The trivalent europium ion (Eu3+) is well known for its strong luminescence in the red spectral region, but this ion is also interesting from a theoretical point of view. Due to the even number of electrons in the 4f shell (4f(6) configuration), the crystal-field perturbation by the crystalline host matrix lifts partly or completely the degeneracies of the L-2S+1(J) levels. The Eu3+ ion has the great advantage over other lanthanide ions with an even number of 4f electrons that the starting levels of the transitions in both the absorption and the luminescence spectrum are non-degenerate (J=0). Moreover, the interpretation of the spectra is facilitated by the small total angular momentum J of the end levels in the transitions. The number of lines observed for the D-5(O) > F-J transitions in the luminescence spectrum or the D-5(J) < F-7(O) transitions in the absorption spectrum allows determining the site symmetry of the Eu3+ ion. This review describes the spectroscopic properties of the trivalent europium ion, with emphasis on the energy level structure, the intensities of the f-f transitions (including the Judd-Ofelt theory), the decay times of the excited states and the use of the Eu3+ ion as a spectroscopic probe for site symmetry determination. It is illustrated how the maximum amount of information can be extracted from optical absorption and luminescence spectra of europium(III) compounds, and how pitfalls in the interpretation of these spectra can be avoided. 2015 (C) Elsevier B.V. All rights reserved.
Metal-organic frameworks (MOFs) are a class of porous materials that have attracted enormous attention during the past two decades due to their high surface areas, controllable structures and tunable pore sizes. Besides the applications in gas storage and separation, catalysis, sensor, and drug delivery, MOFs are receiving increasing research interest in the field of electrochemical energy storage. By focusing on recent advances, this review provides a broad overview of MOF-based or MOF-derived rechargeable lithium ion batteries and supercapacitors. (C) 2015 Elsevier B.V. All rights reserved.
Metal-organic frameworks (MOFs) have been emerging as very important multifunctional hybrid materials due to their inherent advantages of organic linkers and inorganic metal ions, tunable porosity and diverse functionality. The combination of the intrinsic luminescent features of lanthanide ions together with the unique characteristics of MOFs provides a fascinating opportunity for designing novel luminescent MOF materials. In this review, we summarize our research progress on the design and construction of luminescent lanthanide MOFs, as well as their potential functions and applications on luminescent sensing and light-emitting. (C) 2013 Elsevier B.V. All rights reserved.
Presently, phosphors and luminescent materials for lighting, telecommunications, displays, security inks and marking, as well as for probes in biosciences represent one third of the total value of the lanthanides used worldwide. If optical glasses and laser materials are added, this figure is close to 40%, explaining the large interest that the scientific community is devoting to such materials. The present review focuses on the design of highly luminescent lanthanide complexes and discusses all aspects needing optimization. Reference is made to the mastering of the various energy migration processes in luminescence sensitization by organic ligands, to minimizing non-radiative deactivation mechanisms, as well as to other parameters such as the radiative lifetime, the refractive index, and the benefit of inserting luminescent complexes into inorganic-hybrid structures. Comparative tables list the most luminescent complexes emitting in the visible and near-infrared ranges and the best chromophores are pointed out. (C) 2014 Elsevier B.V. All rights reserved.
The last few years have seen a huge renaissance in the study of the magnetism of lanthanide coordination complexes, especially in the field of single molecule magnets (SMMs) due to the large inherent anisotropy of lanthanide metal ions. It has led to intense activity on the part of synthetic chemists to produce systems suitable for detailed study by physicists and materials scientists, thus synthetic development has been playing a major role in the advancement of this field. In this review, we demonstrate the research developed in the few years in the fascinating and challenging field of Dy-based SMMs with particular focus on how recent studies tend to address the issue of relaxation dynamics in these systems from synthetic point of view. In addition, the assembly of multinuclear Dy SMMs using various ligands is summarized, showing that several typical motifs are favorable structural units which could be exploited in the formation of new Dy-based SMMs and supramolecular architectures. (C) 2013 Elsevier B.V. All rights reserved.
