Ultrasound-Assisted Polymerization of Dyes with Phenylenediamines: Facile Method To Design Polymeric Photosensitizers with Enhanced Singlet Oxygen Generation Characteristics and Anticancer Activity

The present work reports for the first time ultrasound-assisted polymerization of Alizarin Red (AR), Amido Black 10B (AB-10B), and 1,4-benzoquinone (BQ) with o- and p-phenylenediamines. The synthesized polymeric dyes were characterized for their spectral and morphological characteristics. Theoretical calculations were performed via DFT/B3LYP and M06-2X methods with 6-311++G(d,p) basis set using Gaussian 09 software, and the results were analyzed for the prediction of the optoelectronic properties of the polymers. The theoretically predicted IR and UV spectra determined by DFT/B3LYP and M06-2X methods were found to be in good agreement with the experimental results. Fourier transform infrared (FTIR) and H-1 NMR studies confirmed the polymerization of the dyes, while transmission electron microscopy (TEM) and scanning electron microscopy (SEM) studies revealed the formation of well-organized nanostructured morphology. X-ray diffraction (XRD) studies confirmed the formation of semicrystalline polymers. The polymeric dyes exhibited singlet oxygen quantum yields ranging between 20 and 70% and hold immenense potential to be used in photodynamic therapy.