Excited state deprotonation reactions of aromatic amines: a diffusion-controlled process

Chattopadhyay, Nitin; Samanta, Anunay; Kundu, Tapanendu; Chowdhury, Mihir

doi:10.1016/1010-6030(89)87090-x

Cited by 18 publications

(8 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As such, K SV,OH − values can be converted into bimolecular quenching rate constants using τ o,NS-NHd 2 * = 4.7 ns, which was experimentally measured using nanosecond timeresolved photoluminescence spectroscopy (Figure S1). Doing so yielded values that are remarkably close to rate constants predicted for encounter-controlled diffusion-limited reactivity, 40,51,62 k +q,ss,OH − = (10 ± 0.3) × 10 9 M −1 s −1 and k +q,τ,OH − = (12 ± 1) × 10 9 M −1 s −1 , which are consistent with protontransfer rate constants measured by Brønsted and Eigen for ground-state proton-transfer processes. 50−53 To further support the hypothesis that pK a * pseudo values derived from steady-state photoluminescence spectroscopy data are kinetically gated by ESPT with OH − and photoacid excited-state lifetime, pK a * pseudo values were determined for several aromatic amine photoacids with different excited-state lifetimes (Figures S2−S4).…”

Section: ■ Results and Discussionmentioning

confidence: 53%

Quantification of Excited-State Brønsted–Lowry Acidity of Weak Photoacids Using Steady-State Photoluminescence Spectroscopy and a Driving-Force-Dependent Kinetic Theory

et al. 2022

View full text Add to dashboard Cite

Photoacids and photobases constitute a class of molecules that upon absorption of light undergoes a reversible change in acidity, i.e. pK a . Knowledge of the excited-state pK a value, pK a *, is critical for predicting excited-state proton-transfer behavior. A reasonable approximation of pK a * is possible using the Forster cycle analysis, but only when the ground-state pK a is known. This poses a challenge for the study of weak photoacids (photobases) with less acidic (basic) excited states (pK a * (pK b *) > 7), because ground-state pK a (pK b ) values are >14, making it difficult to quantify them accurately in water. Another method to determine pK a * relies on acid−base titrations with photoluminescence detection and Henderson−Hasselbalch analysis. This method requires that the acid dissociation reaction involving the thermally equilibrated electronic excited state reaches chemical quasi-equilibrium, which does not occur for weak photoacids (photobases) due to slow rates of excited-state proton transfer. Herein, we report a method to overcome these limitations. We demonstrate that liquid water and aqueous hydroxide are unique proton-accepting quenchers of excited-state photoacids. We determine that Stern−Volmer quenching analysis is appropriate to extract rate constants for excited-state proton transfer in aqueous solutions from a weak photoacid, 5-aminonaphthalene-1sulfonate, to a series of proton-accepting quenchers. Analysis of these data by Marcus−Cohen bond-energy−bond-order theory yields an accurate value for pK a * of 5-aminonaphthalene-1-sulfonate. Our method is broadly accessible because it only requires readily available steady-state photoluminescence spectroscopy. Moreover, our results for weak photoacids are consistent with those from previous studies of strong photoacids, each showing the applicability of kinetic theories to interpret driving-force-dependent rate constants for proton-transfer reactions.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 53%

Quantification of Excited-State Brønsted–Lowry Acidity of Weak Photoacids Using Steady-State Photoluminescence Spectroscopy and a Driving-Force-Dependent Kinetic Theory

et al. 2022

View full text Add to dashboard Cite

show abstract

“…11 The precise positioning of the band and the fluorescence lifetime (5.0, 4.6 and 4.5 ns, for R = i Pr, Ph and Bn respectively) were subtly dependent on the specific composition of the ligand. The diphenylamine anion is known to be non-emissive, 12 and therefore the visible fluorescence was attributed to a ligand-centred excited state with a contributing charge transfer (N-to-p*) component originating from the deprotonated/coordinated amide bridge-head.…”

mentioning

confidence: 99%

Near-IR luminescent neodymium complexes: spectroscopic probes for hydroamination catalysis

2013

View full text Add to dashboard Cite

show abstract

“…1000 cm –1 ); the precise positioning of the emission showed a small dependence on the specific identity of the BOPA ligand. The diphenylamine anion is known to be non‐emissive, and therefore the fluorescence from these complexes is attributed to a ligand‐centred excited state with a significant charge transfer (N→π*) component originating from the deprotonated/coordinated amide bridge‐head.…”

Section: Resultsmentioning

confidence: 99%

Scandium Complexes Bearing Bis(oxazolinylphenyl)amide Ligands: An Analysis of Their Reactivity, Solution‐State Structures and Photophysical Properties

et al. 2016

View full text Add to dashboard Cite

Excited state deprotonation reactions of aromatic amines: a diffusion-controlled process

Cited by 18 publications

References 16 publications

Quantification of Excited-State Brønsted–Lowry Acidity of Weak Photoacids Using Steady-State Photoluminescence Spectroscopy and a Driving-Force-Dependent Kinetic Theory

Quantification of Excited-State Brønsted–Lowry Acidity of Weak Photoacids Using Steady-State Photoluminescence Spectroscopy and a Driving-Force-Dependent Kinetic Theory

Near-IR luminescent neodymium complexes: spectroscopic probes for hydroamination catalysis

Scandium Complexes Bearing Bis(oxazolinylphenyl)amide Ligands: An Analysis of Their Reactivity, Solution‐State Structures and Photophysical Properties

Contact Info

Product

Resources

About