Experimental and theoretical studies of benzoquinone modified poly( ortho -phenylenediamine): singlet oxygen generating oligomers

The present work reports microwave-assisted polymerization of 1,4-benzoquinone with ortho-phenylenediamine for the effective generation of singlet oxygen (1O2). The oligomeric structures were confirmed by the experimental IR, 1H-NMR, ultraviolet-visible and TEM analyses. The theoretical IR and UV data were computed using DFT/B3LYP method with 6-311G basis set, and the 1H-NMR spectra were computed by gauge-independent atomic orbital (GIAO) method. The experimental IR, 1H-NMR, and UV studies were found to be in close agreement with the experimental investigations. The TEM studies confirmed the formation of mixed morphology consisting of cluster of fused particles joined together to form entangled chains. 1O2 generation studies revealed that the oligomer containing 70% benzoquinone content exhibited the highest quantum yield value of 0.057. These results hold promise for utilization of these oligomers as photosensitive probes applicable in photodynamic therapy for the treatment of various infectious diseases.