Synthesis and Properties of Acridone Oligomers

Abstract

Length‐defined 2,7‐acridone oligomers were synthesized via a sequence of bromination, borylation and Suzuki–Miyaura cross‐coupling reaction. Both the single crystal structure analysis and the theoretical calculations demonstrate that the anti conformation is favored in the oligomer. The relationship of the properties and the number of acridone units in the oligomer was investigated. The UV/Vis absorption and fluorescence spectroscopy reveal that the absorption and emission of oligomers are red‐shifted and energy gaps narrow with the increase of acridone moieties, as well as a decline in the radiative decay rate. Cyclic voltammetry measurements and theoretical calculations elucidate that the quantity of acridone in the oligomer plays a greater effect on the HOMO energy levels than on the LUMO ones.

Effects of N‐Substitution on the Property of Acridone

“…At the same time, the situation of LUMOs alters according to the properties of linkers, thus a large change in LUMO energy levels. This is different from the acridone oligomers, of which the variation in HOMO energy levels is more than that of LUMO's …”

“…This is different from the acridone oligomers, of which the variation in HOMO energy levels is more than that of LUMO's. [17]…”

N-Substitution of acridone with electron-donating groups: crystal packing, intramolecular charge transfer and tuneable aggregation induced emission

“…[8][9][10][11][12] The acridone units could also couple with each other at the phenyl ring to form acridone oligomers with tuneable energy levels. 13 The functionalization of carbonyl of acridone usually involved the formation of C-C double bonds with another functional group, such as malononitrile, or uorene, to furnish molecules with variable colour upon external stimuli due to the conformational change. [14][15][16] The introduction of biphenyl carbazole or tetraphenylethylene to the amino position of acridone can also supply molecules with interesting electroluminescence and piezochromic luminescence properties.…”

Carbazole Dendrimers with Acridone at the Core and Periphery: Synthesis and Properties

“…The absorption spectra of the dendrimers with acridone at the core in chloroform show no evident absorption bands of acridone (Figure , Table ). The absorption band between 240–375 nm are assigned to the absorption of carbazole dendrons with the exception of the broad bands in the range 314–326 nm, which are the typical bands for the 2,7‐substituted acridone derivatives . The broad absorption bands with weak molar absorbance (less than 10 4 M −1 cm −1 ) between 390–460 nm are assigned to the intramolecular charge transfer transition .…”