Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

Selective gas adsorption and separation in metal–organic frameworks

In the past decade, mesoporous silica nanoparticles (MSNs) have attracted more and more attention for their potential biomedical applications. With their tailored mesoporous structure and high surface area, MSNs as drug delivery systems (DDSs) show significant advantages over traditional drug nanocarriers. In this review, we overview the recent progress in the synthesis of MSNs for drug delivery applications. First, we provide an overview of synthesis strategies for fabricating ordered MSNs and hollow/rattle-type MSNs. Then, the in vitro and in vivo biocompatibility and biotranslocation of MSNs are discussed in relation to their chemophysical properties including particle size, surface properties, shape, and structure. The review also highlights the significant achievements in drug delivery using mesoporous silica nanoparticles and their multifunctional counterparts as drug carriers. In particular, the biological barriers for nano-based targeted cancer therapy and MSN-based targeting strategies are discussed. We conclude with our personal perspectives on the directions in which future work in this field might be focused.

Mesoporous Silica Nanoparticles: Synthesis, Biocompatibility and Drug Delivery

The purpose of this critical review is to give a representative and comprehensive overview of the arising developments in the field of magnetic metal–organic frameworks, in particular those containing cobalt(II). We examine the diversity of magnetic exchange interactions between nearest-neighbour moment carriers, covering from dimers to oligomers and discuss their implications in infinite chains, layers and networks, having a variety of topologies. We progress to the different forms of short-range magnetic ordering, giving rise to single-molecule-magnets and single-chain-magnets, to long-range ordering of two- and three-dimensional networks (323 references).

Magnetic metal-organic frameworks.

Polyoxometalates represent a diverse range of molecular clusters with an almost unmatched range of physical properties and the ability to form structures that can bridge several length scales. The new building block principles that have been discovered are beginning to allow the design of complex clusters with desired properties and structures and several structural types and novel physical properties are examined. In this critical review the synthetic and design approaches to the many polyoxometalate cluster types are presented encompassing all the sub-types of polyoxometalates including, isopolyoxometalates, heteropolyoxometalates, and reduced molybdenum blue systems. As well as the fundamental structure and bonding aspects, the final section is devoted to discussing these clusters in the context of contemporary and emerging interdisciplinary interests from areas as diverse as anti-viral agents, biological ion transport models, and materials science.

Polyoxometalate clusters, nanostructures and materials: From self assembly to designer materials and devices

Over the past three decades a new spectroscopic technique with unique possibilities has emerged. Based on coherent and time-resolved detection of the electric field of ultrashort radiation bursts in the far-infrared, this technique has become known as terahertz time-domain spectroscopy (THz-TDS). In this review article the authors describe the technique in its various implementations for static and time-resolved spectroscopy, and illustrate the performance of the technique with recent examples from solid-state physics and physical chemistry as well as aqueous chemistry. Examples from other fields of research, where THz spectroscopic techniques have proven to be useful research tools, and the potential for industrial applications of THz spectroscopic and imaging techniques are discussed.

Terahertz spectroscopy and imaging – Modern techniques and applications

Cytotoxicity of mesoporous silica nanomaterials.

Hydrothermal reactions of 1,2,4-triazole with the appropriate copper salt have provided eight structurally unique members of the Cu/triazolate/X system, with X = F-, Cl-, Br-, I-, OH-, and SO42-. The anionic components X of [Cu3(trz)4(H2O)3]F2 (1) and [Cu6(trz)4Br]Cu4Br4(OH) (4) do not participate in the framework connectivity, acting as isolated charge-compensating counterions. In contrast, the anionic subunits X of [CuIICuI(trz)Cl2] (2), [Cu6(trz)4Br2] (3), [CuIICuI(trz)Br2] (5), [Cu3(trz)I2] (6), [Cu6IICu2I(trz)6(SO4)3(OH)2(H2O)] (8), and [Cu4(trz)3]OH·7.5H2O (9·7.5H2O) are intimately involved in the three-dimensional connectivities. The structure of [CuIICuI(trz)2][Cu3II4] (7) is constructed from two independent substructures:  a three-dimensional cationic {Cu2(trz)2}nn+ component and {Cu3I4}nn- chains. Curiously, four of the structures are mixed-valence CuI/CuII materials:  2, 5, 7, and 8. The only CuII species is 1, while 3, 4, 6, and 9·7.5H2O exhibit exclusively CuI sites. The magnetic properties o...

Solid-State Coordination Chemistry of the Cu/Triazolate/X System (X = F-, Cl-, Br-, I-, OH-, and SO42-)

Fixing a hole: Hydrothermal chemistry has been exploited in the preparation of a 3D framework material exhibiting 48% accessible void volume and 1.5% hydrogen uptake by weight at 120 kPa (see picture). The title compound also exhibits single-chain magnetic behavior and reversible changes in magnetic properties upon solvation and desolvation.

A thermally and hydrolytically stable microporous framework exhibiting single-chain magnetism: structure and properties of [Co2(H0.67bdt)3] x 20 H2O.

Hydrothermal reactions of 1,2,4-triazole with zinc and cadmium salts have yielded 10 structurally unique materials of the M(II)/trz/Xn- system, with M(II) = Zn and Cd and Xn- = F-, Cl-, Br-, I-, OH-, NO3-, and SO42- (trz = 1,2,4-triazolate). Of the zinc-containing phases, [Zn(trz)2] (1), [Zn2(trz)3(OH)]·3H2O (3·3H2O), and [Zn2(trz)(SO4)(OH)] (4) are three-dimensional, while [Zn(trz)Br] (2) is two-dimensional. All six cadmium phases, [Cd3(trz)3F2(H2O)]·2.75H2O (5·2.75H2O), [Cd2(trz)2Cl2(H2O)] (6), [Cd3(trz)3Br3] (7), [Cd2(trz)3I] (8), [Cd3(trz)5(NO3)(H2O)]·H2O (9·H2O), and [Cd8(trz)4(OH)2(SO4)5(H2O)] (10), are three-dimensional. In all cases, the anionic components Xn- participate in the framework connectivity as bridging ligands. The structural diversity of these materials is reflected in the variety of coordination polyhedra displayed by the metal sites:  tetrahedral; trigonal bipyramidal; octahedral. Structures 3, 5, and 7−9 exhibit two distinct polyhedral building blocks. The materials are also charact...

Hydrothermal and Structural Chemistry of the Zinc(II)- and Cadmium(II)-1,2,4-Triazolate Systems

Hydrothermal Chemistry of the Copper–Triazolate System: A Microporous Metal–Organic Framework Constructed from Magnetic {Cu3(μ3‐OH)(triazolate)3}2+ Building Blocks, and Related Materials

Wayne Ouellette

Papers

Cytotoxicity of mesoporous silica nanomaterials.

Solid-State Coordination Chemistry of the Cu/Triazolate/X System (X = F-, Cl-, Br-, I-, OH-, and SO42-)

A thermally and hydrolytically stable microporous framework exhibiting single-chain magnetism: structure and properties of [Co2(H0.67bdt)3] x 20 H2O.

Hydrothermal and Structural Chemistry of the Zinc(II)- and Cadmium(II)-1,2,4-Triazolate Systems

Hydrothermal Chemistry of the Copper–Triazolate System: A Microporous Metal–Organic Framework Constructed from Magnetic {Cu3(μ3‐OH)(triazolate)3}2+ Building Blocks, and Related Materials