# Advances and Challenges in the Creation of Porous Metal Phosphonates
## 3 Applications
### Catalysis  
A list of the catalytic applications for which metal phosphonates have been used for is summarized in Table 2. As an example, mesoporous vanadium phosphonate has been employed as catalyst for the oxidation of benzyl alcohols. The oxidation reaction resulted in high conversion (>99%) and selectivity (96%) in the formation of benzaldehyde. There was no formation of side reaction products such as benzoic acid or ethers due to the over-oxidation or acid condensation, respectively. Benzyl alcohols containing electron-donating groups (4-MeOPhCH\({}_{2}\)OH and 4-MePhCH\({}_{2}\)OH) and electron withdrawing groups (4-NO\({}_{2}\)PhCH\({}_{2}\)OH and 4-CF\({}_{3}\)PhCH\({}_{2}\)OH) were also successfully converted to the respective aldehydes with similar conversion and selectivity as in the case of benzaldehyde. Evidence of some shape selectivity was observed, as 2,4,6-trimethyl benzyl alcohol oxidation resulted in poor conversion (56%) and low selectivity (79%) compared to other benzyl alcohol substrates [81]. One of the benefits of hybrid inorganic-organic materials is that they can introduce chirality in the material's porous network through the organic moiety on the phosphonate linker. The hydrolysis of styrene oxide under confined homochiral environment available in the hydrophobic pores of hybrid titanium phosphonate containing leucine moieties was evaluated. The yield of the reaction in the presence of the hybrid catalyst was 30% S-styrene oxide with an enantiomer efficiency (EE) of >99%. Moreover, other epoxides such as 4-methyl styrene oxide and \(\alpha\)-4-methyl styrene oxide reacted in an identical manner, with a yield of \(\sim\)20% having \(\sim\)98% and \(\sim\)95% EE, respectively. The authors \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Metal Precursor** & **Phosphonic Linker** & **Synthesis** & **Application—Separation/Extraction** & **Reference** \\ \hline Al(O\({}^{9}\)Bu)\({}_{3}\) & ATMP & Hydrothermal & Cu\({}^{2+}\) adsorption and lysozyme & [94] \\ ZrOCl\({}_{2}\) & ATMP & Precipitation & Cation exchange—divalent metal ions & [99] \\ ZrCl\({}_{4}\) & H\({}_{3}\)PMP & Hydrothermal & Adsorption and delivery of DNA & [101] \\ ZrCl\({}_{4}\) & PPA & Hydrothermal & Immobilized metal affinity & \\  & & & chromatographic adsorbent for & [104] \\ MnCl\({}_{2}\) & EDTMP & Hydrothermal & Cu\({}^{2+}\) sorption and selective protein & \\  & HEDP & & adsorption of Cyt–C over BSA & [100] \\ SnCl\({}_{4}\) & ATMP & Hydrothermal & Radionuclide separation of Th\({}^{4+}\) & [105] \\  & EDTMP & & & \\ ZrOCl\({}_{2}\) & BDP & Hydrothermal & Lanthanide and actinide separation & [108] \\  & BMP & & & \\ ZrOCl\({}_{2}\) & BDPA & Hydrothermal & Ion-exchange metal ions & [106] \\ ZrOCl\({}_{2}\) & H\({}_{3}\)PO\({}_{4}\) & Hydrothermal & Actinides separation & [107] \\ ZrOCl\({}_{2}\) & BDPA & Hydrothermal & Lanthanides extraction & [109] \\ SnCl\({}_{4}\) & H\({}_{3}\)PO\({}_{4}\) & Hydrothermal & Lanthanides separation & [107] \\ ZrCl\({}_{4}\)/Zr(O\({}^{3}\)Pr)\({}_{4}\) & ATMP & Hydrothermal & Lanthanides extraction & [109] \\ \hline \hline \end{tabular}  
* Abbreviation: ATMP = aminotris(methylene phosphonic acid); BHMT = bis(hexamethylene-triamine)-penta (methylene phosphonic acid); H\({}_{3}\)PMP = 1-phosphomethylproline; BPMP = 1.4-bis(phosphomethyl) piperazine; PPA = phenyl phosphonic acid; EDTMP = ethylenediamine tetra(methylene phosphonic acid); HEDP = 1-hydroxyethane 1,1-diphosphonic acid; BTP = benzene 1,3,5-triphosphonic acid; BDP = 3,5-diphosphonobenzoic acid; BMP = 5-phosphonobisphthal acid; BDP = 1,4-phenylenediamine acid.  
\end{table} 
Table 1: Separation and extraction application list for porous metal phosphonates. postulated that the epoxide was activated by moieties having a partial positive charge in the titanium phosphonate framework such as the phosphonate, or Ti(IV) centers, followed by the attack of water directed by the homochiral leucine peptide to yield S-styrene glycol [110].