Photochemical processes induced by the irradiation of 4-hydroxybenzophenone in different solvents

Abstract

The singlet and triplet excited states of 4-hydroxybenzophenone (4BPOH) undergo deprotonation in the presence of water to produce the anionic ground-state, causing fluorescence quenching and photoactivity inhibition. The same process does not take place in an aprotic solvent such as acetonitrile. In acetonitrile, 4BPOH is fluorescent (interestingly, one of its fluorescence peaks overlaps with peak C of humic substances), it yields singlet oxygen upon irradiation and induces the triplet-sensitised transformation of phenol (with a rate constant of (6.6 ± 0.3) × 10(7) M(-1) s(-1) (μ ± σ) between phenol itself and a triplet 4BPOH). The 4BPOH shows an intermediate behaviour in a partially protic solvent such as 2-propanol, where some deprotonation of the excited states is observed. In acetonitrile/2-propanol mixtures (at least up to 50% of 2-propanol) there is also some evidence of alcohol oxidation by the 4BPOH triplet state, while the experimental data are silent concerning such a possibility in pure 2-propanol. Considering that benzophenones are important components of chromophoric dissolved organic matter (CDOM) in surface waters, the present findings could have significance for the photoactivity of the hydrophilic surface layers vs. the hydrophobic cores of CDOM.

Mechanistic Insights on the Photosensitized Chemistry of a Fatty Acid at the Air/Water Interface

“… 37 , 38 The formation of a ketyl radical can be explained by electron or hydrogen transfer from organic molecules (i.e., NA), a process which has previously been reported for other benzophenone derivatives. 39 , 40 …”

“…37,38 The formation of a ketyl radical can be explained by electron or hydrogen transfer from organic molecules (i.e., NA), a process which has previously been reported for other benzophenone derivatives. 39,40 Figure S3 (Supporting Information) reports the rate constant for the pseudo-first-order decay of 4-BBA* followed at 540 nm as a function of NA concentration in an aqueous solution. The data allows for the determination of the second-order rate constant for the quenching the triplet state by nonanoic acid k 4−BBA*, NA = 3.0 ± 0.5 × 10 7 M −1 s −1 , which is competitive with rate constants reported for aliphatic carboxylic acids and hydroxyl radicals.…”

The C-terminal tail of the bacterial translocation ATPase SecA modulates its activity

“…hydrophobicity, pH, etc .) can influence its photo-reactive properties (Barsotti et al, 2015; Barsotti et al, 2017). Because Bpa is typically incorporated at surface-exposed positions in order to capture protein-ligand interactions, these environmental effects are normally negligible.…”

Benzophenone based photostable fluorescent monoazo disperse dyes: Synthesis, AIE, viscosity, UPF and TD-DFT study

“…It is reported in the literature that benzophenone and some of it's derivatives are emissive in nature [23][24][25][26]. Recently, Barsotti et al have done wide-ranging work on4hydroxy benzophenone for it's fluorescence properties [23,27].…”

“…It is reported in the literature that benzophenone and some of it's derivatives are emissive in nature [23][24][25][26]. Recently, Barsotti et al have done wide-ranging work on4hydroxy benzophenone for it's fluorescence properties [23,27]. In general emission properties of azobenzene dyes were induced or altered by various ways which include restricted isomerisation and rotations across -N=N-group by N-B bond formation [28], by incorporation of benzothiazole fluorescent moiety to the azo dyes [29,30], by cooling of dye sample to very low temperature or by embedding dyes in rigid solvents [31].…”