Currently, the realization of rationally designed architectures based on polyoxometalates (POMs) with designed functions has mostly been achieved through the preparation of functional films. However, the traditional approaches suffer from the drawbacks such as time-consuming processes, ill-defined structure and quality, random orientation of the POM molecules, and unsatisfactory performance. In this study, microcrystals of Ag9[EuW10O36]·36H2O (denoted as Ag9[EuW10O36]) were synthesized via a titration method by treating Na9[EuW10O36]·32H2O (denoted as Na9[EuW10O36]), selected as a prototype, with Ag+, leading to the formation of a water-insoluble crystalline powder with a uniform hexagonal platelet morphology. After this, a simple yet efficient manual assembly method was used to rapidly manufacture Ag9EuW10O36 microcrystal thin films on a glass substrate with high coverage, high crystallinity, and highly preferential orientation. Note that the as-prepared films emit orange polarized fluorescence with an anisotropy value of about 0.21, which places them among the materials of largest anisotropy. It is expected that the manual assembly approach can be generally adopted for the fabrication of many other kinds of polyoxometalate-based materials on various substrates for practical applications.

Calcination is considered to be a key step in the process of preparation of titanium dioxide based catalysts; however, it consumes a lot of energy. We describe unequivocally here for the first time that high-energy consuming calcination is a surplus process in the preparation of phosphotungstic acid@titanium dioxide (PW12@TiO2) catalysts with various loadings of phosphotungstic acid (10–40 wt%) for oxidative catalytic reactions. To prove this, a case study on the preparation of PW12@TiO2 nanospheres via the sol–gel procedure is discussed here. The structure and morphology of the nanospheres were characterized by FT-IR, FT-Raman, BET XRD, ICP and SEM analyses. Oxidative desulfurization of a model oil composed of 350 ppmwS dibenzothiophene (DBT) in n-octane was investigated using these nanospheres. The results showed that both calcinated and un-calcinated-PW12@TiO2 nanospheres exhibited almost parallel yet excellent oxidative desulfurization performances in the model oil. The 350 ppmwS of sulfur content in 20 mL of n-octane was dropped down to 2.4 and 2.6 ppmwS within 2 hours at 60 °C using 70 mg of calcinated and un-calcinated-PW12@TiO2 nanospheres with 30 wt% PW12 loading, respectively. The high desulfurization efficiency of the catalyst remained unchanged even after the regeneration of the catalyst ten times. This excellent desulfurization performance makes the as-prepared composite without calcination treatment a promising catalyst in practical oxidative desulfurization processes.

Cu3(BTC)2 (H3BTC = 1,3,5-benzenetricarboxylic acid) was anchored onto the surface of carboxymethylated chitosan non-woven fabrics by a controllable layer-by-layer technique in alternating solution baths of Cu(OAc)2·H2O and H3BTC solutions, and the resulting [Cu3(BTC)2]n@chitosan non-woven fabric composite materials (n = number of alternate deposition cycles) were thoroughly characterized. The results showed that the composite materials not only exhibited excellent decontamination ability against sulfur mustard (HD), with an enhanced degradation rate of HD with increasing n, but also possessed remarkable haemostasis performance. The degradation efficiency of sulfur mustard by [Cu3(BTC)2]4@chitosan was found to be much higher than that of pristine [Cu3(BTC)2]4. The inherent haemostatic capabilities of the chitosan non-woven fabrics were not affected by the growth of Cu3(BTC)2 on the surface of chitosan. Oral and histological toxicity examinations of the pristine Cu3(BTC)2 sample showed that damage and toxicity in the viscera of mice was very low, even if the intra-gastric administration dose of Cu3(BTC)2 reached a very high level (50 mg of Cu3(BTC)2 per kg of mouse). The results have shown that the as-prepared composite can be used safely as a promising haemostatic decontaminant with good recyclability against sulfur mustard.

Composite films with alternating layers (PAH/PSS)3(AB/POM)n (PAH = polyallylamine hydrochloride, PSS = polystyrene sulfonate) derived from Alcian Blue-tetrakis(methyl-pyridinium) chloride (abbreviated as AB) and Keggin type polyoxometalates (POM = H4SiW12O40, H3PW12O40, H3PMo12O40, H5PMo10V2O40) have been fabricated and characterized. Under laser irradiation at 532 nm with a pulse duration of 6–7 ns, a repetition rate of 10 Hz and the intensity of the light at focus E0 being 10 μJ, the composite films exhibit self-defocusing behavior and saturated absorption effects, and the nonlinear optical absorption coefficient β (m W−1) and refractive index n2 (m2 W−1) of the films are 4–5 times larger than those of pure AB solution in view of their magnitude. Interestingly, it is found that third-order NLO susceptibilities χ(3) of films are in the order of χ(3)(AB/PSS) < χ(3)(AB/SiW12) < χ(3)(AB/PW12) < χ(3)(AB/PMo12) < χ(3)(AB/PMo10V2), which is reversed to the order of ELUMO(SiW12) > ELUMO(PW12) > ELUMO(PMo12) > ELUMO(PMo10V2), affirming that the incorporation of different Keggin type POMs of a lower LUMO energy level with phthalocyanine molecules into multilayers could tune the NLO responses of phthalocyanine films. It is concluded that the lower LUMO level of POM than that of the phthalocyanine can stimulate the easier transformation of excited electrons from AB to the POM within the donor–acceptor system (phthalocyanine molecules acted as an electron donor while POMs as an electron acceptor in the composite films) when flashed with the laser, which is thought to be accountable for the profound third-order optical nonlinearity of the composite films.

HKUST-1 was impregnated effectively on millimeter-sized mesoporous γ-Al2O3 beads under hydrothermal conditions, resulting in formation of a composite material HKUST-1@γ-Al2O3 that features high specific surface area, remarkable enhanced mechanical strength, chemical and thermal stability, and low cost. The composite material exhibited excellent performance with the adsorptive desulfurization capacity of 59.7 mg S/g MOF (versus 49.1 mg S/g MOF for bare HKUST-1) for a model oil composed of dibenzothiophene (with the initial S-content being 1000 ppmwS) and n-octane. Experimental results also revealed that HKUST-1@γ-Al2O3 could reduce 35 ppmwS sulfur content of the model oil lower than 9.6 ppmwS at a ratio of HKUST-1@γ-Al2O3 to oil over 30 wt %, indicating effectiveness for deep adsorptive desulfurization. The Gibbs free energy for DBT adsorption by HKUST-1@γ-Al2O3 was found smaller than that by HKUST-1 due to efficient utilization of active centers, shorter diffusion channels and larger specific surface area of nanosized HKUST-1 particles formed under confined environment of γ-Al2O3 channels/pores. Remarkably, the used HKUST-1@γ-Al2O3 beads can easily be regenerated by acetone washing and the adsorptive desulfurization capacity just slightly decreased after experiencing five recycles. The results indicate that the as-synthesized HKUST-1@γ-Al2O3 beads have great potential as an adsorbent for adsorptive desulfurization in practical applications.

