Spectroscopic Investigations of Intermolecular Interactions between Different Parts of Molecules

Abstract

Dedicated to Dr. Karl Heinzinger on the occasion of his 60th birthday With the low temperature matrix techique we have observed different isolated IR OH vibration bands caused by van der Waals forces of single atom groups of the matrix molecules. With a series of different perhalogenated matrix molecules these different OH band frequency shifts AvO H can be correlated to OH interactions with C-F, C-Cl, C-Br resp. C-I groups. At higher temperatures T (solution spectra) the band positions of the different interactions become more similar because dv/d T increases with increasing interaction. This result clarifies why at room temperature band shoulders are observed and correlates these clearly to the different matrix bands and therefore to different interactions. These experiments demonstrate that intermolecular van der Waals potentials of asym metric molecules cannot be approximated by one spheric potential but are angle dependent. This indicates the complexity of describe condensed media.S p e c tr o s c o p ic I n v e s tig a tio n s o f I n te r m o le c u la r I n te r a c tio n s b e tw e e n D if fe r e n t P a r t s o f M o le c u le s *

Breaking the Structure of Liquid Hydrogenated Alcohols Using Perfluorinated tert-Butanol: A Multitechnique Approach (Infrared, Raman, and X-ray Scattering) Analyzed by DFT and Molecular Dynamics Calculations

“…It is in this context that we have focused our attention to perfluorinated tert -butanol (TBF). This molecule has been studied in the gaseous phase, in rare gas matrices and in the liquid state. − Recent investigations combining several techniques (vibrational spectroscopy and X-ray diffraction) analyzed at the light of quantum density functional theory (DFT) and molecular dynamics have confirmed that this alcohol is poorly associated . In particular, it was found that the liquid phase is essentially constituted by monomers, with a population of about 70%, accompanied by a minor fraction of dimers and almost negligible trimers.…”