A series of remarkable crystalline compounds [Cu(2)(BTC)(4/3)(H(2)O)(2)](6)[H(n)XM(12)O(40)].(C(4)H(12)N)(2) (X = Si, Ge, P, As; M = W, Mo) were obtained from the simple one-step hydrothermal reaction of copper nitrate, benzentricaboxylate (BTC), and different Keggin polyoxometalates (POMs). In these compounds, the catalytically active Keggin polyanions were alternately arrayed as noncoordinating guests in the cuboctahedral cages of a Cu-BTC-based metal-organic framework (MOF) host matrix. X-ray crystallographic analyses, TG, FT-IR, UV-vis, N(2) adsorption studies, and acid-base titration demonstrated their high stability and toleration for thermal and acid-base conditions. No POM leaching or framework decomposition was observed in our study. The representative acid catalytic performance of a compound containing PW(12) species was assessed through the hydrolysis of esters in excess water, which showed high catalytic activity and can be used repeatedly without activity loss. Moreover, catalytic selectivity, which is dependent on the molecular size of substrates, and substrate accessibility for the pore surface were observed. It is the first time that the well-defined, crystalline, MOF-supported POM compound has behaved as a true heterogeneous acid catalyst. The unique attributes of MOF and well-dispersed level of POMs prohibited the conglomeration and deactivation of POMs, which allowed for the enhancement of their catalytic properties.

A sodalite-type porous metal-organic framework with polyoxometalate templates, H(3)[(Cu(4)Cl)(3)(BTC)(8)](2)[PW(12)O(40)]·(C(4)H(12)N)(6)·3H(2)O (NENU-11; BTC = 1,3,5-benzenetricarboxylate), was obtained by a hydrothermal reaction. As a reasonable candidate for eliminating nerve gas, NENU-11 displays good adsorption behavior for dimethyl methylphosphonate (15.5 molecules per formula unit). In virtue of the catalytic activity of polyoxometalate guests, this nerve gas mimic could be facilely decomposed by a hydrolysis reaction.

A series of novel lanthanide metal-organic frameworks were synthesized using a ligand featuring three carboxylate groups stationed on a triazinyl central motif. The readily accessible multiple Lewis basic triazinyl N atoms allow for complexation of incoming metal ions. Such interactions have been established quantitatively.

A lanthanide metal-organic framework (MOF) compound of the formulation [Eu2(CO3)(ox)2(H2O)2]·4H2O (1, ox = oxalate) was prepared by hydrothermal synthesis with its structure determined crystallographically. Temperature-dependent but humidity-independent high proton conduction was observed with a maximum of 2.08 × 10(-3) S cm(-1) achieved at 150 °C, well above the normal boiling point of water. Results from detailed structural analyses, comparative measurements of conductivities using regular and deuterated samples, anisotropic conductivity measurements using a single-crystal sample, and variable-temperature photoluminescence studies collectively establish that the protons furnished by the Eu(III)-bound and activated aqua ligands are the charge carriers and that the transport of proton is mediated along the crystallographic a-axis by ordered hydrogen-bonded arrays involving both aqua ligands and adjacent oxalate groups in the channels of the open framework. Proton conduction was enhanced with the increase of temperature from room temperature to about 150 °C, which can be rationalized in terms of thermal activation of the aqua ligands and the facilitated transport between aqua and adjacent oxalate ligands. A complete thermal loss of the aqua ligands occurred at about 160 °C, resulting in the disintegration of the hydrogen-bonded pathway for proton transport and a precipitous drop in conductivity. However, the structural integrity of the MOF was maintained up to 350 °C, and upon rehydration, the original structure with the hydrogen-bonded arrays was restored, and so was its high proton-conduction ability.

