The synthesis, spectroscopic properties and X-ray structure of Zn(II) complexes with amino derivatives of chromone
摘要:
Three new Zn(II) complexes containing the ligands 5-amino-8-methyl-4H-chromen-4-one (1), 6- or 7-amino-2-phenyl-4H-chromen-4-one (2,3) were prepared. The new synthesised compounds were characterised by IR, H-1 NMR and MS spectroscopy. The crystal structure of complex 4 was determined with the use X-ray diffraction. The Zn(II) centre of 4 is linked by two chlorido and two N-bound aminochromone ligands, 1, in a strongly distorted tetrahedral configuration with the dissymetric point group C-2. The protonation constants of the ligands 1, 2 and 3 corresponded to 3.68, 3.88 and 6.83, respectively. The stability constants of the Zn(II) complexes were calculated from the potentiometric titration data. The complexes were found to have the formulae ML and ML2 for ligands 1 and 2, and ML for ligand 3. Fluorescence spectroscopic properties were also studied; the strongest fluorescence in solution was exhibited by complex 6. (C) 2011 Elsevier Ltd. All rights reserved.