過往的研究中，實驗室的陳怡惠學姊發表鄰位胺基之綠色螢光蛋白衍生物 o-ABDI之合成，之後黃世昱學長使用 o-DHPBDI 與銅離子試劑進行反應時發現環化重排產物 DHPIO，加上簡翊婷同學發現其副產物 DHPIO-Cl、DHPIO-Cl2進一步了解環化反應產率低之原因 。
起初為了解環化反應之反應機制，於本文研究中嘗試引入TEMPO試劑，一種自由基捕捉試劑參與環化反應，結果卻得另一新環化產物 TPO-TBAF ，此產物為七元環、五元環、六元環相連之多環結構，以及 TEMPO之基團接在 imidazole二號甲基位子上，從光物理性質來看可以發現 TPO-TBAF螢光量子產率比起 o-DHPDBFI有顯著提升，推論原因為TPO-TBAF為環化結構，整體較 o-DHPDBFI剛性，分子旋轉及振動自由度較低，以及 TPO-TBAF無 TICT現象產生，整體以LE態螢光放射為主，造成螢光量子產率大幅上升。
此外，本文研究引入二苯呋喃骨架及苯環取代基增加整體分子共軛性，探討其吸收及螢光光譜紅移現象，結果顯示本文研究衍生物o-DHPDBFI與o-DHPBDI於光譜中無顯著紅移現象，推測原因為取代基角度扭曲及整體分子平面性較低所導致電子供體-受體區域共軛重疊性不佳，才無預期之紅移現象產生 。

In previous studies, Yi-Hui Chen, a senior member of our laboratory, reported the synthesis of o-ABDI, a green fluorescent protein derivative containing an ortho-amino group. Subsequently, Shih-Yu Huang discovered a cyclized rearrangement product, DHPIO, when reacting o-DHPBDI with a copper reagent. Later, Yi-Ting Chien identified side products DHPIO-Cl and DHPIO-Cl₂, further elucidating the reasons behind the low yield of the cyclization reaction.
To investigate the reaction mechanism, the present study introduced TEMPO, a known radical scavenger, into the cyclization process. Unexpectedly, a new cyclized product, TPO-TBAF, was obtained. This compound features a polycyclic structure composed of a seven-membered, five-membered, and six-membered ring, with the TEMPO group attached to the 2-position methyl group of the imidazole ring. From a photophysical perspective, a significant increase in fluorescence quantum yield was observed. This enhancement is attributed to the cyclized and more rigid structure of TPO-TBAF compared to o-DHPDBFI, resulting in reduced intramolecular rotation and vibrational freedom. Additionally, the absence of TICT (twisted intramolecular charge transfer) behavior in TPO-TBAF leads to fluorescence dominated by the LE (locally excited) state, thereby boosting emission efficiency.
Furthermore, this study introduced a dibenzofuran core and phenyl substituents to enhance the overall π-conjugation of the molecule and examined the resulting red-shift behavior in absorption and fluorescence spectra. However, no significant red-shift was observed between the derivatives o-DHPDBFI and o-DHPBDI. This is likely due to the torsional distortion of the substituents and the low planarity of the overall molecular structure, which diminish the conjugative overlap between the donor and acceptor regions, thus preventing the expected bathochromic shift.

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