9, 9-Dimethyl-9, 10-dihydroacridine-based donor–acceptor cruciform luminophores: Envident aggregation-induced emission and remarkable mechanofluorochromism. (February 2020)

• Record Type: Journal Article
• Authors: Cheng, Dandan; Xu, Defang; Wang, Ying; Zhou, Hongke; Zhou, Zhifu; Liu, Xingliang; Han, Aixia; Zhang, Chao
• Is Part Of: Dyes and pigments. Volume 173(2020)
• Publication Date: 2020-02
• Subjects: Cruciform -- 9, 9-Dimethyl-9, 10-dihydroacridine -- Intramolecular charge-transfer -- Aggregation-induced emission -- Mechanofluorochromism; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2019.107937
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Two donor–acceptor cruciform luminophores MB-CACEB and DFB-CACEB, which show unique intramolecular charge transfer (ICT) process originating from electron-donors 9, 9-Dimethyl-9, 10-dihydroacridine units and electron-acceptors dicyanovinylbenzene moieties, are designed and synthesized. Owing to the presence of the large steric hindrance between the four surrounding substituents attaching to the central benzene ring, MB-CACEB and DFB-CACEB adopt the spatial conformation with high degree of distortion, which endows the two compounds with aggregation-induced emission (AIE) properties, effective solid-state luminescence and high contrast mechanofluorochromic (MFC) behavior. Upon external force stimuli, the emission color of MB-CACEB and DFB-CACEB solid powders changes from initial bright yellow-green (535 nm and 537 nm) to orange (604 nm) and red (628 nm), respectively, thus large spectral red-shifts of 69 nm and 91 nm are obtained. PXRD and spectral results suggest that the remarkable MFC phenomenon comes from the planarization of the molecular conformation and subsequent planar intramolecular charge transfer (PICT) during the process of destruction of the crystals in the as-prepared samples by external force. Moreover, compared to MB-CACEB, DFB-CACEB shows more significant MFC behavior, this is because DFB-CACEB possesses the larger distortion degree and the stronger ICT process than that of MB-CACEB . Graphical abstract: Image 1 Highlights: Two twisted donor–acceptor π-conjugated cruciform luminophores showing unique ICT properties were prepared. They exhibited evident AIE characteristics and effective solid-state luminescence efficiency. They showed high contrast MFC behavior tuning by the substitution groups in molecules.