Reducing anthropogenic CO2 emission and lowering the concentration of greenhouse gases in the atmosphere has quickly become one of the most urgent environmental issues of our age. Carbon capture and storage (CCS) is one option for reducing these harmful CO2 emissions. While a variety of technologies and methods have been developed, the separation of CO2 from gas streams is still a critical issue. Apart from establishing new techniques, the exploration of capture materials with high separation performance and low capital cost are of paramount importance. Metal-organic frameworks (MOFs), a new class of crystalline porous materials constructed by metal-containing nodes bonded to organic bridging ligands hold great potential as adsorbents or membrane materials in gas separation. In this paper, we review the research progress (from experimental results to molecular simulations) in MOFs for CO2 adsorption, storage, and separations (adsorptive separation and membrane-based separation) that are directly related to CO2 capture. (C) 2011 Elsevier B.V. All rights reserved.
The rational construction of coordination polymers (CPs), normally existing as infinite crystalline lattices extended from inorganic vertices and organic struts, essentially benefits from the development of crystal engineering strategies. In this review, we summarily comment on the key advances in the design of CPs using mixed-ligand synthetic strategy and discuss the relationship between the specifically selected mixed organic ligands and the resulting CPs. Significantly, fine tuning on the structural features of organic ligands, such as spacers, positional isomers, and substituents, can lead to a delicate regulation of the diverse network structures of CPs. Additionally, such mixed-ligand coordination assemblies may also be heavily affected by metal ion, synthetic route, and some other external stimuli such as solvent and pH condition, etc. The advantages of mixed-ligand systems as promising approaches to construct CPs-based crystalline materials with interesting structures and useful properties will also be demonstrated. (C) 2012 Elsevier B.V. All rights reserved.
Metal-organic frameworks (MOFs), a class of porous materials bring great promise for a diverse array of applications ranging from gas storage and separation to heterogeneous catalysis. The ability to incorporate multiple functional sites into a single system enhances the interest seen in MOFs. The solid, well-defined nature of MOFs allow for the engineering of materials capable of performing multiple functions through multiple independent processes or cooperative and synergetic interactions or pathways. In this review, we aim to encompass and summarize research that introduces techniques and strategies to incorporate multiple functional sites within a single MOF system, highlight exceptional examples of work that exploits MFS-MOFs to perform noteworthy processes, and give direction to further enhance our ability to move MFS-MOFs forward in a way that addresses current problems faced by our society. (C) 2015 Elsevier B.V. All rights reserved.
History shows that metal-based drugs and remedies have been known and used since very ancient times. For example, silver was employed in the treatment of wounds and ulcers according to the Greek physician Hippocrates, but its antimicrobial properties had probably been recognized long before because was used to make vessels for storing liquids in pure form. The ancient Egyptians also knew how to sterilize water with copper. The medical use of gold can be dated back to 2500 B.C. in China. However, the new era of metal-based medicine started almost 50 years ago when cisplatin was shown to inhibit cellular division in Escherichia coli, thereby leading to the first studies of its antitumor activity in rats and its assessment as one of the most powerful drugs for use against different types of cancer, although many other novel metal-based drugs are promising and they are attracting growing attention in modern clinical medicine. Gold salts and arsenic compounds have been in use for decades in the treatment of rheumatoid arthritis and syphilis, respectively, but studies of cisplatin have definitely shifted the attention of researchers to the pool of transition "heavy" metals as potential therapeutic agents. Rhodium, iridium, palladium, osmium, and the other so-called noble elements have been the subjects of intensive investigations, thereby leading to the production of a series of complex compounds with remarkable anticancer activities, as well as antirheumatic, antimalarial, and antimicrobial drugs. The number of published studies in this field is huge and they have already been the subjects of careful review. In this review, we provide a detailed account of the latest results (2010-2013) and their potential uses in the cure of severe diseases. (C) 2014 Elsevier B.V. All rights reserved.
