Synthesis and fluorescence properties of cyclophosphazenes containing thiazole or thiadiazole rings

In the present work, a series of cyclophosphazenes containing thiazole or thiadiazole rings (5-8) was synthesized. The hexakis-[3'-(1',2',3'-thiadiazol-4'-yl)phenoxy] (5) and hexakis-[5'-oxy-2'-methylbenzothiazole] (6) cyclotriphosphazene derivatives were synthesized from the reactions of hexachlorocyclotriphosphazene (1) with 3-(1,2,3-thiadiazol-4-yl)phenol (3) and 5-hydroxy-2-methylbenzothiazole (4), respectively. The octakis-[3'-(1',2',3'-thiadiazol-4'-yl)phenoxylcyclotetraphosphazene (7) was obtained from the reaction of octachlorocyclotetraphosphazene (2) with compound 3. Furthermore, heptakis(5'-oxy-2'-methylbenzothiazole)monochlorocyclotetraphosphazene (8) was also synthesized from the reaction of compound 2 with 4. All the obtained compounds (5-8) were fully characterized by elemental analysis and spectroscopic techniques (such as mass, H-1, C-13 and P-31 NMR). The molecular and crystal structure of 6 was also characterized by X-ray crystallography. Compounds 5-8 are reported for the first time in this study. The fluorescence properties of these cyclophosphazene derivatives (5-8) were investigated in tetrahydrofuran (THF) solution. (C) 2017 Elsevier Ltd. All rights reserved.