Solvent-Induced Structural Diversity of Partially Fluorinated, Stable Pb(II) Metal–Organic Frameworks and Their Luminescence Properties

Abstract

Rigid, linear partially fluorinated ligand 2,2′-bis-trifluoromethyl-biphenyl-4,4′-dicarboxylic acid (H2L) was synthesized and used to construct five metal organic frameworks with Pb(II) through hydro- and solvothermal techniques. Depending on the nature of the solvent or solvent mixture, five different coordination polymers, {[Pb6(L)5(OH)2]·2H2O}n (1), {[Pb3(L)2(O)(EtOH)]·(EtOH)}n (2), {[Pb3(L)2(O)(PrOH)]·(PrOH)}n (3), {[Pb3(L)2(O)(i-PrOH)]·(i-PrOH)}n (4), and {[Pb6(L)4(O)2]·(benzylalcohol)2(H2O)2}n (5), were synthesized. All of these compounds were characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, elemental analysis, and powder X-ray diffraction measurements. Complex 1, which is a 3D MOF, can be synthesized hydrothermally. However, isostructural complexes 2–4 can be obtained solvothermally using ethanol, propanol, and isopropanol, respectively, with water. The alcohols (ethanol, propanol, and isopropanol) are incorporated in the final 3D structures. Complex 5, having a 2D layer structure, was synthesized using a benzyl alcohol and water mixture. All of the complexes exhibit rare rod-type topology. Solid-state photoluminescence studies were carried out for all of the complexes at room temperature.