New design of cyclotriphosphazene derivatives bearing carbazole units: The syntheses, characterization, and photophysical properties

In the current work, di- and tetra- aniline substituted cyclotriphosphazene derivatives (1a-b) were prepared from commercially available cyclotriphosphazene and underwent nucleophilic substitution reaction with 9-ethyl-9Hcarbazol-3-ol (2) to produce three new cyclotriphosphazene compounds having two- (3a), three- (4b) and fourcarbazole units (5b), respectively. The full characterization data of the targeted compounds were obtained by utilizing elemental analysis, mass spectrometry, H-1, and P-31 NMR spectroscopies. The structure of compound 3a was further supported by single crystal X-Ray diffraction technique. As the photophysical aspect of the synthesized compounds 3a, 4b and 5b, UV- Vis and steady-state fluorescence spectroscopies were used in different organic solvents. In addition, time-resolved fluorescence and 3D-fluorescence spectroscopies were applied to get deeper information about the photophysical properties of targeted compounds.