Synthesis, structural, TD-DFT, and optical characteristics of indole derivatives

New compounds of (E)-1-(3-chloro-1H-indol-2-yl)-N-(4-methoxyphenyl)methanimine [Indol-M] and (E)-1-(4-(((3-chloro-1H-indol-2-yl)methylene)amino)phenyl)ethan-1-one [Indol-A] were synthesized and subsequently converted to thin films via physical vapor deposition technique. Numerous characterization techniques were used including FTIR, nuclear magnetic resonance, X-ray diffraction, scanning electron microscope, and optical spectroscopy. Additionally, the optimization using TD-DFTD/Mol3 and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP) was performed. The XRD and FTIR spectra recorded experimentally were confirmed by TD-DFT calculations, proving their molecular structure. As determined by XRD, the crystallite size of [Indol-M]TF and [Indol-A]TF is 72.26 and 62.05 nm, respectively. SEM image depicts a one-dimensional morphological structure made up of tightly packed nanorods. The direct optical energy bandgaps computed using Tauc's equation for the [Indol-M]TF and [Indol-A]TF are 4.49 eV and 3.31 eV, respectively. As predicted by CASTEP TD-DFT, the optical properties agree well with the experimental values. [Indol-M]TF and [Indol-A]TF present good candidates for optoelectronics and solar cell applications.