Multifunctional Anthracene Derivatives’ Design, Synthesis And Piezochromic Based Properties

In this article, we have derived two series of anthracene centered compounds from the anthracene-centered and the different end groups:tetradonor-capped anthracene-centered cruciform 2,6,9,10-tetra(pdibutylaminostyryl)anthracene (TDC) and the linear 9,10-bis(N-alkylindole-3-yl-vinyl-2)anthracenes (IACn) and studied in comprehensive with their unique optical properties by fluorospectro photometer, ultraviolet spectrophotometer, XRD, DSC. What is worth for our attention is we find that both of them has the obviously piezochromic behavior.But each of them has their special optical properties. Firstly, TDC is a light-and heat-stable dye and shows aggregation-enhanced emission (AEE), large and enhanced two-photon absorption cross sections, fluorescence sensing selectively to transition metal ions such as Zn2+ and Cu2+, and appreciable piezofluorochromism (PFC), which is rarely found to exist simultaneously in cruciform or other configuration dyes. The AEE and PFC behaviours result from the existence of a strongly twisted 9,10-branch, and the large and enhanced 8 is ascribed to the multiple conjugation pathways and introduction of donor end-groups. TDC possesses a non-centrosymmetric structure and a semi-disjoint frontier molecular orbital, which could rationalize its fluorescence sensing selectively to Zn2+ and Cu2+. These findings indicate further that an anthracene ring is indeed a unique π-center that is different from other π-centers and can construct novel cruciforms with interesting optical properties.Secondly, we have designed and synthesized 9,10-bis(N-alkylindole-3-yl-vinyl-2)anthracenes (IACn) with alkyl length-dependent piezofluorochromic. The study of IACn shows that moderate aggregation-induced emission but enhanced solid-state fluorescence and remarkable PFC behaviour of IACn have been found. Moreover, their PFC spectral shifts are strongly alkyl length-dependent. With the increase of N-alkyl lengths, IACn exhibits an decreasing PFC spectral shifts (27-65 nm). Wide-angle X-ray diffraction evidenced that the transformation between crystalline and amorphous states under various external stimuli is responsible for the PFC behaviour.