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Silicon nanoparticles (NPs) serve a wide range of optical, electronic, and biological applications. Chemical grafting of various molecules to Si NPs can help to passivate their reactive surfaces, 'fine-tune' their properties, or even give them further interesting features. In this work, 1H, 13C, and 29Si solid-state NMR spectroscopy has been combined with density functional theory calculations to study the surface chemistry of hydride-terminated and alkyl-functionalized Si NPs. This combination of techniques yields assignments for the observed chemical shifts, including the contributions resulting from different surface planes, and highlights the presence of physisorbed water. Resonances from near-surface 13C nuclei were shown to be substantially broadened due to surface disorder and it is demonstrated that in an ambient environment hydride-terminated Si NPs undergo fast back-bond oxidation, whereas long-chain alkyl-functionalized Si NPs undergo slow oxidation. Furthermore, the combination of NMR spectroscopy and DFT calculations showed that the employed hydrosilylation reaction involves anti-Markovnikov addition of the 1-alkene to the surface of the Si NPs. [ABSTRACT FROM AUTHOR]

Magic-angle spinning dynamic nuclear polarization (MAS-DNP) has been proven to be a powerful technique to enhance the sensitivity of solid-state NMR (SSNMR) in a wide range of systems. Here, we show that DNP can be used to polarize lipids using a lipid-anchored polarizing agent. More specifically, we introduce a C16-functionalized biradical, which allows localization of the polarizing agents in the lipid bilayer and DNP experiments to be performed in the absence of excess cryo-protectant molecules (glycerol, dimethyl sulfoxide, etc.). This constitutes another original example of the matrix-free DNP approach that we recently introduced. [ABSTRACT FROM AUTHOR]

Matrix ‐ Free DNP on Lipid Membranes Dynamic nuclear polarization (DNP) has been proven to be a powerful technique to enhance the sensitivity of solid ‐ state NMR. However, until now, there has been limited success in its application to synthetic membrane ‐ type systems. In their Communication on page 4512 ff., G. De Paëpe et al. present an innovative approach based on system ‐ driven radical design in order to insert the polarizing agent inside a lipid bilayer. Combined with matrix ‐ free DNP, this strategy solves additive ‐ induced problems by releasing the need for a DNP ‐ compatible solvent. [ABSTRACT FROM AUTHOR]