Synthesis and structural characterization of lithium-based metal-organic frameworks

Two lithium-based metal-organic frameworks, Li₂(C ₁₄H₈O₄) [Li₂(4,4'-BPDC) [1]; ULMOF-2, UL = ultralight; BPDC = biphenyldicarboxylate]; space group P2 ₁/c, a = 12.758(2)Å, b = 5.142(4)Å, c = 8.00(2)Å, β = 97.23°, V= 520.6(14) ų and Li₂(C ₁₄H₈O₆S) [Li₂(4,4'-SDB) [2]; ULMOF-3, UL = ultralight; SDB = sulfonyldibenzoate], space group P21/n, a = 5.5480(11)Å, b = 23.450(5) Å, c = 10.320(2) Å, β = 96.47(3)°, V= 1334.1(5) ųwere synthesized. Compounds 1 and 2 were synthesized by solvothermal methods and were characterized using single crystal X-ray diffraction. Structure 1 consists of layers of two-dimensional antifluorite related LiO motif connected by BPDC linkers, whereas structure 2 is constructed by a combination of tetrameric lithium polyhedral clusters connected by the sulfonyldibenzoate linker. The frameworks are stable up to 575 and 500 °C, respectively, under N₂ atmosphere.