abstract
The present work emphasizes the value of periodic density functional theory (DFT) calculations in the assessment of the vibrational spectra of molecular crystals. Periodic calculations provide a nearly one-to-one match between the calculated and observed bands in the inelastic neutron scattering (INS) spectrum of crystalline 4-phenylbenzaldehyde, thus validating their assignment and correcting previous reports based on single molecule calculations. The calculations allow the unambiguous assignment of the phenyl torsional mode at ca. 118-128 cm(-1), from which a phenyl torsional barrier of ca. 4000 cm(-1) is derived, and the identification of the collective mode involving the antitranslational motion of CH...O bonded pairs, a hallmark vibrational mode of systems where C-H...O contacts are an important feature.
keywords
INELASTIC NEUTRON-SCATTERING; DOT-O INTERACTIONS; HYDROGEN-BOND; FLUORESCENCE-SPECTRA; MOLECULAR-CRYSTALS; RAMAN; ROTATION; IR; SPECTROSCOPY; S-0
subject category
Biochemistry & Molecular Biology; Chemistry
authors
Nolasco, MM; Araujo, CF; Vaz, PD; Amado, AM; Ribeiro-Claro, P
our authors
Catarina F. Araújo
Researcher
Mariela Martins Nolasco
Assistant Researcher
Paulo Ribeiro-Claro
Associate Professor with Aggregation
Pedro Miguel Duarte Vaz
Collaboratoracknowledgements
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. A.M.A. acknowledges financial support given by POCentro, COMPETE 2020, Portugal 2020, European Community through the FEDER and FCT to Unidade de I&D Quimica-Fisica Molecular of the University of Coimbra (UIDB/00070/2020). FCT is gratefully acknowledged for funding a PhD grant to C.F.A. (SFRH/BD/129040/2017) and a researcher contract to M.M.N. (IF/01468/2015) under the program IF 2015.