Structures of the 5 PIH analogues examined in the present study: salicylaldehyde p-t-butylbenzoyl hydrazone (206), 2-hydroxy-1-naphthylaldehyde m-chlorobenzoyl hydrazone (308), 2-hydroxy-1-naphthylaldehyde m-fluorobenzoyl hydrazone (309), 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311), and 2-hydroxy-1-naphthylaldehyde 2-thiophenecarboxyl hydrazone (315). The structure of these ligands is compared with DFO and the parent compound, PIH.