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

Hydrothermal reactions of Pb(NO3)(2) and 3-fluorophthalic acid (H(2)Fpht) 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)(H2O)]center dot 3H(2)O (2). The 3-fluorobenzoic acid (HFba) results from an in situ decarboxylation of H(2)Fpht. 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 mu(6 ): eta(5)eta(3) and mu(6 ): eta(3)eta(4) unusual bridging coordination modes. A 3-D supramolecular architecture is formed via C-HMIDLINE HORIZONTAL ELLIPSISF hydrogen bonds. Solid 2 possesses a 1-D chain structure, comprising center-related tetranuclear [Pb-2(COO)(4)](2) units. There are two crystallographically different Pb(II) ions. The Fpht ligands adopt mu(3 ): eta(2)eta(3) and mu(4 ): eta(3)eta(3) bridging coordination. The free water molecules form (H2O)(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 pi*-pi transitions of the ligands.