(759f) A Structure-Function Relationship for the Optical Modulation of Phenyl Boronic Acid-Grafted, Polyethylene Glycol Complexed to Single Walled Carbon Nanotubes

Phenyl boronic acids are important binding ligands to pendant diols useful for saccharide recognition.  The aromatic ring can also function to anchor an otherwise hydrophilic polymer backbone to the surface of hydrophobic graphene or carbon nanotube.  In this work, we synthesize a homologous series of seven phenyl boronic acid conjugated poly ethylene glycol 8 membered branched polymers using different phenyl boronic acids. We evaluate the resulting dispersion of single walled carbon nanotubes (SWNTs) in aqueous suspension, and the nIR fluorescence of these polymer-SWNT complexes. FTIR, UV-visible, NMR, and visible fluorescence spectroscopies were applied to characterize these polymers.  The fluorescence of SWNTs wrapped by these polymers presents apparent variation in the intensity and the wavelength shift. An examination of the fluorescent excitation-emission profile demonstrated that the varied boronic acid structures have an ability to quench the fluorescence of the different SWNT species to the different level. Finally, the screening results of a library of sugar molecules demonstrated the success of the new design concept toward saccharide biosensor.