This Account is dedicated to our postdoctoral mentors, Profs. Julius Rebek Jr. and Peter Vollhardt, who shaped our research interests by supporting the exploration of areas where one follows one’s nose – letting serendipity take you where it may
Abstract
The Haley and Johnson labs at the University of Oregon have been collaborating since 2006, combining skillsets in synthetic organic, physical organic, and supramolecular chemistries. This joint project has produced many examples of host molecules that bind anionic guests and give chemical, photophysical, and/or electrical responses. Many of these receptors utilize two-armed arylethynyl backbones that have a variety of hydrogen- or halogen-bonding functional groups appended. However, in attempts to produce a bisamide-containing host using a peptide-coupling protocol with P(OPh)3 present, we isolated something unexpected – a heterocycle containing neighboring P and N atoms. This ‘failed’ reaction turned into a surprisingly robust synthesis of phosphaquinolinones, an unusual class of PN-heterocycles. This Account article tells the rollercoaster story of these heterocycles in our lab. It will highlight our key works to this field, including a suite of fundamental studies of both the original PN-naphthalene moiety, as well as a variety of structural modifications to the arene backbone. It will also discuss the major step forward the project took when we developed a phosphaquinolinone-containing receptor molecule capable of binding HSO4
– selectively, reversibly, and with recyclability. With these findings, the project has gone from hospice care to making a full, robust recovery.
1 Introduction
2 Initial Discovery
3 Setbacks Breathe New Life
4 A New Dynamic Duo Develops Dozens of Derivatives
5 Physicochemical Characterization
5.1 Fluorescence
5.2 Molecular Structures
5.3 Solution Dimerization Studies
6 Applying What We Have Learned
6.1 Development of Supramolecular Host
6.2 Use of PN Moiety as an Impressive Fluorophore
7 Conclusions and Outlook
Keywords
fluorophore - PN-heterocycles - hydrogen bonding - supramolecular chemistry - anion binding