•Spherical millimeter-sized mesoporous γ-Al2O3 beads are selected as catalyst carrier.•Surface of the beads is functionalized with amino groups.•Phosphotungstic acid is stably anchored on the beads via electrostatic interaction.•The obtained materials show excellent oxidative desulfurization for DBT.•Remarkable advantages are witnessed for the obtained materials.The composite material HPW/NH2–Al2O3 was successfully prepared by immobilization of phosphotungstic acid H3PW12O40 (HPW) on the surface of amino functionalized spherical millimeter-sized mesoporous γ-Al2O3 beads (NH2–Al2O3), that featured high specific surface area, remarkable enhanced mechanical strength, chemical stability and low cost. This composite material was characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Brunner−Emmet−Teller (BET) and mechanical strength measurements. The experimental results showed that introduction of NH2 group in between HPW and Al2O3 surface not only provide strong binding sites for catalytic centers HPW to get high dispersion on the carrier surface but also prevent HPW from structural decomposition. As a consequence, the prepared HPW/NH2–Al2O3 exhibited excellent catalytic performance in the oxidative desulfurization of model oil composed of dibenzothiophene (DBT) and n-octane. The 350 ppmwS of sulfur content in 20 mL of n-octane can be dropped down to 2.8 ppmwS in 2 h using 60 mg of HPW/NH2–Al2O3 catalyst under the optimal conditions. Remarkably, the catalyst can be conveniently recycled by simple decantation method. After 10 times recycling, the oxidation desulfurization efficiency just dropped down slightly from 99.2% to 98.6%. The results indicate that synthesized HPW/NH2–Al2O3 beads have great potential as a catalyst in oxidative desulfurization for special practical applications.Phosphotungstic acid immobilized on amino functionalized spherical millimeter-sized mesoporous γ-Al2O3 beads possesses high potentials for practical oxidative desulfurization of dibenzothiophene.

Integrating polyoxometalates into porphyrin moieties via covalent bond is expected to be a new approach to tune and enhance the nonlinear optical responses of porphyrins. The effectiveness and efficiency of this proposal has been examined and witnessed by studying two new hybrid compounds as a prototype, namely, (Bu4N)4K2[{C52H32N5O2Zn}HNC(CH2O)3P2V3W15O59]·2(C4H9NO) (1) and (Bu4N)4K2[{C52H34N5O2}HNC(CH2O)3P2V3W15O59]·3(C4H9NO) (2), in which porphyrins acting as electron donor and Dawson type polyoxometalate acting as electron acceptor are connected via short tether through covalent bond. The new compounds are systematically characterized by means of elemental analyses, FT-IR, 1H NMR, ESI-MS, TG/DTA, UV–vis, fluorescence emission spectra, and cyclic voltammetry measurement. Remarkably, great enhancement in reverse saturation absorption is achieved in 1 and 2 which is ca. 1 order of magnitude greater than their individual reactants. Additionally, optical-limiting thresholds are obtained being 0.484 J/cm2 for 1 and 0.501 J/cm2 for 2, respectively, implying their high potential as low-power optical-limiting materials.

A series of uniform and smooth (TCPP/LDH)n films and (TCPP/P5W30/LDH)n films were fabricated with meso-tetrakis(p-carboxyphenyl)porphyrin (TCPP), Preyssler-type polyoxometalate K12.5Na1.5[NaP5W30O110]·15H2O (P5W30), and exfoliated Mg2Al–NO3 layered double hydroxide (LDH) monolayer nanaosheets by layer-by-layer assembly technique. The resulting films were characterized by UV–visible spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and fluorescence spectroscopy. Their third-order nonlinear optical properties were studied by Z-scan measurement with laser pulse duration of 6–7 ns at a wavelength of 532 nm. The (TCPP/LDH)n films exhibit notable self-defocusing effect and saturated absorption effect which is different from TCPP solution. The optical nonlinearity of films becomes larger with the increase of the number of bilayers. The third-order nonlinear optical coefficient χ(3) of (LDH/TCPP)50/LDH is calculated to be (6.4 ± 0.18) × 10–11 esu. Remarkably, experimental results showed that the (LDH/P5W30/LDH/TCPP)n/LDH films exhibit much larger nonlinearity than that of the (LDH/TCPP)n/LDH films when n is the same, which is thought to result from the interlayered charge/energy transfer between porphyrin and polyoxometalate although the LDH sheet is electron-inert material.

A family of covalently bonded hybrid compounds composed of Anderson type polyoxometalate (POM) moiety and porphyrin moiety have been synthesized and thoroughly characterized. The compounds all show remarkable nonlinear reverse saturable absorption and self-defocusing effect at 532 nm with a pulse duration τ = 6 ns, rendering them promising candidate materials for device applications in photonics and optoelectronics. More importantly, it is found that the hybrid wherein POM is coupled covalently to porphyrin through shorter bridge has an NLO response superior to the hybrid wherein POM is bonded via longer bridge to porphyrin, and the hybrid having two porphyrins connected to POM shows more enhancement than the hybrid having single porphyrin fused to POM. Disclosure of the inherent structure–property relationship is expected to be instructive for exploration of new porphyrin-POM based NLO materials. Meantime, the hybrid compounds have optical-limiting thresholds lower than 1.0 J/cm2, implying their high potential as lower power OL materials.

