Fengyan Li

CO2 Coordination by Inorganic Polyoxoanion in Water

Two inorganic polyoxoanions react with carbon dioxide in aqueous solution to yield two polymeric chainlike complexes, where an activated CO2 molecule covalently bonds to polyoxoanions in a linear mu-eta1,eta1-OCO style. For the first time, the CO2 coordination is realized by an economic and environmentally friendly approach.

Coordination assemblies of polyoxomolybdate cluster framework: From labile building blocks to stable functional materials

Polyoxomolybdates, an important branch in polyoxometalates chemistry, present complicated solution chemistry and unmatched physicochemical properties, which endows us with both great opportunities and considerable challenges in creating new functional materials. This perspective highlights the recent development on the coordination assembly of transition-metal-substituted heteropolymolybdates by using labile lacunary heteropolymolybdates as inorganic multidentate ligands. A series of strategies have been used to stabilize the lacunary heteropolymolybdate building blocks. Finally, we introduce some researches on the modification of polymolybdates by organic groups in aqueous media, which may shed light on the green chemistry of the functionalization of polyoxomolybdates.

Enhanced electrochromic performance of composite films by combination of polyoxometalate with poly(3,4-ethylenedioxythiophene)

A composite film containing poly(3,4-ethylenedioxythiophene) (PEDOT), polyoxometalate (POM) clusters K6P2W18O62·14H2O (P2W18) and polyallylamine hydrochloride (PAH) was fabricated by a smart combination of layer-by-layer (LbL) with electro-polymerization methods. The composite film displays enhanced electrochromic performance by incorporation of P2W18 into the PEDOT film. The electrochromic property of the film is significantly improved, resulting in an optical contrast of 54.7% at 600 nm and an absorbance that does not change after 1500 cycles. Additionally, the film provides broader absorption throughout the visible region. These results demonstrate the essential role of POMs in improving functionality on PEDOT for applications in electrochromic devices.

Enhanced photovoltaic response of the first polyoxometalate-modified zinc oxide photoanode for solar cell application

A photovoltaic electrode consisting of polyoxometalate (SiW12) and zinc oxide (ZnO) was fabricated on indium tin oxide (ITO) glass by one-step electrodeposition. The addition of SiW12 strongly influences the morphology and crystallographic orientation of the ZnO. The photovoltaic properties of the ZnO film and the SiW12–ZnO composite films were investigated via solar cell assembly. Both transient photocurrent and current–voltage curve measurements demonstrate that the photocurrent and power conversion efficiency of the SiW12–ZnO composite film were markedly enhanced in comparison with that of the ZnO film. Based on the results of fluorescence quenching measurements, the enhanced photovoltaic effect should be attributed to the occurrence of the photoinduced electron transfer between polyoxometalate and ZnO, which increases the efficient dissociation of excited electron–hole pairs (excitons).

Self-Organized Honeycomb Structures of Mn12 Single-Molecule Magnets

In this paper, Mn(12)-based ordered honeycomb structures were successfully constructed from a simple solution casting process at high relative humidity through the modification of fatty acids to Mn(12) clusters. Mn(12)-fatty acid complexes maintain typical features of a single-molecule magnet as confirmed by IR spectra and magnetization hysteresis studies. Investigation of the effects of concentration, velocity of humid airflow, solvent, substrate, and alkyl chain length of the Mn(12) complex on the morphology of the honeycomb structures demonstrated wide generality and high reproducibility of the formation of Mn(12)-based self-organized honeycomb-patterned films. Both two-dimensional and three-dimensional honeycomb structures were obtained by adjusting the concentration of the complex solution. Mn(12)-based, honeycomb-patterned films maintain a paramagnetic response at room temperature, and thus give rise to a spatially distributed magnetic pattern on the substrate, which can be imaged by magnetic force microscopy. Importantly, the single-molecule magnetic property of the Mn(12) complex at low temperature is well maintained in the honeycomb-patterned film, which represents a promising outlook for high-density information storage and quantum computing applications.

