Alkaline-earth metal phenylphosphonates and their intercalation chemistry.

The intercalation chemistry of layered alkaline-earth metal phenylphosphonates with the general formula MeCHPO·2HO (Ca, Sr, Ba) is reviewed. The preparation of the host materials is described and their behavior in dependence on the relative humidity and pH of the reaction medium is discussed. Mutual relationships between MeCHPO·2HO and Me(CHPOH) were investigated using a method of computer-controlled addition of reagents. The MeCHPO·2HO compounds are able to intercalate species having a free electron pair through the so-called coordination intercalation. In this way, 1-alkylamines, 1-alkanols, 1,n-diols and 1,2-diols were intercalated. In the case of the ethanol and methanol intercalates of strontium phenylphosphonate we were able to determine the structure of the host part by single-crystal X-ray diffraction. By combination of the data obtained from the diffraction with molecular modeling we suggested the arrangement of the host molecules in the interlayer space of the host. The arrangement of the shorter diols in the interlayer space of strontium phenylphosphonate was also proposed on the basis of molecular modeling calculations. These models help us to understand the structure of the prepared intercalates.