Various ligands with structural modifications of the N, N, N′, N′-tetraoctyl-3- oxapentanediamide (TODGA) skeleton were synthesised in good yields. These modifications include (1) the increase in chain length from one carbon to two carbons between the central ether oxygen atom and the amide moieties,(2) the addition of substituents on the carbon between the central oxygen atom and the amide moieties on ...