“Where do we go from here?” is the underlying question regarding the future (perhaps foreseeable) developments in computational chemistry. Although this young discipline has already permeated ...practically all of chemistry, it is likely to become even more powerful with the rapid development of computational hard‐ and software.
London dispersion, which constitutes the attractive part of the famous van der Waals potential, has long been underappreciated in molecular chemistry as an important element of structural stability, ...and thus affects chemical reactivity and catalysis. This negligence is due to the common notion that dispersion is weak, which is only true for one pair of interacting atoms. For increasingly larger structures, the overall dispersion contribution grows rapidly and can amount to tens of kcal mol−1. This Review collects and emphasizes the importance of inter‐ and intramolecular dispersion for molecules consisting mostly of first row atoms. The synergy of experiment and theory has now reached a stage where dispersion effects can be examined in fine detail. This forces us to reconsider our perception of steric hindrance and stereoelectronic effects. The quantitation of dispersion energy donors will improve our ability to design sophisticated molecular structures and much better catalysts.
Center of attraction: Dispersion attraction makes all the difference in the stability of molecular structures, reactivity, and the design of catalysts. Although small for one pair of interactions, dispersion grows rapidly as the molecular size increases.
The present critical review outlines the close relationship and mutual interplay between molecular recognition, active site considerations in enzyme catalysis involving anions, and organocatalysis ...utilizing explicit hydrogen bonding. These interconnections are generally not made although, as we demonstrate, they are quite apparent as exemplified with pertinent examples in the field of (thio)urea organocatalysis. Indeed, the concepts of anion binding or binding with negatively (partially) charged heteroatoms is key for designing new organocatalytic transformations. Utilizing anions through recognition with hydrogen-bonding organocatalysts is still in its infancy but bears great potential. In turn, the discovery and mechanistic elucidation of such reactions is likely to improve the understanding of enzyme active sites (108 references).
The well‐known Corey–Bakshi–Shibata (CBS) reduction is a powerful method for the asymmetric synthesis of alcohols from prochiral ketones, often featuring high yields and excellent selectivities. ...While steric repulsion has been regarded as the key director of the observed high enantioselectivity for many years, we show that London dispersion (LD) interactions are at least as important for enantiodiscrimination. We exemplify this through a combination of detailed computational and experimental studies for a series of modified CBS catalysts equipped with dispersion energy donors (DEDs) in the catalysts and the substrates. Our results demonstrate that attractive LD interactions between the catalyst and the substrate, rather than steric repulsion, determine the selectivity. As a key outcome of our study, we were able to improve the catalyst design for some challenging CBS reductions.
London dispersion (LD) interactions facilitate the enantioselectivity in the Corey–Bakshi–Shibata (CBS) reduction. Employing a combination of computational and experimental studies, we provide a modern view on the origin of enantioselectivity in this powerful organocatalyzed reaction. The results demonstrate that attractive LD interactions between the catalyst and the substrate rather than steric repulsion determine the selectivity.
London dispersion (LD) interactions are the main contribution of the attractive part of the van der Waals potential. Even though LD effects are the driving force for molecular aggregation and ...recognition, the role of these omnipresent interactions in structure and reactivity had been largely underappreciated over decades. However, in the recent years considerable efforts have been made to thoroughly study LD interactions and their potential as a chemical design element for structures and catalysis. This was made possible through a fruitful interplay of theory and experiment. This review highlights recent results and advances in utilizing LD interactions as a structural motif to understand and utilize intra‐ and intermolecularly LD‐stabilized systems. Additionally, we focus on the quantification of LD interactions and their fundamental role in chemical reactions.
It has by now been realized that London dispersion (LD) interactions, the main contributor to the attractive part of the van der Waals potential, are ubiquitously present and need to be taken into consideration in structures and dynamics of chemical reactions. This review highlights recent experimental and theoretical advances in utilizing LD interactions as a design element.
12 not so angry men: Hexaphenylethane is unstable, a phenomenon traditionally attributed to steric repulsion between the six phenyl rings. However, adding 12 bulky tert‐butyl groups, one to each of ...the 12 meta positions, gives a stabile ethane derivative (see space‐filling model and potential energy curve for the dissociation of the central CC bond). This unexpected stabilization is shown to result from attractive dispersion interactions between the substituents.
As low‐temperature conditions (e.g. in space) prohibit reactions requiring large activation energies, an alternative mechanism for follow‐up transformations of highly stable molecules involves the ...reactions of higher energy isomers that were generated in a different environment. Hence, one working model for the formation of larger organic molecules is their generation from high‐lying isomers of otherwise rather stable molecules. As an example, we present here the synthesis as well as IR and UV/Vis spectroscopic identification of the previously elusive 1,1,2‐ethenetriol, the higher energy enol tautomer of glycolic acid, a rather stable and hence unreactive biological building block. The title compound was generated in the gas phase by flash vacuum pyrolysis of tartronic acid at 400 °C and was subsequently trapped in argon matrices at 10 K. The spectral assignments are supported by B3LYP/6–311++G(2d,2p) computations. Upon photolysis at λ=180–254 nm, 1,1,2‐ethenetriol rearranges to glycolic acid and ketene.
The simple yet uncharacterized high energy tautomer of glycolic acid, namely 1,1,2‐ethenetriol, an important molecule in the abiotic synthesis of sugar acids, has now been identified by IR and UV/Vis spectroscopy. With these data now in hand, it now awaits its identification in space as another building block for prebiotic chemistry.
Rethinking Chemistry Danielmeier, Karsten; Schreiner, Peter R.
Angewandte Chemie International Edition,
September 4, 2023, Letnik:
62, Številka:
36
Journal Article
Recenzirano
Odprti dostop
The German Chemical Society (GDCh) Board of Directors chose the motto “Rethinking Chemistry” last year to address challenges connected to climate change, loss of natural resources, and geopolitical ...conflicts as the guiding principle of all our endeavors and actions. Rethinking Chemistry indicates the Board's desire to encourage scientists to approach chemistry in a new way, with a focus on reconsidering the field from many different angles. By taking a holistic approach, the Board intends to foster innovative, sustainable, and effective ways to use chemistry.
Rethinking Chemistry is also the motto of the GDCh Science Forum Chemistry (WiFo) 2023, and a Special Collection on the homepage of Angewandte Chemie is dedicated to this event and its motto. Rethinking Chemistry means something different in each area of chemistry, and the WiFo 2023 as well as this Special Collection of Angewandte Chemie showcase its many facets.
Climate change, loss of natural resources, and geopolitical conflicts are some of the global challenges humanity faces. As chemists, we have the unique possibility and the duty to contribute to a livable future for all. “Rethinking Chemistry” is the motto of the German Chemical Society Science Forum Chemistry (WiFo) 2023 to address these challenges as the guiding principle of all our endeavors and actions.
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