Synthesis, crystal structure and thermal properties of Ca sub(6)(C sub(12)H sub(14 )O sub(4)) sub(4)(CO sub(3))(OH) sub(2)(H sub(2)O) sub(x) - a 3D inorganic hybrid material

• Published in: Dalton transactions : an international journal of inorganic chemistry 2012-09, Vol.41 (39), p.12082-12089
• Main Authors: Nielsen, Renie Birkedal, Norby, Poul, Kongshaug, Kjell Ove, Fjellvag, Helmer
• Format: Article
• Language: English
• Subjects: Cages; Channels; Crystal structure; Dehydration; Holes; Porosity; Synchrotrons; Three dimensional
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt30651d

The inorganic-organic compound Ca sub(6)(1,3-adamantanedicarboxylate) sub(4 )(CO sub(3))(OH) sub(2) (H sub(2)O) sub(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 sub(6)(C sub(12)H sub(14 )O sub(4)) sub(4)(CO sub(3))(OH) sub(2)(H sub(2)O) sub(14) is tetragonal, space group I4 sub(1)/amd(14 1) with a= 29.12 Aa, c= 15.85 Aa, V= 13 440 Aa super(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 Aa. The largest hydrophilic cavity has a diameter of 10 Aa and the pores connecting the channels have a diameter of 5 Aa. 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.