A very basic tutorial-style introduction to Single-Molecule Magnetism, intended for a general chemistry audience, is provided. This is followed by a review of the synthesis, structures and magnetic properties of Single-Molecule Magnets (SMMs) that contain just one lanthanide ion and are either (a) monometallic or (b) di- or polymetallic as they also contain one or more transition metal ions (so are heterometallic). We use the term "monolanthanide" to refer to both. This review covers papers published before July 2013. (C) 2014 Elsevier B.V. All rights reserved.
This review presents the basic concepts and recent developments and advances of gold nanoparticle (AuNP)-catalyzed 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) by sodium borohydride, including the catalytic mechanism, the variety of stabilizers, and dendritic, natural and heterogeneous AuNP supports. The nano-gold catalysts are classified according to different stabilizers, the review contains 205 citations. (C) 2015 Elsevier B.V. All rights reserved.
Metal-organic frameworks (MOFs) are a fascinating class of highly porous materials composed of metal ions/clusters and organic linkers, which promise great potential in numerous fields. Recently, the use of MOFs as luminescent sensors has been extensively explored due to their unique crystallinity, tunable porosity and structural diversity. In this review, we intend to highlight some of recent studies in this active research area and update the database of various luminescent MOF-based sensors on the basis of different sensing targets including ions, organic molecules, and gases, and temperature. (C) 2017 Published by Elsevier B.V.
General principles and recent developments in the synthesis of gold nanoparticles (AuNPs) are reviewed. The "in situ" Turkevich-Frens and Brust-Schiffrin methods are still major synthetic routes, with citrate and thiolate ligands, respectively, that have been improved and extended to macromolecules including biomacromolecules with a large biomedical potential of optical and theranostic applications. Along this line, however, recently developed seed-growth methods have allowed a precise control of AuNP sizes in a broad range and multiple shapes. AuNPs and core@shell bimetallic MAuNPs loosely stabilized by nitrogen and oxygen atoms of embedding polymers and dendrimers and composite solid-state materials containing AuNPs with supports including oxides, carbons, mesoporous materials and molecular organic frameworks (MOFs) have attracted much interest because of their catalytic applications. (C) 2012 Elsevier B.V. All rights reserved.
3d-4f heterometallic discrete complexes have enjoyed increasing attraction in recent decades because of their potential advantages to create new single-molecule magnets: the moderate magnetic couplings between 3d and 4f spin carriers and significant single-ion magnetic anisotropies of 4f ions. Herein we review the synthetic strategy, structures and magnetic properties of 3d-4f discrete complexes. Particular attention is paid in this review to the examples showing dynamics of the magnetization. (C) 2014 Elsevier B.V. All rights reserved.
Based on a very comprehensive set of experimental data and on theoretical models, an understanding of the triplet state properties of organo-transition metal compounds is worked out. Important trends and guidelines for controlling photophysical properties are revealed. In this respect, we focus on spin-orbit coupling (SOC) and its importance for radiative as well as for nonradiative transitions between the lowest triplet state and the electronic ground state. Moreover, as is discussed on the basis of an extensive data set, summarized for the first time, the efficiency of SOC also depends on the geometry of a complex. The investigations are exemplified and supported by instructive case studies, such as efficient blue and very efficient green and red emitters. Additionally, trends being important for applications of these compounds as emitters in OLEDs are worked out. In particular, the properties of the emitters are discussed with respect to the harvesting of singlet and triplet excitons that are generated in the course of the electroluminescence process. The well-known triplet harvesting effect is compared to the recently discovered singlet harvesting effect. This latter mechanism is illustrated by use of a blue light emitting Cu(I) complex, which represents an efficient fluorescent emitter at ambient temperature. By this mechanism, 100% of the generated singlet and triplet excitons can, at least in principle, be harvested by the emitting singlet state. Potentially, this new mechanism can successfully be applied in future OLED lighting with a distinctly reduced roll-off of the efficiency. (C) 2011 Elsevier B.V. All rights reserved.
