Regiocontrolled Synthesis of Ethene‐Bridged para‐Phenylene Oligomers Based on Pt^II‐ and Ru^II‐Catalyzed Aromatization

Abstract

We report the regiocontrolled syntheses of ethene-bridged para-phenylene oligomers in three distinct classes by using Pt(II)- and Ru(II)-catalyzed aromatization. This synthetic approach has been developed based on twofold aromatization of the 1-aryl-2-alkynylbenzene functionality, which proceeds by distinct regioselectivity for platinum and ruthenium catalysts. Variable-temperature NMR spectra provide evidence that large arrays of these oligomers are prone to twist from planarity. The UV/Vis and photoluminescence (PL) spectra as well as the band gaps of these regularly growing arrays show a pattern of extensive pi conjugation with increasing array sizes, except for in one instance.

Pyrenes, Peropyrenes, and Teropyrenes: Synthesis, Structures, and Photophysical Properties

“…Alkyne benzannulation reactions have been shown to proceed using a variety of π‐Lewis acids such as gold(III), platinum(II), ruthenium(II), indium(III), and antimony(V) . Brønsted acids and some other electrophiles, such as ICl, I 2 , and NBS have also been used for alkyne benzannulation reactions .…”

Construction of Polycyclic π‐Conjugated Systems Incorporating an Azulene Unit Following the Oxidation of 1,8‐Diphenyl‐9,10‐bis(phenylethynyl)phenanthrene

“…[36] The approximate arrangement of the aromatic and arylethynylg roups in 1 could be ap otential motif that could be used to construct ah ighly fused polycyclic system via alkyne benzannulation reactions. [37] Alkyne benzannulationr eactions using av ariety of Lewis/Brønsted acids [38][39][40][41][42][43][44][45] and some electrophiles [46,47] have been powerful strategies for the direct p-extensiono fa romatic compounds. [48][49][50] During the course of our study of phenanthrenes 1,w ef ound that the transannulation of 1a upon two-electron oxidation selectively afforded the azulene-embeddedP AH 2a,w hich exhibited long-wavelength absorption and amphoteric redox events originating from the non-alternant characteristics of the embedded azulene core.…”

Nanographene and Graphene Nanoribbon Synthesis via Alkyne Benzannulations

“…Ruthenium catalysts have been shown to be effective at effecting alkyne benzannulations to afford NGs [68,75,76,77,78,79,80,81]. NGs doped with boron and silicon have also been produced using Ru(II) catalysts [82].…”