonation processes have been clearly observed at pH values that are in accordance with the reported pK a2 values of LM and TLM, 7.95 and 6.84 ± 0.07, respectively.…”

Section: Resultssupporting

confidence: 88%

“…The predominant protonation sites involved are N 1 H and N 3 H both in LM and TLM ( cis and trans ). Thus, the N 1 H and N 3 H protons are less acidic than N 8 H. Finally, the pK a3 range of LM and TLM is 12.7–15.0, Schemes and , in good agreement with the experimental values of >11.…”

Section: Resultssupporting

confidence: 83%

“…The deprotonation of N 8 (H 8 ) in cis ‐38‐TLM has a pK a2 of 5.0 (4.2 for the trans conformer), and the calculated pK a2 values of cis ‐13‐TLM are 7.9 for 3‐TLM (8.0 for the trans conformer) and 10.1 for the 1‐TLM (for both cis and trans conformers), Scheme . The calculated pK a2 values, Scheme , of TLM are in good agreement with the experimental values of 4.8 and 6.8 for N 8 –H and N 1 –H, respectively . The predominant protonation sites involved are N 1 H and N 3 H both in LM and TLM ( cis and trans ).…”

Section: Resultssupporting

confidence: 81%

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Conformation/Tautomerization effect on the pK_a values of lumazine and 6‐thienyllumazine

Afaneh

Schreckenbach

2014

J of Physical Organic Chem

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Density functional theory p)] was used in combination with the conductor-like polarizable continuum model (CPCM) solvation model to investigate the relative stability and site-specific pK ij a values of neutral and ionized tautomers of lumazine (LM) and 6-thienylLM (TLM). Two types of populations should be taken into consideration when calculating the pK ij a , tautomers, and conformers. The major tautomer of neutral LM in aqueous solution is 13-LM (the 13 notation refers to the acidic protons being in positions 1 and 3 of LM) TLM has decreased acidity at N 8 relative to LM. Further, the trans conformer of TLM is more acidic than cis. Similar to the case of LM, for TLM, N 1 is more acidic than N 3 in the uracil part. However, N 8 is predicted to be a stronger acid than N 1 for TLM. This acidity enhancement is essentially because of a specific stabilization of the anion when the thienyl group replaces H. Two factors are responsible for the acidity strength of N 8 : The thienyl ring upon deprotonation acts inductively as an electron-withdrawing group, and the excess electron density is dispersed better when the system is trans and contains second-row atoms. Accurate pK a calculation requires that all conformers/tautomers be included into the calculation.

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“…Lm compounds are known to form coordination bonds with biologically essential metals in some metalloen zymes [23]. In fact, TLm itself was designed and prepared by our research group [24] as selective fluorescent sensors for pH [25] and heavy metal ions, such as Cd 2+ and Hg 2+ in pure water [24,26]. Thus, our second aim is to fabricate TLmNFs as a fluorescence-based solid sensor to detect micromoles or less of Hg 2+ ions, urged by the increasing global concern on water pollutions [27].…”

Section: Introductionmentioning

confidence: 99%

Time-resolved photoluminescence of 6-thienyl-lumazine fluorophores in cellulose acetate nanofibers for detection of mercury ions

Al-Shamsi

Laptenok

Bufaroosha

et al. 2019

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Pteridine-based fluorescent pH sensors designed for physiological applications

Cited by 13 publications

References 56 publications

Excited-State Proton Transfer and Phototautomerism in Nucleobase and Nucleoside Analogs: A Mini-Review

Excited-State Proton Transfer and Phototautomerism in Nucleobase and Nucleoside Analogs: A Mini-Review

Conformation/Tautomerization effect on the pK_a values of lumazine and 6‐thienyllumazine

Time-resolved photoluminescence of 6-thienyl-lumazine fluorophores in cellulose acetate nanofibers for detection of mercury ions

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Pteridine-based fluorescent pH sensors designed for physiological applications

Cited by 13 publications

References 56 publications

Excited-State Proton Transfer and Phototautomerism in Nucleobase and Nucleoside Analogs: A Mini-Review

Excited-State Proton Transfer and Phototautomerism in Nucleobase and Nucleoside Analogs: A Mini-Review

Conformation/Tautomerization effect on the pKa values of lumazine and 6‐thienyllumazine

Time-resolved photoluminescence of 6-thienyl-lumazine fluorophores in cellulose acetate nanofibers for detection of mercury ions

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Conformation/Tautomerization effect on the pK_a values of lumazine and 6‐thienyllumazine