Conspectus High-nuclearity cluster-type metal complexes are a unique class of compounds, many of which have aesthetically pleasing molecular structures. Their interesting physical and chemical ...properties arise primarily from the electronic and/or magnetic interplay between the component metal ions. Among the extensive studies in the past two decades, those on lanthanide-containing clusters, lanthanide-exclusive or heterometallic with transition metal elements, are most notable. The research was driven by both the synthetic challenges for these generally elusive species and their intriguing magnetic properties, which are useful for the development of energy-efficient and environmentally friendly magnetic cooling technologies. Our efforts in this vein have been concentrated on developing rational synthetic methods for high-nuclearity lanthanide-containing clusters. By means of the now widely adopted approach of “ligand-controlled hydrolysis” of lanthanide ions, a great variety of cluster-type lanthanide hydroxide complexes had been prepared in the first half of this developing period (1999–2006). In this Account, our efforts since 2007 are summarized. These include (1) further development of synthetic strategies in order to expand the ligand scope and/or to increase the nuclearity (>25) of the cluster species and (2) magnetic studies pertinent to the pursuit of materials with a large magnetocaloric effect (MCE). Specifically, with the hope of expanding the family of ligands and producing clusters of previously unknown structures, we tested under hydrothermal or solvothermal conditions the use of readily available yet not commonly used ligands for controlling lanthanide hydrolysis; such ligands, carboxylates as mundane examples, tend to form insoluble complexes prior to any possible hydrolysis. We have also validated the use of preformed transition metal complexes as metalloligands for subsequent control of lanthanide hydrolysis toward heterometallic 3d–4f clusters. Furthermore, we demonstrated using ample examples that the presence of small anions as templates is essential to the assembly of high-nuclearity lanthanide-containing clusters and that maintaining a low concentration of the anion template(s) is a key to such success. It has been found that slow production/release of such anion templates by in situ ligand decomposition or absorption of atmospheric CO2 is effective in preventing precipitation of their lanthanide salts, allowing not only controllable lanthanide hydrolysis but also gradual and modular assembly of the giant cluster species. Magnetic studies targeting potential applications of such clusters as molecular magnetic coolers have also been conducted. The results are summarized in the second portion of this Account in an effort to establish a certain magneto–structure relationship. Of particular relevance is the possible correlation between MCE (evaluated using the isothermal magnetic entropy change, −ΔS M) and magnetic density, and the intracluster antiferromagnetic exchange coupling. We have also made some preliminary attempts at preparing processable and practically useful materials in the form of a monodisperse core–shell nanostructure. We succeeded in encapsulating a single nanosized heterometallic molecular cluster in a nanoshell of silica. It was found that such passivation not only helped stabilize the cluster but also reduced the magnetic interactions between individual clusters. These effects are reflected in the slightly enhanced value of −ΔS M for the core–shell composite over the parent unprotected cluster.
The synthetic strategy and building block about high-nuclearity lanthanide clusters are summarized, demonstrating the role of template anion in their assembly.
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•High-nuclearity ...lanthanide clusters, because of their unique physical and chemical properties and their potential application, have attracted great much attention in different fields. Owing to the final structures of the lanthanide clusters not only sensitive to starting materials used in the synthesis, but also to reaction conditions including metal ions/ligands ratio, pH, solvents, temperature, duration, rational design and synthesis of lanthanide clusters remains a great challenge. Thus, it is necessary to review the recent advance in the assembly of high-nuclearity lanthanide clusters.•In this review, the synthesis of high-nuclearity lanthanide clusters using the anion template strategy was outlined based on recently reported results. The presence of small anionic species appears to be essential as a template for modular build-up of higher-nuclearity cluster complexes. Compared with a single-anion template, the slow release of anions, multiple anions or mixed anions as templates is more conducive to the assembly of high-nuclearity lanthanide clusters because of their dispersive effect on the positive charges of the clusters.•Based on the structures of the lanthanide clusters recently achieved, the building blocks in the lanthanide clusters were analysed. Some of the high-nuclearity lanthanide clusters with sophisticated structures are assembled from two or more types of structural motifs. Using this building block strategy, abundant clusters featuring multiple combinations of these basic motifs have appeared at a fast rate.•Perspective in future study on the high-nuclearity clusters is discussed. For the rational design and synthesis of lanthanide clusters, future investigations should focus on the assembly mechanism of the lanthanide clusters, which not only being helpful to the rational design and construction of the high-nuclearity lanthanide clusters, but also to the properties study on the high-nuclearity lanthanide clusters.
