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设计合成了3-芳基-2-腈基丙烯酰胺类有机发光小分子2-氰基-3-(3,4-二甲氧基苯基)-2-丙烯酰胺(CDMPA)。经研究发现,CDMPA化合物具有明显的压致变色和酸致变色现象。在外力刺激下,化合物CDMPA荧光最大发射峰发生20 nm的红移,经过加热或蒸汽处理后可恢复初始状态。对样品研磨前后粉末的X射线衍射图谱及荧光寿命衰减曲线进行测试分析得出,CDMPA压致变色现象归因于分子构型由晶态到无定形态的转化。另外,在酸刺激下CDMPA发光颜色由蓝光红移至黄光,最大发射波长红移33 nm。经过二甲基甲酰胺(DMF)处理后可恢复到初始状态。由测试得到的红外光谱及分子轨道理论计算推测,酸致变色现象是由氨基取代基的质子化影响了CDMPA前线分子轨道引起的。本研究可使人们深入了解这种类型材料的多刺激响应发光机制,且显著的颜色变化性能使CDMPA在传感器和检测装置方面具有潜在的应用前景。
The 3-aryl-2-cyanoacrylamide-based organic light-emitting small molecule 2-cyano-3- (3,4-dimethoxyphenyl) -2-acrylamide (CDMPA) was designed and synthesized. The study found that CDMPA compounds have significant pressure-induced discoloration and acid discoloration. Under external stimuli, the maximal emission peak of the compound CDMPA was red-shifted by 20 nm, and then recovered to its initial state after heating or steaming. The results of X-ray diffraction (XRD) and fluorescence lifetime decay curves of powders before and after grinding show that CDMPA is due to the conversion of molecular configuration from crystalline to amorphous phase. In addition, under acid stimulation, the color of CDMPA luminescence shifted from blue to red and the maximum emission wavelength was red-shifted by 33 nm. After dimethylformamide (DMF) treatment can be restored to its original state. According to the infrared spectra and molecular orbital calculations obtained from the tests, it is speculated that the acidochromism is caused by the protonation of the amino substituent on the CDMPA frontier molecular orbital. This study will provide insight into the multi-stimulus-responsive luminescence mechanism of this type of material, and the significant color change performance of CDMPA has potential applications in sensors and detection devices.