Estimation of pKa* in the first excited singlet state. A physical chemistry experiment that explores acid-base properties in the excited state

Marciniak, Bronisław; Kozubek, Halina; Paszỳc, S.

doi:10.1021/ed069p247

Cited by 55 publications

(28 citation statements)

References 3 publications

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“…Deprotonation occurs during the excited state lifetime of the molecule. This phenomenon correlates to the widely studied photophysics of 2-Naphthol [25,[67][68][69][70][71] where the molecule undergoes the ESPT process at high pH conditions, revealing emission of the Naptholate anion around 410 nm [67]. Observation of the emissions from both the deprotonated NpTP and NpTP-F − hinted at the fact that the excited state reaction is partially completed during the excited state lifetime [67].…”

Section: Absorption and Fluorescence Studiessupporting

confidence: 75%

Nuclear Magnetic Resonance Spectroscopy Investigations of Naphthalene-Based 1,2,3-Triazole Systems for Anion Sensing

et al. 2018

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Detailed Nuclear Magnetic Resonance (NMR) spectroscopy investigations on a novel naphthalene-substituted 1,2,3-triazole-based fluorescence sensor provided evidence for the "turn-on" detection of anions. The one-step, facile synthesis of the sensors was implemented using the "Click chemistry" approach in good yield. When investigated for selectivity and sensitivity against a series of anions (F − , Cl − , Br − , I − , H 2 PO 4 − , ClO 4 − , OAc − , and BF 4 − ), the sensor displayed the strongest fluorometric response for the fluoride anion. NMR and fluorescence spectroscopic studies validate a 1:1 binding stoichiometry between the sensor and the fluoride anion. Single crystal X-ray diffraction evidence revealed the structure of the sensor in the solid state.

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Section: Absorption and Fluorescence Studiessupporting

confidence: 75%

Nuclear Magnetic Resonance Spectroscopy Investigations of Naphthalene-Based 1,2,3-Triazole Systems for Anion Sensing

et al. 2018

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“…The value of pK a was determined as 1.17 from absorption and emission spectra. The excited state protonation constant pK a * was calculated by using the following relation: 21,22 pK a -pK a *＝2.…”

Section: Effect Of Medium Aciditymentioning

confidence: 99%

Effect of Medium Acidity and Photostability of 3‐(4‐Dimethylamino‐phenyl)‐1‐(2,5‐dimethyl‐thiophen‐3‐yl)‐propenone (DDTP): A New Green Emitting Laser Dye

et al. 2011

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On the line of a previous work on the spectral properties of some of heteroaryl chalcone, the effect of medium acidity and photoreactivity of 3-(4-dimethylamino-phenyl)-1-(2,5-dimethyl-thiophen-3-yl)-propenone (DDTP) has been investigated in dimethylformamide and in chloromethane solvents such as methylenechloride, chloroform and carbon tetrachloride. The dye solution (ca. 5×10-4 mol•L -1 in DMF) gives a good laser emission in the range 470 -560 nm with emission maximum at 515 nm upon pumping by nitrogen laser (λ ex ＝337.1 nm). The laser parameters such as gain coefficient (α), emission cross section (σ e ) and half life energy (E 1/2 ) at maximum laser emission are also determined.Keywords 3-(4-dimethylamino-phenyl)-1-(2,5-dimethyl-thiophen-3-yl)-propenone, laser dyes, effect of acidity, possibility Chin.

