Controlled Hydrolysis of Phosphate Esters: A Route to Calixarene-Supported Rare-Earth Clusters

Phosphate ester bonds are widely present in nature (e.g. DNA/RNA) and can be extremely stable against hydrolysis without the help of catalysts. Previously, we showed how the combination of phosphoryl and calix[4]arene moieties in the same organic framework (LPO) allows isolation of single lanthanide (Ln) metal ions as [LnIII(LPO)2](O3SCF3)3. Here we report how by controlling the reaction conditions a new hydrolyzed phosphoryl-calix[4]arene ligand (H3LHPO) is formed as a result of LnIII-mediated P–OEt bond cleavage in three out of the eight possible sites in LPO. The chelating nature of H3LHPO traps the LnIII species in the form of [LnIII(LHPO)((EtO)2P(O)OH)]2 dimers (Ln = La, Dy, Tb, Gd), where the Dy derivative shows slow magnetization relaxation. The strategy presented herein could be extended to access a broader library of hydrolyzed platforms (H x LHPO; x = 1–8) that may represent mimics of nuclease enzymes.