Decoding structural transitions from CdSe nanoclusters to quantum dots through dynamic nuclear polarization NMR.

Xu, Yunyao; Zhang, Lichirui; Sergeyev, Ivan V; Greenberg, Matthew W; Saenz, Natalie; Beecher, Alex; Cooke, Daniel; Friesner, Richard A et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Achieving control over quantum dot size is essential for their performance, but remains challenging due to the limited atomic-level understanding of quantum dot growth. In this study, we employ signal-enhancing Dynamic Nuclear Polarization solid-state NMR to investigate the structural features of intermediate CdSe clusters and mature quantum dots to gain valuable insights. By integrating quantum mechanical calculations with experimental data, we leverage <sup>113</sup>Cd chemical shift to elucidate local Cd environments at various positions, decoding the complex ligand distribution on cluster surfaces. Our findings reveal that ligand distribution is stabilizing through inter-ligand hydrogen bonds, while minimizing steric clashes during ligand packing on space-constrained planar facets. This study underscores the unique capability of <sup>113</sup>Cd NMR to probe local Cd environments, offering a framework for monitoring structural transitions and improving size control during quantum dot growth.