General procedure for the synthesis of 1,4,7-tris-tosyl-1,4,7-triazacyclononane from 1,2-bis(tolyloxy)ethane and N,N′,N′′-tris(p-toluenesulfonyl)diethylidene tris(amine) disodium salt: a solution of bis(p-toluenesulfonyl)ethylene glycol (59.5 g, 0.16 mol) in DMF (300 ml) was added slowly and dropwise over a period of three hours to a solution containing tris (p-toluenesulfonyl) diethylenetriamine disodium salt (98 g, 0.16 mol) solution in DMF (950 ml). The reaction mixture was heated and stirred at 100°C. After completion of the reaction, heating was stopped and distilled water (575 ml) was added to induce precipitation of the product. The immediately formed white precipitate was collected by filtration and dried under vacuum to afford the target macrocyclic compound 1,4,7-tri-tosyl-1,4,7-triazacyclononane (71.8 g, 76% yield). The product was characterized as follows: 1H NMR (200 MHz, CDCl3) δ 7.67 (d, 6H), 7.29 (d, 6H), 3.39 (s, 12H), 2.41 (s, 9H).