Two series of lanthanide(III)–organic frameworks with the molecular formula [Ln2(NNO)2(OX)2(H2O)4]n (Ln = Eu 1, Tb 2, Sm 3, Dy 4, Gd 5) and [Ln2(NNO)4(OX)(H2O)2]n (Ln = Eu 6, Tb 7, Sm 8, Dy 9, Gd 10) were synthesized successfully under the same hydrothermal conditions with nicotinic N-oxide (HNNO) and oxalic acid (H2OX) as the mixed ligands merely through varying the molar ratio of the reactants. The compounds were characterized by IR, elemental analysis, UV, TG-DTA and powder X-ray diffraction (XRD). X-ray single-crystal diffraction analyses of compounds 1 and 7 selected as representatives and powder XRD analysis of the compounds revealed that both the series of compounds feature three-dimensional (3-D) open frameworks, and crystallize in the triclinic P space group while with different unit cell parameters. In compound 1, pairs of Eu3+ ions and pairs of NNO− ligands connect with each other alternately to form a 1-D infinite Eu-NNO double chain, the adjacent 1-D double-chains are then joined together through OX2− ligands leading to a 2D layer, the 2-D layers are further ‘pillared’ by OX2− ligands resulting in a 3-D framework. In compound 7, the 1-D Tb-NNO infinite chain and its 2-D layer are formed in an almost similar fashion to that in compound 1. The difference between the structures of the two compounds 1 and 7 is that the adjacent 2-D layers in compound 7 are further connected by NNO− ligands resulting in a 3-D framework. The photoluminescence properties and energy transfer mechanism of the compounds were studied systematically. The energy level of the lowest triplet states of the HNNO ligand (23148 cm−1) was determined based on the phosphorescence spectrum of compound 5 at 77 K. The 5D0 (Eu3+) and 5D4 (Tb3+) emission lifetimes are 0.46 ms, 0.83 ms, 0.69 ms and 0.89 ms and overall quantum yields are 1.03%, 3.29%, 2.58% and 3.78% for the compounds 1, 2, 6 and 7, respectively.

Composite films derived from the water-soluble Keplerate-type polyoxometalate (NH4)42[Mo132O372(CH3COO)30(H2O)72]·ca. 300H2O·ca. 10CH3COONH4 (denoted (NH4)42{Mo132}) and chloroform-soluble tetraphenylporphyrin perchlorate [H2TPP](ClO4)2 are successfully fabricated by a layer-by-layer self-assembly method and characterized by UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The structure of the {Mo132} and [H2TPP]2+ in the films remain intact in light of the results of UV-vis spectroscopy and XPS. UV-vis spectra measurements reveal that the amounts of deposition of {Mo132} and [H2TPP]2+ remain constant in every adsorption cycle in the composite films assembly process. Nonlinear optical properties of the composite films have been investigated by using the Z-scan technique at a wavelength of 532 nm and pulse width of 7 ns. The results show that the composite films have notable nonlinear saturated absorption and self-defocusing effects. The combination of {Mo132} with [H2TPP]2+ can result in composite films with remarkably enhanced optical nonlinearities. The interfacial charge transfer induced by laser from porphyrin to POM in the films is thought to play a key role in the enhancement of NLO response. The third-order NLO susceptibility χ(3) of the composite films increases with the increase of film thickness.

A series of 3D coordination polymers {[Ln2(bdcd)(ox)2(H2O)3]·4H2O}n (Ln = Eu (1), Tb (2), Sm (3), Dy (4), and Gd (5)), which crystallize in the triclinic space group P with Z = 2, have been synthesized successfully based on the versatile ligands 2,2′-bipyridine-3,3′-dicarboxylic acid 1,1′-dioxide (H2bdcd) and oxalic acid (H2ox). The compounds were characterized by means of IR spectroscopy, elemental analysis, TG, and powder X-Ray diffraction, whereby compounds 1 and 2 were structurally characterized. All of the compounds are isomorphous and have a 3D open framework in which ox2− ligands bridge Ln3+ ions through their carboxylate groups resulting in the formation of a 1D Ln–ox infinite chain in the ac plane. The adjacent 1D Ln–ox infinite chains are then connected to each other through coordination interactions between Ln3+ ions and the carboxylate groups and N-oxide atoms of bdcd2− ligands resulting in a 3D (7,8)-connected open framework with a (38·49·54) (37·49·511·6) topology possessing 1D channels with lattice water molecules as residents. The photoluminescence properties of compounds 1, 2 and 4 were investigated in detail.

Keggin-type polyoxoanion PW12O403−-containing one-dimensional nano-tubular arrays, with the structure polyethylenimine/polystyrenesulfonate/(poly(allylammonium)/polystyrenesulfonate)3(poly(allylammonium)/PW12O403−)8, were fabricated as a prototype using a layer-by-layer deposition technique in porous anodic aluminum oxide and polycarbonate templates with a pore diameter of 200 nm, and characterized by IR, UV-vis and SEM. The resulting nano-tubes have a uniform diameter of 180 ± 20 nm and a uniform wall thickness of 30 ± 5 nm. These arrays have shown superior performance in the UV light irradiated photo-degradation of Rhodamine B (selected as a representative dye) under mild conditions with respect to both the catalytic efficiency and operating convenience due to the confinement within the nano-tubes both in the latitudinal and radial direction. Remarkably, the catalytic activity of the nano-tubular arrays could be recovered by means of simple immersion in the polyoxoanion solution when the catalytic reactivity became reduced, which is vital in view of practical applications. The total organic carbon content changes and GC-MS measurements were conducted to identify the degradation products. The hydroxyl radical mechanism was found to be adopted by the photo-degradation reaction.

Correction for ‘Towards applications in catalysis: investigation on photocatalytic activities of a derivative family of the Keplerate type molybdenum–oxide based polyoxometalates’ by Yunshan Zhou et al., RSC Adv., 2014, 4, 54928–54935.

A new family of silver(I)–lanthanide(III) heterometallic-organic frameworks having the formula [AgLn(bpdc)2] (Ln = Eu (1), Tb (2), Sm (3), Dy (4), Y (5), Yb (6), Er (7), Ho (8); H2bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid), each of which crystallizes in the monoclinic space group C2/c with Z = 4, has been hydrothermally synthesized. The compounds were characterized by means of IR, elemental analysis, thermogravimetric-differential thermal analysis, and powder X-ray diffraction (XRD), wherein compounds 1, 2, and 4–8 were structurally characterized. The powder XRD and single-crystal structures of the title compounds indicate that all the compounds are isostructural and feature a three-dimensional (3-D) open framework. In the structures of the compounds, bpdc2– ligands link Ln3+ through their carboxylic groups, resulting in the formation of a one-dimensional {Ln(bpdc)2}n infinite chain along the c direction. The adjacent chains are then connected to each other through the coordination interaction between Ag+ and the pyridyl N atoms of bpdc2– ligands from the chains, resulting in a 3-D (2,4,6)-connected open framework with (411·64)(43·82·10)(8)2 topology. The compounds show remarkable good thermally stability up to 370 °C because neither aquo ligands nor lattice water molecules exist in the composition of the compounds. The photoluminescent properties of compounds 1 and 2 were studied in detail. The energy level of the triplet states of the ligand H2bpdc 21 505 cm–1 (465 nm) was determined based on the 77 K emission spectrum of the compound [Gd2(bpdc)3(phen)2(H2O)2]·6H2O 9. The 5D0 and 5D4 emission lifetimes (1.58 and 1.76 ms) and the overall quantum yields (21% and 22%) were determined for the compounds 1 and 2, respectively.

