Electronic Supporting Data: Prism[5]MaxQ: A Sulfated Prism[5]arene and its Molecular Recognition Properties towards a Panel of Quaternary Ammonium Guests

Abstract

We report the synthesis of a sulfated prism[5]arene macrocyclic host. The uncomplexed sulfated prism[5]arene exhibits broadened resonances at NMR concentrations (100 M) but addition of acetone (0.6%) results in a diagnostic 1H NMR spectrum indicative of a D5-symmetry. Variable temperature fluorescence spectroscopy titrations performed at very low concentrations ([thionin] = 1.5 M) allowed determination of the Ka (2.99 × 107 M-1) and H (-2.60 kcal mol-1) values for the sulfated prism[5]arene•thionin complex. Subsequent competitive ITC experiments allowed determination of the thermodynamic parameters for complexation of sulfated prism[5]arene toward a 17-membered panel of hydrophobic (di)cationic guests. The sulfated prism[5]arene•methylated bipiperidine complex exhibits ultrahigh binding affinity with Ka exceeding 1012 M-1 in phosphate buffered saline (PBS). We find that sulfated prism[5]arene preferentially complexes quaternary diammonium over the corresponding primary diammonium ions by factors up to 5136-fold leading us to name it Prism[5]MaxQ. The sulfated prism[5]arene host binds more tightly than the carboxylated prism[5]arene host by factors up to 4300-fold but is a less potent host than sulfated pillar[6]arene by factors up to 88000-fold. Sulfated prism[5]arene is the newest member of the family of ultrahigh binding affinity hosts that is poised for application as a sequestrant for various compounds.