Lead(II) coordination frameworks with 3-fluorophthalic acid: hydrothermal synthesis, crystal structure, and luminescence

摘要

Hydrothermal reactions of Pb(NO_3)_2 with 3-fluorophthalic acid (H_2Fpht) in the absence or presence of bpy yielded 2-D network Pb_5(Fpht)_4(Fba)_2 (Fba = 3-fluorobenzoate) and 1-D chain [Pb_2(Fpht)_2(bpy)(H_2O)]-3H_2O.Hydrothermal reactions of Pb(NO_3)_2 and 3-fluorophthalic acid (H_2Fpht) in the absence or presence of 2,2'-bipyridine (bpy) gave two coordination polymers: Pb_5(Fpht)_4(Fba)_2 (1) and [Pb_2(Fpht)_2(bpy) (H_2O)]-3H_2O (2). The 3-fluorobenzoic acid (HFba) results from an in situ decarboxylation of H_2Fpht. Solid 1 displays a 2-D structure, comprising center-related hexanuclear [Pb_3(COO)_6]_2 units. There are three crystallographically different Pb(II) ions and two different ligands, Fpht and Fba. The Fpht ligands adopt μ_6: η~5η~3 and μ_6: η~3η~4 unusual bridging coordination modes. A 3-D supramo-lecular architecture is formed via C-H-F hydrogen bonds. Solid 2 possesses a 1-D chain structure, comprising center-related tetranuclear [Pb_2(COO)_4]_2units. There are two crystallographically different Pb(II) ions. The Fpht ligands adopt μ_3: η~2η~3 and μ_4: η~3η~3 bridging coordination. The free water molecules form (H_2O)_3 clusters to link the 1-D chain by hydrogen bonds. A 3-D supramolecular assembly is constructed via hydrogen bonds between the free water and the F of Fpht ligands. Fluorescence of the complexes originates from π*-π transitions of the ligands.