Vinyl-functionalized multicolor benzothiadiazoles: design, synthesis, crystal structures and mechanically-responsive performance

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2019,（4）
• 页码范围: 440-450
• 页数: 11页
• 语种: 英文

摘要

Benzothiadiazole (BTD) has been extensively used as a building block in optical materials.In this work,a class of π-conjugated BTD-based luminogens BTD-685,BTD-580,BTD-675 and BTD-565 were designed by varying donor units and facilely synthesized by Heck coupling reaction.It was found that their emission in solid state covered the regio from orange,red to near infrared fluorescence.Investigation on photo-physical property manifested that they had strong solvatochromic behavior except symmetric 2-vinylpyridine substituted BTD-565.Crystal X-ray diffraction analysis revealed that they involved in multi weak intermolecular interactions.And loose molecular packing implied that they can be easily rearranged under external force stimuli.Indeed,all compounds showed reversible mechanically-responsive behavior in solid state.Interestingly,the vinylpyridinecontaining BTD-565 exhibited hypochromatic mechanochromic behavior,whereas others showed bathochromic mechanochromism behavior.It was worth mentioning that BTD-675 had self-recovery behavior after grinding.The powder X-ray diffraction study showed that these chromic processes may be mainly attributed to the reversible morphological changes between crystalline and amorphous phase upon grinding or fuming.These observations suggested that the vinyl-functionalized benzothiadiazoles can be considered as a type of excellent candidates in mechanically-responsive chromic materials.