Synthesis and spectral properties of fluorene substituted cyclic and polymeric phosphazenes

Abstract

Two new fluorene chromophores were prepared by the Suzuki cross-coupling reactions of 9,9-dimethylfluorene-2-boronic acid pinacol ester with bromophenol or 3,5-dibromophenol, respectively. The cyclic compounds were obtained by the reactions of chromophores with hexachlorocyclotriphosphazene (N3P3Cl6). For the comparison of spectral properties of cyclic compounds, the poly(bis-fluorenyl)phosphazene was also prepared from nucleophilic displacement reactions of chromophore with polydichlorophosphazene (Cl2P=N)(n). The synthesized compounds were characterized by standard spectroscopic methods (MALDI-TOF mass spectrometry, gel permeation chromatography for poly(bis-fluorenyl)phosphazene, FT-IR, H-1, C-13 and P-31 NMR spectroscopy) and their structure was confirmed by elemental analysis. The spectral properties were analysised by UV-Vis and fluorescence spectroscopy, thermogravimetric analysis, differential scanning calorimetry and cyclic voltammetry. (C) 2016 Elsevier B.V. All rights reserved.