One-Pot Preparation of Mechanically Robust, Transparent, Highly Conductive, and Memristive Metal-Organic Ultrathin Film

Application of Conductive MOF in Zinc-Based Batteries

The use of conductive MOFs (c-MOFs) in zinc-based batteries has been a popular research direction. Zinc-based batteries are widely used with the advantages of high specific capacity and safety and stability, but they also face many problems. c-MOFs have excellent conductivity compared with other primitive MOFs, and therefore have better applications in zinc-based batteries. In this paper, the transfer mechanisms of the unique charges of c-MOFs: hop transport and band transport, respectively, are discussed and the way of electron transport is further addressed. Then, the various ways to prepare c-MOFs are introduced, among which solvothermal, interfacial synthesis, and postprocessing methods are widely used. In addition, the applications of c-MOFs are discussed in terms of their role and performance in different types of zinc-based batteries. Finally, the current problems of c-MOFs and the prospects for their future development are presented.

Insulator-to-metal-like transition in thin films of a biological metal-organic framework

Temperature-induced insulator-to-metal transitions (IMTs) where the electrical resistivity can be altered by over tens of orders of magnitude are most often accompanied by structural phase transition in the system. Here, we demonstrate an insulator-to-metal-like transition (IMLT) at 333 K in thin films of a biological metal-organic framework (bio-MOF) which was generated upon an extended coordination of the cystine (dimer of amino acid cysteine) ligand with cupric ion (spin-1/2 system) - without appreciable change in the structure. Bio-MOFs are crystalline porous solids and a subclass of conventional MOFs where physiological functionalities of bio-molecular ligands along with the structural diversity can primarily be utilized for various biomedical applications. MOFs are usually electrical insulators (so as our expectation with bio-MOFs) and can be bestowed with reasonable electrical conductivity by the design. This discovery of electronically driven IMLT opens new opportunities for bio-MOFs, to emerge as strongly correlated reticular materials with thin film device functionalities.

Resistive Memory Devices Based on Reticular Materials for Electrical Information Storage

Recently, reticular materials, such as metal-organic frameworks and covalent organic frameworks, have been proposed as an active insulating layer in resistive switching memory systems through their chemically tunable porous structure. A resistive random access memory (RRAM) cell, a digital memristor, is one of the most outstanding emergent memory devices that achieves high-density electrical information storage with variable electrical resistance states between two terminals. The overall design of the RRAM devices comprises an insulating layer sandwiched between two metal electrodes (metal/insulator/metal). RRAM devices with fast switching speeds and enhanced storage density have the potential to be manufactured with excellent scalability owing to their relatively simple device architecture. In this review, recent progress on the development of reticular material-based RRAM devices and the study of their operational mechanisms are reviewed, and new challenges and future perspectives related to reticular material-based RRAM are discussed.

Rational Design of Copper(II)-Uracil Nanoprocessed Coordination Polymers to Improve Their Cytotoxic Activity in Biological Media

This work is focused on the rational structural design of two isostructural Cu(II) nano-coordination polymers (NCPs) with uracil-1-acetic acid (UAcOH) (CP1n) and 5-fluorouracil-1-acetic acid (CP2n). Suitable single crystals for X-ray diffraction studies of CP1 and CP2 were prepared under hydrothermal conditions, enabling their structural determination as 1D-CP ladder-like polymeric structures. The control of the synthetic parameters allows their processability into water colloids based on nanoplates (CP1n and CP2n). These NCPs are stable in water at physiological pHs for long periods. However, interestingly, CP1n is chemically altered in culture media. These transformations provoke the partial release of its building blocks and the formation of new species, such as [Cu(UAcO)₂(H₂O)₄]·2H₂O (Cu(II)-complex), and species corresponding to the partial reduction of the Cu(II) centers. The cytotoxic studies of CP1n versus human pancreatic adenocarcinoma and human uveal melanoma cells show that CP1n produces a decrease in the cell viability, while their UAcOH and Cu(II)-complex are not cytotoxic under similar conditions. The copper reduction species detected in the hydrolysis of CP1n are closely related to the formation of the reactive oxygen species (ROS) detected in the cytotoxic studies. These results prompted us to prepare CP2n that was designed to improve the cytotoxicity by the substitution of UAcO by 5-FUAcO, taking into account the anticancer activity of the 5-fluorouracil moiety. The new CP2n has a similar behavior to CP1n both in water and in biological media. However, its subtle structural differences are vital in improving its cytotoxic activity. Indeed, the release during the hydrolysis of species containing the 5-fluorouracil moiety provokes a remarkable increase in cellular toxicity and a significant increase in ROS species formation.

Electrically Conductive Coordination Polymers for Electronic and Optoelectronic Device Applications

Electrically conductive coordination polymers (generally known as metal-organic frameworks, MOFs) are a class of crystalline hybrid materials produced by the reasonable self-assembly of metal nodes and organic linkers. The unique and intriguing combination of inorganic and organic components endows coordination polymers with superior optical and electrical properties, which have recently aroused much attention in several electronic and optoelectronic technological applications. However, there are many challenging obstacles and issues that need to be addressed in this burgeoning field. In this Perspective, we first provide a fundamental understanding about the electronic design strategies that provide better guidance for realizing high conductivities and good mobilities in coordination polymers. We then examine the current established synthetic approaches to construct high-quality working samples of electrically conductive coordination polymers for device integration. This is followed by a discussion of the current state-of-the-art progress toward the preliminary achievements in (opto)electronic devices spanning chemiresistive sensors, field-effect transistors, organic photovoltaics, photodetectors, etc. Finally, we conclude this Perspective with the existing hurdles and limitations in this area, along with the critical directions and opportunities for future research.

Copper(i)–iodide cluster structures as functional and processable platform materials

This review provides a complete overview of the progress towards implementation of CuI-nanoclusters in functional materials and devices.