A regioselective route to new polytopic receptors by diaminolysis of chlorocyclotriphosphazatriene-containing crown ethers

A general strategy is reported for the facile preparation of diamino-deriva tized PNP-crowns, giving access to a large range of new host molecules of d ifferent sizes, shapes, and topology. Reactions of the tetrachloro-PNP-crow n precursor 1 with polymethylene-diamines 2a-h (n = 2-6, 8, 10, 12) proceed rapidly and regioselectively via substitution reactions of CI at the PNP-c rown-forming P-atoms; the reaction is assisted by the macrocyclic 1,3-oxy(t etraethylenoxy) substituent at the N3P3 ring which provides a site for the hydrogen-bond-driven assembly of reagents 1 and 2. The products belong to t hree different classes of polytopic receptors: lateral macrobicycles (ansa, 5a-h), bola-amphiphilic tritopic bis-crowns (bino, 6a-h), and tetratopic c ylindrical. macrotricycles (bis-bino, 8a-h). The structures of 5, 6, 8, and 10b were established by MS and P-31 NMR spectroscopy, and an X-ray crystal structure was obtained for the bis-bino 1,3-diaminopropane PNP-crown deriv ative 8b. Preliminary screening by a simple TLC test of the metal-cation co mplexing properties of the series of compounds 5, 6, and 8 revealed their c apacity to bind both harder (alkali and alkaline earth) and softer (transit ion) metal cations, with significant affinity being displayed toward potass ium and silver cations by many of the ligands studied.