Crystal structure, spectroscopic and electronic features of 6-(Chloromethyl)uracil

Abstract

The structural, spectroscopic and electronic features of the 6-(Chloromethyl)uracil (6CMU) have been characterized by using single crystal X-ray diffraction (XRD), 1H and 13C NMR, UV–Vis. and vibrational (FT-IR and Raman) spectroscopies. The classical geometry analyses of intermolecular interactions, which were performed on the basis of experimental crystal structure, have been supported by Hirshfeld surface analysis. Theoretical molecular geometry optimization parameters (bond lengths and angles), vibrational wavenumbers, proton and carbon NMR chemical shifts, UV–Vis. parameters (wavelengths, excitation energies, oscillator strength) and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies have been calculated using density functional theory (DFT/B3LYP) quantum chemical method with 6–311++G (d,p) basis set to compare with the experimental results. Assignments of the vibrational wavenumbers have been carried out by Potential Energy Distribution (PED) analyses by using VEDA 4 software. UV–Vis. electronic absorption parameters, HOMO-LUMO analyses, Natural Bond Orbital (NBO) results and Molecular Electrostatic Potential (MEP) surface of 6CMU have been studied to explicate electronic transitions, intramolecular charge transfer and interaction sites in the molecule. The computed vibrational wavenumbers, NMR chemical shifts and UV–Vis. parameters have been in good agreement with the corresponding experimental data and literature.