Synthesis, structure and photoluminescence of Zn(II) and Cd(II) complexes with pyridophenazine derivative

The [ZnLCl2] (1) and Cd2L2Cl4 (2) complexes, where L is ethyl 2-methyl-5-(prop-1-en-2-yl)pyrido[2,3-a]phenazine-3-carboxylate, were synthesized. The complexes were characterized by elemental analyses, 1H and 13C NMR spectroscopy, and X-ray powder diffraction. Single crystals of 1 and [Cd2L2Cl4]·4CH2Cl2 (3) have been grown. The structure of 1 consists of mononuclear molecules, while the structure of 3 is built up of centrosymmetrical binuclear [Cd2L2Cl4] complex molecules and uncoordinated CH2Cl2 molecules. In 1 and 3, L acts as a bidentate chelating ligand. There is five-membered ZnN2C2 chelate cycle in the [ZnLCl2] molecule. There are two five-membered CdN2C2 chelate cycles and a Cd2Cl2 dinuclear unit in the molecule of [Cd2L2Cl4]. The coordination polyhedra are distorted tetrahedron Cl2N2 (in the structure 1) and distorted tetragonal pyramid Cl3N2 (in the structure of 3). According to IR-spectroscopic data, complex 2 is binuclear. Complexes 1 and 2 display bright luminescence in CHCl3 solutions (λmax = 477 and 475 nm, respectively) and in the solid state (λmax = 510 and 529 nm, respectively). The free L ligand shows weak luminescence intensity (λmax = 441 and 467 nm in CHCl3 and solid state, respectively).

ZnII and CdII complexes with the tetracyclic pyridophenazine derivative have been prepared. X-ray structural analysis showed that the Zn(II) complex has a mononuclear molecular structure. The Cd(II) complex has a binuclear molecular structure in the solvate with CH2Cl2. The photoluminescence measurements reveal that the complexes show bright luminescence.Figure optionsDownload as PowerPoint slide