Search

Porous supramolecular assemblies constructed by noncovalent interactions are promising for adsorptive purification of methane because of their easy regeneration. However, the poor stability arising from the weak noncovalent interactions has obstructed their practical applications. Here, we report a robust and easily regenerated polyhedron-based cationic framework assembled from a metal-organic square. This material exhibits a very low affinity for CH

Incorporating metal clusters within the skeleton of the organic polymers through click reaction can not only effectively prepare cluster-polymer composites, but also effectively avoid the cluster aggregation. Herein, an azide-contatining Lanthanide-Titanium oxo cluster of Eu 8 Ti 10 -N 3 ( Eu 8 Ti 10 -N 3 = [Eu 8 Ti 10 ( µ 3 -O) 14 (H 2 O) 4 (OAc) 2 (tbba) 30 (paza) 4 (THF) 2 ]•4THF•8H 2 O ( 1 ), Htbba = 4-tert-butylbenzoic acid, Hpaza = 4-azidobenzoate, HOAc = acetic acid, THF = Tetrahydrofuran) through in situ solvothermal reaction of 4-Azidobenzoic acid and 4-tert-butylbenzoic acid. Reaction of 1 with PEG ( PEG = Methoxypoly(ethyleneglycol)alkyne, 2000 g/mol) through Cu(I)-catalyzed click chemistry generates a lanthanide-polymer composite of Eu 8 Ti 10 -N 3 @PEG ( 2 ). Investigation on IR, 1 H NMR ICP-OES of 2 indicates that the structural integrity of 1 is maintained in 2 . Study on luminescent properties of 1 and 2 reveals that the quantum yield of 1 itself basically keeps unchanged in 2 . Significantly, the formation of 2 can not only effectively prevent the cluster 1 from aggregation, but also greatly enhance its solubility and adhesion to the substrate. Owing to the solubility and adhesion of luminescent materials being the key to their practical application, present work is thus of great significance for the development of metal cluster-polymer composite luminescent materials.

The formation mechanism of ferrihydrite is the key to understand its treatment of pollutants in waste water and purification of surface water and groundwater. Although emerging evidence suggests that formation of the ferrihydrite occurs through the aggregation of prenucleation clusters, rather than classical atom-by-atom growth, its formation mechanism remains unclear. Herein, an iron-oxo anionic cluster of [Fe22 (μ4 -O)8 (μ3 -OH)20 (μ2 -OH)18 (CH3 COO)16 (H2 O)2 ]4- viewed as a dimer of bivacant β-Keggin-Fe13 clusters was for the first time obtained by using lanthanide ions as stabilizers. Upon dissolution in a mixed solution of isopropanol and water, the lacunary β-Keggin-Fe13 cluster can transform into an α-Keggin-Fe13 cluster, distinctly demonstrating that the Keggin-Fe13 cluster rotational isomerization can be realized through the vacant Keggin-Fe13 cluster.

