Pyrazine-tuned metal cluster-based CuI13 chain and CuI14 layer for efficient photo-thermal synergistic degradation of methyl orange

By anti-disproportionation reaction, two Cu(I)-alkynyl cluster compounds, [Cu₁₃(^tBuCC)₈(CF₃COO)₅(pz)]_n (Cu^I₁₃) and [Cu₁₄(^tBuCC)₈(CF₃COO)₆(pz)₂]_n (Cu^I₁₄), with different dimensions were precisely and directionally synthesized under solvothermal conditions, in which Cu(CF₃COO)₂·xH₂O, copper powder, ^tBuCCH, and CF₃COOH ligand reacted with varying molar quantities of pyrazine (pz) ligand. The increase in the quantity of pz ligand, not only promoted the increase of the number of copper cores from 13 to 14 but also realized the growth from the one-dimensional (1D) Cu^I₁₃ chain to the two-dimensional (2D) Cu^I₁₄ layer accompanied by strengthening Cu⋯Cu interactions. The photo-thermal conversion performance together with the degradation of methyl orange (MO) by Cu^I₁₃ and Cu^I₁₄ were studied under 532 nm light irradiation. The equilibrium temperature of photo-thermal conversion of Cu^I₁₃ and Cu^I₁₄ was separately 64.5 °C and 89.0 °C in the solid state and 46.0 °C and 53.0 °C in the aqueous solution. The better photo-thermal conversion of Cu^I₁₄ can be assigned to the higher absorption intensity at 532 nm than that of Cu^I₁₃. The photo-thermal synergistic degradation of MO by Cu^I₁₃ and Cu^I₁₄ was observed. The degradation rate of Cu^I₁₄ reached 80 %, which is better than that of Cu^I₁₃ (71 %). This work may shed light on designing metal cluster-based photo-thermal catalysts and explaining their structure–property relationship.