Understanding difficulties of irregular number-membered ring transition states for intramolecular proton transfer in excited state
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- 关键词：Proton transfer ; Excited state ; Transition sate ; Organic dye ; Molecular geometry optimization
- 刊名：Tetrahedron
- 出版年：2017
- 出版时间：26 January 2017
- 年：2017
- 卷：73
- 期：4
- 页码：403-410
- 全文大小：1034 K
- 卷排序：73
文摘
This study presents a variety of organic dyes with similar molecular structures that could undergo intramolecular proton transfer in excited states via five-, six- and seven-number-membered ring transition states, respectively. In addition, the dyes without proton transfer segments are also synthesized to use as references. X-ray single crystal diffraction, NMR spectra as well as UV/visible spectra suggests the presence of internal hydrogen bond with different strength in the target dyes. The steady and transient fluorescence measurements demonstrate occurrence of excited state intramolecular proton transfer via a six number-membered ring transition state. In contrast, it cannot be processed through five- and seven-number-membered ring transition states of the studied dyes. The molecular geometry optimization of the studied dyes reveals fundamental factors for the difficulties of intramolecular proton transfer in excited states via five- and seven-number-membered ring transition states.