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), [Cu₃(TCPB)₂(H₂O)₃]·2H₂O (<b>1</b>), {[Cu₂(TCPB) (DMA)­(H₂O)]·H₂O}_<i>n</i> (<b>2</b>), [(Cu₈I₈) (Cu₆I₆)_0.5(DABCO)₃·2H₂O]_<i>n</i> (<b>3</b>), and [(Cu₄I₈) (DABCO)₂·6H₂O]_2<i>n</i> (<b>4</b>) (H₃TCPB = 1,3,5-tris­(4-carbonylphenyloxy)-benzene, DABCO = 1,4-diazabicyclo[2.2.2]­octane) have been synthesized and characterized. Complexes <b>1</b> and <b>2</b> are driven by noncovalent interactions to assemble into supramolecular metal–organic frameworks. Considering H₃TCPB ligand with different geometrical structures, <b>1</b> forms an Eiffel Tower shaped supramolecular cage based on equilateral triangle shaped trinuclear [Cu₃(CO₂)₃] unit, which possesses effective free volume about 24.7%. Changing the solvent, <b>2</b> displays 1D chain structure based on linear bivalent copper trinuclear {Cu₃(CO₂)₂(H₂O)₂}. When inducing auxiliary ligand DABCO, H₃TCPB serves as additive agent and <b>3</b> consists of mixed CuI clusters (Cu₆I₆ and Cu₈I₈) and plays a 2D layer, which is a rare example. Without additive agent, <b>4</b> exhibits a 2D cuprous iodide layer, where <b>3</b> and <b>4</b> are two novel copper-iodide supramolecular isomers. Owing to large voids in the framework, <b>1</b> 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 <b>1</b>, 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, <b>1</b> 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 <b>3</b> and <b>4</b> 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