Bipyridine Receptors As Metal Ligands

The zinc ion (Zn²⁺) is ubiquitous in our natural environment and performs vital functions in the human body.  The creation of a synthetic receptor capable of fluorescently sensing zinc may have far reaching bio-medical applications including testing for epilepsy and Parkinson’s disease.  The environmentally relevant aptitude of 2,6-Bis(2-anilinoethynyl)pyridine to sense negatively charged ions such as chloride (Cl^-) and cyanide (CN^-) has previously been investigated.  Theory suggests a bipyridinyl adaptation of this molecule may be used for positive ions such as potassium (Li⁺) and magnesium (Mg²⁺).  We are analyzing two different modifications, 6,6-Bis-(5-tert-butyl-2-methoxy-phenylethynl)-[2,2]bipyridinyl and 6,6-Bis-(5-tert-butyl-2-nitro-phenylethynl)-[2,2]bipyridinyl,  and their ability to complex with Zn²⁺ over the biologically abundant materials, iron (Fe²⁺) and copper (Cu²⁺).  By deriving association constants using nuclear magnetic resonance spectroscopy, ultra violet-visible spectroscopy, isothermal titration calorimetry, and fluorescence spectroscopy as well as characterizing the relationship between the host and ions using x-ray crystallography and mass spectrometry, a foundation will be set for future experimentation with this receptor class.