6.1.1. Frontier molecular orbitals

6.1.1. Frontier molecular orbitals (FMOs) and electronic absorption spectra
The HOMO and LUMOare also called frontiermolecular orbital since
they lie at the outermost electron boundaries of the molecules. The
HOMO and LUMO energy levels are found related to the nucleophilic
and electrophilic characters of compound, respectively. Also, they
have great importance in describing the electronic transitions and excitation
properties of molecules. The orbital energy level analysis of the
studied compounds showed EHOMO values of −6.6500, −6.6851,
−6.6287 and −6.6097 eV and ELUMO values of −0.2874, −0.2868,