Synthesis, crystal structure and thermal properties of Ca6(C12H14O4)4(CO3)(OH)2(H2O)x – a 3D inorganic hybrid material

Abstract

The inorganic-organic compound Ca(6)(1,3-adamantanedicarboxylate)(4)(CO(3))(OH)(2)(H(2)O)(x) with 0 < x < 15.2 was synthesized by hydrothermal methods. The crystal structure was determined on the basis of high resolution synchrotron powder diffraction data and poly-crystal measurements. The crystal structure of Ca(6)(C(12)H(14)O(4))(4)(CO(3))(OH)(2)(H(2)O)(14) is tetragonal, space group I4(1)/amd (141) with a = 29.12 Å, c = 15.85 Å, V = 13,440 Å(3) and Z = 8. The compound is classified as a 3D inorganic hybrid material with a 3-dimensional inorganic framework consisting of Ca and O, connected to 1,3-adamantanedicarboxylate anions. The structure shows hydrophilic channels in a diamond-like network. In between the channels there exist hydrophobic pores with surfaces defined by adamantane cages. The shortest distance between hydrogen atoms from different molecules in these pores is 3.6 Å. The largest hydrophilic cavity has a diameter of 10 Å and the pores connecting the channels have a diameter of 5 Å. In the as-synthesised state these channels are filled with water molecules. Reversible dehydration-rehydration occurs. The dehydrated compound easily takes up water from ambient air.

Calcium‐Based Metal–Organic Frameworks and Their Potential Applications

“…The Ca 2+ centers in each SBU are interconnected by bridging water (Figure 1d). Fjellvag and co-workers [33] reported a 3D Ca-MOF comprising 1,3-adamantanedicarboxylate as the organic ligand. The structure is built on interconnected CaO chains which contains tetrameric building units as shown in Figure 1e.…”

Cobalt(II) and cadmium(II) square grids supported with 4,4′-bipyrazole and accommodating 3-carboxyadamantane-1-carboxylate

“…Adamantane-1,3-dicarboxylate (ADC 2À ) is a paradigmatic ligand used for the generation of metal-organic frameworks (MOFs), providing such important features as multivalence and a geometrically rigid angular configuration of binding sites at the entirely aliphatic 'nanodiamond scaffold'. These issues are particularly significant for the elegant three-dimensional frameworks adopted by Eu 3+ (Millange et al, 2004) and Ca 2+ cations (Nielsen et al, 2012), the layered network in Mg(ADC) (Plonka et al, 2011), and one-dimensional polymers of UO 2 2+ (Rusanova et al, 2010) and Th 4+ (Nazarenko et al, 2010). From the perspective of crystal design, even more versatile possibilities may be found for transition metal complexes when combining anionic ADC 2À or HADC À and exo-bidentate neutral N-donor co-ligands.…”