Stimuli-Responsive Azulene-Based Conjugated Oligomers with Polyaniline-like Properties

Abstract

Novel azulene building blocks, prepared via the cycloaddition of thiophene-S,S-dioxides and fulvenes, allow for incorporation of the seven-membered ring of the azulene nucleus directly into the backbone of conjugated materials. This unique mode of incorporation gives remarkably stable, stimuli-responsive materials upon exposure to acid. This simple doping/dedoping strategy provides for effective optical band gap control and on/off fluorescence switching, reminiscent of polyaniline.

Breakdown of Interference Rules in Azulene, a Nonalternant Hydrocarbon

“…In addition, we synthesize a control pyridine functionalized azulene with connections at the 1,3 position (1,3PyAz) to support our studies. Our recent advancements to make functional azulenes 27 made possible the synthesis of 4,7Az, 5,7Az and 2,6Az in only a few steps, whereas the synthesis of 1,3Az was accomplished by standard aromatic coupling strategies, from 2,3-dibromoazulene 28 as detailed in the Supporting Information (SI) document.…”

Switchable bioelectronics

“…Many different light responsive molecular systems have been employed as lightharvesting elements to construct light-switchable interfaces, including azobenzenes (Schumers et al 2010), diarylethenes (Browne and Feringa 2009), spiropyrans (Florea et al 2012), fulgides (Yokoyama 2000), azulenes (Amir et al 2011), overcrowded alkenes (Feringa et al 2000) and others (Feringa 2001) (Figure 1). These switchable elements have been used in different forms such as individual molecules or monolayers (SAM), covalently bound to polymer backbones or conjugated with nanoparticles to construct different forms of interface (Bunzli and Piguet 2005;Jeong and Gutowska 2002;Qiu and Park 2001).…”

Stimuli‐Responsive Cyclopenta[ef]heptalenes: Synthesis and Optical Properties

“…These values are consistent with the difference between the HOMO and LUMO energies determined through www.eurjoc.orgquantum chemical calculations, and similar to other azulene derivatives previously reported. [12] Inspired by reports that discuss the intramolecular photoinduced electron transfer (PeT) from the S 2 state of azulene to the excited state of various electron acceptors, [20] the possible intermolecular PeT of 4 to the excited state of a commercial PAG, diphenyliodonium hexafluorophosphate (DPIHFP), was investigated. Such a PAG is photoactivated at wavelengths ranging from vacuum ultraviolet (VUV, Ͻ 200 nm) to UV.…”

“…[11] Various substitution patterns on the azulene core have been tailored in order to alter the azulene structure and understand the effect of acid doping on the optical and electronic properties of azulene-containing systems. [12][13][14][15] The selective synthesis of azulene derivatives having a single isomeric arrangement of functional groups at the 4-and 7-positions of the seven-membered ring was reported. [12] Such a connectivity pattern allowed for the incorporation of two thiophenyl groups at these positions by Stille coupling.…”

“…[12][13][14][15] The selective synthesis of azulene derivatives having a single isomeric arrangement of functional groups at the 4-and 7-positions of the seven-membered ring was reported. [12] Such a connectivity pattern allowed for the incorporation of two thiophenyl groups at these positions by Stille coupling. The corresponding azulenium cation showed a significantly smaller energy gap with a concomitant redshift of the ab-…”