Four isostructural lanthanide–organic complexes [Ln(HPDH)(ox)(H2O)]n (Ln = Eu3+1, Tb3+2, Sm3+3, Gd3+4; H2PDH = 6,7-dihydropyrido(2,3-d)pyridazine-5,8-dione; H2ox = oxalic acid) have been synthesized successfully under hydrothermal conditions and characterized by means of elemental analysis, powder XRD, TG-DTA, IR and UV-vis spectroscopy. Complexes 1 and 2 were structurally characterized by single crystal X-ray diffraction analysis. All complexes are composed of 2-D layers, which further construct a 3-D supramolecular network. Each 2-D layer in complexes 1–4 is composed of 1-D Eu–ox infinite chains, which are further connected by biconnected HPDH− ligands. The photoluminescent properties of complexes 1–4 were studied in the solid state at room temperature. The singlet energy level (34722 cm−1) and the lowest triplet energy level (21786 cm−1) for the ligand H2PDH were calculated on the basis of its UV-vis absorbance edges (1 × 10−4 M in ethanol) and phosphorescence spectrum of complex 4 at 77 K, respectively. The complexes 1, 2, and 3 exhibit metal centered luminescence with characteristic red, green and pink emission, respectively. The energy transfer mechanism and photoluminescence properties were investigated. Complex 1, in which the energy transition from the triplet energy level (3ππ*) of ligand HPDH− to Eu3+ cation is more effective, has been selected as a representative to examine the potential for sensing small molecules by its luminescence properties in different emulsions. EtOH was found to be an excellent enhancing while DMF a highly quenching solvent in this study.

The photocatalytic potential of a derivative family of the Keplerate type nano-porous Mo–O based polyoxometalates with general formula [Mo72VIMo60VO372(L)30(H2O)72]n− (L = CH3COO−, SO42−) (denoted Mo132) has been evaluated by a prototype photocatalytic decoloration reaction of aqueous rhodamine B. The Mo132 anions are found to be photocatalytically active centers, however they are unstable and subjected to decomposition in the solution form. The introduction of organic counter cations such as tetrabutylammonium (n-Bu4N+) and dioctadecyldimethylammonium (DODA+) can endow significant stability to the giant anions during the catalytic process. TOC changes and GC/MS measurements were done to identify the degradation products. Among the derivatives, compound 2 composed of n-Bu4N+ and Mo132 (L = CH3COO−) has been found to be the most active one towards the photocatalytic decoloration of RhB solution. The analytical mechanism indicates that both OH radicals and 1O2 participate in the photo degradation process.

Three new supramolecular compounds [H2TPP]1.5[SW11VO40]·5CH3CN·4H2O 1, [H2TPP]2[SW10V2O40]·4CH3CN·3H2O 2, and [H2TPP][SW12O40]·4H2O 3 composed of [H2TPP]2+ cation and vanadium substituted Keggin-type polyoxometalate (POM) anion [SW12−nVnO40](2+n)− (n = 0–2) were prepared and characterized. The third-order nonlinear optical (NLO) and optical limiting (OL) properties of resulting hybrids were studied by using an Nd:YAG laser at 532 nm with a pulse duration of τ = 7 ns. The results demonstrate that all of these supramolecular compounds have significant nonlinear reverse saturated absorption, self-defocusing behavior, and good OL performance, especially for compound 1, which has a second hyperpolarizability γ value of 7.05 × 10−29 (esu) and exhibits a comparable OL performance with the most well-known OL materials such as In(Pc*)Cl indicating that they are potentially excellent NLO materials. Remarkably, it was also observed that the degree of vanadium substitution in POM anions corresponding to different onset of reduction potential influences the NLO and OL properties of the resulting compounds: third-order NLO and OL properties of compound 2 are inferior to those of compound 1, and are better than those of compound 3. Both their second hyperpolarizability γ values and the OL performance were observed to be inversely proportional to the HOMO–LUMO gaps of the resulting compounds. The excited charge transfer from porphyrin to POM anions in the supramolecular compounds when exposed to laser irradiation is thought to play key role in the enhancement of NLO and OL response.

A new series of four isostructural mononuclear lanthanide complexes Ln(HPDH)3(H2O)3·H2O (Ln = Sm(III) 1, Eu(III) 2, Tb(III) 3 and Dy(III) 4; H2PDH = 6,7-dihydropyrido(2,3-d)pyridazine-5,8-dione) has been prepared and characterized by IR, elemental analysis, XRD and TG-DTA methods. Single crystal X-ray diffraction analysis of both complexes 1 and 3 revealed that the mononuclear discrete complexes form 3-D supramolecular networks via hydrogen bonds and offset stacking (–H⋯π) interactions. The photoluminescence study of the title complexes revealed the photoluminescent potential of the antenna ligand (H2PDH) toward the concerned lanthanide cations. The luminescence based sensing ability of the partially dehydrated complex Tb(HPDH)3(H2O)33a towards small solvent molecules, along with its reusability, has been studied. Isopropyl alcohol was found to be an excellent sensitizer, while tetrahydrofuran was a highly quenching solvent with a first order behavior towards the photoluminescence intensity. The photoluminescence intensity was found to decrease with the increase of the dielectric constant and normalized Dimroth–Reichardt ET parameter values for protic solvents, while reverse behavior was observed for dipolar aprotic solvents.

•Rhombic dodecahedral polyoxometalate microcrystals are selected as a protype.•They are assembled into single-crystal-like structure with [110] orientation.•Concentration of microcrystals and character of solvents affect quality of the resulting films.Rhombic dodecahedral Keggin type (NH4)3PW12O40 microcrystals selected as a protype were fabricated on plane glass substrates by using a horizontal deposition method and characterized. It was found that experimental parameters such as concentration of microcrystals in a solvent and character (polarity, volatility) of the solvent affected significantly the quality of the resulting films. The adopted approach allowed the microcrystals to be assembled into single-crystal-like 2D and/or 3D structure with preferential [110] orientation under optimal conditions. Compared with those films produced by other methods reported in the literature, the resulting films fabricated under optimal conditions are superior in view of the easy-to-fabrication, thickness controllability, and remarkable preferential orientation, which are vital for device fabrication in nano-, micro- and macro-scale.

