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Polyoxometalate (POM)-based materials are ideal candidates for implementing molecular memories, and rational POM molecule design is key to higher resistive switching (RS) performance. In this work, in order to obtain a deep structure–property correlation of POM-based memristors, three Anderson-based hybrids, i.e. two-component hybrids (MV)3(MnMo6O18L2)2·4DMF (1) and (MV)2[Cu(DMF)2](MnMo6O18L1)2·6DMF (2), and the three-component one (MV)2(Cu2I3)(MnMo6O18L2)·4CH3CN (3) (L = 2-(hydroxymethyl)-2-(pyridine-4-yl)-1,3-propanediol) have been structurally determined. These hybrids together with the precursors (methyl viologen (MV2+), CuI, and (MnMo6O18L2)) were further fabricated as memristors with the structure of ITO/active layer/Ag. Interestingly, three precursors are RS silent or have bad RS performance, but the incorporation of MV2+ in 1 and 2 can trigger the RS performances, and the further decoration of iodocuprate in 3 can render enhanced RS behavior (ON/OFF ratio: 2.32 × 102) with high thermal-tolerance temperature (240 °C) and extremely long-term stability. The RS mechanism could be assigned to the valence change (VC) induced by oxygen vacancy migrations. The presence of air-stable (MnMo6O18L2)3−-MV2+ donor–acceptor couples can stabilize the oxygen vacancies, which not only trigger the RS behaviors in ITO/1/Ag and ITO/2/Ag, but also result in extremely long-term stability in ITO/3/Ag. Besides, the oxygen vacancies can also be stabilized by Cu2I3 with intense cuprophilic interactions, which corresponds to enhanced RS properties in ITO/3/Ag. This mechanism could be validated by the following structural characters in 3: the stronger POM-MV2+ interactions, the better planarity of MV2+, the very short Cu⋯Cu distances and the ABAB-type packing fashion. The structure–property correlation in this work can provide a new strategy for the development of highly efficient and reliable memristors. [ABSTRACT FROM AUTHOR]

Atomically precise low‐nuclearity (n<10) silver nanoclusters (AgNCs) have garnered significant interest due to their size‐dependent optical properties and diverse applications. However, their synthesis has remained challenging, primarily due to their inherent instability. The present study introduces a new feasible approach for clustering silver ions utilizing highly negative and redox‐inert polyoxoniobates (PONbs) as all‐inorganic ligands. This strategy not only enables the creation of novel Ag‐PONb composite nanoclusters but also facilitates the synthesis of stable low‐nuclearity AgNCs. Using this method, we have successfully synthesized a small octanuclear rhombic [Ag8]6+ AgNC stabilized by six highly negative [LiNb27O75]14− polyoxoanions. This marks the first PONb‐protected superatomic AgNC, designated as {Ag8@(LiNb27O75)6} (Ag8@Nb162), with an aesthetically spherical core–shell structure. The crystalline Ag8@Nb162 is stable under ambient conditions, What's more, it is water‐soluble and able to maintain its molecular cluster structure intact in water. Further, the stable small [Ag8]6+ AgNC has interesting temperature‐ and pH‐dependent reversible fluorescence response, based on which a multiple optical encryption mode for anti‐counterfeit technology was demonstrated. This work offers a promising avenue for the synthesis of fascinating and stable PONb‐protected AgNCs and sheds light on the development of new‐type optical functional materials. [ABSTRACT FROM AUTHOR]

Two inorganic–organic hybrid polyoxotantalates, H4[Na(H2O)5]2[CoII(en)3]2{[CoIII(en)]2(Ta6O19)2}·22H2O (1) and H2K2Na6 (H2O)24{[CoIII(en)]2(Ta6O19)2}·33H2O (2) have been constructed from {[CoIII(en)(Ta6O19)]2}10− ({Co2Ta12}) dimers. Compound 1 has a three-dimensional supramolecular framework with a pcu-type topology. Compound 2 possesses a three-dimensional structure composed of {Co2Ta12} dimers and alkali metal ions (Na+/K+) via coordination bonds. Polyoxotantalates 1 and 2 have been used as active materials for ITO/1/Ag and ITO/2/Ag RRAM devices. These devices exhibit stable non-volatile storage behavior and rewritable resistive switching with high ON/OFF ratios of 1.43 × 103 and 2.17 × 104 for 1-based and 2-based RRAM devices, respectively, and stable cyclic performance during 100-cycle stability tests. This discovery opens up new opportunities for the development of electrical bistability materials. [ABSTRACT FROM AUTHOR]

Three new group IIIA metal phosphate–oxalate (MPO) compounds, namely [(CH3)2NH2]2[M2(HPO4)2(H2PO4)2(C2O4)] (M = Al (1), Ga (2)) and [(CH3)2NH2]2[In2(HPO4)2(H2PO4)2(C2O4)]·H2O (3), have been synthesized. Their crystal structures feature an anionic layer with the sql topology net. In particular, 1 displays a proton conductivity (σ) of 9.09 × 10−3 S cm−1 at 85 °C and under 98% relative humidity, which is the highest among MPOs. This study not only endows the main group metal-based MPO family with new members, but also contributes to further understanding of the structure-directing roles of amines and provides a feasible idea for improving the proton conductivity of MPOs. [ABSTRACT FROM AUTHOR]