High-nuclearity lanthanide clusters have attracted much attention in different fields because of their unique physical and chemical properties and their potential applications. In this review, the synthetic strategy and building blocks for the assembly of high-nuclearity lanthanide clusters are outlined based on recently reported high-nuclearity lanthanide clusters. Perspectives for future studies on high-nuclearity lanthanide clusters are also discussed. We hope this review will provide insight into future research on high-nuclearity lanthanide clusters.
The structural transformation of high-nuclearity silver clusters from one to another induced by specific stimuli is of scientific significance in terms of both cluster synthesis and reactivity. ...Herein, we report two silver-thiolate clusters, Mo
O
@Ag
and Mo
O
@Ag
, which are templated by isopolymolybdates inside and covered by
PrS
and PhCOO
ligands on the surfaces. Amazingly, the Mo
O
@Ag
can be transformed from Mo
O
@Ag
by adding PhCOOH which increases the degree of condensation of molybdates template from Mo
O
to Mo
O
, then enlarging the outer silver shell from Ag
to Ag
. The evolution of solution species revealed by time-dependent electrospray ionization mass spectrometry (ESI-MS) suggests a breakage-growth-reassembly (BGR) transformation mechanism. These results not only provide a combined assembly strategy (anion-template + induced transformation) for the synthesis of silver-thiolate clusters but also help us to better understand the complex transformation process underpinning the assembly system.
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 Ln52Ni56 on a CdS photoabsorber surface. Interestingly, some Ni2+ ions in the clusters Ln52Ni56 were exchanged by the Cd2+ to form Ln52Ni56−xCdx/CdS composites. Photocatalytic studies show that the efficient synergistic multipath charge separation and transfer from CdS to the Eu52Ni56−xCdx 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.
Assembling lanthanide–transition‐metal (4f–3d) clusters Ln52Ni56 (Ln=Eu, Pr, Nd and Gd) onto CdS composites achieved enhanced photocatalytic H2 production. Some Ni2+ ions in the clusters were exchanged by Cd2+ to form Ln52Ni56−xCdx/CdS composites. An Eu52Ni56−xCdx/CdS species shows the highest activity of 25 353 μmol h−1 g−1 and an apparent quantum efficiency of 42.4 %.
Abstract
Photocatalytic reduction of CO
2
is a promising approach to achieve solar-to-chemical energy conversion. However, traditional catalysts usually suffer from low efficiency, poor stability, ...and selectivity. Here we demonstrate that a large porous and stable metal-organic framework featuring dinuclear Eu(III)
2
clusters as connecting nodes and Ru(phen)
3
-derived ligands as linkers is constructed to catalyze visible-light-driven CO
2
reduction. Photo-excitation of the metalloligands initiates electron injection into the nodes to generate dinuclear {Eu(II)}
2
active sites, which can selectively reduce CO
2
to formate in a two-electron process with a remarkable rate of 321.9 μmol h
−1
mmol
MOF
−1
. The electron transfer from Ru metalloligands to Eu(III)
2
catalytic centers are studied via transient absorption and theoretical calculations, shedding light on the photocatalytic mechanism. This work highlights opportunities in photo-generation of highly active lanthanide clusters stabilized in MOFs, which not only enables efficient photocatalysis but also facilitates mechanistic investigation of photo-driven charge separation processes.
