Solvothermal Synthesis and Structural Characterization of Ultralight Metal Coordination Networks

Abstract

Two lithium-based coordination polymers and a framework Li-3(C7H3O4N)(2)center dot 0.21(H2O) (C2H8N) [1]; ULCP-1 (ULCP = ultralight coordination polymer); Li-3(C7H3O4N)center dot(C6H3O2N) [2]; [ULCP-1A]; and Li-2(C7H3O4N) [3]; ULMOF-4 (ULMOF = ultralight metal organic framework) were synthesized using solvothermal techniques. The compounds were characterized using single-cry tal X-ray diffraction methods and thermal analysis techniques. Compound [1] [space group P2(1)/c, a = 11.51(2) angstrom, b = 15.33(3) angstrom, c = 10.93(2) angstrom, beta = 99.98(3)degrees] consists of trimeric corner- and edge-sharing lithium tetrahedral chains. Organic linkers connect each of these chains to form a two-dimensional (2-D) layered structure. Positively charged dimethyl amine (DMA) molecules and sites partially occupied by water molecules are present between the layers. Compound [2] [space group P2(1)/c, a = 10. 190(2) angstrom, b = 13.390(3) angstrom, c = 10.450(2) angstrom, beta = 106.02(3)degrees] contains trimeric clusters of corner- and edge-sharing lithium tetrahedra. Each of these clusters is connected by the organic linkers to form an overall 2-D structure. Compound [3] [space group C2/c, a = 12.692(2) angstrom, b = 10.977(2) angstrom, c = 11.200(2) angstrom, beta = 105.83(3)degrees] consists of edge- and corner shared one-dimensional (1-D) chains of lithium tetrahedra. The lithium polyhedral chains are then connected by the organic linkers to form a dense three-dimensional (3-D) network. All compounds are stable above 300 degrees C under N-2 atmosphere, with [3] stable to 550 degrees C.