New functionalized water-soluble benzophenones: a laser flash photolysis study

Abstract

Two water-soluble ionic benzophenones containing a quatemized amine and a sulphonate group have been investigated by laser flash photolysis. The decay kinetics and spectra of their triplet states were studied and quenching constants by triethanolamine, isopropanol, and methyl viologen determined. These data are of interest when these benzophenones are used as initiators for photo-polymerizing water-soluble acrylates in homogeneous solution or in reverse micellar assemblies. The high water solubility of these compounds allows the bimolecular deactivations due to triplet–triplet (kTT) and triplet–ground state (kSQ) interactions to be determined more accurately than in the case of benzophenone itself.

Aromatic Carbonyl and Nitro Compounds as Photosensitizers and Their Photophysical Properties in the Tropospheric Aqueous Phase

“…From the first-order rate constants, the triplet lifetimes in the absence of oxygen were determined giving values ranging from 12 to 342 μs (Table ), which are in good agreement with the values obtained from the spectroscopic studies (Table ). Furthermore, the obtained values of benzophenone and 4-benzoylbenzoic acid are comparable with the literature. ,, The results show that benzophenone and 4-benzoylbenzoic acid are independent of the analysis wavelength, while xanthone has different decay rate constants at the respective wavelengths. From the spectroscopic studies, it was found that the excited triplet state of xanthone absorbs at higher wavelengths.…”

“…Furthermore, the obtained values of benzophenone and 4benzoylbenzoic acid are comparable with the literature. 86,98,99 The results show that benzophenone and 4-benzoylbenzoic acid are independent of the analysis wavelength, while xanthone has different decay rate constants at the respective wavelengths. From the spectroscopic studies, it was found that the excited triplet state of xanthone absorbs at higher wavelengths.…”

Photoinitiation Processes of Radical Polymerization in the Presence of a Three-Component System Based on Ketone-Amine-Bromo Compound

“…This is well supported by the fact that the benzenesulfonyl radical is known to exhibit an absorption up to 500 nm. 24 In DETX/CBr4, a residual absorption is also clearly observed at approximately 430 nm. By analogy with the above-mentioned lines of thought with regard to DETX/ BMPS, the formation of a Br' radical may be expected in the sequence of reactions:…”

Influence of the chloro substituent position on the triplet reactivity of benzophenone derivatives: a time‐resolved resonance Raman and density functional theory study

“…The DPK radical formation mechanism in aqueous solutions has been a question for many years. A thermochemical calculation indicated the direct hydrogen abstraction of the BP triplet from a H 2 O molecule could be energetically feasible, but the reaction rate has an upper limit of only ~10 3 M –1 s –1 . Assuming the DPK radical has the same Raman intensity under the same concentration in IPA and in aqueous solution, comparison of the 3‐Cl‐DPK radical Raman spectra in IPA and in a MeCN:H 2 O/1:1 mixed solvent obtained under the same experimental conditions suggests that the yield of the 3‐Cl‐DPK radical is only about 0.09 in the MeCN:H 2 O/1:1 solvent (see supplemental information for details).…”

“…A thermochemical calculation [41] indicated the direct hydrogen abstraction of the BP triplet from a H 2 O molecule could be energetically feasible, but the reaction rate has an upper limit of only~10 3 M -1 s -1 . [42,43] Assuming the DPK radical has the same Raman intensity under the same concentration in IPA and in aqueous solution, comparison of the 3-Cl-DPK radical Raman spectra in IPA and in a MeCN:H 2 O/1:1 mixed solvent obtained under the same experimental conditions suggests that the yield of the 3-Cl-DPK radical is only about 0.09 in the MeCN: H 2 O/1:1 solvent (see supplemental information for details). This result suggests that the 3-Cl-DPK radical formation rate in a MeCN:H 2 O/1:1 solvent is~3.6 Â 10 4 M -1 s -1 , which is faster than the predicted limit but much slower than the hydrogen abstraction rate of the BP triplet from IPA (2.3 Â 10 6 M -1 s -1 ).…”