Synthesis and Properties of Isotruxene and Its Derivatives
Date Issued
2010
Date
2010
Author(s)
Huang, Hsin-Hau
Abstract
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.
Subjects
isotruxene
truxene
fluorene
photochemistry
electrochemistry
Type
thesis
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