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40361-AC1
Study of Arene-Arene Interactions in Lewis Acid Complexes
The support from the Petroleum Research Fund-administered by the American Chemical Society has had a major impact on the research project of the PI and many students at Miami University. We have been able to study non-covalent interactions involving aromatic rings both experimentally and computationally. From these studies, several publications have been produced, and several are under review or preparation, with both graduate and undergraduate co-authors. The PRF fund also enabled us to study the total synthesis of biologically active natural products. The results have also been published with both graduate and undergraduates. In addition to benefit Miami University students, a summer fellowship was awarded by the PRF to Jennifer Holt, an assistant professor at Penn State Erie, in conjunction with the type AC award. This fellowship enabled collaboration between the PI and the young investigators from Penn State (Dr. Jay Amicangelo is also participating in our study). As a result, a manuscript has been published, one under review, and another one under preparation, all from the work done from this collaboration. The following are some highlights from our recent study.
Triptycene-derived molecular model system has been used to quantitatively study arene-arene, arene-heterocycle, and oxygen lone pair-arene interactions in a minimal model system. Both enthalpy and entropy are obtained for these non-covalent interactions via variable temperature NMR spectroscopy. Similar to parallel-displaced arene interaction models, arene-arene interaction in the sandwich configurations also prefers the syn conformation if the two arenes are of opposite polarity, i.e., one electron-rich and the other electron-poor. Overall the sandwich configuration shows a smaller attractive interaction than the parallel-displaced configuration. Electrostatic model based on quadrupole moments alone cannot completely explain the preference for the parallel-displaced arrangement. A theoretical study in conjunction with the experimental results supports the notion that dispersion forces are import in non-covalent interactions involving aromatic rings. More recent results show that dispersive forces are critically important in the interactions between oxygen lone pair and electron-rich aromatic rings.
We are grateful to PRF-ACS for the support to the PI's research and to Miami University students. We will continue to work hard to make the best use of the funds from PRF, and we hope to earn continued support from PRF in the future.
