title: Vibrational spectra of quinoline-4-carbaldehyde: combined experimental and theoretical studies.
abstract: The FT-IR (4000-50 cm(-1)), FT-Raman (4000-50 cm(-1)) and Dispersive-Raman (3500-50 cm(-1)) spectra of solid sample of quinoline-4-carbaldehyde (Q4C) have been recorded. The molecule structure, vibrational frequencies, IR intensities, Raman intensities and thermodynamic properties of the two possible aldehyde rotamers of Q4C have been obtained with the Hartree-Fock (HF) and density functional B3LYP calculations employing the 6-311++G(d,p) basis set. Q4C has two stable conformers, in one of which the O atom of the aldehyde is oriented to form a H-bond with one of the hydrogens of quinoline, while in the other there is no such a H bond. The conformer with an extra H-bond is more stable and, thus it is the ground state. The computed vibrational frequencies of the lowest energy conformer agree also slightly better than those of the higher energy rotamer with the experimental frequencies after the computed frequencies are scaled. The temperature dependence of the standard heat capacities (C), standard entropies (S) and standard enthalpy (H) changes of Q4C has been discussed.
authors.affiliation: Department of Physics, Faculty of Arts and Sciences, Fatih University, Büyükçekmece, 34500 Istanbul, Turkey. mkumru@fatih.edu.tr
authors.forename: M
authors.initials: M
authors.lastname: Kumru
authors.forename: V
authors.initials: V
authors.lastname: Küçük
authors.forename: P
authors.initials: P
authors.lastname: Akyürek
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D008968:Molecular Conformation; D011804:Quinolines / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013816:Thermodynamics; D014732:Vibration
chemical_list: D000447:Aldehydes; D011804:Quinolines; C585856:quinoline-4-carbaldehyde; C037219:quinoline
keywords: DFT; HF; IR spectra; Normal mode; Quinoline-4-carbaldehyde; Raman spectra