Multiscale Structural Control of Thiostannate Chalcogels with Two-Dimensional Crystalline Constituents

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 ([Sn₂S₆]⁴⁻)-transformation-induced self-assembly, yielding Na-Mn-Sn-S, Na-Mg-Sn-S, and Na-Sn(II)-Sn(IV)-S aerogels. The aerogels exhibited [Sn₂S₆]⁴⁻:Mn²⁺ stoichiometric-variation-induced-control of average specific surface areas (95–226 m² g⁻¹), 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_2xMn_xSn_3-xS₆, KMS-1), featuring a layer-by-layer stacking structure and effective radionuclide (Cs⁺, Sr²⁺)-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 twodimensional chalcogenide clusters can be used to design unique chalcogels with unprecedented structural hierarchy.