By reacting the unique Keplerate type molybdenum-oxide based polyoxometalate (NH4)42·[Mo132O372·(CH3COO)30(H2O)72]·ca.300H2O·ca.10CH3COONH4(1) with tetramethylammonium bromide, a new derivative (NH4)26[TMA]16{Mo132O372(H2O)72(CH3COO)30}·ca.7NH4CH3COO·ca.189H2O(2, TMA=tetramethylammonium) was prepared. Compound 2 was characterized by Fourier transform infrared spectroscopy(FTIR), UV-Vis, elemental and thermogravimetric analyses. By the well-established Z-scan technique, investigations on the nonlinear optical(NLO) properties of the series of compounds derived from the Keplerate type molybdenum-oxide-based poly-oxometalate, namely, the newly prepared compound 2, the three previously reported compounds, included compound 1, (NH4)18(TBA)24{Mo132O372(H2O)72(CH3COO)30}·ca.7NH4CH3COO·ca.173H2O(3, TBA=tetrabutylammonium) and (DODA)40(NH4)2[(H2O)nMo132O372(CH3COO)30(H2O)72](4, DODA=dimethyldioctadecylammonium), reveal that the third-order nonlinearity[χ(3)] values of compounds 1, 2 and 3 in the DMF/H2O solution and compound 4 in chloroform are almost the same, which indicates that the counter cations with different length of alkyl chains show ignorable impacts on the NLO susceptibility. In other words, the remarkable third-order nonlinearities[χ(3)≈10−19 m2/V2] mainly come from the [Mo132O372(CH3COO)30(H2O)72]42− anions. This fact reveals that the applications of the NLO active polyoxometalates in various environments(such as hydrophilic, hydrophobic, polar, apolar, etc.) can be achieved by simply varying cations to meet the demands in the design of diverse devices.

The investigation on interactions between tetraphenylporphyrin (TPP) and α-Keggin-type heteropolyoxometalates (POMs) (POMs sequentially refer to H5PMo10V2O40·36H2O (PMoV), H3PMo12O40·14H2O (PMo), H4SiMo12O40·xH2O (SiMo), and H4SiW12O40·xH2O (SiW)) in THF reveals that TPP evolves into a monosalt and successively into a disalt by accepting protons from POMs and that the 2:1 hybrid between PMoV and TPP and the 1:1 hybrids between TPP and PMo, SiMo, and SiW are formed in the THF solution. The reaction equilibrium constants calculated for the 1:1 complexes are quite large, indicative of strong interaction between TPP and POMs. When the concentration of the reactants were simply increased, four hybrids [H2TPP][H4PMo10V2O40]2·6C4H4O·H2O (1), [H2TPP][HPMo12O40]·5C4H8O·5H2O (2), [H2TPP][H2SiMo12O40]·3C4H8O·3H2O (3), and [H2TPP][H2SiW12O40]·4C4H8O·8H2O (4) were isolated and characterized. Z-scan measurement showed that POMs themselves had negligible nonlinear optical response, whereas they imposed remarkable effect on the third-order nonlinear optical properties of resulting TPP–POM hybrid systems. It is found that the second hyperpolarizability values of compounds 1–4 are inversely proportional to the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gaps of these compounds and directly proportional to the discrepancy between the LUMO levels of TPP and POMs, i.e., the low-lying LUMO level of the POMs is important for the improved second hyperpolarizability value of the compounds.

Hydrothermal reactions of lanthanide nitrates with glyphosate have resulted three new isostructural 3D lanthanide–organic frameworks, Ln(NO3)(H2L) [Ln = Eu (1), Tb (2), Gd (3); H4L = 2,5-dioxo-1,4-piperazinylbis(methylphosphonic) acid], with good yields, where H4L as a new ligand was formed via in situ cyclodehydration of original ligand glyphosates during the hydrothermal reaction. The compounds were thoroughly characterized by IR, UV–vis, elemental analysis, single-crystal X-ray diffraction analysis, powder X-ray diffraction analysis, and thermogravimetric/differential thermal analysis (TG-DTA). Three compounds display 3D 6,6-connected open frameworks with 413·62 topology possessing 1D channels in which NO3– anions act as troglodytes by chelating Ln3+ centers. The TG-DTA study of the compounds showed remarkable thermal stability up to 380 °C. Under room temperature UV-light irradiation, the Eu3+ and Tb3+ compounds showed the corresponding characteristic Ln3+ intra 4fn emission peaks. The triplet energy level (21882 cm–1) of the ligand (H4L) was determined from the emission spectrum of its Gd3+ compound at 77 K. The emission lifetimes (1.54 ms of 5D0 for compound 1 and 1.98 ms of 5D4 for compound 2) and absolute emission quantum yields (10.1% for compound 1 and 5.9% for compound 2) were also determined.

•A new ternary photoluminescence enhancement system has been developed.•A simple yet effective method is built for determination of trace amount of Eu3+.•Interferences of other lanthanide ions and common ions are described.•Energy transfer mechanism and photoluminescence enhancement were studied.A new Schiff base ligand N-(2-hydroxy-1-naphthaldehyde)-1,8-diaminonaphthalene (NHND) was synthesized and characterized, and a new ternary photoluminescence enhancement system Eu–NHND–1,10-phenanthroline in acetonitrile was successfully developed to determine trace amounts of Eu3+. The excitation and emission wavelengths were 274 and 617 nm, respectively. Under optimal conditions, the photoluminescence intensities of the system showed a linear response toward Eu3+ in the range of 7.0×10−8 to 3.2×10−6 M with a detection limit of 7.5×10−9 M. The interferences of other trivalent lanthanides and some common ions were described. The system was applied to determine the trace amounts of Eu3+ in a high purity Gd2O3 matrix and in a synthetic rare earth oxide mixture, and satisfactory results proved applicability of the system. Mechanism of energy transfer and photoluminescence enhancement was also studied.

Structural comparison of a new compound [(bpp)3H6]Fe2IIIFe2IIMo24V(H2PO4)8(HPO4)4(PO4)4O48(OH)12· (H2O)4·2H2O(1)[bpp=1,3-di(4-pyridyl)propane] with our previously reported two compounds [(bpy)3FeII]3sdFe2IIIFe2IIMo24V(H2PO4)8(HPO4)4(PO4)4O48(OH)12(H2O)4·12H2O(2) and [(bpy)3FeII]2FeIIFeIIIMo12V(H2PO4)2(H2−xPO4)·(H1+xPO4)(HPO4)2(PO4)2O24(OH)6(H2O)2·9H2O(x=0-21)(3)(bpy=2,2′-bipyridine), which all exhibit one-dimensional mixed-valence iron molybdophosphate anionic chains constructed by alternating connection of FeIII ions and magic [FeII(Mo6P4O31)2] units, reveals that the non-hydrogen atomic ratios of Mo:Fe:P:O within the polymeric anionic chains are the same for all the three compounds, while the polymeric anionic chains of the different compounds bear different numbers of negative charges. And therefore there exist different numbers of counter cations per {Fe2III[Fe2II(P16Mo24VO124)]} unit found in the titled compounds. It discloses that not only are the spatial assembling of counter cations and polymeric inorganic chains of three compounds quite different, but also the O—FeIII—O bond angles and FeIII—O bond lengths of the three different inorganic chains exhibit small differences. What is more important is that such small changes in bond length and bond angle in the assemblage of FeIII—O bonds lead to the considerable fluctuations of inorganic chains in their structural conformation within the three compounds, reflecting an interesting phenomenon of “flexibility” in the pure inorganic one dimensional mixed-valence iron molybdophosphate chains.

