NMR allo stato solido

Analytical solid-state NMR spectroscopic applications

Analytical solid-state NMR spectroscopy (ssNMR) covers a wide range of applications by collecting structural, dynamical and surface information of solids (especially important for insoluble and non-crystalline solids) that cannot be addressed by liquid-state NMR experiments. In solid-state NMR spectroscopy, powdered samples are placed in a spinning rotor and spun at high speeds, at an angle (magic angle) with respect to the external magnetic field direction, in order to permit acquisition of NMR spectra with appropriate resolution to allow structural, chemical and dynamics determinations to be achieved.

Solid-state NMR spectroscopy is a very powerful technique capable of looking at a variety of materials. Among the characterization techniques, the huge advantage of ssNMR over other traditional solid-state techniques, such as diffraction, is that they can be applied not only to crystalline samples but also to amorphous, disordered or inhomogeneous systems. Therefore, ssNMR can be used, for instance, to measure atomic coordinates, lattice parameters, inter-atomic distances, occupancy of atomic positions, compositions and surface features as well as solid state dynamics.

On the other hand, our laboratories employ integrated multidisciplinary approaches involving diffraction (X-ray and synchrotron), thermal (TGA/DSC), chromatographic (GCMS, LCMS), microscopic (SEM and optical), multiple-spectroscopic (FT-IR, RAMAN, UV-VIS, NMR, EPR), and computational methods allowing in achieving an in-depth understanding of the structural, surface, interfacial and confined space processes in structurally and compositionally complex solid systems that are beneficial for the establishment of structure-properties relationships. Most of the NMR active nuclei in the periodic table are available, for investigation by solid-state NMR spectroscopy, and is able to provide different spectral insights through the observation of multiple nuclei in the same solid sample. Three MAS NMR probes with various capabilities are available for recording the solid-state NMR spectra.

Applications – solid-state NMR spectroscopy:

• Product traceability, quantitative analysis and authentication of ancient wheat grains and other commercial grains by ¹³C and ¹H MAS NMR spectroscopy [insert1]
• Cement Analysis – Solid-state ¹H, ²⁹Si, ²⁷Al NMR [insert2]
• Competitive analysis – polymers (PIM, PAF): ¹³C and ¹H MAS NMR [insert3]
• Catalyst (porous aluminosilicates, aluminophosphates (AlPO) and silicoaluminophosphates (SAPO)) characterization – solid-state NMR – ²⁷Al, ³¹P, ²⁹Si of molecular sieves and heterogeneous catalysts [insert4]
• Catalyst poisoning studies – ¹³C and ¹H MAS NMR [insert5]
• Clays, minerals, layered silicates, phosphates and double hydroxides – multi-nuclear NMR studies [insert6]
• Ligno-cellulosic analysis related to bio-based industries [insert7]
• Polymer Analysis – Detailed backbone analysis, determination of degree of cross-linking, residual monomer content estimation [LINK8]
• Soil analysis – Various NMR active nuclei [insert9]
• Polymorph identification in API samples by Solid-state ¹³C NMR [insert10]
• Relaxation measurements (T₁, T₂, T_CH, T_1rho) [insert11]
• Antibiotic chemistry in soils and water bodies by ssNMR [insert12]
• Natural and synthetic rubber analysis [insert13]
• Teflon and fluorocarbon studies; ¹⁹F, ¹⁹F-¹³C and ¹H-¹³C ssNMR analysis [insert14]