The high-nuclearity polyoxothiomolybdate [H(8)Mo(84)S(48)O(188)(H(2)O)(12)(CH(3)COO)(24)](32-) has been prepared and characterized by single-crystal X-ray crystallography and (1)H NMR, IR, Raman, and UV-vis spectroscopy. The solid-state structure reveals an unprecedented and intriguing arrangement consisting of a nanoscaled anionic cube. The surprisingly open structure of this {Mo(84)}-type cubic box features a large inner void that is accessible via its six open square faces with diameters of ca. 9 Å. Importantly, this molecular system appears to be highly functionalizable because of the presence of 24 exposed exchangeable acetate ligands.

Silicon nanoparticles (Si NPs) are highly attractive materials for typical quantum dots functions, such as in light-emitting and bioimaging applications, owing to silicon’s intrinsic merits of minimal toxicity, low cost, high abundance, and easy and highly stable functionalization. Especially nonoxidized Si NPs with a covalently bound coating serve well in these respects, given the minimization of surface defects upon hydrosilylation of H-terminated Si NPs. However, to date, methods to obtain such H-terminated Si NPs are still not easy. Herein, we report a new synthetic method to produce size-tunable robust, highly crystalline H-terminated Si NPs (4–9 nm) using microwave irradiation within 5 min at temperatures between 25 and 200 °C and their further covalent functionalization. The key step to obtain highly fluorescent (quantum yield of 7–16%) green-red Si NPs in one simple step is the reduction of triethoxysilane and (+)-sodium l-ascorbate, yielding routinely ∼1 g of H–Si NPs via a highly scalable route in 5–15 min. Subsequent functionalization via hydrosilylation yielded Si NPs with an emission quantum yield of 12–14%. This approach can be used to easily produce high-quality H–Si NPs in gram-scale quantities, which brings the application of functionalized Si NPs significantly closer.

Two nanosized polyoxothiometalates were synthesized based on linking oxomolybdate building blocks with {Mo2O2S2}(2+) groups. Remarkably, both compounds are formed selectively primarily upon changing the related concentrations in a logical way; they exhibit common structural features based on the same {Mo9O6S3}-type pores, which result in connections between {Mo6O21} pentagons and {Mo2O2S2}(2+) linkers. Whereas the much larger spherical Mo132-type Keplerate contains twenty pores, the smaller Mo63 -type cluster remarkably contains only two. The two compounds and a similar Keplerate exhibit interesting supramolecular properties related to interactions with the unusual predominantly apolar NMe4(+) cations. Structural characterization of the Mo63 -type compound reveals in the solid state a clathrate-like species that contains four NMe4(+) cations embedded in two types of structurally well-adapted pockets. Related NMR spectroscopic investigations in solution using NMe4(+) as the NMR spectroscopic probe are in agreement with the solid-state description. (1)H NMR spectroscopic experiments (1D variable-temperature, 2D total correlation spectroscopy (TOCSY), exchange spectroscopy (EXSY), and diffusion-ordered spectroscopy (DOSY)) feature firmly immobilized and mobile NMe4(+) ions in relationship with the type of host-guest arrangements. The use of the (1)H NMR DOSY spectroscopic methodology has been successfully applied to track the interactions of the NMe4(+) cations with the {Mo9O6S3} pores of a sulfurated Keplerate, thereby allowing the first quantitative analysis of this type of plugging process. The stability constant K=(210±20) mol(-1)  L is discussed related to the character of the process.

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