在過去，實驗室的黃世昱學長將綠色螢光蛋白發光團衍生物o-DHPBDI與銅(II)試劑進行反應，而在養晶的過程中得到了環合的產物DHPIO，其相較於尚未反應前的o-DHPBDI，提升一些螢光量子產率，但相比過去眾多各種銅離子所引發的環化反應，此反應的產率較為不理想。
本文針對此環化反應做深入的探討，我們透過再結晶的方式去發掘反應中可能產生的額外產物以及其實際結構，藉由這些產物去推論反應中可能進行的其他路徑，進而解釋產率不佳的問題。
在此我們發現過去銅離子試劑使用的錯誤外，也發現了在預期產物DHPIO其2號甲基上接上氯的產物，該產物不僅大量且也無可避免的生成，是最主要造成環化產物DHPIO產率不佳的因素。另外，環化後的產物在吸收光譜與放射光譜上皆呈現藍移，但也提升了螢光量子產率，而針對兩種氯化產物和預期產物做比對，三者在吸收光譜的結果上相似，但在螢光光譜上，氯的增加會導致放射波長越藍移。

In the past, lab senior Shih-yu Huang reacted the green fluorescent protein chromophore derivative o-DHPBDI with a copper(II) reagent and obtained a cyclized product, DHPIO, through crystallization. This product showed a improvement in fluorescence quantum yield compared to the unreacted o-DHPBDI. However, the yield of this reaction was not ideal compared to other cyclization reactions induced by various copper ions in the past. This study conducts an in-depth investigation of this cyclization reaction. Using recrystallization, we investigated the potential byproducts and their actual structures to identify other possible reaction pathways, which helped explain the low yield issue. In our research, we not only found errors in the copper ion reagent used previously but also identified a chlorinated product with a chlorine attached to the 2-methyl position of the expected product DHPIO. This chlorinated product is abundant and inevitably forms, becoming the primary factor in low yield of DHPIO. Furthermore, after cyclization, the products exhibit a blue shift in both the absorption and emission spectra, while also showing an increase in fluorescence quantum yield. And a comparison between the two chlorinated products and the expected product showed that their absorption spectra were similar, while in the fluorescence spectra, an increase in chlorine leads to a blue shift in the emission wavelength.

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