A general class of C₃-symmetric Ag₉ clusters, [Ag₉S(tBuC₆H₄S)₆(dpph)₃(CF₃SO₃)] (1), [Ag₉(tBuC₆H₄S)₆(dpph)₃(CF₃SO₃)₂]⋅CF₃SO₃ (2), [Ag₉(tBuC₆H₄S)₆(dpph)₃(NO₃)₂] ⋅NO₃ (3), and [Ag₉(tBuC₆H₄S)₇(dpph)₃(Mo₂O₇)_0.5]₂⋅2 CF₃COO (4) (dpph=1,6-bis(diphenylphosphino)hexane), with a twisted trigonal-prism geometry was isolated by the reaction of polymeric {(HNEt₃)₂[Ag₁₀(tBuC₆H₄S)₁₂]}_n, 1,6-bis(diphenylphosphino)hexane, and various silver salts under solvothermal conditions. The structures consist of discrete clusters constructed from a girdling Ag₉ twisted trigonal prism with the top and bottom trigonal faces capped by diverse anions (i.e., S²⁻ and CF₃SO₃⁻ for compound 1, 2×CF₃SO₃⁻ for compound 2, 2×NO₃⁻ for compound 3, and tBuC₆H₄S⁻ and Mo₂O₇²⁻ for compound 4). This trigonal prism is bisected by another shrunken Ag₃ trigon at its waist position. Interestingly, two inversion-related Ag₉ trigonal-prismatic clusters are dimerized by the Mo₂O₇²⁻ ion in compound 4. The twist is amplified by the bulkier thiolate, which also introduces high steric-hindrance for the capping ligand, that is, the longer dpph ligand. Four more silver–sulfur clusters (namely, compounds 5–8) with their nuclearity ranging from 6–10 were solely characterized by single-crystal X-ray diffraction to verify the above-described synergetic effect of mixed ligands in the construction of Ag₉ twisted trigonal prisms. Surprisingly, only cluster 1 emits yellow luminescence at λ=584 nm at room temperature, which may be attributed to a charge transfer from the S 3p orbital to the Ag 5s orbital, or mixed with metal-centered (MC) d¹⁰d⁹s¹ transitions. Upon cooling from 300 to 80 K, the emission intensity was enhanced along with a hypsochromic shift. The good linear relationship between the maximum emission intensity and the temperature for compound 1 in the range of 180–300 K indicates that this is a promising molecular luminescent thermometer. Furthermore, cyclic voltammetric studies indicated that the diffusion- and surface-controlled redox processes were determined for compounds 1 and 3 as well as compound 4, respectively.

Assembly of small clusters into rigid bodies with precise shape and symmetry has been witnessed by the significant advances in cluster-based metal–organic frameworks (MOFs), however, nanosized silver cluster based MOFs remain largely unexplored. Herein, two anion-templated silver clusters, CO₃@Ag₂₀ and SO₄@Ag₂₂, were ingeniously incorporated into a 2D sql lattice (1, [CO₃@Ag₂₀(iPrS)₁₀(NO₃)₈(DMF)₂]_n) and an unprecedented 3D two-fold interpenetrated dia network (2, [SO₄@Ag₂₂(iPrS)₁₂(NO₃)₆⋅2 NO₃]_n), respectively, under mild solvothermal conditions. Their atomically precise structures were confirmed by single-crystal X-ray diffraction analysis and further consolidated by IR spectroscopy, thermogravimetric analysis (TGA), and elemental analysis. Each drum-like CO₃@Ag₂₀ cluster is extended by twelve NO₃⁻ ions to form the 2D sql lattice of 1, whereas each ball-shaped SO₄@Ag₂₂ cluster with a twisted truncated tetrahedral geometry is pillared by four [Ag₆(NO₃)₃] triangular prisms to form the 3D interpenetrated dia network of 2. Notably, 2 is the first interpenetrated 3D MOF constructed from silver clusters. These results demonstrate the dual role of the anions, which not only internally act as anion templates to induce the formation of silver thiolate clusters but also externally extend the cluster units into the rigid networks. The photoluminescent and electrochemical properties of 2 are discussed in detail.

