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

Abstract

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-9H-carbazol-3-ol (2) to produce three new cyclotriphosphazene compounds having two- (3a), three- (4b) and four-carbazole units (5b), respectively. The full characterization data of the targeted compounds were obtained by utilizing elemental analysis, mass spectrometry, 1H, and 31P 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.