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Structural elucidation of synthesized 2,6-diphenylspiro[cyclohexane-1,3’-pyrido[1,2-
a]pyrimidine]-2’,4,4’-trione has been done by UV, FT-IR, 1H, 13C NMR and mass spectroscopy. The
molecule was further subjected to density functional theory (DFT) studies with B3LYP function using
6-31G(d,p) basis atomic set. The title molecule was investigated on the basis of thermodynamic properties,
polarizability, hyperpolarizability, intermolecular interactions, HOMO and LUMO energy values,
MESP, ESP and NBO computations to correlate experimental results with in-silico studies.
The FT-IR and FT-Raman spectra of (E)-1-(4-flourobenzylidene)urea (4FBU) was recorded and analyzed. The optimized geometrical parameters were calculated. The complete vibrationally assignments were performed based on PED analysis with the help of SQM method. NBO analysis was carried out to explore the various conjucative/hyperconjucative interactions within the molecule and their second-order stabilization energy. The HOMO and LUMO energy gap was studied. All theoretical calculations were performed based on B3LYP/6-31G (d,p) level of theory. The first order hyperpolarizability (β0) and related properties (β, α0, Δα) of 4FBU were calculated. Besides, FMOs, MEP, Mulliken atomic charges and various thermodynamic parameters such as entropy, heat capacity and enthalpy were also calculated.
Semi-empirical AM1 SCF-MO calculations have been used to find the structure optimization and conformational interconversion pathways of a system containing a six-membered ring. The system has the two symmetrical energy-minimum conformations, chair and twist. The chair conformation has the most stable geometry. Some quantum parameters such as HOMO and LUMO energy, the chemical hardness and chemical potential are discussed
Nonlinear optical investigation of (E)-1-(4-flourobenzylidene)urea using theoretical calculations