異參?并苯及其衍生物之合成與性質之研究

Abstract

異參茚并苯為不對稱二維平面分子，具有鄰位及對位共軛效應。本論文的目的為探討異參茚并苯的共軛結構。在本研究中，我們開發了三種可大量合成異參茚并苯的方法，並進一步合成異參茚并苯茀衍生物ITF1-ITF4及異參茚并苯星狀梯型衍生物Sn。藉由探討其衍生物的光物理及電化學行為進一步了解寡聚苯類分子系統的鄰、對共軛效應。 在異參茚并苯合成方面，首先利用[2 + 2 + 2]三聚反應或是狄耳士-阿德爾反應建立起不對稱的鄰-對位共軛骨架，再經由氧化、合環、還原等步驟獲得異參茚并苯及異參茚并苯酮。相較於之前的合成方法，本論文所發表的方法有較高的產率(27-36%:18%)及較易純化(不須經過管柱層析)且能大量反應等優點。 星狀化合物ITFn和Sn顯示有趣的光電性質。化合物ITF1-ITF4的光物理及電化學性質均顯示三個茀支鏈間有很強的電子偶合，主要由於異參茚并苯的鄰、對共軛效應所造成的。ITF1-ITF4的吸收光譜顯示，隨著共軛的增長鄰位共軛效應的影響會減弱，而以對位共軛效應為主。由於較剛硬及較平面的結構，化合物Sn的系統相較於ITF1及ITF2有更強的鄰位共軛效應。而研究中也發現Sn系統相較於線型的一維共軛系統有較長的有效共軛長度。對此現象，我們提出了二維共軛系統的概念

Isotruxene is a planar unsymmetrical star-shaped molecule, which have ortho- and para-conjugation interaction. This thesis is oriented to explore isotruxene-derivatives structured π-conjugation. In this context, three new synthetic methods for isotruxene have been developed. Further, a series of isotruxene-oligofluorenes ITF1-ITF4 and a series of isotruxene-based star-shaped ladder-type oligophenylenes Sn (n = 4, 7, 10, 13, 16) have been prepared in order to understand the ortho- and para-conjugation effect in oligophenylene systems. Regarding the synthesis of isotruxene building blocks, the backbone was constructed by either Co-catalyzed [2 + 2 + 2] cyclotrimerization or the [4 + 2] Diels-Alder reactions. The subsequebt oxidation, Friedel-Crafts acylation, and reduction reactions lead to isotruxene and isotruxone. Compared to the previous method, the current approaches are more efficient in terms of product yield (27-36% vs 4-18%) and purification (i.e., no column chromatography required). We observed strong electronic couplings among the three oligofluorene arms in star-shaped compound ITFn and Sn as a result of the para-ortho interactions. According to the absorption spectra of ITF1-ITF4, the ortho-conjugation effect becomes weaker as the oligofluorene arms are longer. Compounds Sn have stronger ortho-conjugation effect than ITF1, ITF2, and ITF3 due to the more planar and rigid structures. The effective conjugation length in Sn systems is larger than that in rod-shaped ladder-type polyphenylene systems. We thus proposed the concept of two-dimensional conjugation interactions.