Synthesis, crystal structure, and sensing properties of organic molecules based on a Terbium-nitronyl nitroxide complex

Abstract

A new Terbium-nitronyl nitroxide radical complex [Tb(hfac)3(NITPh-m-CHO)2]·0.5C7H16 (Tb-rad) (hfac = hexafluoroacetylacetonate; NITPh-m-CHO = 2-(3′-formylphenyl)-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide) was prepared and characterized. Tb-rad crystallizes in triclinic space group P1¯, possessing a mononuclear structure, in which the geometrical configuration of Tb(III) is triangular dodecahedron consisted of six oxygen atoms from three hfac ligands and two oxygen atoms from the NO groups of two NITPh-m-CHO ligands. In Tb-rad, isolated mononuclear structures were connected to form 1D supramolecular chain structures via intermolecular π···π interaction and free n-heptane molecules fill the void in the crystal. Significantly, the luminescence explorations demonstrate that Tb-rad is an excellent fluorescent sensor for identifying nitrobenzene (NB) and nitromethane (NM) molecules. Because of the linear relationship at low concentration with the quenching constant (Ksv) is 5.4 × 105 and 6.6 × 103 M−1 for NB and NM, respectively, it can be considered as a potential luminescent sensor for detecting NB and NM molecules. Moreover, the possible sensing mechanisms of selective detection have been discussed in detail.