title: Combined spectroscopic and DFT studies on 6-bromo-4-chloro-3-formyl coumarin.
abstract: The FTIR and FT-Raman spectra of 6-bromo-4-chloro-3-formyl coumarin (6B4C3FC) have been recorded in the region 4000-400 and 4000-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands were obtained by the density functional theory (DFT) using 6-31G(d,p) basis set. The harmonic vibrational frequencies were scaled and compared with experimental values. The observed and the calculated frequencies were found to be in good agreement. The UV-Visible spectrum was also recorded and compared with the theoretical values. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The first order hyperpolarizability (β0) of 6B4C3FC is 21 times greater than that of urea. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. Information about the charge density distribution of the molecule and its chemical reactivity has been obtained by mapping molecular electrostatic potential surface. In addition, the non-linear optical properties were discussed from the dipole moment values and the excitation wavelength in the UV-Visible region.
authors.affiliation: Department of Physics, SCSVMV University, Enathur, Kanchipuram 631561, India; Department of Physics, Pachaiyappa's College for Men, Kanchipuram 631 503, India. Electronic address: jsrkraj@gmail.com.
authors.forename: R K
authors.initials: RK
authors.lastname: Raj
authors.affiliation: Research & Development, St. Peter's University, Avadi, Chennai 600 054, India.
authors.forename: S
authors.initials: S
authors.lastname: Gunasekaran
authors.affiliation: Department of Physics, Pallavan College of Engineering, Kanchipuram 631 502, India.
authors.forename: T
authors.initials: T
authors.lastname: Gnanasambandan
authors.affiliation: Department of Physics, L.N. Govt. Arts College, Ponneri, India.
authors.forename: S
authors.initials: S
authors.lastname: Seshadri
mesh_terms: D003374:Coumarins / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D017711:Nonlinear Dynamics; D055620:Optical Phenomena; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D055672:Static Electricity; D013816:Thermodynamics; D014732:Vibration
chemical_list: D003374:Coumarins
keywords: 6B4C3FC; DFT; FT-Raman; FTIR; NBO