RESUMEN
We study the metal-organic framework (MOF) ZIF-67 with 1H and 13C nuclear magnetic resonance (NMR). In addition to the usual orbital chemical shifts, we observe spinning sideband manifolds in the NMR spectrum due to hyperfine interactions of the paramagnetic cobalt with 1H and 13C. Both orbital and paramagnetic chemical shifts are in good agreement with values calculated from first principles, allowing high-confidence assignment of the observed peaks to specific sites within the MOF. Our measured resonance shifts, line shapes, and spin lattice relaxation rates are also consistent with calculated values. We show that molecules in the pores of the MOF can exhibit high-resolution NMR spectra with fast spin lattice relaxation rates due to dipole-dipole couplings to the Co2+ nodes in the ZIF-67 lattice, showcasing NMR spectroscopy as a powerful tool for identification and characterization of "guests" that may be hosted by the MOF in electrochemical and catalytic applications.
RESUMEN
We demonstrate a hybrid ZnO nanoparticle decorated SWNT network device that can conductometrically differentiate between xylene isomers at room temperature with minimal interference from background VOCs. Field effect transistor measurements are conducted to identify the sensing mechanism which is attributed to enhanced SWNT transduction of chemical interaction with ZnO surfaces.