Alkaline-earth metal phenylphosphonates and their intercalation chemistry

Abstract

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.

Catalytic use of layered materials for fine chemical syntheses

“…Due to their remarkable stability, the most studied representatives are phosphates and organophosphonates of zirconium, but other metals, such as calcium, barium and strontium, were also employed as components of these layered materials. 81,82 As concerns catalytic applications in the field of fine chemical syntheses, the inherent acidity of metal phosphates and organophosphonates is particularly appealing. 83 For example, Piermatti and co-workers reported the aza-Diels-Alder reaction of 2-cyclohexen-1-one with benzaldimines using layered α-zirconium hydrogen phosphate as a heterogeneous Brønsted acid catalyst in water as an environmentally-benign reaction medium.…”

“…81 Among supported catalysts, intercalated ones are the most interesting as concerns the scope of this survey, as they directly utilize the lamellar nature for immobilization purposes. 82 As an intriguing example, Lu and co-workers intercalated polyfluorinated palladium complexes into an α-zirconium phosphate matrix for Sonogashira and Heck reactions (Scheme 20a). 91 The authors managed to build the catalytic material into the layers directly, without the need for a pre-intercalation step, which is generally required to increase the interlayer distance.…”

Thermal stability and fire safety of polycarbonate flame retarded by the brominated flame retardant and a non-antimony synergistic agent

“…Rare-earth phenylphosphonate (ReH(O 3 PC 6 H 5 ) 2 , abbreviated as ReHPP) exists in the form of layered nanocrystals due to the strong coordination ability and varieties of coordination modes of rare earths [10][11][12] . The lamellar structure of ReHPP makes it possible to form a dense char layer that can withstand high temperature and prevent heat and gas transfer between gas phase and condensed phase, which may induce the effect of forming the carbon layer in condensed phase to block the exchange of gases and heat [13][14][15][16][17][18] , so it is expected to inhibit the release of toxic and asphyxiate smoke during the combustion of brominated ame-retarded polymers.…”

Layered calcium phenylphosphonate: a hybrid material for a new generation of nanofillers

“…Many different types of layered metal organophosphonates have been prepared. Well-known and well-studied are the organophosphonates of zirconium because of their good stability; however, it is also possible to prepare layered structures with divalent metals such as calcium, strontium or barium [ 6 – 9 ]. Although the properties of these compounds differ with the metal and organic group incorporated in their structure, the main characteristic remains the same: a strong in-plane bonding in combination with weak van der Waals interactions between the planes.…”