A new sensitive quaternary luminescence enhancement system was developed successfully to determine the trace amounts of Eu3+ and Zn2+. The luminescence intensity of Eu–N-(3-methoxysalicylidene)-2-aminopyridine system was greatly increased by the addition of 1,10-phenanthroline and Zn2+. The excitation and emission wavelengths were 274 and 617 nm, respectively. Under optimal conditions, the luminescence intensity of the system showed a linear response toward Eu3+ in the range of 6.0 × 10−6–2.5 × 10−5 mol L−1 with a detection limit of 2.0 × 10−9 mol L−1. This method was successfully applied for the determination of trace amounts of Eu3+ in a high purity Gd2O3 matrix and a synthetic matrix. In addition, it was found that under optimal conditions, the luminescence intensity of the system decreased linearly with the increase of Zn2+ concentration, ranging from 2.0 × 10−6 to 1.8 × 10−5 mol L−1 with a detection limit of 2.8 × 10−8 mol L−1. This method was also successfully applied to determine the trace amounts of Zn2+ in a high purity Mg(NO3)2·6H2O matrix and a synthetic sample. The interferences of other lanthanide ions and some common coexisting ions were investigated. The mechanism for energy transfer and luminescence enhancement of this quaternary system was also studied systematically.Graphical abstractHighlights► A new quaternary luminescence enhancement system has been built. ► The system can be used for the determination of Eu3+ and Zn2+. ► The luminescence enhancement and energy transfer mechanisms are studied.

A sensitive luminescence enhancement system has been developed for the determination of trace amounts of trivalent europium. The luminescence intensity of europium complex with N-(3,5-dibromosalicylidene)-2-aminopyridine (HL) was greatly enhanced after the addition of 1,10-phenanthroline (Phen) in acetonitrile solution. The excitation and emission wavelengths were 274 and 617 nm respectively. Under optimal conditions, the luminescence intensities varied linearly with Eu3+ concentration in the range of 4.0 × 10−6 ∼ 2.4 × 10−5 mol L−1 with a detection limit of 4.3 × 10−10 mol L−1. This method was successfully applied to determine the trace amounts of Eu3+ in a high purity Gd2O3 matrix and in a mixed lanthanide sample. Energy transfer mechanism and luminescence enhancement of HL–Phen–Eu ternary system were studied. The results indicate that both HL and Phen are good sensitizers for the luminescence of Eu3+ ions, as energy gap between the lowest triplet level of HL/Phen and the resonant level of Eu3+ (5D1) exists around the optimal value (3000 ± 500 cm−1). The interference by some other lanthanide ions and common ions were also studied.Graphical abstractHighlights► A new ternary system composed of Schiff base, phenanthroline and Eu is estabilished. ► A simple yet sensitive method is built to determine trace amounts of Eu3+. ► The energy transfer mechanism of the system is studied. ► The luminescence enhancement is explained.

Three new tetramolybdenum organophosphonate compounds, (NH4)7{FeIII[MoVI2O6CH3C(O)(PO3)2]2}·10H2O 1, (NH4)4[Na(H2O)6]{CrIII[MoVI2O6CH3C(O)(PO3)2H]2}·7.67H2O 2 and (NH4)8{MnII[MoVI2O6CH3C(O)(PO3)2]2}·9H2O 3 have been successfully synthesized by reacting metal-containing oxidants Fe2(C2O4)3, MnO4− and CrO42− with a simple aqueous solution containing {MoV2O4(H2O)6}2+, respectively, in the presence of (hydroxylethylidene) diphosphonic acid. These compounds are characterized by elemental analyses, spectroscopic methods (IR, UV-Vis, XPS), TG-DTA, single-crystal X-ray diffraction analyses (including bond valence sum calculations) and powder X-ray diffraction analysis. Single crystal X-ray diffraction analyses have revealed that Mo–Mo bonds of {MoV2O4(H2O)6}2+ are cleavaged in the oxidation reaction to form {MoVI2O6} motifs, which are concomitantly stabilized by organophosphate and linked by the resulted metal ions coming from the metal-containing oxidants and bring on the formation of compounds 1–3, whose anions have a general formula {M[MoVI2O6CH3C(O)(PO3)2]2}n−(M = FeIII1; CrIII2; MnII3). It is important that the successful synthesis and characterization of the three new compounds induces a simple yet general strategy which can be utilized for the preparation of polyoxomolybdenum(VI) organophosphonates through oxidative Mo–Mo bond cleavage with various metal-containing oxidants like FeIII, MnVII and CrVI in the presence of various organophosphonates.

Functional ultrathin films ({Mo132}/PEI)n have been fabricated by using the Keplerate-type polyoxometalate (NH4)42[Mo132O372(CH3COO)30(H2O)72].ca.300H20.ca.10CH3COONH4 (denoted by {Mo132}) and polyethyleneimine (PEI) through the electrostatic layer-by-layer self-assembly method. The structure of the {Mo132} in the multilayers is kept intact; the deposition amounts of PEI and {Mo132} remain constant in every adsorption cycle in the ultrathin multilayers assembly process. Nonlinear optical properties of the ultrathin films and aqueous solution of {Mo132} have been investigated by using the Z-scan technique at a wavelength of 532 nm and pulse width of 5 ns. The results show that both the aqueous solution of {Mo132} and the resulting ultrathin multilayer films have nonlinear self-defocusing effects, while the ultrathin films also have notable nonlinear saturable absorption. The third-order NLO susceptibility χ(3) increases with the increase of film thickness. The ultrathin films of ({Mo132}/PEI)n (n=28) have the nonlinear refractive index coefficient n2=−3.37×10−10 esu, nonlinear absorption coefficient β=−5.09×10−6 esu and the third-order NLO susceptibility χ(3)=3.8×10−11 esu.graphical abstractHighlights► Unique Keplerate-type polyoxometalate is incorporated into ultrathin multilayer films. ► Electrostatic layer-by-layer self-assembly. ► The films show large self-defocusing and notable nonlinear saturable absorption.

