Title

Advantages of Halogen Bonding for Halide Recognition in Wet Solvents

Presentation Type

Presentation

Abstract

The goal of anion recognition is to develop molecules capable of binding to specific anions, such as chloride, in solutions that mimic biological and environmental systems. Anion detection in biological solutions has implications for medical technologies, such as diagnostics. For example, cystic fibrosis is often diagnosed by measuring chloride levels in sweat. However, challenges arise while designing receptors because anions and their receptors are affected by anything with a charge. Because water, the solvent of biology, is polarized, it is an especially challenging solvent for anion recognition. To overcome recognition challenges, we can make small structural changes to the anion receptor, such as switching an atom, and drastically change how the receptor interacts with the anion and solvent. Understanding non-covalent interactions (e.g. hydrogen bonding, and hydrophobic interactions) is the driving force in the evolution of anion recognition because it allows chemists to predict the properties of a molecule in a given environment and how changing these properties can alter activity in different solvents. An underexplored non-covalent interaction is the halogen bond—an attractive force between an electropositive halogen and an electronegative Lewis base (e.g. anion). Our research develops two anion receptors, only differing through exchange of hydrogen for iodine, which allows comparison of halogen and hydrogen bonding. X-ray diffraction, NMR titrations, and computational methods were used to explore the significance of this exchange. Interestingly, the halogen bond was found to maintain strong selective halide recognition in competitive polar environments (1% D2O:CD3CN), while the hydrogen bond showed poor recognition capability in the same conditions. This provides evidence that halogen bond donors can be used to overcome anion recognition challenges of competitive biological environments (e.g. water) and have a positive impact on the development of medical technologies.

Category

Physical Sciences

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Apr 17th, 10:00 AM Apr 17th, 10:20 AM

Advantages of Halogen Bonding for Halide Recognition in Wet Solvents

UC 330

The goal of anion recognition is to develop molecules capable of binding to specific anions, such as chloride, in solutions that mimic biological and environmental systems. Anion detection in biological solutions has implications for medical technologies, such as diagnostics. For example, cystic fibrosis is often diagnosed by measuring chloride levels in sweat. However, challenges arise while designing receptors because anions and their receptors are affected by anything with a charge. Because water, the solvent of biology, is polarized, it is an especially challenging solvent for anion recognition. To overcome recognition challenges, we can make small structural changes to the anion receptor, such as switching an atom, and drastically change how the receptor interacts with the anion and solvent. Understanding non-covalent interactions (e.g. hydrogen bonding, and hydrophobic interactions) is the driving force in the evolution of anion recognition because it allows chemists to predict the properties of a molecule in a given environment and how changing these properties can alter activity in different solvents. An underexplored non-covalent interaction is the halogen bond—an attractive force between an electropositive halogen and an electronegative Lewis base (e.g. anion). Our research develops two anion receptors, only differing through exchange of hydrogen for iodine, which allows comparison of halogen and hydrogen bonding. X-ray diffraction, NMR titrations, and computational methods were used to explore the significance of this exchange. Interestingly, the halogen bond was found to maintain strong selective halide recognition in competitive polar environments (1% D2O:CD3CN), while the hydrogen bond showed poor recognition capability in the same conditions. This provides evidence that halogen bond donors can be used to overcome anion recognition challenges of competitive biological environments (e.g. water) and have a positive impact on the development of medical technologies.