Aromatic guest inclusion by a tripodal ligand: Fluorescence and structural studies

Abstract

The newly synthesized simple tripodal ligand tris-[2-(naphthalen-2-yloxy)-ethyl]-amine (L 1) act as a fluorescence signaling system for aromatic guest. It forms inclusion complexes with several electron deficient aromatic compounds. This inclusion phenomenon has been studied by steady-state fluorescence spectroscopy and solid-state structural analysis. Electron-rich L 1 shows dramatic color change and a concomitant quenching of luminescence in solution as well as solid phase when titrated with several other electron deficient aromatic guest molecules. Rather high selectivity towards the picric acid was observed. L 1 simultaneously forms inclusion complex and organic salt co-crystal with the composition [(L 1H +) (Pic −)] ⊂ PicH (PicH = picric acid) when crystallized in the presence of picric acid. In the solid state, it forms a strong π–π, C–H⋯π and C–H⋯O type interactions.