Spectroscopic and molecular structure investigation of Propachlor herbicide: A combined experimental and theoretical study.

• Propachlor FT-IR and FT-Raman has been measured. • The QTAIM and ELF reveals the inter and intramolecular hydrogen and chemical bonding. • The most stable conformer has been carried out with the aid of PES. • Molecular docking and bioactivity study shows the herbicidal active nature of propachlor. • MDS exhibits the binding stability of propachlor. The Fourier Transform Infrared (FT-IR) and FT- Raman spectra of propachlor(PCRM) herbicide are recorded in the region 400–4000cm−1and 50–3500cm−1 respectively. Vibrational spectrum is performed with NCA and the wavenumber's are scaled by using wavenumber linear scaling (WLS) method to discover the herbicidal active region. The optimized molecular structure, vibrational frequencies corresponding vibrational assignments of PCRM have been investigated experimentally and theoretically using Gaussian 09 software package. The solvent effect of monomer with water complexes (PCRW) has been investigated at the B3LYP/6-311G (d,p) level to identify the hydrogen bonding interactions. The two methodologies used in recent years to partition the molecular space are the AIM theory and the ELF function, which are used to provide new insights into chemical bonding of potential propachlor herbicide. Potential energy surface (PES) scanning with six dihedral angles is performed to identify the stable conformer. The structure activity descriptors are measured from UV, HOMO-LUMO analysis, molecular electrostatic potential etc. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analysed using NBO analysis. Hirshfeld surface analysis is performed to explain intermolecular interactions. Furthermore, the herbicidal activity is confirmed with molecular docking studies and molecular dynamic simulations (MDS). Image, graphical abstract [ABSTRACT FROM AUTHOR]