Single Molecule Discrimination of Heteropolytungstates and Their Isomers in Solution with a Nanometer-Scale Pore

We report a new method to identify metallic nanoclusters (polyoxometalate structures) in solution at the single molecule limit using a nanometer-scale pore. The technique allows the measurement of polyoxometalates with over 2 orders of magnitude lower analyte concentration than conventional analytical chemistry tools. Furthermore, pH-dependent structural changes in phosphotungstic acid are measured with protein nanopores and validated with NMR. We further demonstrate that the method can also discriminate [PW9O34]9– structural isomers. The results suggest this technique can serve as a complementary approach to traditional methods.