Preparation of HOPO-containing lariate ethers based on the diaza-18-crown-6 scaffold

Cyclic and acyclic ligands containing the hydroxypyridinone (HOPO) moiety as donor group are known as strong coordinating compounds for a wide variety of metal ions. Based on the diaza-crown[18]ether Kryptofix K22, five different tendentate ligands were prepared using 1,2-HOPO, 1,2,3-HOPO and 2,3-Me-HOPO as additional binding moieties. The diaza-crown ether basic skeleton was furnished with two primary amine functions and subsequently reacted with the respective HOPO acids or the HOPO acid chlorides to obtain the desired HOPO derivatives in two synthesis steps after final deprotection. All compounds were evidenced by NMR and MS analyses.