Electronic absorption and fluorescence study of ionization and intramolecular hydrogen-bonding in the α, β-o-hydroxynaphthoic acids

Kovi, Peter J.

doi:10.1016/s0003-2670(01)80859-x

Cited by 19 publications

(11 citation statements)

References 8 publications

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“…The green emission at 540 nm is characteristic of carboxylic groups in their protonated state while the blue emission at 425 nm is due to dissociated carboxylic groups. It is well-known that dissociation of the carboxylic group in aromatic carboxylic acids raises the energy of the first singlet state, causing a blue-shift . In the present experiments the pH of the dispersions was maintained at 4.0.…”

Section: Resultsmentioning

confidence: 89%

“…It is well-known that dissociation of the carboxylic group in aromatic carboxylic acids raises the energy of the first singlet state, causing a blueshift. 35 In the present experiments the pH of the dispersions was maintained at 4.0. The green emission band at 540 nm may therefore be identified with acid groups with pK 6.6 that remain protonated at this pH, while the band at 425 nm may be assigned to the dissociated acid groups with pK 4.3.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Engineering a Water-Dispersible, Conducting, Photoreduced Graphene Oxide

Konkena

Vasudevan

2015

J. Phys. Chem. C

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A critical limitation that has hampered widespread application of the electrically conducting reduced graphene oxide (r-GO) is its poor aqueous dispersibility. Here we outline a strategy to obtain water-dispersible conducting r-GO sheets, free of any stabilizing agents, by exploiting the fact that the kinetics of the photoreduction of the insulating GO is heterogeneous. We show that by controlling UV exposure times and pH, we can obtain r-GO sheets with the conducting sp2-graphitic domains restored but with the more acidic carboxylic groups, responsible for aqueous dispersibility, intact. The resultant photoreduced r-GO sheets are both conducting and water-dispersible.

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Section: Resultsmentioning

confidence: 89%

Section: ■ Results and Discussionmentioning

confidence: 99%

Engineering a Water-Dispersible, Conducting, Photoreduced Graphene Oxide

Konkena

Vasudevan

2015

J. Phys. Chem. C

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“…The absorption spectrum of NCS-Chrom A, which accounts for 90% of the total UV-absorbing and bioactive material in NCS, has considerable fine structure with band maxima in spectral regions characteristic of various hydroxynaphthoic acids (Schulman & Kovi, 1973): specifically in the regions 230-270 nm and 320-340 nm, where the isolated hydroxynaphthoic acid derivative of NCS-Chrom and its methyl ester (Edo et al, 1980; . A. Napier and I. H. Goldberg, unpublished experiments) absorb.…”

Section: Discussionmentioning

confidence: 99%

Neocarzinostatin chromophore: purification of the major active form and characterization of its spectral and biological properties

Napier¹,

Holmquist²,

Strydom³

et al. 1981

Biochemistry

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“…SM5): 2HBA (k ex = 310 nm, k em = 440 nm), 1H2NA (k ex = 340 nm, k em = 415 nm) and 1,4DH2NA (k ex = 340 nm, k em = 445 nm). These fluorescence emission bands can be assigned to monomers of ligands existing in polar solvents at low concentrations [60][61][62][63]. The emission intensities depend on the protonation of the carboxylate group [64] i.e.…”

Section: Fluorescence Spectramentioning

confidence: 99%