Project description
Halogens and chalcogens: novel non-covalent bonds for chemistry and organocatalysis
Strong covalent bonds in which electrons are equally shared by two atoms support the formation of molecules. Hydrogen bonds are weaker, with an electrostatic attraction between a given atom and a hydrogen atom covalently bound to another atom. These non-covalent bonds are important in supramolecular chemistry, organic chemistry and organocatalysis. The European Research Council-funded XBCBCAT project will develop the first applications for two additional non-covalent interactions based on halogens or chalcogens, so-called halogen-bonds and chalcogen bonds. The team will focus on halogen bonds for chiral recognition and chalcogen bonds for applications in organic synthesis and organocatalysis. These unprecedented applications will enhance the chemists’ toolbox of non-covalent interactions and flexibility regarding the hydrogen requirement.
Objective
Hydrogen-bonds have found widespread use in various fields of chemistry, including supramolecular chemistry, organic chemistry, and more lately organocatalysis. Although a multitude of structurally different hydrogen-bond donors has been developed, their mode of action is in all cases necessarily based on the same interacting atom, hydrogen.
In this proposal, we aim to develop first applications for two, previously very little explored non-covalent interactions that are based on electrophilic halogen or chalcogen substituents (“halogen-bonds” and “chalcogen bonds”).
The first objective is to open the way for the use of chiral multidentate halogen-bond donors (i.e. halogen-based Lewis acids) for enantiodiscrimination. After the synthesis of suitable candidate compounds, we will apply them in the following research areas: a) the resolution of racemic mixtures by co-crystallization with chiral halogen-bond donors, and b) the use of these Lewis acids in enantioselective organocatalysis.
Within the second objective, we will strive to establish first-of-its-kind applications of chalcogen-based Lewis acids in organic synthesis and organocatalysis. In contrast to halogen-bonds, chalcogen-bonds feature two substituents on the interacting atom as well as two electrophilic axes. In the first phase of this aim, we will synthesize neutral and cationic, mono- and bidentate candidate compounds and determine their association constants with a variety of Lewis bases. Based on this date, we subsequently seek to use these novel Lewis acids as activators or catalysts in organic transformations.
We anticipate that the realization of these applications, all of which are unprecedented, will be a crucial first step towards establishing further non-covalent interactions as useful tools in chiral recognition and chemical synthesis. In the long-term, we foresee these little-explored interactions becoming powerful complements to the ubiquitous hydrogen-bonds.
Fields of science
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Funding Scheme
ERC-STG - Starting GrantHost institution
44801 Bochum
Germany