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Intramolecular charge transfer in photoexcited hydroxyterphenyls: Evidence for formation of terphenyl quinone methides in aqueous solution

Paper ID Volume ID Publish Year Pages File Format Full-Text
28653 44084 2008 8 PDF Available
Title
Intramolecular charge transfer in photoexcited hydroxyterphenyls: Evidence for formation of terphenyl quinone methides in aqueous solution
Abstract

The photochemistry of a number of p-terphenyls substituted with hydroxy and hydroxymethyl substituents at the terminal benzene rings has been studied in aqueous solution. Previous work has shown that a simple hydroxyl group can strongly activate appropriately substituted benzenes or biphenyls towards dehydroxylation, via its highly electron-donating nature upon deprotonation in S1. The intermediates formed are the corresponding quinone methides (QMs) or biphenyl quinone methides (BQM). We show in this work that the methodology also works for appropriately substituted p-terphenyls. Thus, a number of p-terphenyls with the appropriate substituents at the terminal benzene rings were synthesized via consecutive Suzuki-type coupling reactions from commonly available starting materials. Although these terphenyls are much less soluble than their simpler biphenyl analogs, they were sufficiently soluble in aqueous CH3CN or CH3OH for their photosolvolytic reactivity to be studied by product studies and fluorescence measurements which are consistent with formation of terphenyl quinone methides (TQMs) as intermediates. Their quantum yields of formation are attenuated compared to the corresponding biphenyl and benzene analogs and one possible reason is the highly fluorescent nature of both phenol and phenolate forms.

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Keywords
Terphenyl quinone methide; Photosolvolysis; Photodehydroxylation; Photosolvolysis; Excited state proton transfer
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Intramolecular charge transfer in photoexcited hydroxyterphenyls: Evidence for formation of terphenyl quinone methides in aqueous solution
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 198, Issue 1, 5 July 2008, Pages 26–33
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us