Cluster-based metal–organic frameworks as sensitive and selective luminescent probes for sensing nitro explosives

Abstract

One new cluster-based metal–organic framework, namely, [Cd_2.5Na(NTB)₂(DMF)₄]·3DMF (1) (NTB = 4,4′,4′′-nitrilotrisbenzoic acid; DMF = N,N-dimethylformamide) has been successfully obtained by employing a C₃ symmetric ligand. In 1, the NTB links two different metal centers (single metal and Cd₃ cluster) to form two kinds of 1D chains, which linked through the carboxylate O atom of the NTB ligand to give rise to a 3D framework. Moreover, desolved 1 can be well dispersed in different solvents, which demonstrate distinct solvent-dependent luminescence spectra with emission intensities significantly quenched toward nitrobenzene (NB) and 2,4,6-trinitrophenol (TNP). The results reveal that 1 could be applied as a fluorescence sensor for TNP with high sensitivity and selectivity.