Synthesis and Photocatalytic Performance of Five Organic–Inorganic Hybrid Supramolecules with Chain-like Organic Cations for Tetracycline Degradation

In this paper, we synthesized a chain-like organic cation structure directing agent L·Cl₂ by reacting triethylenediamine with 1,2-bis(2-chloroethoxy)ethane. We then used a room temperature volatilization method to react L·Cl₂ with inorganic metal salts to synthesize five organic-inorganic hybrid supramolecules: {[L][HgI₄]} (<b>1</b>), {[L][CdI₄]} (<b>2</b>), {[(L)(Cu₂I₃)]·[CuI₂]CH₃CN}_n (<b>3</b>) {[L][CoCl₃]₂} (<b>4</b>), and {[L][Ce(NO₃)₅·(H₂O)₂]} (<b>5</b>) (L=1,1'-((ethane-1,2-diylbis(oxy))bis(ethane-2,1-diyl))bis(1,4-diazabicyclo [2.2.2]octan-1-ium) chloride). The compounds were characterized by X-ray diffraction, infrared spectroscopy, elemental analysis, and thermogravimetric analysis. Compounds <b>1</b>, <b>2</b>, and <b>5</b> are mononuclear anion compounds, while compound <b>3</b> is a 1D chain, and <b>4</b> is a binuclear anion compound. The results showed that 10 mg of compound <b>3</b> achieved 92.22% of tetracycline degradation efficiency in the initial TC solution pH = 7. The optimal conditions such as solution pH, catalyst dosage, and solution temperature for the photocatalytic degradation of TC wastewater by compound <b>3</b> were explored. Moreover, the photocatalytic degradation efficiency of compound <b>3</b> was above 86% each time after four cycles, indicating a good recyclability. The mechanism of photocatalytic degradation was also discussed.