Two new 3-D isomorphous lanthanide(III) compounds [Eu2(H2L)2(C2O4)2]·2.51H2O (1) and [Tb2(H2L)2(C2O4)2]·2.46H2O (2, H3L = glyphosate), based on glyphosate and oxalate have been successfully synthesized under hydrothermal conditions, and structurally characterized. In the two compounds, tetra-connected glyphosate ligands are coordinated to Ln3+, resulting in the formation of 1-D {Ln2(H2L)2}n double chains along the c direction. Each of the chains is connected to its four neighbors via the O atoms of phosphates of H2L− ligands, resulting in a 3-D (4, 6)-connected framework with 43·58·63·7 topology, which possesses 1-D channels with oxalates and lattice water molecules as troglodytes. The oxalates are stabilized via chelating Ln3+ in the form of 1-D Ln-C2O42− zigzag chains along the c direction. To the best of our knowledge, compounds 1 and 2 represent the first single-crystal structures of lanthanide(III)-glyphosate compounds incorporating second ligands. The luminescent properties of compounds 1 and 2 have been investigated at room temperature. The energy gaps between the triplet excited state of oxalic acid and the lowest excited resonance levels of Eu3+ (5D0) and Tb3+ (5D4) are 7270 cm−1 and 4070 cm−1, respectively, indicating that oxalate is more suitable for the sensitization of Tb3+ luminescence than Eu3+ luminescence.

Four europium(III) complexes of 3-D open frameworks [Eu2(NNO)4(ox)(H2O)2]n (1), [Eu2(INO)2(ox)2(H2O)2]n (2), {[Eu2(INO)2(suc)2]·2.99H2O}n (3) and {[Eu2(suc)3(H2O)2]·H2O}n (4) (HNNO = nicotinic acid N-oxide, H2ox = oxalic acid, HINO = isonicotinic acid, H2suc = succinic acid) have been synthesized and characterized by IR, elemental analysis, TG/DTA and single-crystal X-ray diffraction analysis. Each of the four complexes has 1-D channels, and in 3 and 4 these are filled with solvent water molecules, making them bigger than in 1 and 2, where no lattice water molecules can reside. The formation of the four 3-D europium(III) frameworks of different molecular and crystal structures reflects the influence of the ligands’ coordination modes, the length of the acyclic binary carboxylates, the ligand conformation as well as the molar ratio of reactants. At room temperature, all the complexes in the solid state exhibit typical red luminescence from Eu3+ ions, indicating effective energy transfer from the ligand to Eu3+ ion; however, their luminescence intensities are clearly different. The luminescence of 3 is the most intense due to the absence of coordinated water, while the complexes 1, 2 and 4 exhibit weaker luminescence due to oscillation of coordinated water molecules, which partially quenches their luminescence.

Two new ferrous molybdophosphates, (H2enMe)7FeII[Mo12V(HPO4)2(PO4)6(OH)6O24]·7H2O 1 and (H2enMe)6FeII[Mo12V(HPO4)4(PO4)4(OH)6O24]·4H2O 2 (enMe = 1,2-propanediamine), have been synthesized from an identical starting mixture through hydrothermal reactions using temperature as the only independent variable, and thoroughly characterized by IR, TG, single crystal X-ray diffraction and cyclic voltammetry. The structures of both 1 and 2 are built from the building blocks of the formula, {FeII[Mo6P4O31]2}, consisting of a network of MO6 (M = Fe, Mo) octahedra and PO4 tetrahedra linked through their vertices as anions, and protonated 1,2-propanediamine as cations, respectively. The most important aspect is that the non-hydrogen atomic ratio of Mo, Fe, P, O in the anions of 1 and 2 is the same, but the protonation of the PO4 groups is different in 1 and 2. Less protonation of the PO4 groups in 1 obtained at high temperature results in the anion carrying more charges and gives rise to more H2enMe cations per [FeII(P8Mo12V)] unit compared with that in 2 obtained at low temperature, and as a consequence, different interpenetrating hydrogen-bonded network structures are formed in the two different compounds in terms of packing efficiency and the system energy minimization.

An unprecedented H-bonded 2-D arrangement consisting of water dimers, V-shaped water trimers and protonated diethylenetriamine (deta) molecules is crystallographically characterized for the first time in the host crystal lattice of a new reduced molybdenum(V) phosphates [H2deta]4{Na[NaMo12VO24(OH)6(H2PO4)2(HPO4)4(PO4)2]}·8H2O which is prepared under hydrothermal condition and characterized by elemental analyses, IR, UV–Vis, TG–DTA, cyclic voltammetry and single-crystal X-ray diffraction. The harmonious assembly of the small dimer and trimer water clusters and deta molecules is significant in stabilizing and influencing the arrangement of their surroundings which herein refers to the 1-D inorganic anion chains constructed by the versatile building blocks of the formula [Mo6P4O31] covalently connected with NaO6 octahedra, giving rise to a 3-D arrays via complex hydrogen bonding interactions.

Three new homodinuclear lanthanide(III)/Schiff-base compounds [{Ln(clapi)}2] · 2CH3CN {Ln = La 1, Ce 2, and Eu 3; H3clapi = 2-(5-chloride-2-hydroxyphenyl)––1,3-bis [4-(5-chloride-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine} have been prepared successfully by template procedure and characterized by elemental analysis, IR spectra, and the dinuclear cerium compound (2) selected as a representative was structurally characterized. The crystal system is triclinic with space group P-1, a = 10.588 Å, b = 11,521(2) Å, c = 13.979(3) Å, α = 109.66(3)°, β = 97.77(3)°, γ = 106.33(3)°, V = 1486.2(5) Å3 and Z = 1. In compound 2, each Ce atom is coordinated to four N and four O atoms from two clapi3− ligands, forming a distorted square antiprism. Two phenol oxygen atoms from the middle arms of the two heptadentate ligands as μ2-bridging connect the two Ce atoms. Compounds 1, 2 and 3 in CH2Cl2 exhibit strong blue fluorescence at room temperature, compound 3 has no typical red emission of Eu3+ at room temperature while exhibits strong red fluorescence at 77 K in CH2Cl2.

