In this paper, imidazole-based ionic liquids with different alkyl chains were covalently grafted onto calix[4]arene, which resulted in the formation of 4–6 with the molecular formula [C₄₄H₅₆O₄·2C₄H₆N₂(CH₂)_n]·2Br [n = 5 (4), n = 8 (5), n = 12 (6)]. Ion exchange of 4–6 with Na₉EuW₁₀O₃₆·32H₂O (denoted EuW₁₀) led to the formation of new inorganic–organic hybrid materials 7–9 with a molecular composition of [C₄₄H₅₆O₄·2C₄H₆N₂(CH₂)_n]_4.5·EuW₁₀O₃₆·xH₂O [n = 5, x = 10 (7); n = 8, x = 7 (8); n = 12, x = 20 (9)]. Contact angles above 139° suggested superhydrophobicity of the resulting hybrid materials 7–9. Sulfur removal of dibenzothiophene by applying hybrid materials 7–9 as heterogeneous catalytic systems indicated that deep desulfurization could be achieved at 70 °C in 7, 5.5, and 5 min, respectively. Hybrid materials 7–9 were demonstrated to be highly efficient and selective desulfurization systems that could be reused more than 10 times without a clear decrease in reactivity.

The polyoxometalate (POM) cluster Na₇H₂LaW₁₀O₃₆⋅32 H₂O (denoted LaW₁₀) is immobilized onto dihydroimidazolium-based ionic-liquid (IL)-modified mesoporous silica, resulting in the formation of a new catalyst: LaW₁₀/IL-SiO₂. Compared with other reported extractive catalytic oxidative desulfurization (ECODS) systems, LaW₁₀/IL-SiO₂ has the following advantages: 1) the heterogeneous catalyst LaW₁₀/IL-SiO₂ achieves deep desulfurization of dibenzothiophene (DBT), benzothiophene (BT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in 25, 30, and 25 min, respectively, under mild conditions; 2) deep desulfurization of DBT follows zero-order reaction kinetics; 3) there is no need to add ionic liquid each time the catalyst is reused; 4) the catalyst can be separated easily by filtration and reused at least ten times without a decrease in catalytic efficiency. As such, LaW₁₀/IL-SiO₂ shows great potential for practical applications.

A new photosensitive polyoxometalate (POM) organic–inorganic hybrid compound has been prepared by covalently tethering coumarin moieties onto a Mn–Anderson cluster. This compound has been fully characterized by ¹H NMR, ¹³C NMR, FTIR, and UV/Vis spectroscopy, and ESI-MS. This organic–inorganic hybrid compound can undergo reversible light-driven polymerization and this process has been characterized in detail.

A covalently tethered polyoxometalate (POM)–pyrene hybrid (Py–SiW₁₁) is utilized for the noncovalent functionalization of single-walled carbon nanotubes (SWNTs). The resulting SWNTs/Py–SiW₁₁ nanocomposite shows that both SiW₁₁ and pyrene moieties could interact with SWNTs without causing any chemical decomposition. When used as anode material in lithium-ion batteries, the SWNTs/Py–SiW₁₁ nanocomposite exhibits higher discharge capacities, and better rate capacity and cycling stability than the individual components. When the current density is 0.5 mA cm⁻², the nanocomposite exhibits the initial discharge capacity of 1569.8 mAh g⁻¹, and a high discharge capacity of 580 mAh g⁻¹ for up to 100 cycles.

Two lanthanide-containing polyoxometalates (POMs) have been developed as Lewis acid–base catalysts for highly selective and efficient oximation of various aldehydes and ketones under mild conditions.

Amphiphilic lanthanide-containing polyoxometalates (POMs) were prepared by surfactant encapsulation. Investigation of these lanthanide-containing POMs in oxidative desulfurization (ODS) showed that highly efficient deep desulfurization could be achieved in only 14 min with 100 % conversion of dibenzothiophene under mild conditions by using (DDA)₉LaW₁₀/[omim]PF₆ (DDA=dimethyldioctadecylammonium, omim=1-octyl-3-methyl-imidazolium) in the presence of H₂O₂. Furthermore, deep desulfurization proceeds smoothly in model oil with an S content as low as 50 ppm. A scaled-up experiment in which the volume of model oil was increased from 5 to 1000 mL with S content of 1000 ppm indicated that about 99 % sulfur removal can be achieved in 40 mins in an ionic-liquid emulsion system. To the best of our knowledge, the (DDA)₉LaW₁₀/[omim]PF₆ catalyst system with H₂O₂ as oxidant is one of the most efficient desulfurization systems reported so far.

Highly efficient, deep desulfurization of model oil containing dibenzothiophene (DBT), benzothiophene (BT), or 4,6-dimethyldibenzothiophene (4,6-DMDBT) has been achieved under mild conditions by using an extraction and catalytic oxidative desulfurization system (ECODS) in which a lanthanide-containing polyoxometalate Na₇H₂LnW₁₀O₃₆⋅32 H₂O (LnW₁₀; Ln=Eu, La) acts as catalyst, [bmim]BF₄ (bmim=1-butyl-3-methylimidazolium) as extractant, and H₂O₂ as oxidant. Sulfur removal follows the order DBT>4,6-DMDBT>BT at 30 °C. DBT can be completely oxidized to the corresponding sulfone in 25 min under mild conditions, and the LaW₁₀/[bmim]BF₄ system could be recycled for ten times with only slight decrease in activity. Thus, LaW₁₀ in [bmim]BF₄ is one of the most efficient systems for desulfurization using ionic liquids as extractant reported so far.

Well-ordered, ultra-thin films (UTFs) based on the hybrid assembly of Na₉[EuW₁₀O₃₆]⋅32 H₂O (denoted as EuW₁₀) and exfoliated MgAl layered double hydroxide (LDH) monolayers have been fabricated by utilising a layer-by-layer (LBL) technique. The assembly process was monitored by UV/Vis absorption and fluorescence spectroscopy measurements to get a stepwise and regular growth of the UTFs upon increasing the deposited cycles. In the resulting (EuW₁₀/LDH)_n UTFs, the intercalation of EuW₁₀ anions into LDH monolayers allows the UTFs to retain their optical properties. Meanwhile, LDH monolayers provide EuW₁₀ with a confined and protective microenvironment to isolate them from each other between adjacent layers. The UTFs exhibit a periodic, long-range, ordered structure. Anisotropic luminescence spectroscopy measurements show that the (EuW₁₀/LDHs)_n UTFs display well-defined red luminescence with an anisotropy value, r, of about 0.15. Therefore, the cooperative and orientation effects between the host layers and guest anions play significant roles for the improved properties of the (EuW₁₀/LDHs)_n UTFs. This work could benefit the design and fabrication of novel electro-optical devices based on the UTFs of hybrid materials.