A Lanthanide-Containing Coordination Polymer Using Tetraphenylethene-Based Linkers with Selective Fe³⁺ Sensing and Efficient Iodine Adsorption Activities

Abstract

As a star ligand, the construction of coordination polymers (CPs) based on tetrakis(4-carboxyphenyl)ethylene (H₄<b>TCPE</b>) has drawn much attention, due to not only the various coordination configurations but also the intriguing chromophore feature causing aggregation-induced emission (AIE). Herein, by the solvothermal reaction of H₄<b>TCPE</b> as connected nodes with lanthanide La(III) salts, the first example of the La(III)-<b>TCPE</b>-based CP (<b>1</b>) has been obtained. The structural analyses indicate that <b>1</b> exhibits a 3D framework connected by the sharing carboxylate groups with two kinds of 1D rhombic channels when viewed along the <i>c</i> direction. The photophysical properties of <b>1</b> have been explored by luminescence, photoluminescence decay, and quantum yield in the solid state. <b>1</b> shows strong luminescence in tetrahydrofuran that was attributed to a "pseudo-AIE process" and sensitive and selective sensing activity of Fe³⁺ toward metal ions via the obvious luminescent quenching. The sensing mechanism has been investigated and reveals a synergetic effect of the competitive absorption and weak interactions between <b>1</b> and Fe³⁺. Moreover, the high porosity, multiple conjugated π-electrons within the tetrakis(4-carboxyphenyl)ethylene backbone, and the uncoordinated carboxyl oxygen sites in this material also provide the capacity for iodine adsorption. The adsorption experiments indicate that <b>1</b> could efficiently remove almost complete I₂ from the cyclohexane solution after 24 h contact time with an adsorption capacity of 690 mg/g toward I₂.