具推拉電子基之香豆素及苯并噻唑炔類衍生物之合成與電致化學發光性質之研究

Abstract

本篇論文主要是討論D-π-A(Donor-π-Acceptor)系統的電致化學發光性質(ECL)，其中D為-H(H)、-Me (M)、-OMe (OM)、-OiPr (OP)或-NMe2 (DMA)，π為苯乙炔或二苯乙炔，A為香豆素(coumarin)或苯并噻唑(benzathiazole)。我們希望探討位置異構物對D-π-A系統ECL性質的影響。 以香豆素為電子受體的化合物為5-香豆素(5Cs)及7-香豆素(7Cs) 系列。除了5C-DMA和7C-DMA之外，其餘化合物隨著推電子基增強 (H<M<OM~OP<DMA)，螢光光譜有紅位移的趨勢，螢光量子產率也增高。雖然DMA取代基的推電子能力是五個取代基中最強的，但5C-DMA的螢光最大放射波長(450 nm)位於5C-H(430 nm)和5C-OM(473 nm)之間；7C-DMA的螢光光譜有447 nm及560 nm兩個放射峰，其中447 nm介於7C-H(406 nm)和7C-OM(458 nm)的放射峰之間。5C-DMA及7C-DMA的螢光量子產率較其他化合物低且均小於0.01。在氮氣除氧的乙腈溶液中，5Cs和7Cs沒有任何ECL的行為。但在通氧氣的條件下且當還原電壓大於氧氣的還原電位時，我們便可測得ECL的訊號(λmax = 460- 500 nm)。 以苯并噻唑作為電子受體的化合物為2-苯并噻唑(BTs)、m-PhBTs 及p-PhBTs系列化合物。除了m-PhBT-DMA有425 nm及556 nm兩個放射峰，其餘化合物只有一放射峰。隨著推電子基增強，此系列化合物的螢光光譜有紅位移的趨勢。如同5C-DMA和7C-DMA，BT-DMA、m-PhBT-DMA及p-PhBT-DMA的螢光量子產率均小於0.01，其餘化合XIII物隨則著推電子基增強，螢光量子產率也增高。與5Cs、7Cs不同的是m-PhBTs及p-PhBTs在氮氣除氧的乙腈溶液環境下，可觀察到與螢光光譜相似的ECL訊號。此外，在通氧氣的條件下，施加化合物氧化電位及大於氧氣還原電位的電壓時，所有BTs、m-PhBTs及p-PhBT化合物所表現的ECL光譜均極為相似(λmax = 460- 500 nm)，且與相對應的螢光 光譜無特定關係。

In this dissertation, we report the photophysical, electrochemical, and electrogenerated chemiluminescent properties of a series of donor-p-acceptor (D-p-A) systems, where D is H(H), Me(M), OMe(OM), OiPr(OP) or NMe2(DMA),p is phenylacetylene or diphenylacetylene, and A is coumarin or benzathiazole. The position-dependent substituent effects on the ECL behavior of these D-p-A systems are also reported. The investigated coumarin systems are 5- and 7-substitued coumarins, which are referred to as 5Cs and 7Cs, respectively. The fluorescence of 5Cs and 7Cs are at longer wavelengths for those with stronger donors(i.e., H < M < OM < OP < DMA). Except for 5C- DMA and 7C-DMA that possess low fluorescene quantum yields (<0.01), 5Cs and 7Cs display stronger fluorescence for those with stronger donors. ECL signals (λmax = 460- 500 nm) can be observed for 5Cs and 7Cs under aerated conditions but not under outgassed solutions. Three benzathiazole systems (BTs, m-BTPhs and p-BTPhs) were inwestigated herein.The dependence of fluorescence position and fluorescence quantum yield on the donor group for these benzathiazole systems resembles that for 5Cs and 7Cs. However, unlike the cases of 5Cs and 7Cs, BT-DMA, m-BTPhs and p-BTPhs display ECL signals in outgassed acetonitrile solution, and the ECL spectra can be correlated to the corresponding fluorescence spectra. Under aerated conditions, all these benzathiazole systems show ECL signals and maxima are all within the range of 460-500 nm, independent of the nature of substrates. The ECL mechanisms for both the coumarin and benzathiazole systems are also elucidated and discussed.