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“…emission maxima of the anionic forms in water are determined as 548 nm and 553 nm from the smoothed spectra of BOH and MOH in water (pH 13.0) with direct excitation of the anion form λ ex = 445 nm). Using the published method described in ref 38,. the pKa* values for BOH and MOH in water are estimated to be -2.3 and -2.4 from the above parameters of [pKa = 5.8, λ a = (378 nm, 447 nm), λ f = (458nm, 548 nm)] and [pKa = 5.3, λ a = (380 nm, 446 nm), λ f = (464 nm, 553 nm)], respectively.…”

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confidence: 99%

Excited-state proton transfer of 4-hydroxyl-1, 8-naphthalimide derivatives: A combined experimental and theoretical investigation

Zhang

Wang

et al. 2016

Journal of Luminescence

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The photophysical properties of N-butyl-4-hydroxyl-1, 8-naphthalimide (BOH) and N-(morpholinoethyl)-4-hydroxy-1, 8-naphthalimide (MOH) in various solvents are presented and the density functional theory (DFT) / time-dependent density functional theory (TDDFT) methods at the B3LYP/TZVP theoretical level are adopted to investigate the UV-visible absorption and emission data. An efficient intermolecular excited-state proton transfer (ESPT) reaction occurs for both compounds in DMSO, methanol and water. In aqueous solution, both BOH and MOH can be used as ratiometric pH probes and perform as strong photoacids with pKa* = −2.2, −2.4, respectively. Most interestingly, in the steady-state fluorescence spectra of BOH and MOH in concentrated HCl, an unexpected blue-shifted band is observed and assumed to originate from the contact ion pair (CIP) formed by hydronium ion and the anionic form of the photoacid resulted from ESPT. Theoretical calculations are used to simulate the CIP in the case of BOH, which afford reasonable results compared with the experimental data. Keywords: Naphthalimide Excited-state proton transfer Photoacid Contact ion pair Time-dependent density functional theory 1. Introduction Upon photoexcitation, aromatic alcohols (ROH) such as naphthols, hydroxyquinolines, and hydroxypyrenes may increase the acidity dramatically. Research on this photoinduced deprotonation is first described by Fὅrster in 1949 [1] and still attracting intensive attention in the field of biology and physical chemistry [2-11]. The Eigen-Weller model for proton transfer is used to depict this process, where the initial short-range proton transfer forms a contact ion pair (CIP) as a reaction intermediate followed by diffusion controlled separation of the ions [12-13]. © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/Recently, Brouwer and coworkers synthesized and characterized some hydroxy-substituted 1, 8-naphthalimide derived "super" photoacids, where the hydroxyl group is located at the 3 or 6 position of the naphthalimide ring [6,14]. However, for 4-hydroxyl-1, 8-naphthalimide derivatives, which are extensively used for designing turn-on or rationmetric fluorescent indicators for bioimaging [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], the photophysical properties and the excited-state proton transfer (ESPT) reactions are rarely studied [30].In this contribution, the steady-state absorption and emission spectra of two 4-hydroxyl-1, 8-naphthalimide derivatives (BOH and MOH, Scheme 1) in organic solvents and water with various pH values are recorded. The density functional theory (DFT) / time-dependent density functional theory (TDDFT) methods at B3LYP/TZVP theoretical level are adopted to investigate the UV-visible absorption and emission data. In the study of the ESPT of 5-cyano-2-naphthol in sub-and supercritical water, Kobayashi and coworkers [31] found that the band of their excited neutral (ROH*) and anionic (RO − *) species...

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Estimation of pKa* in the first excited singlet state. A physical chemistry experiment that explores acid-base properties in the excited state

Abstract: The acid-base reactions in excited states are some of the most elementary processes both in photochemistry and biochemistry and are, therefore, well-suited to form the basis for an undergraduate physical chemistry experiment.

Cited by 55 publications

References 3 publications

Nuclear Magnetic Resonance Spectroscopy Investigations of Naphthalene-Based 1,2,3-Triazole Systems for Anion Sensing

Nuclear Magnetic Resonance Spectroscopy Investigations of Naphthalene-Based 1,2,3-Triazole Systems for Anion Sensing

Effect of Medium Acidity and Photostability of 3‐(4‐Dimethylamino‐phenyl)‐1‐(2,5‐dimethyl‐thiophen‐3‐yl)‐propenone (DDTP): A New Green Emitting Laser Dye

Excited-state proton transfer of 4-hydroxyl-1, 8-naphthalimide derivatives: A combined experimental and theoretical investigation

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