Information about your use of this website will be shared with Google and other third parties. Read our privacy policy. Solvent effects control competition between hydrogen bonding and halogen bonding in supramolecular systems, new research shows. The upshot of the finding is a potential new tool to direct supramolecular self-assembly. During self-assembly, each molecule breaks its bonding interactions with neighbouring solvent molecules, then forms new interactions.
To investigate competition between hydrogen bonding and halogen bonding when co-crystals form, researchers from an ongoing collaboration between the UK Universities of Sheffield , York and Cambridge chose seven solvents of different polarities to study three aromatic molecules known to self-assemble. In a halogen bond, a covalently-bound halogen atom — usually iodine — interacts in a similar directional manner with an electron-rich site via a partially positively-charged polar region on the halogen atom.
In most of the experiments, solvent choice directed the exclusive formation of either the hydrogen-bonded or the halogen-bonded co-crystals. More polar solvents weakened hydrogen bonding in solution and favoured softer halogen bonding, whereas less polar solvents favoured hydrogen-bonded co-crystals.
Using toluene resulted in exclusively hydrogen-bonded co-crystals, while halogen bonding occurred within most of the co-crystals formed in isopropanol. The group also identified borderline solvents that did not clearly favour either hydrogen or halogen bonding and found that the crossover point in solvent polarity correlates with the relative strength of the hydrogen and halogen bonds in the co-crystals.
Guerra, Faraday Discuss. To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given.
Read more about how to correctly acknowledge RSC content. Fetching data from CrossRef. This may take some time to load. Loading related content. Jump to main content. Jump to site search. You do not have JavaScript enabled. Please enable JavaScript to access the full features of the site or access our non-JavaScript page. Volume , To get a polar covalent bond , the difference in EN between hydrogen and the other atom it bonds with must be greater than 0. Which one of the following bonds would you expect to be the most polar?
Stefan V. Apr 11, The answer is b N - H. Related questions What causes bond polarity? Is the bond between H and S atoms polar?
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