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

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.