Synthesis, crystal structures and photocatalytic properties of Zn(II), Ni(II), Co(II) complexes with a symmetric open-chain N2O4-donor bis-Schiff base ligand

Abstract Three complexes, Zn(C 40 H 36 N 4 O 8 )·3CH 3 OH ( 1 ), Ni(C 40 H 36 N 4 O 8 )·3CH 3 OH ( 2 ) and Co(C 40 H 36 N 4 O 8 )·3CH 3 OH ( 3 ), with a sexidentate (N 2 O 4 ) symmetric bis-Schiff base ligand (C 40 H 36 N 4 O 8  = 1,2-bis(2-methoxy-6-formylphenoxy)ethane- l -tryptophan) have been synthesized and characterized by physicochemical and spectroscopic methods. The X-ray crystal structures show that the metal atoms of three complexes are all six-coordinated by two nitrogens from C=N groups, two oxygens from ether groups and two carboxylic oxygens in the mono-ligand, forming a distorted octahedral geometry. The complexes were screened as photocatalysts for the degradation of methylene blue, rhodamine B and methyl violet. All three complexes proved to be good candidates for the photocatalytic degradation of methylene blue and complexes 2–3 are also good photocatalysts for the degradation of rhodamine B. The mechanism of these photocatalytic degradations is discussed. Graphical Abstract The main characterization and photocatalytic experiment of three complexes.