Liu Xiao-Yan, Yin Xue-Mei, Yang Shuai-Liang, Zhang Lin, Bu Ran, Gao En-Qing
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
ACS Appl Mater Interfaces. 2021 May 5;13(17):20380-20387. doi: 10.1021/acsami.1c03937. Epub 2021 Apr 20.
Sensory materials that show color and/or fluorescence changes in response to specific gases or vapors have important applications in many fields. Here, we report the postsynthetic preparation of novel sensory metal-organic frameworks (MOFs) and their multiple responsive properties. Through postsynthetic N-amination, the 2,2'-bipyridyl spacers in a Zr(IV) MOF are partially transformed into -aminobipyridinium. The new MOF (Zr-bpy-A) shows chromic behavior toward ammonia and amines because the electron-deficient pyridinium groups form charge-transfer complexes with amino moieties. It also shows a unique chromic response to formaldehyde owing to the Schiff-base condensation with the -amino groups. Furthermore, the -amino group can be used to graft different polycyclic aromatic hydrocarbons, which endow the MOF with strong fluorescence of variable colors and afford a high-contrast fluorescence response to ammonia/amines and formaldehyde associated with the chromic response. The presence of the unquaternized bipyridyl group also leads to a fluorescence response to HCl. The multiple responsive behaviors hold appeal for applications in sensing, switching, and antifake marking, which are illustrated with a test paper and writing ink.
对特定气体或蒸汽能呈现颜色和/或荧光变化的传感材料在许多领域都有重要应用。在此，我们报道了新型传感金属有机框架（MOF）的后合成制备及其多重响应特性。通过后合成N-胺化反应，Zr(IV) MOF中的2,2'-联吡啶间隔基部分转化为氨基联吡啶鎓。新型MOF（Zr-bpy-A）对氨和胺呈现变色行为，因为缺电子的吡啶鎓基团与氨基部分形成电荷转移络合物。由于与氨基发生席夫碱缩合反应，它对甲醛也表现出独特的变色响应。此外，氨基可用于接枝不同的多环芳烃，这赋予MOF强烈的可变颜色荧光，并对与变色响应相关的氨/胺和甲醛产生高对比度荧光响应。未季铵化的联吡啶基团的存在也导致对HCl的荧光响应。这些多重响应行为在传感、开关和防伪标记应用方面具有吸引力，通过试纸和书写墨水进行了说明。