A new reduced ferrous molybdophosphate composite solid of the formula, [(C10H14N2)H]4[FeII10MoV24(H2PO4)4(HPO4)12(PO4)4(H2O)16(OH)16O44]·12H2O, has been synthesized from a reaction mixture of MoO3, FeSO4·7H2O, C2H2O4·2H2O, nicotine, H3PO4, and H2O under hydrothermal conditions. The crystal data: monoclinic, space group C2/m, a = 24.4349(124), b = 12.9935(66), c = 14.7281(74) Å, β = 104.87(1) Å, V = 4520(4) Å3, Z = 2, R1 = 0.0874, wR2 = 0.2179. The structure is built from the building blocks of the formula, {FeII[Mo6P4O31]2}, consisting of a network of MO6 (M = Fe, Mo) octahedral and PO4 tetrahedral linked through their vertices. The connectivity of the building blocks with two pairs of face-sharing dinuclear Fe(II) clusters of the formula of [FeII2(H2O)4O5] on which a phosphate group is hanging gives rise to one-dimensional chains with eight-membered apertures. The remarkable hydrogen bonded interactions between the chains form a unique and interesting framework with three-dimensional intersecting tunnels where the protonated nicotine molecules as structuring templates and crystallization water molecules are situated.

Composite films derived from the water-soluble Keplerate-type polyoxometalate (NH4)42[Mo132O372(CH3COO)30(H2O)72]·ca. 300H2O·ca. 10CH3COONH4 (denoted (NH4)42{Mo132}) and chloroform-soluble tetraphenylporphyrin perchlorate [H2TPP](ClO4)2 are successfully fabricated by a layer-by-layer self-assembly method and characterized by UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The structure of the {Mo132} and [H2TPP]2+ in the films remain intact in light of the results of UV-vis spectroscopy and XPS. UV-vis spectra measurements reveal that the amounts of deposition of {Mo132} and [H2TPP]2+ remain constant in every adsorption cycle in the composite films assembly process. Nonlinear optical properties of the composite films have been investigated by using the Z-scan technique at a wavelength of 532 nm and pulse width of 7 ns. The results show that the composite films have notable nonlinear saturated absorption and self-defocusing effects. The combination of {Mo132} with [H2TPP]2+ can result in composite films with remarkably enhanced optical nonlinearities. The interfacial charge transfer induced by laser from porphyrin to POM in the films is thought to play a key role in the enhancement of NLO response. The third-order NLO susceptibility χ(3) of the composite films increases with the increase of film thickness.

Two series of lanthanide(III)–organic frameworks with the molecular formula [Ln2(NNO)2(OX)2(H2O)4]n (Ln = Eu 1, Tb 2, Sm 3, Dy 4, Gd 5) and [Ln2(NNO)4(OX)(H2O)2]n (Ln = Eu 6, Tb 7, Sm 8, Dy 9, Gd 10) were synthesized successfully under the same hydrothermal conditions with nicotinic N-oxide (HNNO) and oxalic acid (H2OX) as the mixed ligands merely through varying the molar ratio of the reactants. The compounds were characterized by IR, elemental analysis, UV, TG-DTA and powder X-ray diffraction (XRD). X-ray single-crystal diffraction analyses of compounds 1 and 7 selected as representatives and powder XRD analysis of the compounds revealed that both the series of compounds feature three-dimensional (3-D) open frameworks, and crystallize in the triclinic P space group while with different unit cell parameters. In compound 1, pairs of Eu3+ ions and pairs of NNO− ligands connect with each other alternately to form a 1-D infinite Eu-NNO double chain, the adjacent 1-D double-chains are then joined together through OX2− ligands leading to a 2D layer, the 2-D layers are further ‘pillared’ by OX2− ligands resulting in a 3-D framework. In compound 7, the 1-D Tb-NNO infinite chain and its 2-D layer are formed in an almost similar fashion to that in compound 1. The difference between the structures of the two compounds 1 and 7 is that the adjacent 2-D layers in compound 7 are further connected by NNO− ligands resulting in a 3-D framework. The photoluminescence properties and energy transfer mechanism of the compounds were studied systematically. The energy level of the lowest triplet states of the HNNO ligand (23148 cm−1) was determined based on the phosphorescence spectrum of compound 5 at 77 K. The 5D0 (Eu3+) and 5D4 (Tb3+) emission lifetimes are 0.46 ms, 0.83 ms, 0.69 ms and 0.89 ms and overall quantum yields are 1.03%, 3.29%, 2.58% and 3.78% for the compounds 1, 2, 6 and 7, respectively.

Currently, the realization of rationally designed architectures based on polyoxometalates (POMs) with designed functions has mostly been achieved through the preparation of functional films. However, the traditional approaches suffer from the drawbacks such as time-consuming processes, ill-defined structure and quality, random orientation of the POM molecules, and unsatisfactory performance. In this study, microcrystals of Ag9[EuW10O36]·36H2O (denoted as Ag9[EuW10O36]) were synthesized via a titration method by treating Na9[EuW10O36]·32H2O (denoted as Na9[EuW10O36]), selected as a prototype, with Ag+, leading to the formation of a water-insoluble crystalline powder with a uniform hexagonal platelet morphology. After this, a simple yet efficient manual assembly method was used to rapidly manufacture Ag9EuW10O36 microcrystal thin films on a glass substrate with high coverage, high crystallinity, and highly preferential orientation. Note that the as-prepared films emit orange polarized fluorescence with an anisotropy value of about 0.21, which places them among the materials of largest anisotropy. It is expected that the manual assembly approach can be generally adopted for the fabrication of many other kinds of polyoxometalate-based materials on various substrates for practical applications.

Cu3(BTC)2 (H3BTC = 1,3,5-benzenetricarboxylic acid) was anchored onto the surface of carboxymethylated chitosan non-woven fabrics by a controllable layer-by-layer technique in alternating solution baths of Cu(OAc)2·H2O and H3BTC solutions, and the resulting [Cu3(BTC)2]n@chitosan non-woven fabric composite materials (n = number of alternate deposition cycles) were thoroughly characterized. The results showed that the composite materials not only exhibited excellent decontamination ability against sulfur mustard (HD), with an enhanced degradation rate of HD with increasing n, but also possessed remarkable haemostasis performance. The degradation efficiency of sulfur mustard by [Cu3(BTC)2]4@chitosan was found to be much higher than that of pristine [Cu3(BTC)2]4. The inherent haemostatic capabilities of the chitosan non-woven fabrics were not affected by the growth of Cu3(BTC)2 on the surface of chitosan. Oral and histological toxicity examinations of the pristine Cu3(BTC)2 sample showed that damage and toxicity in the viscera of mice was very low, even if the intra-gastric administration dose of Cu3(BTC)2 reached a very high level (50 mg of Cu3(BTC)2 per kg of mouse). The results have shown that the as-prepared composite can be used safely as a promising haemostatic decontaminant with good recyclability against sulfur mustard.