Synthesis, characterization and aggregation induced enhanced emission properties of tetraaryl pyrazole decorated cyclophosphazenes

Abstract

A series of cyclotriphosphazenes N₃P₃(O-C₆H₄-C₃N₂-(C₆H₅)₃)₆ (3), N₃P₃(O₂C₁₂H₈)(O-C₆H₄-C₃N₂-(C₆H₅)₃)₄ (4), N₃P₃(O₂C₁₂H₈)₂(O-C₆H₄-C₃N₂-(C₆H₅)₃)₂ (5) and N₃P₃(OPh)₅(O-C₆H₄-C₃N₂-(C₆H₅)₃) (7) decorated with aggregation induced enhanced emission (AIEE) luminogen (tetraaryl pyrazole) are synthesized by the reaction of N₃P₃Cl₆, N₃P₃(O₂C₁₂H₈)Cl₄, N₃P₃(O₂C₁₂H₈)₂Cl₂ and N₃P₃Cl₅(O-C₆H₄-C₃N₂-(C₆H₅)₃) (6) with 4-(1,3,5-triphenyl-1H-pyrazol-4-yl)phenol (phenol in the case of 6). Intriguingly all the newly synthesized tetraaryl pyrazole decorated cyclotriphosphazenes exhibit the aggregation induced enhanced emission phenomenon. The luminogen decorated cyclophosphazenes have also been investigated as a probe for the detection of explosive picric acid.