Use chloride to assist in constructing of penta- and nano-nucleus mixed-valent Cu(I/II) clusters and their photo-thermal properties

Abstract

To prepare new series of mixed-valence polynuclear Cu(I/II) clusters, chloride ions are introduced to construct two mixed-valence polynuclear Cu(I/II) clusters for evaluating their photothermal conversion performance. X-ray single-crystal structural analysis reveals their molecular formula are {CuII[CuI(Cy3P)]4(BTA)4Cl2}·5DMF (I·5DMF, Cy3P = triscyclohexylphosphine, BTA = benzotriazole, DMF = N,N-Dimethylformamide) and {(CuII)3[CuI(PPh2Py)]6(BTA)8Cl4}·6DMF (II·6DMF, Ph2PyP = diphenyl-2-pyridylphosphine), respectively. X-ray Photoelectron Spectroscopy (XPS) and Electrospray Ionization Mass Spectrometry (ESI-MS) confirm their chemical composition and charge state. The reported two mixed-valence CuI/CuII clusters have different nucleus (penta-nucleus for I and nano-nucleus for II) and different proportion of valence state (1/4 for I vs 1/2 for II). The thermogravimetric analysis (TGA) reveals the thermal stability of both clusters is less than our previously reported penta-nucleus mixed-valence CuI/CuII clusters. Contrastively studies of their optical absorption properties by the solid-state ultraviolet diffuse reflection spectra indicate high-nucleus mixed-valence CuI/CuII cluster with higher proportion of CuII is superior to those penta-nucleus mixed-valent Cu(I/II) clusters. With the introduction of chloride ions to the structures of mixed-valence CuI/CuII clusters have not remarkably changed their photothermal conversion performance. This study provides a practicable way to construct new mixed-valence CuI/CuII clusters with different photothermal conversion performance.