Vinyl cations as intermediates in photohydration of acetylenes

Wooldridge, Timothy A.; Roberts, T. D.

doi:10.1016/s0040-4039(01)87096-9

Cited by 17 publications

(9 citation statements)

References 5 publications

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“…For the OPE-1 series, conversion of the carboxyester group to a free carboxylate results in a large increase in fluorescence in water and there is little difference between the fluorescence efficiency for this compound in water and in methanol. It has been found that diphenylacetylenes and phenyleneethynlene monomers add water across the triple bond via a mechanism that has been proposed to involve either an initial photoprotonation or, for electron deficient derivatives, nucleophilic attack of structured interfacial water. , We have observed that several OPEs undergo a reasonably rapid photobleaching reaction which is consistent with net addition of water to the triple bond . It is reasonable to infer that the low fluorescence yields may be connected with a reversible attack of water on the excited singlet state.…”

Section: Discussionsupporting

confidence: 68%

Synthesis, Self-Assembly, and Photophysical Properties of Cationic Oligo(p-phenyleneethynylene)s

Tang¹,

Hill²,

Zhou³

et al. 2011

Langmuir

142

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Three series of cationic oligo p-phenyleneethynylenes (OPEs) have been synthesized to study their structure-property relationships and gain insights into the transition from molecular to macromolecular properties. The absorbance maxima and molar extinction coefficients in all three sets increase with increasing number of repeat units; however, the increase in λ(max) between the oligomers having 2 and 3 repeat units is very small, and the oligomer having 3 repeat units shows virtually the same spectra as a p-phenyleneethynylene polymer having 49 repeat units. A computational study of the oligomers using density functional theory calculations indicates that while the simplest oligomers (OPE-1) are fully conjugated, the larger oligomers are nonplanar and the limiting "segment chromophore" may be confined to a near-planar segment extending over three or four phenyl rings. Several of the OPEs self-assemble on anionic "scaffolds", with pronounced changes in absorption and fluorescence. Both experimental and computational results suggest that the planarization of discrete conjugated segments along the phenylene-ethynylene backbone is predominantly responsible for the photophysical characteristics of the assemblies formed from the larger oligomers. The striking differences in fluorescence between methanol and water are attributed to reversible nucleophilic attack of structured interfacial water on the excited singlet state.

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Section: Discussionsupporting

confidence: 68%

Synthesis, Self-Assembly, and Photophysical Properties of Cationic Oligo(p-phenyleneethynylene)s

Tang¹,

Hill²,

Zhou³

et al. 2011

Langmuir

142

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“…In 1973 Wooldridge and Roberts [22] reported--in a preliminary study--the photohydration of a ntunber of aromatic alkynes (eq. (8)).…”

Section: Xylen~mentioning

confidence: 99%

“…The paper by Wooldridge and Roberts [22] initiated our interest in photohydration of aromatic alkynes since it appeared to us that the reaction is a promising method for generating vinyl cations under exceptionall)~ mild conditions (e.g., in neutral water). We decided to study initially the photohydration of aromatic alkynes ArC=CH in aqueous sulfuric acid, under conditions in which the thermal process is negligible or non-existent.…”

Section: B Photohydration Of Aromatic Alkenes and Alkynesmentioning

confidence: 99%

“…Thus it would appear that these two allenes do not possess a high-degree of charge-transfer character in S I.As expected, results for the nitrophenylallenes (36 and 37) were intriguing.The isolated photohydration products were the correspoAding nitrophenylacetones[8] (eq.(22)). The triplet state is the reactive state (~Z and quenching experiments), and the reaction is acid-catalyzed(Figure 7) (22). …”

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confidence: 99%

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Photogenerated carbonium ions and vinyl cations in aqueous solution

Wan

Yates

1984

Reviews of Chemical Intermediates

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“…Photoexcitation, however, increases the reactivity of acetylenes enormously (17), and in a flash photolysis experiment formation of the en01 is more rapid than its ketonization; the en01 may consequently be observed and studied.…”

mentioning

confidence: 99%

Enols and Other Reactive Species

Chiang

Kresge

1991

Science

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Rapid advances in the chemistry of enols and other reactive species have been made possible recently by the development of methods for generating these short-lived substances in solution under conditions where they can be observed directly and their reactions can be monitored accurately. New laboratory techniques are described and a sample of the new chemistry they have made available is provided; special attention is given to ynols and ynamines and the remarkable effects that the carbon-carbon triple bonds of these substances have on their acid-base properties.

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Vinyl cations as intermediates in photohydration of acetylenes

Cited by 17 publications

References 5 publications

Synthesis, Self-Assembly, and Photophysical Properties of Cationic Oligo(p-phenyleneethynylene)s

Synthesis, Self-Assembly, and Photophysical Properties of Cationic Oligo(p-phenyleneethynylene)s

Photogenerated carbonium ions and vinyl cations in aqueous solution

Enols and Other Reactive Species

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