Synthesis, characterization, spectral properties and evaluation of the photophysical behavior of novel Congo Red based polymers

New polyazomethines were synthesized by acid-catalyzed polycondensation of Congo Red azo dye with two dialdehydes to form polymers with azo- and azomethine groups in main chain. Polycondensation proceeded at a reflux temperature in DMF solution with formic acid as a catalyst. Copolymers containing azo- and azomethine groups in main chain were characterized by 1H NMR, FT-IR, and UV–Visible spectrometry, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC). The polymers exhibited photoinduced anisotropy as a result of E-Z photoisomerization. Holograms in thin polymeric films for parallel and perpendicular orientation of the object and reference beams polarization have been recorded. In the case of perpendicular polarization, diffraction efficiencies of the hologram gratings are higher comparing to the parallel. This may be due to the polymer matrix structural rearrangement peculiarities. [Display omitted] •Synthesis and molecular structure of polyazomethines based on Congo Red azo-dye.•During photoinduced isomerization partial photodestruction process can be observed.•Photophysical properties confirmed surface-relief-grating formation.•For perpendicular polarization orientation the values of diffraction efficiency are greater than in case of parallel one.