Over the last 15 years, a plethora of research has provided major insights into the structure and function of hydrogenase enzymes. This has led to the important development of chemical models that mimic the inorganic enzymatic co-factors, which in turn has further contributed to the understanding of the specific molecular features of these natural systems that facilitate such large and robust enzyme activities. More recently, efforts have been made to generate guest-host models and artificial hydrogenases, through the incorporation of transition metal-catalysts (guests) into various hosts. This adds a new layer of complexity to hydrogenase-like catalytic systems that allows for better tuning of their activity through manipulation of both the first (the guest) and the second (the host) coordination spheres. Herein we review the aforementioned advances achieved during the last 15 years, in the field of inorganic biomimetic hydrogenase chemistry. After a brief presentation of the enzymes themselves, as well as the early bioinspired catalysts, we review the more recent systems constructed as models for the hydrogenase enzymes, with a specific focus on the various strategies employed for incorporating of synthetic models into supramolecular frameworks and polypeptidic/protein scaffolds, and critically discuss the advantages of such an elaborate approach, with regard to the catalytic performances. (c) 2014 Elsevier B.V. All rights reserved.
Composites based on Metal-Organic Frameworks (MOFs) are an emerging class of porous materials that have been shown to possess unique functional properties. Nanoparticles@MOFs composites combine the tailorable porosity of MOFs with the versatile functionality of metal or metaloxide nanoparticles. A wide range of nanoparticles@MOFs have been synthesised and their performance characteristics assessed in molecular adsorption and separation, catalysis, sensing, optics, sequestration of pollutants, drug delivery, and renewable energy. This review covers the main research areas where nanoparticles@MOFs have been strategically applied and highlights the scientific challenges to be considered for their continuing development. (C) 2015 Published by Elsevier B.V.
In order to further design and successfully prepare for the functional metal-organic framework materials, it is essential to understand the fundamental correlations between the composition, physical properties and topology of the underlying nets. In this review, we focus on recent advances in metal-organic frameworks (MOFS) that possess more common non-zeotype 4-connected topological nets (such as sql, hag, nbo, lvt, cds, qtz, dia, ion, pts, etc.), and discuss the synthetic strategies of non-zeotype 4-connected MOFs and their related properties. In particular, we emphasize how to establish basic design principles and synthetic methodology to construct the same topological MOFs with different functions using specifically designed organic linkers. (C) 2013 Elsevier B.V. All rights reserved.
This review highlights the recent progress of bulk and nanoscale coordination polymer (CP) materials for energy transfer. Artificial light-harvesting materials with efficient energy transfer are practically useful for a variety of applications including photovoltaic, white emitting devices, and sensors. In the past decades CP (aka Metal-organic framework, MOF) has experienced rapid development due to a multitude of applications, including catalyst, gas storage and separations, non-linear optics, luminescence, and so on. Recent research has shown that CF is a very promising light-harvesting platform because the energy transfers can occur between different ligands, from ligand to metal centers, or from MOF skeleton to guest species. This review comprehensively surveyed synthetic approaches to light-harvesting CPs, and post functionalization. Sensing applications and achievements in energy-transfer CP nanoparticles and thin films were also discussed. (C) 2014 Elsevier B.V. All rights reserved.
Miniaturization of metal-organic frameworks (MOFs) results of great interest in order to integrate these materials in strategic applications such as sensing or drug delivery. This emerging class of nanoscaled MOFs (nanoMOFs), combining the intrinsic properties of the porous materials and the benefits of nanostructures, are expected to improve in some cases the performances of classical bulk crystalline MOFs. In the field of biomedicine, the benefits of MOF miniaturization have already been proved to be effective, not only because establishes a strong influence over the choice of the administration route but also governs their in vivo fate and therefore, their toxicity and/or activity. The scope of this review focuses on the preparation of nanostructured MOFs and their related biomedical applications. We will cover all aspects concerning the various synthetic methods reported so far, as well as the shaping and surface engineering routes required for their use in biomedicine. (C) 2015 Elsevier B.V. All rights reserved.