Cuprous iodide coordination polymers (CuI)x(L)y·z(solvent) built on linear thioether linkers

Abstract

By using bidentate thioether linkers 1,4-bis(ethylthio)benzene (L₁) and 4,4′-bis(ethylthiomethyl)biphenyl (L₂), four novel coordination polymers (CuI)_x(L)_y·z(solvent), MSF–n (metal-sulfide-framework, MSF–6, x = y = 2, L = L₁; MSF–7, x = 4, y = 2, L = L₁; MSF–8, x = y = 2, L = L₂; MSF–9, x = 4, y = 1.5, L = L₂) were obtained and characterized by single-crystal X-ray diffraction, thermogravimetric, solid state diffuse reflectance UV-Vis and photoluminescent studies. MSF–n (n = 6–9) possess 2D layered structures built from (CuI)_x clusters and linear thioether linkers, the formations of which are dependent on the cluster size and linker length. MSF–6 and MSF–8 possess the same structure topology, consisting of lozenge-shaped sql single sheets of 4-connecting Cu₂I₂ units and linear thioether linkers L₁ and L₂, respectively. MSF–7 and –9 are cubane cluster Cu₄I₄-based layered compounds, composed of 2-fold interpenetrating sql and 3-fold interpenetrating hcb sheets, respectively. The solid state diffuse reflectance UV-Vis spectra show that MSF–6 to –9 are wide-gap semiconductors with band gaps of 3.11, 3.25, 3.52 and 3.07 eV, respectively. MSF–7 and –9 are photoluminescent at room temperature owing to the existence of the Cu⋯Cu interactions within the Cu₄I₄ cluster, while MSF–6 and –8 do not emit upon excitation because of luminescence quenching.