Session ThOA. There are 5 abstracts in this session.

Session: Materials 2, time: 08:30-8:55
Exploiting Fast MAS and Proton Detection to Enhance the Sensitivity of Solid-State NMR Experiments with Unreceptive Nuclei
Amrit Venkatesh1, 2; Scott Carnahan1, 2; Michael Hanrahan1, 2; Aaron Rossini1, 2
1Iowa State University, Ames, IA; 2US DOE Ames Laboratory, Ames, IA
In this contribution we describe how fast MAS and proton detection can simultaneously improve the resolution and sensitivity of solid-state NMR experiments with exotic and unreceptive nuclei. For example, 2D constant-time dipolar hetero-nuclear multiple-quantum (D-HMQC) experiments can be used to rapidly obtain wideline MAS solid-state NMR spectra that are broadened by chemical shift anisotropy (CSA) and/or the quadrupolar interaction. Proton detected 2D dipolar correlation NMR spectra of half-integer quadrupolar nuclei can be acquired with the under-utilized dipolar refocused INEPT (D-RINEPT) experiment. 2D proton detected CP-HETCOR pulse sequences significantly accelerate NMR experiments with very low-gyromagnetic ratio nuclei. We demonstrate the utility of these methods for the characterization of a variety of organic and inorganic materials.

Session: Materials 2, time: 08:55-9:20
New Roadmaps for 17O and 43Ca Solid State NMR 
Thomas-Xavier Métro1; Christian Bonhomme2; Christel Gervais2; Daniel Lee3; Gaël De Paëpe3; Danielle Laurencin4
1Institut des Biomolécules Max Mousseron, Montpellier, France; 2Sorbonne Universite, Paris, France; 3CEA - INAC - Université Grenoble Alpes, Grenoble, France; 4Institut Charles Gerhardt Montpellier, Montpellier, France
Calcium-43 and oxygen-17 have long been considered as “exotic” nuclei for NMR spectroscopy, due to their low resonance frequency and low natural abundance. However, several recent advances have made their analysis by solid state NMR become not only more accessible but also more informative. Here, our latest contributions along these lines will be presented, which include (i) innovative labeling schemes for the preparation of 17O-enriched compounds; (ii) new high-resolution experiments for 43Ca, and (iii) natural abundance 43Ca NMR studies performed at ultra-high magnetic fields or using dynamic nuclear polarization.

Session: Materials 2, time: 09:20-9:35
Bulk hyperpolarization of inorganic solids 
Brennan Walder; Snædís Björgvinsdóttir; Arthur Pinon; Lyndon Emsley
ISIC, EPFL, Lausanne, Switzerland
Incipient wetness impregnation DNP can be used to hyperpolarize bulk organic solids but relies upon the efficient transport of magnetization by spontaneous proton spin diffusion. We report here an impregnation DNP strategy for bulk hyperpolarization of heteronuclei in proton-free inorganic solids. The method uses multiple-contact CP during the polarization period to maintain a low spin temperature of surface heteronuclei. Provided bulk heteronuclear T1 values are sufficiently long, even slow spin diffusion transports enough magnetization from the surface such that the sensitivity of a conventional MAS NMR experiment can be exceeded. With pulse cooling we demonstrate sensitivity enhanced 31P NMR of gallium phosphide at MAS rates up to 12.5 kHz.

Session: Materials 2, time: 09:35-9:50
In Situ Description of Biomineralization Processes: Pressure and MAS Effects Under Fast MAS
César Leroy; Christel Gervais; Christian Bonhomme
Sorbonne Universite, Paris, France
The in situ dehydration of calcium oxalates was followed by variable MAS spinning frequency experiments. New insight in biomineralization processes of calcium oxalates was proposed with the first observation of a transient disordered phase. The obtained results illuminate clinical observations made in the field of pathological calcifications (kidney stones).
DNP crystallography approach led to full assignment of 1H/13C data through extensive modeling of ordered/disordered structures.


Session: Materials 2, time: 09:50-10:05
Advances in Characterization of Active Pharmaceutical Ingredients and their Dosage Forms Using 35Cl Solid-State NMR Spectroscopy
David Hirsh1; Sean Holmes1; Austin Peach1; Yongchao Su2; Robert W. Schurko1
1University of Windsor, Windsor, Canada; 2Merck Research Laboratories (MRL), West Point, PA
35Cl SSNMR is an ideal technique for studying bulk and dosage forms of HCl salts of APIs, which constitute ca. 60% of all pharmaceutical compounds. Recent developments and applications of 35Cl SSNMR for studying HCl APIs will be discussed, including (i) ultra-wideline NMR techniques for rapid acquisition of high quality 35Cl SSNMR spectra; (ii) the use of 35Cl SSNMR for quantifying disproportionation (i.e., formation of the free base) of HCl APIs in dosage forms; (iii) the creation of cocrystalline dosage forms of HCl APIs via mechanochemical methods and monitoring of their formation and structures; and (iv) a new method for structural refinement, DFT-D2*, that allows for use of 35Cl EFG tensors as a metric in NMR crystallographic methods.