Poly(azomethine-phenothiazine)s with efficient emission in solid state

A series of poly(azomethine-phenothiazine)s was synthesized by using the reaction of 10-methyl-phenothiazine-3,7-dicarbaldehyde with diamines containing fluorene chromophore or polyethylene glycol (PEG) flexible spacer. The polymers were structurally characterized by H-1 NMR and FTIR spectral techniques, elemental analysis and wide angle X-ray diffraction. Their thermal properties were monitored by using variable temperature polarized light microscopy whilst their photophysical behaviour was demonstrated by using UV-vis absorption and photoluminescence spectroscopy. All of these polymers were found to emit green light with high quantum yield, in both solution and solid state. The emission efficiency in solid state was further improved by mixing the fluorene containing polymers with the PEG containing one, when continuous films with quantum efficiency of up to 16% were obtained.