The Highly Connected MOFs Constructed from Nonanuclear and Trinuclear Lanthanide-Carboxylate Clusters: Selective Gas Adsorption and Luminescent pH Sensing

2017-01-30T00:00:00Z (GMT) by Yun-Jian Li Yu-Ling Wang Qing-Yan Liu
The highly odd-numbered 15-connected nonanuclear [Ln93-O)2­(μ3-OH)12­(O2C−)12­(HCO2)3] and 9-connected trinuclear [Ln33-O)­(O2C−)6­(HCO2)3] lanthanide-carboxylate clusters with triangular and linear carboxylate bridging ligands were synergistically combined into Ln-MOFs, [(CH3)2­NH2]3­{[Ln9­(μ3-O)2­(μ3-OH)12­(H2O)6]­[Ln3­(μ3-O)­(H2O)3]­(HCO2)3­(BTB)6}·(solvent)x (abbreviated as JXNU-3, Ln = Gd, Tb, Er; BTB3– = benzene-1,3,5-tris­(4-benzoate)), displaying a (3,9,15)-connected topological net. The JXNU-3(Tb) exhibits highly selective CO2 adsorption capacity over CH4 that resulted from the high localized charge density induced by the presence of the nonanuclear and trinuclear cluster units. In addition, JXNU-3(Tb) with high chemical stability and characteristic bright green color exhibits fluorescent pH sensing, which is pertinent to the different protonation levels of the carboxylate groups of the benzene-1,3,5-tris­(4-benzoate) ligand with varying pH.