The investigation of structural and thermosensitive properties of new phosphazene derivatives bearing glycol and amino acid

Abstract

In this study, hexachlorocyclotriphosphazene, N₃P₃Cl₆ (cylotriphosphazene), was reacted with hydrophilic and hydrophobic groups to synthesize amphiphilic phosphazene derivatives (4–12). Cylotriphosphazene was reacted triethylene glycol monomethyl ether (TEGME), dipropylene glycol monomethyl ether (DPGME), diethylene glycol monobutyl ether (DEGBE), (1 : 3 mole proportion) in the presence of sodium hydride and using tetrahydrofuran (THF) as solvent at −60 °C. Three isomers (nongeminal cis-2,4,6 (1a–3a); nongeminal trans-2,4,6 (1b–3b); geminal 2,2,4 (1c–3c)) were isolated from the reaction of hexachlorocyclotriphosphazatriene (trimer) (1) with TEGME, DPGME and DEGBE. The substitution reactions of cis-tris isomers (1a–3a) with 4-amino butyric acid, 5-amino valeric acid and 6-amino hexanoic acid were separately done to provide amphiphilic phosphazenes (4–12). All compounds were characterized by using elemental analysis, ³¹P NMR and mass spectroscopy. Thermosensitive properties of compounds were studied. The compounds (4–12) were soluble in both water and organic media that shows they are amphiphilic molecules. Concentration-dependent LCST (Lower Critical Solution Temperature) behaviours of new compounds (4–12) were measured in water. Compounds 7, 9, 11 and 12 exhibited a reversible and thermosensitive phase transition in aqueous medium, from soluble to insoluble states.