Synthesis, structure, and heterogeneous Fenton reaction of new Cu(ii)-based discrete Cu2Lx coordination complexes

Abstract

Discrete and polymeric coordination complexes, namely [Cu₂L₄(ClO₄)₄]·2CH₂Cl₂·CH₃OH (1), [Cu₂L₂(NO₃)₄(CH₃OH)₂] (2) and {[Cu₂L₄(NO₃)₄]}_n (3), were obtained using bridged pyridine ligand 4-methyl-2,6-bis(pyridinyl-3-ethynyl)aniline (L) and Cu(II) salts in CH₂Cl₂/MeOH. The structure of the Cu₂L₄ cage or Cu₂L₂ macrocycle was generated depending on the selection of the anion (ClO₄⁻/NO₃⁻). The heterogeneous Fenton reaction experiments using H₂O₂ showed that discrete coordination complexes are good photocatalysts in which the Cu–N bond plays a major role in the photocatalytic degradation. The degradation mechanism could be described as a synergistic process of the Fenton reaction and high-valence copper ions using t-butanol as the hydroxyl radical scavenger. The photocatalytic degradation of methylene blue (MB) experiments showed that the photodegradation efficiency of the coordination complexes is higher than that of the polymeric Cu-MOFs.