Syntheses and Properties of Thiophene-containing Cycloparaphenylenes and Related Macrocycles and a Strained Cyclophane

摘要

Thiophene-containing cycloparaphenylenes (CPPs) bearing 8, 10 and 16 aromatic and heteroaromatic units in the macrocyclic structure were constructed. Specifically, two and four units of thiophene-2,5-diyl moiety were incorporated into functionalized [6]- and [12]CPP macro-cyclic carbon frameworks, respectively. Insertion of two 2,2'-bithiophene-5,5'-yl units into a functionalized [6]CPP carbon framework led to the formation of the 10-membered macrocycle. In addition, optical and electrochemical properties of these macrocycles were investigated.;The synthetic pathways for thiophene- and 9-fluorenone-containing donor-acceptor macrocycles were also developed. Synthetic pathways to conjugated macrocycles containing one, two, or three 2,7-bis(2-thienyl)-9H-fluoren-9-one (TFOT) units in the macrocyclic frameworks bearing 10, 16, or 24 aromatic units were developed. The Diels--Alder reaction between (E,E)-1-(5-bromo-2-thienyl)-4-(5-iodo-2-thienyl)-1,3-butadiene and dimethyl acetylenedicarboxylate produced the key Diels--Alder adduct for the subsequent macrocyclic ring formation. Oxidative aromatization of the macrocyclic precursors and an acyclic analog with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) under mild conditions led to the formation of fully aromatized macrocycles and a corresponding acyclic analog. In addition, optical properties of the TFOT-containing molecules were recorded, and their electrochemical properties were investigated by cyclic and differential pulse voltammetry. Solvatofluorochromic properties were observed for the TFOT-containing molecules.;Finally, a benz[a]anthracene- and naphthalene-containing strained cyclophane was synthesized. The Lewis acid-catalyzed electrocyclization reaction of the (E,E)-1,4-bis(4-bromonaphthyl)-(2,3-cyclohexane)-1,3-butadiene produced the key intermediate for the subsequent macrocyclic ring formation. The Ni(cod)2-mediated heterocoupling reaction of the electrocyclization product followed by an oxidative aromatization with DDQ, produced a benz[ a]anthracene- and naphthalene-containing strained cyclophane. The structure of this cyclophane was established by X-ray structure analysis. Photophysical and electrochemical properties of this strained cyclophane was also investigated.