Insight into the Controllable Synthesis of Cu(I)/Cu(II) Metal-Organic Complexes: Size-Exclusive Selective Dye Adsorption and Semiconductor Properties

Under the guidance of self-assembly, a series of Cu(I)/Cu(II) metal-organic complexes (MOCs), [Cu-3(TCPB)(2)(H2O)(3)]center dot 2H(2)O (1), {[Cu-2(TCPB) (DMA)(H2O)]center dot H2O}(n) (2), [(Cu8I8) (Cu6I6)(0.5)(DABCO)(3)center dot 2H(2)O](n) (3), and [(Cu4I8) (DABCO)(2)center dot 6H(2)O](2n) (4) (H3TCPB = 1,3,5-tris(4-carbonylphenyloxy)-benzene, DABCO = 1,4-diazabicyclo[2.2.2]octane) have been synthesized and characterized. Complexes 1 and 2 are driven by noncovalent interactions to assemble into supramolecular metal-organic frameworks. Considering H3TCPB ligand with different geometrical structures, 1 forms an Eiffel Tower shaped supramolecular cage based on equilateral triangle shaped trinuclear [Cu-3(CO2)(3)] unit, which possesses effective free volume about 24.7%. Changing the solvent, 2 displays 1D chain structure based on linear bivalent copper trinuclear {Cu-3(CO2)(2)(H2O)(2)}. When inducing auxiliary ligand DABCO, H3TCPB serves as additive agent and 3 consists of mixed CuI clusters (Cu6I6 and Cu8I8) and plays a 2D layer, which is a rare example. Without additive agent, 4 exhibits a 2D cuprous iodide layer, where 3 and 4 are two novel copper-iodide supramolecular isomers. Owing to large voids in the framework, 1 can serve as a host for use in dye adsorption. The experiment results show that different dyes, including just right size Crystal Violet (CV) can be rapidly adsorbed by 1, but smaller Indigo Blue (IB), Methylene Blue (MEB), Methyl Orange (MO), and larger Rhodamine B (RB) and Methyl Blue (MB) can hardly be adsorbed. Surprisingly, 1 also preferentially adsorbs (or separates) CV from MO and CV in their mixed aqueous solution with fast response and high sensitivity (<16.13 s) by the theoretical calculation. Moreover, absorption spectra demonstrate the band gaps of 3 and 4 are 2.37 and 1.98 eV, respectively. When increasing the dimensions of inorganic compositions in cluster-organic complexes, it could exert a remarkable influence on the band gap.