Structure–property relationship of donor–acceptor acridones – an optical, electrochemical and computational study

Abstract

The synthesis of two neutral acridone derivatives was carried out to design media sensitive chromophores by taking advantage of intramolecular charge transfer (ICT) features. The molecules comprised two different donor-acceptor-donor triads, with absorption maxima at 425 nm and 520 nm, for the ketone and dicyanomethylene derivatives, respectively. The ketone variant exhibited fluorescence at room temperature, whereas the dicyanomethylene derivative was only emissive in frozen hexane. The ketone emission was highly solvatochromic, with Stokes shifts that ranged from 5000 cm(-1) to 10 000 cm(-1). Electrochemically, both compounds displayed similar oxidation potentials at approximately 0.35 V versus ferrocene/ferrocenium, which was anticipated since both systems employ the same ethynylaniline donor portion of the molecule, whereas only the 9-dicyanomethylene derivative showed a reduction peak at -1.5 V vs. Fc/Fc(+). Additional spectroelectro-chemical experiments supported a delocalized cationic charge on the ethynylaniline fragments during oxidation and that during electrochemical reduction the dicyanomethylene moieties show localized anionic charge. All of the experimental observations are finally compared to DFT, TDDFT and NICS(0) computations to gain insight into the transitions involved and deduce the role of the acridone core in stabilizing its oxidized and reduced forms.

Organic Electron Acceptors Comprising a Dicyanomethylene‐Bridged Acridophosphine Scaffold: The Impact of the Heteroatom

“…All dicyanomethylene‐bridged compounds 2 – 5 were obtained as air‐stable, colorless solids which were soluble in common organic solvents. To allow for comparison of the electron‐donating/‐accepting properties of the phosphorus center, the nitrogen‐containing benchmark compound S1 was prepared from 10 H ‐acridin‐9‐one in two steps (65 % overall yield) …”

Tailored thioxanthone‐based photoinitiators for two‐photon‐controllable polymerization and nanolithographic printing

“…DBTX was included in the result as a comparison in order to provide a baseline material that did not include any conjugated branches, and the experimental absorption spectrum of DBTX is redshifted relative to ITX. BDAPT and DANT had two broad peaks with relatively high absorbance at 400 nm, which can be attributed to the π→π* transition at higher wavelength and n→σ* jumping at lower wavelength due to the electron lone pair on the hetero atom . DAPT was also redshifted (Supporting Information Fig.…”

Synthesis and Properties of Acridone Oligomers

“…Although there have been plenty of reports on the properties of acridone‐based materials, the study on the π‐extended acridone is quite limited . The formation of the oligomer is one of the methods to construct π‐extended acridone derivatives.…”