Synthesis of fluorescence organocyclotriphosphazene derivatives having functional groups such as formyl, Schiff base and both formyl and Schiff base without using Ar or N2 atmosphere

Abstract

In the present study, hexa(4-formyl-phenoxy)cyclotriphosphazene(2) and hexa(4-formyl-2-methoxy-phenoxy)cyclotriphosphazene(3), which were previously synthesized in boiling solvent under N2 atmosphere, were produced again at room conditions without using Ar or N2 atmosphere by the same method. We detected that both 2 and 3 formed with very high yields even under this mild conditions. After that, 1 equiv of the compounds (2 and 3) were reacted with 12 equiv of some anilines derivatives with different substituted groups such as hydroxyl, cyano, mercapto, heterocyclic, carboxyl, chloro for the synthesis of new organocyclotriphosphazene derivatives incorporating six non-conjugated Schiff base groups. However, such compounds did not form from all of the selected anilines derivatives. The reactions of the compounds (2 and 3) with 4-carboxy-aniline and 4-cyano-aniline led to the formation of the organocyclotriphosphazenes bearing both formyl and Schiff base units. The structures of the synthesized molecules were determined using FT-IR, 1H NMR and 31P NMR. Then, the synthesized compounds were photophysically investigated by UV absorption and fluorescence emission spectroscopy in solution state. Photophysical studies indicate that the compound 1 and all of the obtained compounds have luminescence properties and large Stoke's shifts. Some compounds showed blue-red emission peak having rather large Stoke's shifts in the range of 390–800 nm.