An official website of the United States government
Abstract A recent publication by Wu and co‐workers demonstrated that the workhorse functional B3LYP tends to overemphasize the delocalization in antiaromatic molecules, leading to poor agreement between the calculated proton NMR values and the experimentally obtained numbers. Rather, they showed that the M11 functional affords the best agreement between theory and experiment. We have computationally re‐examined our previously published NICS‐XY scan data using M11‐determined geometries and find that, aside from the placement ofs‐indacene, the antiaromaticity trends for both sets of data are essentially identical.
more »
« less
Three-dimensional aromaticity in an antiaromatic cyclophane
Abstract Understanding of interactions among molecules is essential to elucidate the binding of pharmaceuticals on receptors, the mechanism of protein folding and self-assembling of organic molecules. While interactions between two aromatic molecules have been examined extensively, little is known about the interactions between two antiaromatic molecules. Theoretical investigations have predicted that antiaromatic molecules should be stabilized when they stack with each other by attractive intermolecular interactions. Here, we report the synthesis of a cyclophane, in which two antiaromatic porphyrin moieties adopt a stacked face-to-face geometry with a distance shorter than the sum of the van der Waals radii of the atoms involved. The aromaticity in this cyclophane has been examined experimentally and theoretically. This cyclophane exhibits three-dimensional spatial current channels between the two subunits, which corroborates the existence of attractive interactions between two antiaromatic π-systems.
more »
« less
- Award ID(s):
- 1664674
- PAR ID:
- 10154009
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 10
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract A set of fully‐conjugated indenofluorenes has been synthesized and confirmed by solid‐state structure analysis. The indeno[2,1‐c]fluorenes and their benzo‐fused analogues all contain the antiaromaticas‐indacene core. The molecules possess high electron affinities and show a broad absorption that reaches into the near‐IR region of the electromagnetic spectrum. All of the featured compounds reversibly accept up to two electrons as revealed by cyclic voltammetry. Analysis of molecule tropicity using NICS‐XY scan calculations shows that, while theas‐indacene core is less paratropic thans‐indacene, benz[a]‐annulation further reduces the antiaromaticity of the core. Antiaromatic strength of theas‐indacene core can also be tuned by the position of fusion of additional arenes on the outer rings.more » « less
-
Abstract Recent experimental developments have allowed physicists to freeze molecules' motion down to an ultracold temperature regime where quantum effects become profound. Furthermore, each molecule can be precisely prepared at chosen internal states and the mutual interactions between molecules are also highly tunable. As such, ultracold molecules have emerged as a powerful platform in multiple disciplines across physics and chemistry. Meanwhile, a grand challenge exists as to how losses of molecules depend on a quantum many‐body environment. In this article, the recent experimental and theoretical progress of exploring losses of ultracold molecules is reviewed. Since the conventional theoretical scheme of treating isolated pairs of molecules is no longer applicable to the quantum degenerate regime that has been reached in recent experiments, an alternative framework of universal relations between two‐body losses and many‐body correlations has been established. Regardless of microscopic parameters ranging from the temperature and the particle number to the interaction strength, these universal relations always hold. This approach unfolds a simple universality behind complex loss processes of many‐body systems and provides physicists and chemists with a new tool to explore ultracold molecules.more » « less
-
Abstract The iterative association of monomer units through noncovalent interactions often leads to chiral supramolecular polymers. Monomers comprising these materials can be further divided into those with chiral centers and those without. The latter class is often less studied but attractive since it features monomer designs with chirality at the core rather than the periphery of the molecules. In this mini‐review, we summarize the existing strategies to construct supramolecular polymers from chiral molecules with no chiral centers and offer perspectives on fundamental trends and differences between them and their counterparts with chiral centers. © 2020 Society of Industrial Chemistrymore » « less
-
Abstract This study computationally investigates the elastic interaction of two pressurized cylindrical cavities in a 2D hyperelastic medium. Unlike linear elasticity, where interactions are exclusively attractive, nonlinear material models (neo-Hookean, Mooney–Rivlin, Arruda–Boyce) exhibit both attraction and repulsion between the cavities. A critical pressure-shear modulus ratio governs the transition, offering a pathway to manipulate cavity configurations through material and loading parameters. At low ratios, the interactions are always attractive, while at high ratios, both attractive and repulsive regimes exist depending on the separation between the cavities. The effect of the strain-stiffening on these interactions is also analyzed. These insights bridge theoretical and applied mechanics, with implications for soft material design and subsurface engineering.more » « less
