New thermally stable cyano-substituted D–A–π–A–D molecules with aggregation-induced emission and large two-photo absorption cross-sections

Abstract

In this work, we have designed and synthesized a series of aggregation-induced emission active compounds (4a–c) via Suzuki coupling reaction. Their one and two-photon absorption properties have been investigated. These compounds exhibit high thermal stability, losing only 5% of their weights when heated to 482–503 °C in air. All compounds are quite weakly fluorescent in THF, while a significant AIE effect is observed in water/THF (v/v 70%/30%) mixtures with a sharp increase in fluorescence intensity (about 86, 42, and 103 times, orange, deep yellow and green, respectively). The solid fluorescence of 4a–c is located at 590, 579 and 547 nm, and their Φ_F values are determined to be 9.2%, 2.4%, and 14.5%, respectively. Besides, the two-photon absorption (2PA) cross-sections of 4a–c were also measured by open aperture Z-scan technique, at the wavelength of 800 nm. The excellent aggregation-induced emission and 2PA cross-sections properties of 4a–c promote them as attractive candidates for biophotonic materials.