Atomically precise polyoxometalate–Ag₂S core–shell nanoparticles were generated in a top-down approach under solvothermal conditions and structurally confirmed by X-ray single-crystal diffraction as an interesting core–shell structure comprising an in situ generated Mo₆O₂₂⁸⁻ polyoxometalate core and a mango-like Ag₅₈S₃₈ shell. This result demonstrates the possibility to integrate polyoxometalate and Ag₂S nanoparticles into a core–shell heteronanostructure with precisely controlled atomical compositions of both core and shell.

The encapsulation of carbonate derived from atmospheric CO₂ has resulted in an icosanuclear heteropolyoxocopperate, isolated as a metal–organic 1D chain, 2D sheet, or 3D framework, in which the Cu₂₀ nanocluster represents the first eight-capped α-Keggin polyoxometalate with the late-transition-metal Cu^II as the polyatom, CO₃²⁻ as the heteroanion, and OH⁻ and suc²⁻ or glu²⁻ (H₂suc=succinic acid; H₂glu=glutaric acid) as the terminal ligands, which suggests a conceptual similarity to classical polyoxometalates. Even in the presence of competitive SO₄²⁻ in the assembly system, the CO₃²⁻ anion is still captured as a template to direct the formation of the Cu₂₀ nanocluster, which indicates the stronger templation ability of CO₃²⁻ compared with SO₄²⁻. When other aliphatic dicarboxylates, such as glutaric acid, were used as ligands, the CO₃²⁻-templated Cu₂₀ nanocluster was maintained and acted as a cluster building unit (CBU) to be linked by two glutarate bridges to generate a distinct 1D metal–organic chain. This report presents not only a rare example of a huge anion-templated transition-metal cluster, but also its use as a robust CBU to construct novel coordination architectures. Variable-temperature magnetic susceptibility studies revealed that an antiferromagnetic interaction exists within the Cu₂₀ nanocluster. The correlation between the coordination structure and the electron paramagnetic resonance spectra recorded of both powder and single-crystal samples are discussed in detail.

Through a pillar-ligand extension strategy, a rare breathing behavior in polycatenated 2D3D nets has been achieved. Three variants exhibit interesting sorption properties that range from non-breathing to breathing behaviors, which is influenced by the angles between the pillars and the single honeycomb layers. The increase in pillar length does not lead to an increase in polycatenation multiplicity, which is controlled by the length of intralayer tripodal carboxylate. It also does not induce obviously expanded interlayer separations but occupies much more the free voids, and as a consequence, a smaller pore volume is obtained. This suggests that in 2D3D polycatenated bilayer metal–organic frameworks, the porosity is not always enhanced by increasing the length of the interlayer pillars with the intralayer linker remaining unchanged.

A rare example of coordination at the amino group of NH₂pym (2-aminopyrimidine) relevant to NH activation is described that leads to a novel Ag^I–imide 3D metal–organic framework (MOF). The coordination of Ag^I to NH₂pym produced an electron-withdrawing effect and thus increased its acidity, which facilitated the NH activation and the subsequent formation of the Ag–imide bond. A cooperative metalation/deprotonation process for the NH activation of NH₂pym is suggested. Interestingly, photoluminescence of 1 is switched on at the low temperature of 77 K.

The long-persistent phosphorescent metal–organic framework (MOF) is a kind of highly desirable but rare material. Here, two new molecular MOF materials, {[Zn(tipa)Cl]⋅NO₃⋅2 DMF}_n (1) and {[Cd₂(tipa)₂Cl₄]⋅6 DMF}_n (2) (tipa=tri(4-imidazolylphenyl)amine), which have 3D twofold interpenetrated (utp) and 2D noninterpenetrated (kgd) topologies, respectively, are reported. They exhibit unexpected long-persistent emissions yet reported: At 77 K, they persist in glowing after stopping the UV irradiation on a timescale up to seconds at 77 K, which can be detected by the naked eye (ca. 2 s). Compounds 1 and 2 also undergo single-crystal-to-single-crystal (SC-SC) transformations through different routes; a simple anion-exchange route for 1 and a complicated replacement of μ₁-Cl⁻ ions by DMF molecules accompanying I₃⁻ captured in the void for 2.