Detection and differentiation of diols by 19F NMR with fluorinated benzene boronic acids

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Boronic acid-containing molecular probes have been developed as chemosensors for the recognition of diol-containing analytes, such as carbohydrates, nucleotides, catechols, and hydroxyl carboxylic acids. The objective of this project is the synthesis and characterization of novel fluorinated boronic acids to detect and discriminate diol-containing analytes and anions via 19F NMR at physiological conditions. The presence of a fluorine nucleus in the fluoro-benzene boronic acid, for example, provides an NMR probe which is extremely sensitive to the binding environment of the boron moiety. When a saccharide is added to the receptor in a physiological medium, the boronic acids are converted into boronate esters inducing a chemical shift in the 19F NMR spectrum. First, we investigate diols with commercially available fluorinated arene boronic acids. We will learn which aspects, such as water solubility, pKa and analyte selectivity, can be already addressed by commercial and literature-known fluorinated boronic acids. Density functional theory (DFT) methods will provide theoretical 19F NMR shifts. Subsequently, novel receptors with improved properties in water solubility and analyte selectivity will be synthesized. Boronic acid appended pyridinium and imidazolium salts will be ideal candidates in terms of water solubility and analyte selectivity. Replacing the fluorine moiety by CF3-groups will help to improve sensitivity. With DFT calculations we will be able to predict 19F NMR shifts in combination with specific diol-containing analytes. Then sensor arrays and pattern analysis will be established with fluorinated boronic acid receptors. 19F NMR signals of a group of analytes from several fluorinated receptors will be processed by multivariate analysis to discriminate challenging substrates. Easy-to-read barcodes and acousto-visual discrimination will be generated from 19F NMR spectra. 19F NMR enzyme assays will be created to follow carbohydrate-active enzyme reactions with fluorinated boronic acids. Finally, a virus assay will be developed with sialic-acid coated nanoparticles and competing fluorinated boronic acid receptors to detect influenza virus with 19F NMR spectroscopy.