Fluorescent bis-chelated-1,10-phenanthroline-azido-copper(II) complex for selective sensing of aniline

A pentacoordinated Cu(II) complex, [Cu(phen)2N3](NO3).(H2O) (1) [phen = 1,10-phenanthroline], was synthesized and characterized by elemental analysis, IR, single crystal X-ray crystallography, thermal analysis and DFT calculations. The single crystal structural determination reveals that complex 1 is a discrete complex cation [Cu(phen)2N3]+ with the metal in a distorted trigonal bipyramidal coordination geometry, a nitrate anion and a lattice water molecule. The complex cations are connected by p–p interactions among the phen aromatic rings giving rise to a 1D chain. The complex exhibits intense fluorescence (kex = 271 nm, kem = 350, 366 and 382 nm) in water–MeOH (1:1) solution at room temperature with a fluorescence quantum yield Us = 5.2. Complex 1 was tested with several aromatic compounds such as m-toluidine, aniline and nitrobenzene in water–methanol (1:1) solution, and results show it behaves as a fluorescence sensor for aniline. Results from DFT calculation show a good agreement with X-ray structural data.