Rapid Monitoring of Graphene Exfoliation Using NMR Proton Relaxation

Graphene is now being produced on an industrial scale and there is a pressing need for rapid in-line measurements of particle size for Quality Assurance and Quality Control (QA/QC). Standardised...

Using nuclear magnetic resonance proton relaxation to probe the surface chemistry of carbon 2D materials

Using NMR proton relaxation to rapidly identify surface chemical functionalisation changes of carbon nanomaterials in liquid.

Metal-Ligand Recognition Index Determination by NMR Proton Relaxation Study

In this study, we developed and validated a new proposed parameter quantifying the interaction strength between natural and/or synthetic molecules with paramagnetic metal ions. The Metal ion Recognition Index, Miri, is a quantitative parameter to describe the proton environment and to define their involvement in the inner and/or outer sphere of the paramagnetic metal ion. The method is based on the analysis of NMR proton spin-lattice relaxation rates of a specific ligand in both the diamagnetic and paramagnetic conditions. The proposed procedure is also useful to calculate the ligand proton spin-lattice relaxation rate in the paramagnetic bound conditions, which is typically very difficult to determine experimentally. Miri was used to compare the ligand proton involvement toward different paramagnetic species, in particular the Copper(II)-Piroxicam system. Copper(II)-Piroxicam complex is one of the most active anti-inflammatory and anti-arthritic species. Miri provides an opportunity to improve our knowledge of metal-ligand complexes that play a fundamental role in bioinorganic interactions.

Molecular Dynamics in the System Methanol-Dimethylsulphoxide

NMR proton relaxation rates of normal and oxygen-17 enriched m ethanol-d3 in a mixture of 71 mol% methanol and 29 mol% dimethylsulphoxide-d6 (DMSO) were measured as a function of temperature between 298 and 158 K. From these data rotational correlation times of the methanol molecule in the mixture and the oxygen-proton dipolar spin-lattice coupling parameter were ob­tained. The latter parameter is considerably smaller than the one obtained from neutron diffraction studies of the molecular geometry of methanol. Additionally, deuteron and oxygen-17 relaxation rates were measured over the same temperature range. Using the rotational correlation times obtained from the oxygen-17 induced proton relaxation rates, the quadrupole coupling constant for deuterium was derived; it shows a temperature dependence. Application of the Poplett relation yielded the oxygen-17 quadrupole coupling constants, so that oxygen correlation times could be obtained. Comparison of deuteron and oxygen correlation times indicates that the reorientation of the methanol molecule in the methanol/DMSO mixture is anisotropic.