Experimental and Theoretical Studies of Novel Azo Benzene Functionalized Conjugated Polymers: In-vitro Antileishmanial Activity and Bioimaging

Neetika Singh,Ufana Riaz,Abdur Rub,Mohd Arish,Prabhat Kumar

doi:10.1038/s41598-019-56975-x

Abstract

To study the effect of insertion of azobenzene moiety on the spectral, morphological and fluorescence properties of conventional conducting polymers, the present work reports ultrasound-assisted polymerization of azobenzene with aniline, 1-naphthylamine, luminol and o-phenylenediamine. The chemical structure and polymerization was established via Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (1H-NMR) spectroscopy, while the electronic properties were explored via ultraviolet-visible (UV-vis) spectroscopy. Theoretical IR and UV spectra were computed using DFT/B3LYP method with 6–311G basis set while theoretical 1H-NMR spectra was obtained by gauge independent atomic orbital (GIAO) method. The theoretically computed spectra were found to be in close agreement with the experimental findings confirming the chemical as well as electronic structure of the synthesized polymers. Morphology was investigated by X-ray diffraction and transmission electron microscopy studies. Fluorescence studies revealed emission ranging between 530–570 nm. The polymers also revealed high singlet oxygen (1O2) generation characteristics. In-vitro antileishmanial efficacy as well as live cell imaging investigations reflected the potential application of these polymers in the treatment of leishmaniasis and its diagnosis.

Highlights

UV light which limits their biological applications as UV light is strongly scattered by biological systems and damages the cells and tissues
The molecular weight was determined by Gel Permeation Chromatography (GPC) technique using 0.03% polymer solution dissolved in n-methyl-2-pyrrolidone (NMP) containing 0.1% LiCl and the weight average molecular weights (Mw) were found to be ranging between 10,500–19,00023,27
The synthesized polymers were characterized via fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H-NMR), ultraviolet-visible spectroscopy (UV-vis) while the morphology was investigated by using X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies

Summary

Introduction

UV light which limits their biological applications as UV light is strongly scattered by biological systems and damages the cells and tissues. Theoretical and experimental spectral studies of AB, PANI-AB, PNA-AB, PLu-AB and PPd-AB. The IR spectrum of PLu-AB (given in Supplementary Information as Fig. S2(d)) revealed peaks at 3410 cm−1 and 3020 cm−1 correlated to NH/OH ring stretching vibrations while the peaks associated with azo group were observed at 2164 cm−1 and 2156 cm−1 22,26.

Results

Conclusion