Effects of N‐Substitution on the Property of Acridone

Abstract

A variety of N‐substituted acridone derivatives were synthesized to make a comparison of their properties according to the number of acridone unit and the nature of substituent. The spectroscopic and electrochemical investigations show that the properties of N‐substituted acridone derivatives are substituent‐dependent. With benzene, biphenyl, fluorene and carbazole as linkers, the acridone derivatives demonstrate the properties of acridone itself due to a very weak intramolecular charge transfer (ICT) between acridone and the linker. However, significant ICT process is observed when the electron withdrawing groups are involved to form the donor–acceptor systems with acridone as the electron donating groups, which is different from the previously reported results of which acridone is usually used as an electron acceptor. Moreover, thermally activated delayed fluorescence (TADF) is observed with anthraquinone as linker. The theoretical calculations reveal that the N‐substitutions have more influences on the locations and energy levels of the LUMOs than those of the HOMOs.

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

“…What's more, the carbazole dendron also can be regarded as an electron‐withdrawing group, as having been reported in other types of carbazole dendrimers . No significant changes in chemical shifts of the protons in the acridone unit are observed in the 1 H NMR spectra of the dendrimers with acridone at the periphery due to a weak influence on the electron density in the N ‐substitution of acridone . However, the chemical shifts of protons in the carbazole unit demonstrate a similar variation as in the case of dendrimer with acridone at the core in light of the position of carbazole in the molecule and the dendrimer generation.…”

“…Tert ‐butyl groups were introduced to acridone to improve its solubility . Acridone 1 reacted with N ‐benzyl‐3,6‐dibromocarbazole using cuprous iodide as catalyst and 2,2,6,6‐tetramethylheptane‐3,5‐dione as ligand to give the intermediate 2 in 56% yield . The benzyl group was then removed by stirring under oxygen atmosphere in the presence of potassium tert ‐butoxide to furnish dendron 3 in 97% yield .…”

“…The N ‐substitution of acridone can supply some derivatives with a property of piezochromic luminescence or as efficient hosts for OLED applications . Recently our group found that the role of acridone as an electron donor or acceptor are tuneable by varying the substituents at the amino position . Thus the multiple functional positions and the versatile role of acridone make it a good candidate for the derivatization of carbazole dendrimer.…”

Synthesis, Structure and Properties of Fused π‐Extended Acridone Derivatives

“…The distances of C–C bonds (1.43–1.47 Å) between carbonyl and the adjacent benzene rings and C–N bonds (1.38–1.40 Å) in the molecules are shorter than the lengths of their corresponding single bonds. The alternation of bond lengths in the pyridone moiety clearly demonstrates the delocalization of electron from nitrogen to carbonyl, which can be easily realized when the resonance structures are considered . The two terminal benzene rings always contain C–C bonds with distances (1.33–1.38 Å) less than that of benzene (1.39 Å), due to the influence of intramolecular charge transfer.…”

“…The amino position of acridone can be functionalized with aryl groups to furnish the host materials for OLEDs . Connecting the electron‐withdrawing anthraquinone to the amino position of acridone, the resulted donor‐acceptor system shows TADF feature . When the rotatable triphenylamine and tetraphenylethene groups are linked to the amino position of acridone, the obtained molecules demonstrate interesting tunable aggregation induced emissions and photoluminescence properties according to the external stimuli .…”