The importance of amide moieties as binding groups in anion sensors has gained considerable attention due to their measurable interactions with anions. A luminescent rhenium(I) polypyridyl-based receptor containing amide moieties previously indicated strong hydrogen bond formation between the amide protons of the complex and the anions. Previous work has established that some anions form excited state complexes with the receptor rather than reacting more traditionally with the acidic amide protons on the complex. To better understand the interaction between the amide protons and anions, a similar complex was generated with a methyl group coordinated to each terminal pyridine, increasing the electron density around the N-H hydrogen atoms. N2,N6-bis(2-methylpyridine-4-yl)pyridine-2,6-dicarboxamide was synthesized in a base-catalyzed nucleophilic reaction containing 4-amino-2-methylpyridine and 2,6-dicarboxamide to serve as a bridging ligand between the rhenium subspecies of the sensor. The ligand was analyzed via 1H NMR, 13C NMR, and 2D NMR, and then complexed with (4,4’di-tertbutyl bipyridine)Re(CO)3Br. The generated sensor was analyzed via 1H NMR and IR spectroscopy, and then tested with F-, Cl-, Br-, I-, CN-, NO3-, OAc-, and H2PO4-. The exchanges between the sensor and anions were examined via UV-Vis and fluorescence spectroscopy; binding affinities were extrapolated from the spectral data and will be presented.

Amide protons as binding groups in a polypyridyl rhenium (I) sensor

2019 Spring National Meeting

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