Fluorescence lifetime properties of near-infrared cyanine dyes in relation to their structures

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• 作者：Hyeran Lee ; Mikhail Y. Berezin ; Maged Henary ; Lucjan Strekowski ; Samuel Achilefu
• 关键词：Cyanine dyes ; Fluorescence lifetime
• 刊名：Journal of Photochemistry and Photobiology A: Chemistry
• 出版年：2008
• 出版时间：15 December 2008
• 年：2008
• 卷：200
• 期：2-3
• 页码：438-444
• 全文大小：515 K

文摘

Structurally diverse near-infrared (NIR) absorbing polymethine dyes were prepared and their fluorescence lifetimes (FLT) were evaluated in relation to their structural features. Comparative FLT analysis based on the modification of methine chain length and heterocyclic system showed that indolium or benzo[e]indolium heptamethine dyes exhibited longer FLT than the benzo[c,d]indolium trimethine dye. Modification of heterocyclic system alone with an intact chain length showed that indolium-based heptamethine dyes showed approximately 30 % longer FLT than the benzo[e]indolium-based dyes. In general, the FLT of polymethine dyes increased from polar to non-polar solvents. In addition, correlation study between the theoretical and the experimental FLT for indocyanine green (ICG) suggests that the lack of structural rigidity for these cyanine dyes is primarily responsible for the loss of the excited state energy via non-radiative pathway.