Lanthanide organic frameworks for luminescence sensing of nitrobenzene and nitrophenol with high selectivity

Abstract

A series of lanthanide(III)–organic frameworks, namely {[Ln2(L)3(H2O)4]·10H2O}n (Sm 1, Eu 2, Gd 3, Tb 4, Dy 5 and Ho 6, H2L = 5-(pyridine-4-ylmethoxy)isophthalic acid) have been synthesized under solvothermal conditions. Compounds 1–6 are isostructural and exhibit an interesting 3D pcu topology with binuclear [Ln2(CO2)6] units as 6-connected nodes, and free water molecules are filled in 3D coordination frameworks through hydrogen-bonding interactions. Compound 4 can be used as a fluorescent probe for sensing nitroaromatic compounds with high sensitivity and selectivity based on luminescence quenching effects arising from host−guest interactions in DMF system. In particular, compound 4 can sense nitrobenzene (NB) and nitrophenol isomers (2-, 3- and 4-NP) simultaneously. Thus, this material can be potentially used as a luminescent sensor for nitroaromatic compounds.