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

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.