Heechan Kim, Robert J. Gilliard · 2025 · Journal of the American Chemical Society · ACS Publications · added 2026-04-20
Helicates and helicenes represent two prominent classes of synthetic molecular helices, desirable for their potential in chiroptical applications. Incorporating boron into their backbone presents a pr Show more
Helicates and helicenes represent two prominent classes of synthetic molecular helices, desirable for their potential in chiroptical applications. Incorporating boron into their backbone presents a promising strategy to enhance the optical properties; however, the development of boron-doped helical systems featuring tunable emission, high configurational stability, and strong chiroptical response has been limited by synthetic challenges. We report the chemistry of bora[7]helicene and its dimeric diborahelicate. While the dimeric form is thermodynamically favored in the haloborane precursor, saturation of the boron coordination sphere by exogenous carbene or carbone ligands induces monomerization, reverting the structure to the bora[7]helicene. By employing a variety of ligands, late-stage structural diversification was achieved, yielding the first examples of cationic boron helices, which show exceptional emission tunability across the entire visible spectrum, and chiroptical responses surpassing those of previously reported [7]helicenes. Theoretical studies indicate that the double-helix geometry and the intramolecular charge transfer play a significant role in achieving high dissymmetry factors. Show less
ABSTRACTTo understand the nature of heterogeneous catalytic processes and improve their efficiency, it is necessary to conduct both experimental and theoretical studies. At the same time, there is no Show more
ABSTRACTTo understand the nature of heterogeneous catalytic processes and improve their efficiency, it is necessary to conduct both experimental and theoretical studies. At the same time, there is no unified approach to obtaining the necessary data using quantum chemistry methods. In this work, problems of the existing calculational approaches are analyzed. The obtained information is used to develop the original three‐layer embedded cluster model approach, which is shown to be the most effective. The general algorithm for obtaining such models for various oxides is formulated. The sufficient accuracy of the proposed models in predicting geometric and energy characteristics, vibrational frequencies, activation barriers, and thermodynamic characteristics is verified. The specifics of calculating the thermodynamic characteristics of heterogeneous processes using the proposed cluster models is studied in detail. The developed approach is an effective tool for studying the mechanism of heterogeneous catalytic processes both by itself and in combination with experiment. Show less