13895-74-4Relevant articles and documents
Enhanced mechanofluorochromic properties of 1,4-dihydropyridine-based fluorescent molecules caused by the introduction of halogen atoms
Chen, Yating,Zhou, Yibin,Wang, Zhiqiang,Wang, Mengzhu,Gao, Wenxia,Zhou, Yunbing,Liu, Miaochang,Huang, Xiaobo,Wu, Huayue
, p. 4258 - 4266 (2019)
Four cyano(ethoxycarbonyl)methylene-1,4-dihydropyridine (CMD) derivatives were designed and synthesized to study the influence of halogen atoms on their mechanofluorochromic (MFC) properties. These CMD derivatives are demonstrated to have twisted molecular conformations and display aggregation-induced emission properties. In the crystalline state, the compounds adopt loose J-aggregates and exhibit yellow-green or green solid-state fluorescence. Upon grinding, the original samples of CMD-H, CMD-F, CMD-Cl, and CMD-Br show 21, 60, 61, and 52 nm red shifts in their fluorescence spectra, respectively, revealing MFC characteristics. The MFC properties are demonstrated to be due to the crystalline-to-amorphous transition and the red shifts in the fluorescence spectra are attributed to the increased molecular conjugations by the planarization of molecular conformations. X-ray crystallographic analyses reveal that halogen-substituted CMD derivatives have more twisted conformations and looser stacking arrangements than CMD-H, which are responsible for their higher contrast MFC properties. This work indicates that the introduction of halogen atoms to a specific fluorescent molecule might be used as a simple and feasible route for developing high contrast MFC-active materials.
Mechanochromic and acidochromic response of 4H-pyran derivatives with aggregation-induced emission properties
Zhou, Yibin,Liu, Yanze,Guo, Yang,Liu, Miaochang,Chen, Jiuxi,Huang, Xiaobo,Gao, Wenxia,Ding, Jinchang,Cheng, Yixiang,Wu, Huayue
, p. 428 - 440 (2017)
Several 1- and 2-position naphthylethylene-substituted 4H-pyran derivatives comprising two different end groups were synthesized. These two pairs of positional isomers with aggregation-induced emission properties exhibit different stimuli-responsive solid-state fluorescent properties. Both the linking position of the naphthylethylene and the electron-withdrawing end group have a significant impact on the mechanochromic properties of the compounds, whereas, the acidochromic properties are only related to the latter. The transformation between amorphous and crystalline states accounts for the mechanochromic properties and is attributed to loose molecular packing with weak intermolecular interactions, as revealed by crystallographic data. The reversible acidochromic properties are mainly ascribed to protonation/deprotonation of the carbonyl group, which is confirmed by 1H NMR experiments. Additionally, because the emission of these 4H-pyran derivatives in solid state can be tuned by external stimuli, several molecular logic gates were established by using appropriate stimuli operations as the inputs and fluorescent colors as the outputs.
Polymorphism and mechanochromism of N -alkylated 1,4-dihydropyridine derivatives containing different electron-withdrawing end groups
Lei, Yunxiang,Zhou, Yibin,Qian, Lebin,Wang, Yuxiang,Liu, Miaochang,Huang, Xiaobo,Wu, Ge,Wu, Huayue,Ding, Jinchang,Cheng, Yixiang
supporting information, p. 5183 - 5192 (2017/07/11)
Organic compounds exhibiting polymorphic and/or mechanochromic (MC) properties are promising for applications in multiple areas. However, the design strategy for such compounds is not very clear. Herein, several series of N-alkylated 1,4-dihydropyridine (DHP) derivatives incorporating different electron-withdrawing end groups were synthesized and compared. The electron-withdrawing groups were responsible for their polymorphic and MC properties. Additionally, a number of polymorphs of these DHP derivatives showed a decreasing trend as length of the alkyl chain increased, indicating that a longer alkyl chain was not conducive to formation of the polymorphs. Although differences in emissions of the polymorphs were mainly attributed to their different intermolecular interactions and molecular packing patterns, a subtle difference in the distances of their intermolecular interactions could also be a key factor in the formation of specific polymorphs. Different polymorphs of DHP derivatives could be interconverted by a simple recrystallization process with a specific solvent or through the application of pressure and vapor stimuli. Additionally, the MC properties of these DHP derivatives were ascribed to a phase transition between different crystalline states, instead of the more common transformation between crystalline and amorphous states.
