Systematic design and functionalisation of amorphous zirconium metal-organic frameworks.

Controlling the structure and functionality of crystalline metal-organic frameworks (MOFs) using molecular building units and post-synthetic functionalisation presents challenges when extending this approach to their amorphous counterparts (aMOFs). Here, we present a new bottom-up approach for synthesising a series of Zr-based aMOFs, which involves linking metal-organic clusters with specific ligands to regulate local connectivity. In addition, we overcome the limitations of post-synthetic modifications in amorphous systems, demonstrating that homogeneous functionalisation is achievable even without regular internal voids.

Tuning Electronic and Proton Transfer Properties on Amino-Functionalized Co-Based MOF for Efficient Photocatalytic Hydrogen Evolution.

Efficient hydrogen (H) production through photocatalytic water splitting was achieved by using an amino-functionalized azolate/cobalt-based metal-organic framework (MOF). While previous reports highlighted the amino group's role only as a substituent group for enabling light absorption of MOFs in the visible region, our present study revealed its dual role. The amino substituent not only acts as an electron donor to increase the electron availability at the active Co sites but also provides hydrogen-hopping sites within the pore channel, facilitating proton (H) diffusion along the framework.

Prussian Blue Analogue Glasses for Photoinduced CO Conversion.

Crystal-to-glass transformation is a powerful approach to modulating the chemical and physical properties of crystals. Here we demonstrate that the glass transformation of cobalt hexacyanoferrate crystals, one of the Prussian blue analogues, increased the concentration of open metal sites and altered the electronic state while maintaining coordination geometries and short-range ordering in the structure. The compositional and structural changes were characterized by X-ray absorption fine structure, energy dispersive X-ray spectroscopy, and X-ray total scattering.

Functional metal-organic liquids.

For decades, the study of coordination polymers (CPs) and metal-organic frameworks (MOFs) has been limited primarily to their behavior as crystalline solids. In recent years, there has been increasing evidence that they can undergo reversible crystal-to-liquid transitions. However, their "liquid" states have primarily been considered intermediate states, and their diverse properties and applications of the liquid itself have been overlooked.

Eutectic CsHSO-Coordination Polymer Glasses with Superprotonic Conductivity.

Superprotonic phase transition in CsHSO allows fast protonic conduction, but only at temperatures above the transition temperature of 141 °C (). Here, we preserve the superprotonic conductivity of CsHSO by forming a binary CsHSO-coordination polymer glass system, showing eutectic melting. Their anhydrous proton conductivities below are at least 3 orders of magnitude higher than CsHSO without compromising conductivity at higher temperatures or the need for humidification, reaching 6.

Exploration of glassy state in Prussian blue analogues.

Prussian blue analogues (PBAs) are archetypes of microporous coordination polymers/metal-organic frameworks whose versatile composition allows for diverse functionalities. However, developments in PBAs have centred solely on their crystalline state, and the glassy state of PBAs has not been explored. Here we describe the preparation of the glassy state of PBAs via a mechanically induced crystal-to-glass transformation and explore their properties.

Mechanical Force Induced Formation of Extrinsic Micropores in Coordination Polymers.

Mechanical force can be employed not only to efficiently synthesize new materials under environmentally friendly conditions but also to change the macroscopic and microscopic properties of materials. Although coordination polymers (CPs) are attractive functional materials because they possess high structural designability and diversity, mechanical force-induced structural and functional changes of CPs are challenging issues. In this study, two one-dimensional CPs, one a densely packed nonporous CP [Cu(bza)(pyr)] () and the other a porous CP [Cu(1-nap)(pyr)] () (bza = benzoate, 1-nap = 1-naphthoate and pyr = pyrimidine), were subjected to ball-milling to assess the effect of mechanical force on their porosities.

Mechanics, Ionics, and Optics of Metal-Organic Framework and Coordination Polymer Glasses.

Melt and glassy states of coordination polymers (CPs)/metal-organic frameworks (MOFs) have gained attention as a new class of amorphous materials. Many bridging ligands such as azolate, nitrile, thiocyanide, thiolate, pyridine, sulfonate, and amide are available to construct crystals with melting temperatures in the range of 60-593 °C. Here, we discuss the mechanism of crystal melting, glass structures, and mechanical properties by considering both experimental and theoretical studies.

Proton-conductive coordination polymer glass for solid-state anhydrous proton batteries.

Designing solid-state electrolytes for proton batteries at moderate temperatures is challenging as most solid-state proton conductors suffer from poor moldability and thermal stability. Crystal-glass transformation of coordination polymers (CPs) and metal-organic frameworks (MOFs) melt-quenching offers diverse accessibility to unique properties as well as processing abilities. Here, we synthesized a glassy-state CP, [Zn(HPO)(HO)](1,2,3-benzotriazole), that exhibited a low melting temperature (114 °C) and a high anhydrous single-ion proton conductivity (8.

Effect of Intercalants inside Birnessite-Type Manganese Oxide Nanosheets for Sensor Applications.

Hydrazine is a common reducing agent widely used in many industrial and chemical applications; however, its high toxicity causes severe human diseases even at low concentrations. To detect traces of hydrazine released into the environment, a robust sensor with high sensitivity and accuracy is required. An electrochemical sensor is favored for hydrazine detection owing to its ability to detect a small amount of hydrazine without derivatization.

Effect of intercalated alkali ions in layered manganese oxide nanosheets as neutral electrochemical capacitors.

New insight into the influence of Li+, Na+, and K+ cations between adjacent layers of birnessite-type manganese oxides (MnOx) towards the intercalation/deintercalation charge storage mechanism as a neutral electrochemical capacitor (1 M Na2SO4) is demonstrated. These structural cations play a major role in both the kinetic electron transfer in a faradaic redox reaction and the accessibility of the compensating electrolyte ions. Li-MnOx shows the highest Mn utilization of 51% followed by Na-MnOx (40%) and K-MnOx (31%), respectively.

Insight into the effect of intercalated alkaline cations of layered manganese oxides on the oxygen reduction reaction and oxygen evolution reaction.

The effect of the intercalated alkaline cations between the adjacent layers of multilayered manganese oxide (MnO) towards the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) was investigated. Li-MnO, Na-MnO, K-MnO, Rb-MnO, and Cs-MnO provide OER overpotentials of 1.64, 1.