Photooxidation of the Phenolate Anion is Accelerated at the Water/Air Interface

Abstract

Molecular photodynamics can be dramatically affected at the water/air interface. Probing such dynamics is challenging, with product formation often probed indirectly through its interaction with interfacial water molecules using time-resolved and phase-sensitive vibrational sum-frequency generation (SFG). Here, the photoproduct formation of the phenolate anion at the water/air interface is probed directly using time-resolved electronic SFG and compared to transient absorption spectra in bulk water. The mechanisms are broadly similar, but 2 to 4 times faster at the surface. An additional decay is observed at the surface which can be assigned to either diffusion of hydrated electrons from the surface into the bulk or due to increased geminate recombination at the surface. These overall results are in stark contrast to phenol, where dynamics were observed to be 10 4 times faster and for which the hydrated electron was also a photoproduct. Our attempt to probe phenol showed no electron signal at the interface.

Multiphase Chemistry under Nanoconfinement: An Electrochemical Perspective

“…In recent years, vibrational sum-frequency generation spectroscopy has become a powerful tool to measure kinetics at phase boundaries, including an accelerated photooxidation reaction occurring water–air interface . Verlet’s work also elucidates the solvated electron at such a boundary.…”

“…149 In recent years, vibrational sum-frequency generation spectroscopy has become a powerful tool to measure kinetics at phase boundaries, including an accelerated photooxidation reaction occurring water−air interface. 150 Verlet's work also elucidates the solvated electron at such a boundary. These observations have led to detailed explorations into the microdroplet boundary and the electric field/species that may be stabilized in this extreme microenvironment.…”

High-Throughput Screening for Ultrafast Photochemical Reaction Discovery

“…11,12 Initial reports have also been made of transient absorption implementations using ytterbium amplifiers with repetition rates of up to 60 kHz. 13 This paper presents a system for rapid acquisition of transient absorption spectroscopy coupled with an HPLC sample delivery system capable of characterizing an entire time-resolved excited state absorption spectrum with a > 10fold decrease in acquisition time in comparison with conventional transient absorption at 1 kHz. Even starting with relatively modest pump pulse energies (ca.…”

Locking water molecules via ternary O–H⋯O intramolecular hydrogen bonds in perhydroxylated closo-dodecaborate

“…12 However, anionic HB are highly susceptible to environmental interference due to the competition between ion-water interactions and inter-water HB in aqueous solutions. These subtle competition mechanisms highlight the effects of anionic HB, which are an eternal topic due to its essential role in surface and interface chemistry, [13][14][15][16][17] electron-driven chemistry, 18,19 mass transfer kinetics 20 and solvation sheath structures. 21 Several major open questions regarding anionic HB have been extensively investigated for smaller-sized anions, 6,[22][23][24][25][26][27][28] including the binding motif of the electron or energy extrapolation from water clusters to bulk water, the competitive mechanism of HB, the characteristics of the local first solvation shell, and the thermally activated behaviour under the latent asymmetry of electron density of hydrated anionic clusters.…”