Aggregation-induced emission and mechanofluorochromism of tetraphenylbutadiene modified β-ketoiminate boron complexes. (March 2018)

• Record Type: Journal Article
• Authors: Gao, Huaizhi; Xu, Defang; Wang, Yonghui; Zhang, Chao; Yang, Yan; Liu, Xingliang; Han, Aixia; Wang, Ying
• Is Part Of: Dyes and pigments. Volume 150(2018)
• Page Start: 165
• Page End: 173
• Publication Date: 2018-03
• Subjects: Tetraphenylbutadiene -- β-ketoiminate boron complex -- Mechanofluorochromism -- Aggregation-induced emission -- Intramolecular charge transfer; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2017.12.016
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Two new benzo[ d ]oxazole- and benzo[ d ]thiazole-fused β-ketoiminate boron complexes (BF 2 -TBO andBF 2 -TBT ) modified by tetraphenylbutadiene have been designed and successfully prepared, and their intramolecular charge-transfer (ICT), aggregation-induced emission (AIE) and mechanofluorochromic (MFC) properties were investigated. The results showed that the two D-π-A type compounds exhibited typical ICT emission, evident AIE characteristics (αAIE = 89 and 33, respectively), and high state emission intensity (up to 0.445 and 0.367, respectively). More importantly, BF 2 -TBO andBF 2 -TBT showed the reversible MFC behavior with their emitting colors changing from yellowish green (located at 528 and 530 nm) to yellow and orange (located at 552 and 572 nm) upon grinding, respectively, with red-shifts of 24 and 42 nm were obtained. The X-ray diffraction analyses confirmed that the MFC properties ofBF 2 -TBO andBF 2 -TBT should be derived from a phase transition between crystalline and amorphous states. It was noticed that benzo[ d ]thiazole-fusedBF 2 -TBT showed more contrasting MFC behavior relative to benzo[ d ]oxazole-fusedBF 2 -TBO . The reason is that the existence of sulfur atom inBF 2 -TBT could lead to a larger degree of ICT in the excited state than that ofBF 2 -TBO, which endowed it with greater planar intramolecular charge transfer (PICT) after grinding, resulting in a larger red-shift in the PL spectrum. Graphical abstract: Highlights: Two β-ketoiminate boron complexes exhibited obvious intramolecular charge-transfer (ICT) emission. They showed evident AIE properties and high solid-state efficiency of 0.445 and 0.367, respectively. They possessed distinct mechanofluorochromism with the large spectral shifts of 24 and 42 nm, respectively.