Ionization sequences in the ground and lowest electronically excited singlet states of 3-hydroxy-2-naphthoic acid

Kovi, Peter J.

doi:10.1021/ac60328a043

Cited by 28 publications

(9 citation statements)

References 5 publications

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“…1. Similar analysis has been provided for ortho-hydroxynaphthoic acids 18 and their esters. 19 Next, we focus on the stereoelectronic relationship between the vicinal imidazole and hydroxyl groups in 1NI2OH and 2NI1OH, which provide an orthogonal analysis for structural effects in the ground state.…”

Section: Absorption Studiesmentioning

confidence: 69%

Effective targeting of proton transfer at ground and excited states of ortho-(2′-imidazolyl)naphthol constitutional isomers

Oliveira

Carmo

Murta

et al. 2015

Phys. Chem. Chem. Phys.

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Steady-state and time-resolved spectroscopy and quantum chemical computational studies were employed to investigate ground and excited state proton transfer of a novel series of ortho-(1H-imidazol-2-yl)naphthol constitutional isomers: 1-(1H-imidazol-2-yl)naphthalen-2-ol (1NI2OH), 2-(1H-imidazol-2-yl)naphthalen-1-ol (2NI1OH) and 3-(1H-imidazol-2-yl)naphthalen-2-ol (3NI2OH). Proper Near Attack Conformations (NACs) involving a strong intramolecular hydrogen bond between the naphthol moiety and the ortho-imidazole group account for the highest ground state acidity of 2NI1OH compared with 1NI2OH and 3NI2OH. Moreover, ESIPT for 2NI1OH and 3NI2OH is further associated with planar chelate H-ring formation whereas 1NI2OH shows the highest ESIPT barrier and a noncoplanar imidazole group. In addition to energetic and structural requirements, the final state also depends on electronic configuration of the ESIPT product with the neutral 3NI2OH showing an ICT effect that correlates with the excited state pKa of the cationic species.

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Section: Absorption Studiesmentioning

confidence: 69%

Effective targeting of proton transfer at ground and excited states of ortho-(2′-imidazolyl)naphthol constitutional isomers

Oliveira

Carmo

Murta

et al. 2015

Phys. Chem. Chem. Phys.

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“…This is because of the dissociation of the carboxylic groups that were responsible for the 550 nm emission at lower values of pH (>6.6). It is well-known that protonation causes a red shift in the fluorescence of aromatic carboxylic acids, and a similar explanation is probably true in GO dispersions . The fluorescence spectra of GO dispersions at pH 10.6 shows a single band at 470 nm for excitation at 300 nm that shifts to 495 nm on exciation at longer wavelengths.…”

mentioning

confidence: 68%

Spectral Migration of Fluorescence in Graphene Oxide Aqueous Dispersions: Evidence for Excited-State Proton Transfer

Konkena

Vasudevan

2013

J. Phys. Chem. Lett.

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Aqueous dispersions of graphene oxide (GO) exhibit strong pH-dependent fluorescence in the visible that originates, in part, from the oxygenated functionalities present. Here we examine the spectral migration on nanosecond time-scales of the pH dependent features in the fluorescence spectra. We show, from time-resolved emission spectra (TRES) constructed from the wavelength dependent fluorescence decay curves, that the migration is associated with excited state proton transfer. Both 'intramolecular' and 'intermolecular' transfer involving the quasi-molecular oxygenated aromatic fragments are observed. As a prerequisite to the time-resolved measurements, we have correlated the changes in the steady state fluorescence spectra with the sequence of dissociation events that occur in GO dispersions at different values of pH.

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“…photobases, while the remaining two were more acidic, that is, photoacids. This is unprecedented behavior as decades of research has taught that the identity of the ionizable group regulates excited-state acid–base behavior: all previous organic dyes with conjugated carboxylate groups were identified to be photobases. − Yet among these closely related compounds this clearly was not the case. The excited state studies reported provide insights into the origins of this new behavior and suggest means by which it can be further optimized for practical and fundamental applications.…”

Section: Discussionmentioning

confidence: 99%

Photoacidic and Photobasic Behavior of Transition Metal Compounds with Carboxylic Acid Group(s)

O’Donnell

Sampaio

et al. 2016

J. Am. Chem. Soc.

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Excited state proton transfer studies of six Ru polypyridyl compounds with carboxylic acid/carboxylate group(s) revealed that some were photoacids and some were photobases. The compounds [Ru(II)(btfmb)2(LL)](2+), [Ru(II)(dtb)2(LL)](2+), and [Ru(II)(bpy)2(LL)](2+), where bpy is 2,2'-bipyridine, btfmb is 4,4'-(CF3)2-bpy, and dtb is 4,4'-((CH3)3C)2-bpy, and LL is either dcb = 4,4'-(CO2H)2-bpy or mcb = 4-(CO2H),4'-(CO2Et)-2,2'-bpy, were synthesized and characterized. The compounds exhibited intense metal-to-ligand charge-transfer (MLCT) absorption bands in the visible region and room temperature photoluminescence (PL) with long τ > 100 ns excited state lifetimes. The mcb compounds had very similar ground state pKa's of 2.31 ± 0.07, and their characterization enabled accurate determination of the two pKa values for the commonly utilized dcb ligand, pKa1 = 2.1 ± 0.1 and pKa2 = 3.0 ± 0.2. Compounds with the btfmb ligand were photoacidic, and the other compounds were photobasic. Transient absorption spectra indicated that btfmb compounds displayed a [Ru(III)(btfmb(-))L2](2+)* localized excited state and a [Ru(III)(dcb(-))L2](2+)* formulation for all the other excited states. Time dependent PL spectral shifts provided the first kinetic data for excited state proton transfer in a transition metal compound. PL titrations, thermochemical cycles, and kinetic analysis (for the mcb compounds) provided self-consistent pKa* values. The ability to make a single ionizable group photobasic or photoacidic through ligand design was unprecedented and was understood based on the orientation of the lowest-lying MLCT excited state dipole relative to the ligand that contained the carboxylic acid group(s).

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Ionization sequences in the ground and lowest electronically excited singlet states of 3-hydroxy-2-naphthoic acid

Cited by 28 publications

References 5 publications

Effective targeting of proton transfer at ground and excited states of ortho-(2′-imidazolyl)naphthol constitutional isomers

Effective targeting of proton transfer at ground and excited states of ortho-(2′-imidazolyl)naphthol constitutional isomers

Spectral Migration of Fluorescence in Graphene Oxide Aqueous Dispersions: Evidence for Excited-State Proton Transfer

Photoacidic and Photobasic Behavior of Transition Metal Compounds with Carboxylic Acid Group(s)

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