Outstanding Drug-Loading/Release Capacity of Hollow Fe-Metal-Organic Framework-Based Microcapsules: A Potential Multifunctional Drug-Delivery Platform

Owing to their characteristic structures, metal-organic frameworks (MOFs) are considered as the leading candidate for drug-delivery materials. However, controlling the synthesis of MOFs with uniform morphology and high drug-loading/release efficiencies is still challenging, which greatly limits their applications and promotion. Herein, a multifunctional MOF-based drug-delivery system (DDS) with a controlled pore size of 100-200 nm for both therapeutic and bioimaging purposes was successfully synthesized in one step. Fe-MOF-based microcapsules were synthesized through a competitive coordination method, which was profited from the intrinsic coordination characteristics of the Fe element and the host-guest supramolecular interactions between Fe³⁺ and polyoxometalates anions. This as-synthesized macroporous DDS could greatly increase the drug-loading/release rate (77%; 83%) and serve as a magnetic resonance (MR) contrast agent. Because an Fe-containing macroporous DDS presents ultrahigh drug loading/release, the obtained 5-FU/Fe-MOF-based microcapsules displayed good biocompatibility, extremely powerful inhibition of tumor growth, and satisfactory MR imaging capability. Given all these advantages, this study integrates high therapeutic effect and diagnostic capability via a simple and effective morphology-controlling strategy, aiming at further facilitating the applications of MOFs in multifunctional drug delivery.

Linker Deficiency, Aromatic Ring Fusion, and Electrocatalysis in a Porous Ni8-Pyrazolate Network

The cruciform linker molecule here features two designer functions: the pyrazole donors for framework construction, and the vicinal alkynyl units for benzannulation to form nanographene units into the Ni₈-pyrazolate scaffold. Unlike the full 12 connections of the Ni₈(OH)₄(H₂O)₂ clusters in other Ni₈-pyrazolate networks, significant linker deficiency was observed here, leaving about half of the Ni(II) sites capped by acetate ligands, which can be potentially removed to open the metal sites for reactivity. The crystalline Ni₈-pyrazolate scaffold also retains the crystalline order even after thermal treatments (up to 300 °C) that served to partially graphitize the neighboring alkyne units. The resultant nanographene components enhance the electroactive properties of the porous hosts, achieving hydrogen evolution reaction (HER) activity that rivals that of topical nickel/palladium-enabled materials.

Rare metal-ion metathesis of a tetrahedral Zn(ii) core of a noncentrosymmetric (3,4)-connected 3D MOF

An SHG-active framework of 1-Zn can undergo metal metathesis, in which the tetrahedrally coordinated Zn(ii) ions are completely exchanged with Cu(ii) ions while retaining the integrity of the network.

Mesoporous Metal-Organic Frameworks: Synthetic Strategies and Emerging Applications

Metal-organic frameworks (MOFs) have attracted much attention over the past two decades due to their highly promising applications not only in the fields of gas storage, separation, catalysis, drug delivery, and sensors, but also in relatively new fields such as electric, magnetic, and optical materials resulting from their extremely high surface areas, open channels and large pore cavities compared with traditional porous materials like carbon and inorganic zeolites. Particularly, MOFs involving pores within the mesoscopic scale possess unique textural properties, leading to a series of research in the design and applications of mesoporous MOFs. Unlike previous Reviews, apart from focusing on recent advances in the synthetic routes, unique characteristics and applications of mesoporous MOFs, this Review also mentions the derivatives, composites, and hierarchical MOF-based systems that contain mesoporosity, and technical boundaries and challenges brought by the drawbacks of mesoporosity. Moreover, this Review subsequently reveals promising perspectives of how recently discovered approaches to different morphologies of MOFs (not necessarily entirely mesoporous) and their corresponding performances can be extended to minimize the shortcomings of mesoporosity, thus providing a wider and brighter scope of future research into mesoporous MOFs, but not just limited to the finite progress in the target substances alone.

Amide-containing zinc(ii) metal–organic layered networks: a structure–CO2 capture relationship

An intimate interrelationship between the structural characteristics and their CO₂ adsorption behavior has been demonstrated in this study.

Functional shakeup of metal–organic frameworks: the rise of the sidekick

The ever more versatile side groups, from labile weak donors to strong-binding thiol and dendritic functions, sulfur-enabled framework chemistry heralds a rising trend in the design of solid-state materials.

Anionic bipyridyl ligands for applications in metallasupramolecular chemistry

The facile synthesis of anionic bipyridyl ligands with dinuclear clathrochelate cores is described. These metalloligands can be obtained in high yields by the reactions of M(ClO4 )2 (H2 O)6 (M: Zn, Mn, or Co) with 4-pyridylboronic acid and 2,6-diformyl-4-methylphenol oxime or 2,6-diformyl-4-tert-butylphenol oxime, followed by deprotonation. The ligands are interesting building blocks for metallasupramolecular chemistry, as evidenced by the formation of a Pt-based molecular square and four coordination polymers with 2D or 3D network structures. Competition experiments reveal that the utilization of anionic bipyridyl ligands can result in significantly more stable assemblies.

Guest dependent dielectric properties of nickel(ii)-based supramolecular networks

Nickel-based supramolecular compounds exhibit interesting guest dependent dielectric behaviour and high thermal stability. This study serves as a motivation to expand our research to create both high and low-κmaterials with a judicious selection of guest molecules.

Synthesis of MOFs

A summary of important – theoretical and practical – aspects, approaches and methods is presented, which are utilized in the synthesis of MOFs. Throughout the text the needs of scientists mainly working in the field of catalysis is addressed. Thus in the first half of the chapter, general principles and methods for crystallisation are briefly summarized, followed by detailed descriptions of the important concepts of isoreticular chemistry and high‐throughput methods. Moreover some examples are given for the use of precursors and templates. Topological rules that may affect the final MOF‐structure can also be utilised for the intentional synthesis of MOFs. The second half of the chapter will cover aspects that are more strongly correlated to materials chemistry – the shaping of crystals as well as the introduction of hierarchical mesopores into the particles and the anchoring of MOFs to surfaces. Finally, some important comments on the activation procedures are given, which determine the maximum porosity of a material and thus its catalytic activity. Thus, the text intends to give an insight into the diverse and sometimes complex field of the synthesis of MOFs.