Synthesis and structural studies of copper() complex with NS based -substituted pendant phosphonic acid arms

The synthesis of a heteromacrocyclic bifunctional chelator with phosphonic acid pendent arms is presented along copper( ii ) complexation. Ligand N 2 S 2 -POH featuring N , N ′-bis-substituted phosphonate pendent arms was isolated in respectable yields, characterized, and chelated to copper( ii ). Implementation of both Moedritzer-Irani and Kabachnik-Fields conditions using aza-thia macrocycle 1,8-dithia-4,11-diazacyclotetradecane afforded 1,8-dithia-4,11-diazacyclotetradecane-4,11-diyl-bis-(methylene)-bis-(phosphonic acid) ( N 2 S 2 -POH ). Kinetic NMR studies provided four acid dissociation constants with respect to hydronium ion concentration. Benesi-Hildebrand binding experiment provided a conditional formation constant of 2.8 × 10 4 M −1 . Heteromacrocycle N 2 S 2 -POH readily formed an encapsulated copper( ii ) chelate at room temperature, which was examined through EPR analysis. Physical properties and copper chelation of phosphonic acid substituted 14-[ane]N 2 S 2 macrocycle for use as a potential radio imaging ligand.