Alcohol/aromatic interactions

In this study, alcohol-hydrocarbon solutions were chosen to conduct a systematic study of the effect of hydrogen bonding on the structure of binary solutions composed of t-butanol/cyclohexane, and t-butanol/benzene. In the course of our investigation, we became more concerned about the physical properties of liquids, as monitored by spectroscopy and theory, to enable us to achieve a better understanding of the microscopic properties of such binary mixtures. During the course of our investigation, we studied the intermolecular forces (bonds) involved upon mixing. Benzene and cyclohexane have been chosen due to their comparable size but very different electronic properties. We must also remember that infrared spectroscopy (our spectroscopic method of choice) is not only suited to monitor the alcohol hydroxyl groups, but also other vibrational modes as well, such as C-H bonds. Infrared spectra contain a wealth of information that may be used to describe molecular motion in liquid systems. The latter is best described by intermolecular forces and torques that determine the molecular motion, therefore, infrared band shape analysis of a vibrational mode of a molecule is to be evaluated in terms of a statistical picture of its dynamics in the liquid state. New techniques have been developed, and methods for characterizing molecular re-orientations have been employed in many pure compounds. Due to a need for data describing two-component systems over a wide concentration range, infrared spectroscopy appears to be an important tool to conduct investigations of molecular motion and local structure. Systems with weak hydrogen bonding have been studied for a long However, the aromatic ring\u27s interaction with weak-to-medium strength proton appears to play a major role in the structure of certain biomolecules. Alcohols are of forming clusters (self-association) via hydrogen bonding in the liquid phase. A the alcohol-benzene interaction is of concern, since it will contribute to the understanding of hydrogen bonding with π electrons. The optimized structure butanol and those of tert-butanol/tert-butanol and tert-butanol/benzene (Tb-Tb and Tb-B) dimers were obtained by quantum mechanical ab initio calculations at the HF/6–311++G(d,p) level, with electron correlation energy corrections using the local Moller-Plesset perturbation method. The small H-bond energies for these dimers are mostly compensated by the entropy change that accompanies the complexation reaction. Correlation times and temperature-dependent line width analysis of two selected benzene infrared bands in several liquid Tb-B mixtures indicate that there are marked mode sensitive differences in the relaxation mechanisms taking place in the solution. These are due to formation of Tb-B complexes similar to those predicted by gas-phase theoretical calculations