Abstract
High-nuclearity silver clusters are appealing synthetic targets for their remarkable structures, but most are isolated serendipitously. We report here six giant silver-thiolate clusters ...mediated by solvents, which not only dictate the formation of an octahedral Ag
6
4+
kernel, but also influence the in situ-generated Mo-based anion templates. The typical sevenfold symmetric silver nanowheels show a hierarchical cluster-in-cluster structure that comprises an outermost Ag
56
shell and an inner Ag
6
4+
kernel in the centre with seven MoO
4
2−
anion templates around it. Electrospray ionization mass spectrometry analyses reveal the underlying rule for the formation of such unique silver nanowheels. This work establishes a solvent–intervention approach to construct high-nuclearity silver clusters in which both the formation of octahedral Ag
6
4+
kernel and in situ generation of various Mo-based anion templates can be simultaneously controlled.
Nanoscale inorganic wheel-shaped structures are one of the most striking types of molecular aggregations. Here, we report the synthesis of a gigantic lanthanide wheel cluster containing 140 Gd3+ ...atoms. As the largest lanthanide cluster reported thus far, {Gd 140 } features an attractive wheel-like structure with 10-fold symmetry. The nanoscopic molecular wheel possesses the largest diameter of 6.0 nm and displays high stability in solution, which allows direct visualization by scanning transmission electron microscopy. The newly discovered lanthanide {Gd 140 } cluster represents a new member of the molecular wheel family.
Thiacalix4arenes as a family of promising ligands have been widely used to construct polynuclear metal clusters, but scarcely employed in silver nanoclusters. Herein, an anion-templated Ag
...nanocluster (SD/Ag88a) built from p-tert-butylthiacalix4arene (H
TC4A) is reported. Single-crystal X-ray diffraction reveals that C
-symmetric SD/Ag88a resembles a metal-organic super calix comprised of eight TC4A
as walls and 88 silver atoms as base, which can be deconstructed to eight CrO
@Ag
(TC4A)(EtS)
(OAc) secondary building units arranged in an annulus encircling a CrO
in the center. Local and global anion template effects from chromates are individually manifested in SD/Ag88a. The solution stability and hierarchical assembly mechanism of SD/Ag88a are studied by using electrospray mass spectrometry. The Ag
nanocluster represents the highest nuclearity metal cluster capped by TC4A
. This work not only exemplify the specific macrocyclic effects of TC4A
in the construction of silver nanocluster but also realize the shape heredity of TC4A
to overall silver super calix.
An effective strategy is developed to synthesize high-nuclearity Cu clusters, Cu
(RCOO)
(C≡CtBu)
Cl
H
(Cu
), which is the largest Cu
/Cu
cluster reported to date. Cu powder and Ph
SiH
are employed ...as the reducing agents in the synthesis. As revealed by single-crystal diffraction, Cu
is arranged as a four-concentric-shell Cu
@Cu
Cl
@Cu
@Cu
structure, possessing an atomic arrangement of concentric M
icosahedral and M
dodecahedral shells which popularly occurs in Au/Ag nanoclusters. Surprisingly, Cu
can be dissolved in diethyl ether and spin coated to form uniform nanoclusters film on organolead halide perovskite. The cluster film can subsequently be converted into high-quality CuI film via in situ iodination at room temperature. The as-fabricated CuI film is an excellent hole-transport layer for fabricating highly stable CuI-based perovskite solar cells (PSCs) with 14.3 % of efficiency.
Inorganic–organic hybrid molecular multiferroic and magnetoelectric materials, similar to multiferroic oxide compounds, have recently attracted increasing attention because they exhibit diverse ...architectures, a flexible framework, fascinating physics, and potential magnetoelectric functionalities in novel multifunctional devices such as energy transformation devices, sensors, and information storage systems. Herein, the classification of multiferroicity and magnetoelectricity is briefly outlined and then the recent advances in the multiferroicity and magnetoelectricity of inorganic–organic hybrid molecular materials, particularly magnetoelectricity and the relevant magnetoelectric mechanisms and their categories are summarized. In addition, a personal perspective and an outlook are provided.
Magnetoelectricity plays a huge role in the development of next‐generation devices. Since the discovery of multiferroic properties in inorganic–organic hybrid molecular materials, the related magnetoelectric behaviors have been gradually discovered and advanced at a vigorous pace. This brief development of multiferroicity/magnetoelectricity in inorganic–organic hybrid molecular materials shows their prospect for future development.
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