The development of stimuli-responsive luminescent compounds featuring high solid-state emission and a long-wavelength fluorescence switch between the visible and the near-infrared (NIR) region is still a challenging task. Here we synthesize an aggregation-induced emission (AIE)-active luminogen DPP3A, which exhibits a fluorescence switch between the visible (λ_em,max = 652 nm) and the NIR region (λ_em,max = 800 nm) upon acid/base stimuli, and accessible solid-state NIR emission. NMR spectroscopy, theoretical calculations and powder X-ray diffraction are performed to acquire the mechanisms of acidochromism. The remarkable fluorescence changes on paper and banknotes of DPP3A present its potential as a security ink material with high contrast and easy accessibility that is free of background fluorescence.

中文翻译：

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基于AIEgen的质子化/去质子化，从可见光到近红外区域的固态荧光显着变化

具有高固态发射和可见光与近红外（NIR）区之间的长波荧光切换特性的刺激响应发光化合物的开发仍然是一项艰巨的任务。在这里，我们合成的聚集诱导的发射（AIE）-active luminogen DPP3A，其表现出可见之间的荧光开关（λ _EM，最大= 652纳米）和NIR区域（λ _EM，最大在酸/碱= 800纳米）刺激和可访问的固态近红外发射。进行核磁共振波谱，理论计算和粉末X射线衍射以获取酸致变色的机理。DPP3A在纸和钞票上的显着荧光变化 展示了其作为安全墨水材料的潜力，该材料具有高对比度和易于访问且无背景荧光的特点。