香豆素及嘧啶之炔類衍生物的光物理及電致化學發光性質研究

Studies on the Photophysical and Electroluminescence Properties of Arylethynyl Coumarins and Pyrimidines

梁化舉(Hua-Jyu Liang)

指導教授 ： 楊吉水

國立臺灣大學/理學院/化學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.10090

摘要

本篇論文主要在探討一系列Donor-π-Acceptor(D-π-A)系統的光物理、電化學與電致化學發光(Electrogenerated Chemiluminescence；ECL)的性質，其中D分別為-H(H)、-Me(M)、-OMe(OM)、-OiPr(OP)或-NMe2(DMA)，π為苯乙炔衍生物，A為香豆素(coumarin)或嘧啶(pyrimidine)。
以香豆素為電子受體，分別在4號及8號位置接上推電子基，形成4-香豆素炔類衍生物(4PECs)和8-香豆素炔類衍生物(8PECs)。在UV-Vis吸收光譜方面，4PECs的最大吸收波長隨推電子能力增強(H＜M＜OM＜OP＜DMN)而有紅位移現象(λmaxabs = 316∼400 nm)，然而在8PECs中，除了8PEC-DMA(λmaxabs = 324 nm)有明顯紅位移外，其他化合物的吸收光譜均很類似(λmaxabs = 294∼302 nm)。在螢光光譜方面，放光波長隨推電子能力增強而有紅位移的趨勢。4PECs及8PECs的還原電位分別在-1.5 V及-1.7 V左右，不受推電子基的影響，而氧化電位皆隨推電子基增強而有減小現象(Ep,ox：H＞M＞OM＞OP＞DMN)。在氮氣除氧的條件下，4PECs和8PECs中只有4PEC-H、4PEC-M、4PEC-OM、4PEC-OP有ECL訊號(λmax = 498∼531 nm)；但在氧氣飽和的條件下施加氧氣的還原電位，所有4PECs和8PECs均可測得ECL訊號。
以嘧啶為電子受體，在5號位置接上推電子基，形成5-嘧啶炔類衍生物(5PEPs)。在UV-Vis吸收及螢光光譜皆有隨推電子能力增強而有紅位移現象(λmaxabs = 279∼348 nm, λmaxfl = 399∼507 nm)。在電化學方面，5PEPs的還原電位在-2.1 V左右，而氧化電位有隨推電子基增強而有減小現象(2.10 V∼0.84 V)。在氮氣除氧的條件下，5PEPs系列中沒有ECL現象，但在氧氣飽和的條件下施加氧氣還原電位及氧化電位即可觀察到ECL訊號，可能的ECL機制在文中將有所解釋。

關鍵字

香豆素 ； 嘧啶 ； 電致化學發光 ； 超氧陰離子

並列摘要

In this dissertation, we report the photophysical, electrochemical, and electrogenerated chemiluminescence properties of a series Donor-π-Acceptor (D-π-A) systems, where D is H(H), Me(M), OMe(OM), OiPr(OP) or NMe2(DMA), π is phenylacetylene group, and A is coumarin or pyrimidine.
Two coumarin systems, which differ in the position where theπ-D substituents attach to, are investigated. They are 4- and 8-substitued coumarins and referred to as 4PECs and 8PECs. The UV-Vis absorption maxima of 4PECs (λmaxabs = 316∼400 nm) are at longer wavelengths for those with stronger donors (i.e., H＜M＜OM＜OP＜DMN). However, except for 8PEC-DMA (λmaxabs = 324 nm), the absorption spectra of the other 8PECs are all similar. The fluorescence spectra of 4PECs and 8PECs are more sensitive to the nature of the donor group and they are red-shift with stronger donors. The reductive potentials for 4PECs and 8PECs are about -1.5 and -1.7 V, respectively, independent of the donors, but their oxidative potentials are lower for those with stronger donors. In outgassed acetonitrile solutions, only 4PEC-H, 4PEC-M, 4PEC-OM, and 4PEC-OP display ECL signals ( λmax = 498∼531 nm), but in aerated solutions, all 4PECs and 8PECs show ECL when the solutions are subject to potentials that can readily reduce molecular oxygen. The corresponding behavior of 5-substituted pyrimidines(5PEPs) was also investigated. Both of their UV-Vis absorption and fluorescence spectra (λmaxabs = 279∼348 nm, λmaxfl = 399∼507 nm) depend on the nature of the donor. The reductive potential for all 5PEPs is around -2.1 V, but their oxidative potentials are donor dependent. 5PEPs display ECL under aerated acetonitrile solutions but not under outgassed conditions. The ECL mechanisms for 4PECs, 8PECs, and 5PEPs are also elucidated and discussed.

並列關鍵字

coumarin ； pyrimidine ； ECL ； superoxide ； donor-π-acceptor

參考文獻

1927, 49, 1858.

(3) Harvey, N. J. Phys. Chem. 1929, 33, 1456.

(4) Hercules, D. M. Science 1964, 145, 808.

(5) Faulkner, L. R.; Bard, A. J. In Electroanalytical Chemistry; Bard, A.

(6) Faulkner, L. R. Methods Enzymol. 1978, 57, 494.