Browsing by Author "Fonseca Guerra, Célia"

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    Designing self-assembled rosettes : why ammelineis a superior building block to melamine
    (2019-02-01) Petelski, Andre Nicolai; Fonseca Guerra, Célia
    In supramolecular chemistry, the rational design of self-assembled systems remains a challenge. Herein, hydrogen-bonded rosettes of melamine and ammeline have been theoretically examined by using dispersion-corrected density functional theory (DFT-D). Our bonding analyses, based on quantitative Kohn Sham molecular orbital theory and corresponding energy decomposition analyses (EDA), show that ammeline is a much better building block than melamine for the fabrication of cyclic complexes based on hydrogen bonds. This superior capacity is explained by both stronger hydrogen bonding and the occurrence of a strong synergy.
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    Understanding the influence of alkali cations and halogen anions on the cooperativity of cyclic hydrogen-bonded rosettes in supramolecular stacks
    (2022-11-07) Petelski, Andre Nicolai; Fonseca Guerra, Célia
    Hydrogen-bonded supramolecular systems are known to obtain extra stabilization from the complexation with ions, like guanine quadruplex (GQ). They experience strong hydrogen bonds due to cooperative effects. To gain deeper understanding of the interplay between ions and hydrogen-bonding cooperativity, relativistic dispersion-cor rected density functional theory (DFT-D) computations were performed on triple layer hydrogen-bonded rosettes of ammeline interacting with alkali metal cations and halides. Our results show that when ions are placed between the stacks, the hydrogen bonds are weakened but, at the same time, the cooperativity is strengthened. This phenomenon can be traced back to the shrinkage of the cavity as the ions pull the monomers closer together and therefore the distance between the monomers becomes smaller. On one hand this results in a larger steric repulsion, but on the other hand, the donor-acceptor interactions are enhanced due to the larger overlap between the donating and accepting orbitals leading to more charge donation and therefore an enhanced electrostatic attraction.