Isostructural lanthanide metal-organic frameworks (MOFs) are synthesized through the spontaneous self-assembly of H3BTPCA (1,1',1″-(benzene-1,3,5-triyl)tripiperidine-4-carboxylic acid) ligands and lanthanide ions (we term these MOFs Ln-BTPCA, Ln = La(3+), Tb(3+), Sm(3+), etc.). Prompted by the observation that the different lanthanide ions have identical coordination environment in these MOFs, we explored and succeeded in the preparation of mixed-lanthanide analogues of the single-lanthanide MOFs by way of in situ doping using a mixture of lanthanide salts. With careful adjustment of the relative concentration of the lanthanide ions, the color of the luminescence can be modulated, and white light-emission can indeed be achieved. The mechanisms possibly responsible for the observed photophysical properties of these mixed-lanthanide MOFs are also discussed.

Four novel polytantalotungstates K(5)Na(4)[P(2)W(15)O(59)(TaO(2))(3)]·17H(2)O (1), K(8)Na(8)H(4)[P(8)W(60)Ta(12)(H(2)O)(4)(OH)(8)O(236)]·42H(2)O (2), Cs(3)K(3.5)H(0.5)[SiW(9)(TaO(2))(3)O(37)]·9H(2)O (3), and Cs(10.5)K(4)H(5.5)[Ta(4)O(6)(SiW(9)Ta(3)O(40))(4)]·30H(2)O (4) were synthesized. Compounds 1 and 3 are tris-(peroxotantalum)-substituted Dawson- and Keggin-type derivatives, whereas 2 and 4 are tetrameric oligomers containing respectively an unprecedented {Ta(12)} and {Ta(16)} cluster core. The photocatalytic activities of 2 and 4 for H(2) evolution from water were evaluated. The significantly enhanced performance against the control K(6)[P(2)W(18)O(62)] can be attributed to the modulation of the electronic structures of these novel POMs by Ta incorporation. The highest activity observed so far with the use of 2 can be further rationalized by the presence of distorted heptacoordinate Ta atoms in the form of TaO(7) pentagonal bipyramid.

Solvothermal reactions with different solvents produced two iron trimesates [Fe2(H2O)2(BTC)4/3]Cl x 4.5(DMF) (1) and [Fe4Cl(BTC)8/3]Cl2 x H2O x 2.5(DEF) (2) (BTC = 1,3,5-benzenetricarboxylate, DMF = N,N'-dimethylformamide, DEF = N,N'-diethylformamide). The framework of 1 is a (3,4)-connected net constructed from mixed-valence paddlewheel Fe2(II, III) units and BTC linkers, while the framework of 2 is a (3,8)-connected net built from mixed-valence square-planar Fe4(III, III, III, II) units and BTC linkers. The large volume inside the framework of 1 (or 2) is occupied by disordered Cl- anions and guest DMF (or DEF) molecules. The mixed-valence character of the frameworks of 1 and 2 was confirmed by Mössbauer spectroscopy studies. The active electronic property of iron cations may be the origin of the variability of the iron-organic frameworks, which are readily affected by some synthetic factors, such as solvents. Magnetic studies reveal that there are antiferromagnetic exchange interactions among the Fe atoms in 1 and 2. Ion-exchange studies for 1 show that the Cl- anions inside the framework of 1 can be exchanged by CNS- anions.

Graphene oxide (GO) was prepared and characterized by Fourier transform infrared spectrometry (FT-IR) and scanning electron micrographs (SEM). Batch adsorption studies were carried out to investigate the adsorption data, including the effects of pH, initial concentration, contact time, and temperature. The adsorption of Au(III), Pd(II), and Pt(IV) was optimum at pH 6.0. The adsorption isotherms all obeyed the Langmuir equation in the case of Au(III), Pd(II), and Pt(IV), and the maximum adsorption capacities were 108.342 mg•g −1 , 80.775 mg•g −1 , and 71.378 mg•g −1 , respectively. The adsorption kinetics of Au(III), Pd(II), and Pt(IV) onto GO followed a pseudosecond-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Thermodynamic parameters such as Gibbs energy (ΔG o ), enthalpy (ΔH o ), and entropy (ΔS o ) were calculated, indicating that the adsorption were spontaneous, endothermic, and feasible. The desorption studies showed that the best desorption reagents were 0.5 mol•dm −3 thiourea−0.5 mol•dm −3 HCl for Au(III) and 1.0 mol•dm −3 thiourea−0.5 mol•dm −3 HCl for both Pd(II) and Pt(IV).