Small Panchromatic and NIR Absorbers from Quinoid Zwitterions

Abstract

The transamination of oxoaminobenzoquinonemonoimine (BQI derivatives), an unconventional zwitterionic quinone, allows isolating a series of compounds featuring electron-donating aryl auxochromes. The substitution has a very strong impact on the electrochemical and optical features, which is rationalized by theoretical calculations. Protonation and alkylation of the BQIs towards the corresponding cations lead to surprising redshifts of the absorption, especially in the instance of the most electron-rich dyes which exhibit panchromatic absorption spanning up to the near-infrared (NIR) region, a remarkable achievement for such small molecules.

Electrical monitoring of organic crystal phase transition using MoS2 field effect transistor

“…Figure 1b presents the band diagram alignment of MoS 2 and QZ-C 4 , indicating that an electron transfer from the QZ-C 4 toward the MoS 2 is expected. 41,44 This transfer is confirmed by ab initio calculations (see supporting information). Figure 1c shows typical optical micrographs of both the MoS 2 transistors (the fabrication process is detailed in the experimental method part) and the QZ-C 4 powder which is composed of micrometric crystals exhibiting a flat geometry.…”

The Quinonoid Zwitterion Interlayer for the Improvement of Charge Carrier Mobility in Organic Field-Effect Transistors

“…A series of N -substituted zwitterionic BQMIs compounds ( 1–4 ) was synthesized by straightforward transamination of commercially available 4,6-diaminoresorcinol dihydrochloride in the presence of an excess of amine ( Scheme 1 ) [ 32 ]. The reaction proceeded faster in the presence of alkylamines (compounds 1–2 ), whereas transamination using aniline derivatives required heating for several days to obtain compounds 3–4 [ 33 , 34 ]. The new lipophilic zwitterions 1–2 were isolated with yields of 60–73% after aqueous extraction followed by precipitation in pentane.…”

“…Solvents (HPLC grade) were provided by Sigma-Aldrich (Merck KGaA, Darmstadt, Germany). All compounds and solvents were used as received, without additional treatment, except for compounds 3–4, which were prepared according to procedures described elsewhere [ 33 , 34 ]. The synthesis of all compounds ( 1–4 ) is described below, starting from 4,6-diaminoresorcinol dihydrochloride (Sigma-Aldrich) or unsubstituted BQMI zwitterions.…”

Fully zwitterionic diaminobenzoquinonediimines promoted by cyanoaromatic N-substituents

“…Besides, benzoquinone monoimine (BQMI) derivatives are the most simple quinoidal molecules that feature a ground state zwitterionic structure due to the formation of two polymethine subsystems: one trimethine cyanine being positively charged and one negatively charged trimethine oxonol [29][30][31]. The delocalization of the charges brings to the BQMI unique absorption properties in the visible range, and up to the NIR upon introduction of strong electron-donating N-substituents [32,33]. We recently described that 2,5-diamino-1,4-benzoquinonediimines (DABQDI, Figure 1) can adopt either canonical (uncharged) or zwitterionic forms following an intramolecular proton transfer from one 6π-electrons subunit to the other (Figure 2) [34,35].…”