螢光型鋅和鎘金屬有機框架化合物的
合成、結構鑑定、氣體吸附與揮發性有機物及硝基化合物感測

本研究合成出三個具螢光性的金屬有機框架化合物 [Cd(NI-bapy-34)2]．DMF (1；NI-Hbapy-34 = N-(3-carboxyphenyl)-4-(pyridin-4-yl)-1,8-naphthalimide)，[Zn3(bpdc)3(NI-mbpy-34)]．DMF (2；NI-mbpy-34 = N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide, H2bpdc = biphenyl-4,4′-dicarboxylic acid) 和 [Zn2(2,6-ndc)2(NI-mbpy-34)]．1.5DMAc．2MeOH．H2O (3; 2,6-H2ndc = naphthalene-2,6-dicarboxylic acid)。化合物1是以{Cd2(O2C)4N2}二核金屬簇所架構之三維孔洞型結構，具二重互穿特性，孔隙佔有率為16.6%。化合物2是以{Zn3(O2C)6N2}三核金屬簇所架構之簡單六方堆積之層柱狀結構，具二重互穿特性，空隙佔有率為47.8%。化合物3是以{Zn2(O2C)4N2}二核金屬簇所架構之簡單立方堆積之層柱狀結構，具二重互穿特性，孔隙佔有率為50.2%。化合物1、2和3的二甲基甲醯胺懸浮液有不錯的螢光表現，加入芳香性硝基化合物 2-硝基苯酚、3-硝基苯酚、4-硝基苯酚、1,4-二硝基苯、4-硝基甲苯及 2,4-二硝基甲苯後發生螢光焠熄，但加入硝基苯和非芳香性硝基化合物如硝基甲烷和 2,3-二甲基-2,3-二硝基丁烷等則否，因此可用於感測硝基化合物。化合物2和3以固態螢光進行硝基化合物和揮發性有機小分子的氣相感測，發現螢光焠熄表現大多不佳，但是2-硝基苯酚 (50%)和二乙基胺 (67%)對化合物2以及乙晴 (32%)、苯胺 (40%)、二乙基胺 (78%)和二氯甲烷 (63%)對化合物3有不錯的焠熄表現。化合物2和3可用於吸附氣相碘分子，伴隨晶體顏色變化以及螢光焠熄。吸附的碘分子可藉由浸泡甲醇溶液達到脫附效果。化合物2表現極佳的脫附能力，具可重複使用的潛力，化合物3則否。化合物1、2和3可用於CO2的吸附，在195 K，P/P0 = 1時的吸附量分別為 43.3 cm3/g、28.7 cm3/g和80.2 cm3/g。化合物1於273 K和 298 K吸附CO2表現出gate-opening 效應，粉晶X光繞射圖譜證實結構變化。

關鍵字

金屬有機框架；硝基化合物；揮發性有機小分子；碘；氣體吸附

並列摘要

Fluorescent metal－organic frameworks (MOFs) [Cd(NI-bapy-34)2]．DMF (1； NI-Hbapy-34 = N-(3-carboxyphenyl)-4-(pyridin-4-yl)-1,8-naphthalimide)，[Zn3(bpdc)3(NI-mbpy-34)]．DMF (2；NI-mbpy-34 = N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide, H2bpdc = biphenyl-4,4′-dicarboxylic acid), and [Zn2(2,6-ndc)2(NI-mbpy-34)]．1.5DMAc．2MeOH．H2O (3; 2,6-H2ndc = naphthalene-2,6-dicarboxylic acid) were hydro(solvo)thermally synthesized. MOF 1 suits a 2-fold interpenetrated 3D porous structure with porosity of 16.6%. MOF 2 suits a 2-fold interpenetrated 3D pillared-layer framework of simple hexagonal packing with porosity of 47.8%. MOF 3 suits a 2-fold interpenetrated 3D pillar-layer framework of primitive cubic with porosity of 50.6%. The DMF suspensions of MOFs 1-3 exhibit noticeable fluorescence emissions, which would be effectively quenched by 2-NP (2-nitrophenol), 3-NP (3-nitrophenol), 4-NP (4-nitrophenol), 4NT (4-nitrotoluene), 1,4-DNB (1,4-dinitrobenzene) and 2,4-DNT (2,4-dinitrotoluene). On the contrary, NB (nitrobenzene), NM (nitromethane), and DMNB (2,3-dimethyl-2,3-dinitrobutane) did not show their ability to reduce the fluorescence intensity of these DMF suspensions. These results indicate that MOFs 1-3 might be useful fluorescence sensors for detection of aromatic nitro compounds. Solid-state fluorescence-quenching studies performed by vapor-sensing experiments show that remarkable fluorescence quenching responses were observed in the cases of 2-NP (31%) and Et2NH (67%) toward MOF 2 and 4-NP (50%), acetonitrile (32%), aniline (42%), Et2NH (78%), and DCM (63%) toward MOF 3. MOFs 2 and 3 can be used to uptake volatile iodine (I2) molecules, along with significant crystal color change from yellow to brown and fluorescence quenching of 40% and 90%, respectively, after 60 min adsorption. The I2 molecules can be released by immersing I2-loaded 2 and 3 in methanol, which show 93% and 35% recovery, respectively. Hence, MOF 2 is reusable for capture of volatile iodine. MOFs 1-3 do not adsorb N2 at 77 K, but capture CO2 with adsorption abilities of 43.3, 28.7, and 80.2 cm3/g, respectively at 195 K and P/P0 = 1. Interestingly, MOF 1 at 273 K and 298 K exhibited gate-opening effect to adsorb CO2; PXRD patterns confirm the structure transformation upon adsorbing CO2.