Synthesis and Spectral Properties of Dehydroabioic Acid Diarylamine-based D-A-D-type Aggregation-induced Red-light Compound

A D-A-D-type compound named 6,6′-((9,10-dioxo-9,10-dihydroanth-racene-2,6-diyl) bis((4-methoxyphenyl)azanediyl)) bis(7-isopropyl-1,4-dimethyl-1,2,3,4,4a,9,10,10a-octah-ydrophenanthr-ene-1-carboxylate)(2DDPA-AQ) was synthesized using 12-dehydroabietic acid diarylamine as the donor(D) and anthraquinone group as the acceptor(A), and its structure was characterized by the NMR and MS. The UV-Vis absorption and the fluorescence emission spectrum, the fluorescence quantum yield and lifetime, solvatochromic effect, aggregation-induced luminescence and photobleaching resistance characteristics were tested. The theoretical calculation was used to analyze the relationship between its structure and properties. The research results were as follows: the maximum ultraviolet absorption wavelength of 2DDPA-AQ in toluene was 449 nm, while the maximum emission wavelengths in toluene and solid state were 630 and 653 nm, showing red light emission. The maximum fluorescence emission wavelengths of 2DDPA-AQ in n-hexane, cyclohexane, toluene, dioxane, tetrahydrofuran, and ethyl acetate were 578, 584, 630, 638, 645, and 650 nm, respectively. The red shift of the maximum emission wavelength of 2DDPA-AQ along with the increase of the polarity of the solvent showed that it had solvatochromism effect and intramolecular charge transfer behaviour. The variation trend of fluorescence emission intensity of 2DDPA-AQ with water volume fraction in water/tetrahydrofuran(H₂O/THF) indicated its aggregation induced emission(AIE) characteristics. After continuous 30 minutes of UV lamp irradiation in a H₂O/THF mixed solution with water volume fraction of 95%, the fluorescence emission intensity of 2DDPA-AQ only slightly weakened, indicating its strong anti-photobleaching properties. Based on the experimental data, the HOMO/LUMO energy level of 2DDPA-AQ was -5.18 eV/-2.86 eV with a bandgap value of 2.32 eV. The theoretically calculated HOMO/LUMO energy level was -4.91 eV/2.14 eV with a bandgap value of 2.77 eV. The data showed that 2DDPA-AQ had a relatively narrow bandgap, which was consistent with the bandgap characteristics of red light molecules.