第一部分 自由基對前驅物1-對甲苯磺醯基-苯咪唑及其衍生物之合成與光化學研究 第二部分 4,4´-二羧基聯吡啶釕錯合物之合成及其太陽能電池之應用

Abstract

本篇論文主要的部分為一系列自由基對前驅物1-對甲苯磺醯基-苯咪唑及其衍生物55、56、57的合成與低溫EPR光譜之研究。化合物55於77 K，MTHF低溫介質，230-325 nm波長光源照射後，可觀測到一組明顯之三重態EPR訊號，其zfs參數為|D/hc| = 0.0144 cm-1與|E/hc| = 0.0020 cm-1。另外化合物55與自由基捕捉試劑MNP於常溫，CDCl3溶劑，254 nm波長光源之照光反應，可分別單離出Photo-Fries重排產物72、73，以及自由基捕捉產物Ts-MNP，此一結果說明了化合物55在上述的照光條件下，屬於自由基對前驅物物種84，其化學量子產率為0.24 □ 0.07 ; 另一方面，以m-xylene 單位連結，屬於兩組三重態自由基對之前驅物56，於照光後可觀測到一組三重態EPR訊號物種85及86，而非五重態物種，且於77 K溫度所測得的D´值較化合物55來的小; 最後在化合物57的77 K (MTHF低溫介質) EPR實驗裡，並未如預期觀測到三組三重態自由基對加上一組四重態的EPR光譜訊號，這顯示化合物57於低溫條件下較為不活性，此一部分已經經由低溫介質下照光的UV/vis實驗證實 (由日本Itoh博士代為完成)。 第二部分為染料敏化TiO2太陽能電池之染料合成研究。藉由相關文獻報導，Cis-di(thiocynato)bis(2,2´-bipyridyl-4,4´-dicarboxylate) ruthenium (Ⅱ)，通稱N3 dye，具有光能轉換效率 (10-12 %) 之高量子效率，為首要合成的目標化合物，另外，也嘗試合成相似衍生物92。進一步的工作須待尋找出取代N3 dye且同樣能應用於染料敏化TiO2太陽能電池的化合物。

The major part of this thesis is about the syntheses and EPR studies of a series of radical pair precursors (55, 56 and 57) which contain 1-toluene sulphonyl benzimidazoles as the key components. The photolysis (230-325 nm) of 55 at 77 K in a MTHF matrix gave EPR signals characteristic of a randomly oriented triplet radical pair and its zero-field splitting parameters are determined to be |D/hc| = 0.0144 cm-1 and |E/hc| = 0.0020 cm-1, respectively. Furthermore, the photolysis of 55 in the presence of MNP in CDCl3 at room temperature gave not only the Photo-Fries rearrangement products 72 and 73, but also the radical trapping product, Ts-MNP. The results support that 55 is a good precursor for radical pair under photochemical conditions, and the overall photochemical quantum yield for radical pair formation is determined to be 0.24 □ 0.07. The photolysis of 56, a precursor for two triplet radical pairs linked by a meta-xylene unit, gave EPR signals which are consistent with a triplet species rather than a quintet species and the D´ value of 85 and 86 is smaller than 84 taken at 77 K. Finally, the photolysis of 57 at 77 K in MTHF glassy matrix did not show EPR signals of the predicted three triplet states plus a quartet state. Compound 57 was found to be inert under low temperature glassy matrixes which was confirmed by a low temperature UV/vis study at the same matrixes (carried out by Dr. Itoh in Japan). In part Ⅱ, the preparation of dye sensitized TiO2 solar cells was carried out. Cis-di(thiocynato)bis(2,2´-bipyridyl-4,4´-dicarboxylate) ruthenium (Ⅱ), the N3 dye, which has the record high quantum efficiency (10-12%) for light to energy transfer was out first target compound. A similar analogue, 92, was also synthesized. Further work is needed before we can find a substitute for the N3 dye in Dye Sensitized Solar Cells.