Quantum Amplified Isomerization in Polymers Based on Triplet Chain Reactions

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• 作者：Lorraine Ferrar ; Mark Mis ; Joseph P. Dinnocenzo ; Samir Farid ; Paul B. Merkel ; Douglas R. Robello
• 刊名：Journal of Organic Chemistry
• 出版年：2008
• 出版时间：August 1, 2008
• 年：2008
• 卷：73
• 期：15
• 页码：5683-5692
• 全文大小：404K
• 年卷期：v.73,no.15(August 1, 2008)
• ISSN：1520-6904

文摘

Photoinitiated triplet quantum amplified isomerizations (QAI) of substituted Dewar benzene derivatives in polymeric media are reported. The quantum efficiencies and the ultimate extents of reactant-to-product conversions increase significantly with the incorporation of appropriate co-sensitizers; compounds whose triplet energies are similar to or lower than that of the sensitizer and close to that of the reactant. These co-sensitizers serve to promote chain-propagating energy transfer processes and thereby increase the action sphere of photosensitization. Isomerization quantum yields increase, as predicted, with increasing concentrations of the reactants and the co-sensitizers. Chain amplifications as large as ∼16 and extents of conversion that approach 100% have been achieved. Mechanistic schemes are proposed to account for the dynamics of the inherent energy transfer processes and provide a predictively useful model for the design of a new class of photoresponsive polymers based on changes in the refractive index of the materials.