Anion-Dominated Copper Salicyaldimine Complexes—Structures, Coordination Mode of Nitrate and Decolorization Properties toward Acid Orange 7 Dye

Abstract

A salicyaldimine ligand, 3-tert-butyl-4-hydroxy-5-(((pyridin-2-ylmethyl)imino)methyl)benzoic acid (H2Lsalpyca) and two Cu(II)−salicylaldimine complexes, [Cu(HLsalpyca)Cl] (1) and [Cu(HLsalpyca)(NO3)]n (2), have been synthesized. Complex 1 has a discrete mononuclear structure, in which the Cu(II) center is in a distorted square-planar geometry made up of one HLsalpyca− monoanion in an NNO tris-chelating mode and one Cl− anion. Complex 2 adopts a neutral one-dimensional zigzag chain structure propagating along the crystallographic [010] direction, where the Cu(II) center suits a distorted square pyramidal geometry with a τ value of 0.134, consisted of one HLsalpyca− monoanion as an NNO tris-chelator and two NO3− anions. When the Cu∙∙∙O semi coordination is taken into consideration, the nitrato ligand bridges two Cu(II) centers in an unsymmetrical bridging-tridentate with a μ, κ4O,O′:O′,O″ coordination. Clearly, anion herein plays a critical role in dominating the formation of discrete and polymeric structures of copper salicyaldimine complexes. Noteworthy, complex 2 is insoluble but highly stable in H2O and various organic solvents (CH3OH, CH3CN, acetone, CH2Cl2 and THF). Moreover, complex 2 shows good photocatalytic degradation activity and recyclability to accelerate the decolorization rate and enhance the decolorization performance of acid orange 7 (AO7) dye by hydrogen peroxide (H2O2) under daylight.

Two multifunctional Cu(ii) coordination complexes with mixed ligands as efficient catalysts for the oxygen evolution reaction and photocatalytic degradation of methyl orange azo dyes

“…51,52 In addition, the e − also combines with O 2 in the system to form super-oxide radicals (˙O 2 − ). 53 Moreover, Fei 54 and Wang 55 demonstrated that ˙OH, O 2 − and h + are the main reactive species during the degradation of MO. So, the degradation mechanism of MO can be expressed by the following reactions: 56,57 1 or 2 + hv → h + + e − h + + H 2 O or H 2 O 2 → ˙OH + H + e − + O 2 → ˙O 2 − ˙OH or ˙O 2 − + MO → Products…”

“…51,52 In addition, the e − also combines with O 2 in the system to form superoxide radicals (˙O 2 − ). 53 Moreover, Fei 54 All in all, 1 and 2 exhibited good photocatalytic activities for the degradation of MO in combination with H 2 O 2 under the irradiation of sunlight, and the photocatalytic effect of 1 was better than that of 2, which corresponds to their E g values.…”