Materials Science NMR

Anca Gabriela Mirea (National Institute of Materials Physics, Romania)

Abstract: We present herein the synthesis of novel [2 + 2] and [3 + 3] N-acylhydrazone-based macrocycles using a pool of dialdehydes and dihydrazides. The macrocycles were used in various assays to investigate the hosting capacity of various guests using NMR.

Konstantin Khivantsev – @Khivantsev

We show both experimentally and theoretically that CO can be activated (protonated) by Bronsted acid sites to form the super-electrophilic HCO+ cation in H-zeolites such as mordenite. This mode of activation of carbon monoxide is novel for solid materials and has not been observed before. This reactivity stems from the confining environment of zeolitic micropores. HCO+ is a catalytically active super-electrophile showing catalytic reactivity in C-H and C-O bond activation.

Madhusudan Chaudhary – @thehonestspin

Aliovalent substitution of the B component in ABX3 metal halides has often been proposed to modify the band gap and thus the photovoltaic properties, but details about the resulting structure have remained largely unknown. Here, we examine these effects in Bi-substituted CsSnBr3. Powder X-ray diffraction (XRD) and solid-state 119Sn, 133Cs and 209Bi nuclear magnetic resonance (NMR) spectroscopy were carried out to infer how Bi substitution changes the structure of these compounds. The cubic perovskite structure is preserved upon Bi-substitution, but with disorder in the B site occurring at the atomic level. Bi atoms are randomly distributed as they substitute for Sn atoms with no evidence of Bi segregation. The absorption edge in the optical spectra shifts from 1.8 to 1.2 eV upon Bi-substitution, maintaining a direct band gap according to electronic structure calculations. It is shown that Bi-substitution improves resistance to degradation by inhibiting the oxidation of Sn.

Robert Smith – @RobertSmith2652

We demonstrate the use of solid-state NMR to probe the band structure of cadmium stannate nanocrystals through the use of Knight shifts, with a focus on methods that can be employed to confirm their manifestation. We also explore the relationship between synthetic precursors and free carrier densities.

Wenda Hu – @WendaHu1

We used in situ 13𝐶-1𝐻 CP and 1𝐻 NMR to identify dehydration intermediates on TiO₂ facets. A water-isopropoxide complex on TiO₂(001) and a water-isopropanol complex on TiO₂(101) explain different dehydration rates, crucial for understanding biomass conversion mechanisms.

Mikalai Artsiusheuski – @martsiush

Employing in situ solid-state NMR spectroscopy and label tracing, we elucidated the pathways of methane transformations over copper-containing zeolites. Reaction of methane with copper(II)-oxo sites leads to partial oxidation products, namely methanol, methoxy species and dimethyl ether. These products can undergo coupling over acid sites leading to C2+ hydrocarbons.

Yufei Wu – @YufeiWu811

Generation of formate on the surface of supported ionic liquid phases (SILPs) is related to the catalytic selectivity of hydrogenation reactions. We use solid-state NMR to study molecular interactions between formate and different SILPs. The findings indicate electrostatic interactions which explain the improved immobilization of formate on the surface.

Thomas Swift – @Swifthom

In recent years Pulsed Field Gradient NMR techniques to get Diffusion decays of materials have been successfully adopted in the polymer chemistry community as a sizing technique. It has many advantages over the previous gold standard in the field (size exclusion chromatography) although it has its own drawbacks and difficulties. Here we will focus on applications of NMR for Polymer material characterisation and the limitations thereof.

Michele Pierigé – @MichelePierige

This research compares the effects of natural and petroleum-based resins on Styrene-Butadiene Rubber (SBR) dynamics, using various techniques to understand the correlation between mechanical properties and molecular dynamics in elastomer compounds, with resin content varying from 0 to 45 parts per hundred rubber.

Dominik J. Kubicki – @DominikJKubicki

We developed 125Te MAS NMR of A2TeX6 compounds, where A = Cs, MA, and X = I, Br, Cl. In addition to exploring the chemical shift range, we observed a range of fascinating spin physics phenomena and determined how to use them to study dynamic processes.