以萘醯亞胺雙吡啶與具取代基之對苯二甲酸製備鎘金屬有機框架：
合成、結構鑑定、氣體吸附與揮發性有機物以及硝基化合物感測

本研究合成出具螢光性的有機金屬框架是透過鎘金屬與不同的芳香類二酸有機配體所設計。[Cd(Br-1,4-bdc)(NI-mbpy-44)]•H2O (1，Br-1,4-bdc = 2-bromobenzene-1,4-dicarboxylate)，[Cd(NO2-1,4-bdc)(NI-mbpy-44)]•H2O ( 2，NO2-1,4-bdc = 2-nitrobenzene-1,4-dicarboxylate) 和[Cd(NH2-1,4-bdc)(NI-mbpy-44)]•H2O (3，NH2-1,4-bdc = 2-aminobenzene-1,4-dicarboxylate) 是利用硝酸鎘與雙?啶橋接配體N-(pyridin-4-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide (NI-mbpy-44) 分別和具有不同官能基的1,4-苯二酸經由溶劑熱法合成。化合物1 – 3具有相似結構特性，都是二維層狀結構，有二重互穿的特性。其二重互穿的形式是以2-取代之1,4-苯二酸穿過NI-mbpy-44和鎘金屬所架構之M2L2環形結構，形成聚輪烷狀結構。化合物1 – 3都具有不錯的高孔洞性，孔隙佔有率分別為44.0 %、44.9 %和47.5 %，但是對CO2的吸附能力的效果都不佳，在195 K，p/po = 1 時的吸附量僅分別為 14.90 cm3/g、18.12 cm3/g和14.58 cm3/g。化合物1和化合物2的甲苯懸浮液有良好的螢光效果，用以感測硝基化合物有不同程度的螢光焠熄表現，特別是芳香類的硝基化合物，如4-硝基苯酚 (4-NP)效果較明顯，但是對非芳香類硝基化合物，如硝基甲烷則較差。我們利用化合物1和化合物2的固態螢光特性進行硝基化合物和揮發性有機小分子的氣相感測，結果顯示化合物1對2-硝基苯酚、二乙胺和苯胺有不錯的螢光焠熄效應；化合物2則具有感測2-硝基苯酚、1,4-二硝基苯、硝基甲烷、二乙胺和苯胺的能力。化合物1和化合物2可用以吸附碘蒸氣，晶體顏色有明顯的變深，同時可使螢光在10分鐘內焠熄達80 % 以上。脫附碘分子後的化合物1和化合物2的螢光表現分別有50%和70% 的回復，使兩者均具有可再利用的特性。

關鍵字

萘醯亞胺；金屬有機框架；硝基化合物；碘

並列摘要

This work reports three cadmium-based fluorescent metal－organic frameworks (MOFs) constructed from imide-based bispyridyl ligand, N-(pyridin-4-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide (NI-mbpy-44), and aromatic dicarboxylate ligands. Compounds [Cd(Br-1,4-bdc)(NI-mbpy-44)]•H2O (1, Br-1,4-bdc = 2-bromobenzene-1,4-dicarboxylate), [Cd(NO2-1,4-bdc)(NI-mbpy-44)]•H2O (2, NO2-1,4-bdc = 2-nitrobenzene-1,4-dicarboxylate), and [Cd(NH2-1,4-bdc)(NI-mbpy-44)]•H2O (3, NH2-1,4-bdc = 2-aminobenzene-1,4-dicarboxylate) were synthesized from the hydro(solvo)thermal reactions of cadmium nitrate, NI-mbpy-44, and related 2-substituted benzene-1,4-dicarboxylic acids. Compounds 1 – 3 have similar crystal structures, which adopt a honeycomb-like 2D 63-layer structure, with two Cd2(NI-mbpy-44)2 (M2L2) macrocycles in the ortho positions of each hexagon of the layer structure. Two identical 2D layers interpenetrate each other in the way that the 2-substituted 1,4-bdc ligands thread through the M2L2 macrocycles to form a polyrotaxane-like 2D + 2D → 2D structures. Compounds 1 – 3 showed poor CO2 uptakes of 14.90, 18.12, and 14.58 cm3/g, respectively, at 195 K and p/po = 1, even if they are highly porous with porosities of 44.0, 44.9, and 47.5%, respectively. The toluene suspensions of compounds 1 and 2 exhibit strong fluorescence emissions, which would be quenched by different nitro compounds in different degrees. Among the chosen nitro compounds, aromatic nitro compounds exhibit remarkable fluorescence quenching (> 60%), especially 4-nitrophenol (4-NP) (> 99%). On the contrary, non-aromatic nitro compounds such as nitromethane (NM) and 2,3-dimethyl-2,3-dinitrobutane (DMNB) show only about 20–35% reduction in fluorescence intensity of the toluene suspensions. We have also examined the vapor-sensing ability of compounds 1 and 2 toward volatile nitro and organic compounds. The solid state fluorescence of compound 1 would be effectively reduced by 2-nitrophenol (2-NP), diethylamine (Et2NH), and aniline (C6H5NH2), while that of compound 2 would be quenched by 2-NP, 1,4-dinitrobenzene (1,4-DNB), NM, Et2NH, and C6H5NH2 significantly. Compounds 1 and 2 could be used to uptake volatile iodine (I2) molecules. After adsorbing iodine, the solid state fluorescence intensity of both compounds are reduced more than 80% in ten minutes, and the crystal color is also changed from yellow to brown. After releasing I2 molecules, compounds 1 and 2 can be reused to capture and detect volatile iodine as they exhibit 50% and 70% recovery, respectively, in fluorescence intensity.