Atomically precise molecular metal-oxo clusters provide ideal models to understand metal oxide surfaces, self-assembly, and form-function relationships. Devising strategies for synthesis and isolation of these molecular forms remains a challenge. Here, the synthesis of four Ln-Fe oxo clusters that feature the ϵ-{Fe13 } Keggin cluster in their core is reported. The {Fe13 } metal-oxo cluster motif is the building block of two important iron oxyhydroxyide phases in nature and technology, ferrihydrite (as the δ-isomer) and magnetite (the ϵ-isomer). The reported ϵ-{Fe13 } Keggin isomer as an isolated molecule provides the opportunity to study the formation of ferrihydrite and magnetite from this building unit. The four currently reported isostructural lanthanide-iron-oxo clusters are fully formulated [Y12 Fe33 (TEOA)12 (Hyp)6 (μ3 -OH)20 (μ4 -O)28 (H2 O)12 ](ClO4 )23 ⋅50 H2 O (1, Y12 Fe33 ), [Gd12 Fe33 (TEOA)12 (Hyp)6 (μ3 -OH)20 (μ4 -O)32 (H2 O)12 ](ClO4 )15 ⋅50 H2 O (2, Gd12 Fe33 ) and [Ln16 Fe29 (TEOA)12 (Hyp)6 (μ3 -OH)24 (μ4 -O)28 (H2 O)16 ](ClO4 )16 (NO3 )3 ⋅n H2 O (Ln=Y for 3, Y16 Fe29 , n=37 and Ln=Gd for 4, Gd16 Fe29 n=25; Hyp=trans-4-Hydroxyl-l-proline and TEOA=triethanolamine). The next metal layer surrounding the ϵ-{Fe13 } core within these clusters exhibits a similar arrangement as the magnetite lattice, and Fe and Ln can occupy the same positions. This provides the opportunity to construct a family of compounds and optimize magnetic exchange in these molecules through composition tuning. Small-angle X-ray scattering (SAXS) and high-resolution electrospray ionization mass spectrometry (HRESI-MS) show that these clusters are stable upon dissolution in both water and organic solvents, as a first step to performing further chemistry towards building magnetic arrays or investigating ferrihydrite and magnetite assembly from pre-nucleation clusters.

Heterometallic lanthanide-transition-metal (4f-3d) clusters with well-defined crystal structures integrate multiple metal centers and provide a platform for achieving synergistic catalytic effects. Herein, we present a strategy for enhanced hydrogen evolution by loading atomically precise 4f-3d clusters Ln52 Ni56 on a CdS photoabsorber surface. Interestingly, some Ni2+ ions in the clusters Ln52 Ni56 were exchanged by the Cd2+ to form Ln52 Ni56-x Cdx /CdS composites. Photocatalytic studies show that the efficient synergistic multipath charge separation and transfer from CdS to the Eu52 Ni56-x Cdx cluster enable high visible-light-driven hydrogen evolution at 25 353 μmol h-1 g-1 . This work provides the strategy to design highly active photocatalytic hydrogen evolution catalysts by assembling heterometallic 4f-3d clusters on semiconductor materials.

We report the rational design of coordination-driven self-assembly metal-organic nanostructures for multifunctional nanotheranostics. Zinc(II) coordination-based nano-formulations capable of loading indocyanine green (ICG) and therapeutic genes were prepared to achieve a fluorescence/photoacoustic imaging-guided combination photo/gene therapy strategy. We showed the enhanced theranostic capability of zinc(II)-dipicolylamine-assisted assembly of ICG, as well as simultaneous targeted gene delivery in an experimental mouse model of cancer. Such a co-assembly strategy provides a facile way to achieve combined therapeutic functions for personalized nanomedicine.

A building blocks strategy is an effective approach for constructing the large molecular systems. Herein, we demonstrate that high-resolution electro-spray ionization mass spectrometry (HRESI-MS) provides an effective chance to insight the assemble process of the building blocks and guides the construction of high-nuclearity metal clusters on the basis of the reaction of Ti(Oi Pr)4 , Eu(acac)3 , and salicylic acid. The time-dependent HRESI-MS indicates that not only a Eu3 Ti building block can be formed, but that it can further assemble into a Eu24 Ti8 compound. Temperature-dependent HRESI-MS reveals that increase of the reaction temperature favors the formation and crystallization of the stable Eu24 Ti8 structure. Single-crystal structural analysis demonstrates that the Eu24 Ti8 has a wheel-like structure with diameter of ca. 4.1 nm and is the highest nuclearity lanthanide-titanium oxo cluster reported to date.

The largest Ln-Fe metal cluster [Gd12 Fe14 (μ3 -OH)12 (μ4 -OH)6 (μ4 -O)12 (TEOA)6 (CH3 COO)16 (H2 O)8 ]⋅(CH3 COO)2 (CH3 CN)2 ⋅(H2 O)20 (1) and the core-shell monodisperse metal cluster of 1 a@SiO2 (1 a=[Gd12 Fe14 (μ3 -OH)12 (μ4 -OH)6 (μ4 -O)12 (TEOA)6 (CH3 COO)16 (H2 O)8 ]2+ ) were prepared. Experimental and theoretical studies on the magnetic properties of 1 and 1 a@SiO2 reveal that encapsulation of one cluster into one silica nanosphere not only effectively decreases intermolecular magnetic interactions but also significantly increases the zero-field splitting effect of the outer layer Fe3+ ions.

