Multiscale structural control of thiostannate chalcogels with two-dimensional crystalline constituents.

Ha, Thanh Duy Cam; Lee, Heehyeon; Kang, Yeo Kyung; Ahn, Kyunghan; Jin, Hyeong Min; Chung, In; Kang, Byungman; Oh, Youngtak et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

Chalcogenide aerogels (chalcogels) are amorphous structures widely known for their lack of localized structural control. This study, however, demonstrates a precise multiscale structural control through a thiostannate motif ([Sn<sub>2</sub>S<sub>6</sub>]<sup>4-</sup>)-transformation-induced self-assembly, yielding Na-Mn-Sn-S, Na-Mg-Sn-S, and Na-Sn(II)-Sn(IV)-S aerogels. The aerogels exhibited [Sn<sub>2</sub>S<sub>6</sub>]<sup>4-</sup>:Mn<sup>2+</sup> stoichiometric-variation-induced-control of average specific surface areas (95-226 m<sup>2</sup> g<sup>-1</sup>), thiostannate coordination networks (octahedral to tetrahedral), phase crystallinity (crystalline to amorphous), and hierarchical porous structures (micropore-intensive to mixed-pore state). In addition, these chalcogels successfully adopted the structural motifs and ion-exchange principles of two-dimensional layered metal sulfides (K<sub>2x</sub>Mn<sub>x</sub>Sn<sub>3-x</sub>S<sub>6</sub>, KMS-1), featuring a layer-by-layer stacking structure and effective radionuclide (Cs<sup>+</sup>, Sr<sup>2+</sup>)-control functionality. The thiostannate cluster-based gelation principle can be extended to afford Na-Mg-Sn-S and Na-Sn(II)-Sn(IV)-S chalcogels with the same structural features as the Na-Mn-Sn-S chalcogels (NMSCs). The study of NMSCs and their chalcogel family proves that the self-assembly principle of two-dimensional chalcogenide clusters can be used to design unique chalcogels with unprecedented structural hierarchy.