Insight into the structural properties of methyl orange, hexamethyl pararosaniline chloride dyes doped potassium hydrogen phthalate ammonium sulfate crystals and their antibacterial applications

Abstract

This present work aims to investigate the influence of organic dyes (methyl orange (MO), hexamethyl pararosaniline chloride (HPC)) doped with potassium hydrogen phthalate ammonium sulfate (KHPA) crystals. The solution-grown dye doped KHPA were examined using powder-XRD, FT-IR, UV–visible spectroscopy, dielectric, microhardness, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and antibacterial activity studies. PXRD spectrum revealed that the solution-grown crystal belongs to orthorhombic system with excellent cell parameters. The grain size of the dye doped KHPA crystal was found to be D = 26.609 nm. The FTIR spectral analysis was identified the presence of various functional groups and the UV spectrum showed absorbance around 280 nm for the solution-grown dye doped crystals of KHPA. The Tauc’s plots of pure KHPA exhibited band gap energy of 4.5 eV, whereas the band gap energies of MO and PHC doped KHPA crystals showed 4.25 eV and 4.13 eV, respectively. Thermal stability of the as-grown dye doped KHPA crystals was analyzed by TGA and DTA techniques. The dielectric study revealed that the dielectric constant and dielectric loss decreased while increasing the frequency, whereas the microhardness study showed that the dye-doped crystals belong to the soft material category. CV of dye-doped crystals exhibited a strong reduction potential wave at − 0.75 V for HPC doped KHPA and − 0.6 V for MO doped KHPA. EIS study exhibited the decrease in impedance with change in frequency indicating a negative temperature coefficient of resistance and low ion mobility of the dye doped KHPA crystals. The antibacterial study revealed that the Gram-negative bacteria have more resistivity than Gram-positive bacteria.