Metal-organic frameworks (MOFs) provide a tunable platform for hierarchically integrating multiple components to effect synergistic functions that cannot be achieved in solution. Here we report the encapsulation of a Ni-containing polyoxometalate (POM) [Ni4 (H2 O)2 (PW9 O34 )2 ](10-) (Ni4 P2 ) into two highly stable and porous phosphorescent MOFs. The proximity of Ni4 P2 to multiple photosensitizers in Ni4 P2 @MOF allows for facile multi-electron transfer to enable efficient visible-light-driven hydrogen evolution reaction (HER) with turnover numbers as high as 1476. Photophysical and electrochemical studies established the oxidative quenching of the excited photosensitizer by Ni4 P2 as the initiating step of HER and explained the drastic catalytic activity difference of the two POM@MOFs. Our work shows that POM@MOF assemblies not only provide a tunable platform for designing highly effective photocatalytic HER catalysts but also facilitate detailed mechanistic understanding of HER processes.

Monodisperse metal clusters provide a unique platform for investigating magnetic exchange within molecular magnets. Herein, the core-shell structure of the monodisperse molecule magnet of [Gd52 Ni56 (IDA)48 (OH)154 (H2 O)38 ]@SiO2 (1 a@SiO2 ) was prepared by encapsulating one high-nuclearity lanthanide-transition-metal compound of [Gd52 Ni56 (IDA)48 (OH)154 (H2 O)38 ]⋅(NO3 )18 ⋅164 H2 O (1) (IDA=iminodiacetate) into one silica nanosphere through a facile one-pot microemulsion method. 1 a@SiO2 was characterized using transmission electron microscopy, N2 adsorption-desorption isotherms, and inductively coupled plasma-atomic emission spectrometry. Magnetic investigation of 1 and 1 a revealed J1 =0.25 cm(-1) , J2 =-0.060 cm(-1) , J3 =-0.22 cm(-1) , J4 =-8.63 cm(-1) , g=1.95, and z J=-2.0×10(-3) cm(-1) for 1, and J1 =0.26 cm(-1) , J2 =-0.065 cm(-1) , J3 =-0.23 cm(-1) , J4 =-8.40 cm(-1) g=1.99, and z J=0.000 cm(-1) for 1 a@SiO2 . The z J=0 in 1 a@SiO2 suggests that weak antiferromagnetic coupling between the compounds is shielded by silica nanospheres.

It has been a challenge to develop a new transparent conductor to replace the brittle and expensive indium tin oxide (ITO) film to make film heater with high transmittance in the visible wavelength range, high surface conductivity and mechanical flexibility. Here, we report the synthesis of a transparent composite film comprising a silver nanowire (AgNW) percolation network inlaid in the surface of a heat-resistant polymer film. This composite conductor has a figure-of-merit sheet resistance of 25 Ω · sq−1 with 86.4% transmittance at 550 nm. The composite film possesses outstanding heat-resistant property and can generate high temperature up to 230 °C at low operation voltages as an efficient thin film heater. Compared with the film heaters previously reported, the composite film heater shows faster heating response and higher saturation temperature under the same input voltage. The film heater could be bent to 10 mm diameter and the generated temperature decreased by less than 3 °C after 3 000 bending cycles.

NNSFC[20825103, 20901064, 90922031, 2007CB815304, 21021061]; Fundamental Research Funds for the Central Universities[2010121016]

National Natural Science Foundation of China (NSFC) [20825103, 90922031, 20721001]; Ministry of Science and Technology of China (MSTC) [2007CB815304]; Natural Science Foundation of Fujian Province [2009J01041]