1D lanthanide(III) coordination polymers with disulfide ligand generated in situ

Three 1D Ln(III) - disulfide complexes [Dy(2,2′-DTDN)1.5(DMSO)3]·H2O (1), [Nd(2,2′-DTDN)1.5(DMSO)3] (2), and [Eu(2,2′-DTDN)1.5(DMSO)3]·H2O (3) (DTDN = dithiodinicotinate) have been synthesized and characterized with single-crystal X-ray diffraction analysis. The ligand dithiodinicotinate was generated in situ by two molecules of 2-mercaptonicotinic acid. These complexes are isostructural except for the lattice water molecules and show a double-chain structure built up from two chiral single-chain motifs. Compound 3 shows strong red fluorescent emissions in the solid state at room temperature. The magnetic properties of these three compounds were studied in the range of 2–300 K.

Multidimensional frameworks constructed from Keggin-type heteropoly blue of molybdenum–tungsten cluster

The reaction of polyoxometalate anion [GeW11O39]8− with the complex anion [MoV2O4(H2O)2(ox)2]2− in the presence of CuCl2·2H2O and DMF (DMF = N,N-dimethyl formamide) at 85 °C in aqueous solution produces both a two-dimensional heteropoly blue H2[α-GeW10MoV2O40][Cu(DMF)3H2O]2·5H2O (1) and a three-dimensional heteropoly blue H4[α-GeW10MoV2O40]2 [CuK2(DMF)6] [K4(DMF)6] (2), which demonstrates that different molar ratio of W : Cu in the reaction could conduct different multidimensional structures of 2D and 3D. The magnetic investigation of the two compounds in temperature range from 300 K to 2 K indicated the presence of strong antiferromagnetic interactions related with the two MoV ions in these two compounds.

Enhanced photocatalytic H2 evolution on CdS with cobalt polyoxotungstosilic and MoS2/graphene as noble-metal-free dual co-catalysts

An efficient photocatalyst was designed through dual modification of CdS by cobalt polyoxotungstosilic (SiW11Co) and MoS2/graphene (M/G). The activity of CdS is increased up to 21.3 times with 1 wt% SiW11Co and 5 wt% M/G loaded. In the absence of noble metals, the as-prepared sample reached a H2 evolution rate of 1.7 mmol h−1.

New fabrication of lanthanide complexes based on the polyoxometalate ligand of the [α(1,4)-GeW10O38]12− anion

New-type two lanthanide complexes based on a germanotungstate ligand, Na12[Ln4(α(1,4)-GeW10O38)2 (H2O)6]·nH2O (Ln = Dy (1); Er (2)) which contain four trivalent lanthanide ions and two [α(1,4)-GeW10O38]12− units, have been synthesized and structurally characterised, and their magnetic properties have also been investigated. Each lanthanide ion resides in the vacant site of the [α(1,4)-GeW10O38]12− fragment through bonding to five oxygen atoms, four of which are from the WO6 octahedra, while the other one is from the central GeO4 tetrahedron group.

A 3D all-inorganic architecture based on the [H2W12O42]10− building block with different alkaline-earth metal linkers: crystal structures, surface photovoltage and photoluminescent properties

Three-dimensional (3D) all-inorganic polyoxometalate compounds, Ca2Na6[H2W12O42]·30H2O (1), Sr4H2[H2W12O42]·26H2O (2), Sr4Na2[H2W12O42]·30H2O (3) and Ba4Na2[H2W12O42]·29.5H2O (4) have been synthesized and their structures consist of [H2W12O42]10− building units and alkaline-earth metal cations (Ca2+, Sr2+ and Ba2+) as linkers. The most interesting feature is that compound 2 represents the first example of a 3D all-inorganic framework in which the paradodecatungstate-B anions [H2W12O42]10− were linked by pure alkaline-earth metal cations. Moreover, each [H2W12O42]10− building unit in compound 2 acts as a decadentate ligand coordinated with ten Sr2+ ions, which represents the highest coordination number of [H2W12O42]10− with alkaline-earth metal cations so far. Another interesting feature is that compounds 1–4 exhibit a clear response to surface photovoltage and electric field-induced surface photovoltage, which is indicative of the semiconductor property and suggests these compounds have potential applications as photocatalysts and light-to-electricity conversion materials.