Dinuclear metal complexes: multifunctional properties and applications

The development of metal complexes for optoelectronic applications is a fertile area of research. In contrast to the rigorous development of mononuclear metal complexes, dinuclear species have been less well studied and their fundamental chemistry and applications are under-explored. However, dinuclear species present special properties and functions compared with mononuclear species as a consequence of tuning the bridging ligands, the cyclometalated ligands or the two metal centers. More recently, dinuclear species have enabled important breakthroughs in the fields of OLEDs, photocatalytic water splitting and CO2 reduction, DSPEC, chemosensors, biosensors, PDT, smart materials and so on. Here we present an overview of recent developments of dinuclear metal complexes, their multifunctional properties and their various applications. The relationship between structure and property of dinuclear species and important factors which influence device performance are discussed. Finally, we illustrate some challenges and opportunities for future research into dinuclear metal complexes. This review aims to provide an up-to-date summary and outlook of functional dinuclear metal complexes and to stimulate more researchers to contribute to this exciting interdisciplinary field

Strategic modification of ligands for remarkable piezochromic luminescence (PCL) based on a neutral Ir(iii) phosphor

A new aggregation-induced emission (AIE)-active neutral Ir(III) complex has been rationally designed and synthesized by introducing carboxyl and F substituents into the ancillary and cyclometalating ligands, respectively, to construct different kinds of intermolecular interaction, leading to excellent piezochromic luminescence (PCL) properties. The emission colours are tunable by a grinding–fuming/heating process with good reversibility in the solid state. A combination of powder X-ray diffraction, differential scanning calorimetry, 1H NMR, X-ray photoelectron and Fourier-transform infrared spectroscopy unambiguously confirm that the mechanism of PCL involves disruption of the intermolecular π–π interactions and hydrogen bonding. The combined AIE and PCL properties have enabled an efficient re-writable data recording device to be fabricated using the Ir(III) complex as the active material

Reversible tricolour luminescence switching based on a piezochromic iridium(iii) complex

On the basis of rational molecular design, the tricolour luminescence switching of an Ir(III) complex is achieved for the first time. The transformation between two crystalline states and an amorphous state is responsible for the switching behaviour of this complex between blue, green and yellow states. Solvent molecules are shown to play a crucial role in the crystallization and luminescence processes

New ionic dinuclear Ir(III) Schiff base complexes with aggregation-induced phosphorescent emission (AIPE)

Two new ionic dinuclear Ir(III) Schiff base complexes which are straightforward to synthesise have luminescence quantum yields as high as 37% in neat films. These are the first examples of dinuclear ionic Ir(III) complexes that display aggregation-induced phosphorescent emission (AIPE)

Promoted Photocharge Separation in 2D Lateral Epitaxial Heterostructure for Visible‐Light‐Driven CO2 Photoreduction

Photocarrier recombination remains a big barrier for the improvement of solar energy conversion efficiency. For 2D materials, construction of heterostructures represents an efficient strategy to promote photoexcited carrier separation via an internal electric field at the heterointerface. However, due to the difficulty in seeking two components with suitable crystal lattice mismatch, most of the current 2D heterostructures are vertical heterostructures and the exploration of 2D lateral heterostructures is scarce and limited. Here, lateral epitaxial heterostructures of BiOCl @ Bi2O3 at the atomic level are fabricated via sonicating‐assisted etching of Cl in BiOCl. This unique lateral heterostructure expedites photoexcited charge separation and transportation through the internal electric field induced by chemical bonding at the lateral interface. As a result, the lateral BiOCl @ Bi2O3 heterostructure demonstrates superior CO2 photoreduction properties with a CO yield rate of about 30 µmol g−1 h−1 under visible light illumination. The strategy to fabricate lateral epitaxial heterostructures in this work is expected to provide inspiration for preparing other 2D lateral heterostructures used in optoelectronic devices, energy conversion, and storage fields

Adoptive Transfer of Human Gingiva-derived Mesenchymal Stem Cells Ameliorates Collagen-induced Arthritis via Suppression of Th1 and Th17 Cells and Enhancement of Regulatory T Cell Differentiation

Objective Current approaches offer no cures for rheumatoid arthritis (RA). Accumulating evidence has revealed that manipulation of bone marrow-derived mesenchymal stem cells (BM-MSCs) may have the potential to control or even prevent RA, but BM-MSC-based therapy faces many challenges, such as limited cell availability and reduced clinical feasibility. This study in mice with established collagen-induced arthritis (CIA) was undertaken to determine whether substitution of human gingiva-derived mesenchymal stem cells (G-MSCs) would significantly improve the therapeutic effects. Methods CIA was induced in DBA/1J mice by immunization with type II collagen and Freund\u27s complete adjuvant. G-MSCs were injected intravenously into the mice on day 14 after immunization. In some experiments, intraperitoneal injection of PC61 (anti-CD25 antibody) was used to deplete Treg cells in arthritic mice. Results Infusion of G-MSCs in DBA/1J mice with CIA significantly reduced the severity of arthritis, decreased the histopathology scores, and down-regulated the production of inflammatory cytokines (interferon-γ and interleukin-17A). Infusion of G-MSCs also resulted in increased levels of CD4+CD39+FoxP3+ cells in arthritic mice. These increases were noted early after infusion in the spleens and lymph nodes, and later after infusion in the synovial fluid. The FoxP3+ Treg cells that were increased in frequency mainly consisted of Helios-negative cells. When Treg cells were depleted, infusion of G-MSCs partially interfered with the progression of CIA. Pretreatment of G-MSCs with a CD39 or CD73 inhibitor significantly reversed the protective effect of G-MSCs on CIA. Conclusion The role of G-MSCs in controlling the development and severity of CIA mostly depends on CD39/CD73 signals and partially depends on the induction of CD4+CD39+FoxP3+ Treg cells. G-MSCs provide a promising approach for the treatment of autoimmune diseases. Copyright © 2013 by the American College of Rheumatology

Fast detection and structural identification of carbocations on zeolites by dynamic nuclear polarization enhanced solid-state NMR

Acidic zeolites are porous aluminosilicates used in a wide range of industrial processes such as adsorption and catalysis. The formation of carbocation intermediates plays a key role in reactivity, selectivity and deactivation in heterogeneous catalytic processes. However, the observation and determination of carbocations remain a significant challenge in heterogeneous catalysis due to the lack of selective techniques of sufficient sensitivity to detect their low concentrations. Here, we combine 13C isotopic enrichment and efficient dynamic nuclear polarization magic angle spinning nuclear magnetic resonance spectroscopy to detect carbocations in zeolites. We use two dimensional 13C–13C through-bond correlations to establish their structures and 29Si–13C through-space experiments to quantitatively probe the interaction between multiple surface sites of the zeolites and the confined hydrocarbon pool species. We show that a range of various membered ring carbocations are intermediates in the methanol to hydrocarbons reaction catalysed by different microstructural β-zeolites and highlight that different reaction routes for the formation of both targeted hydrocarbon products and coke exist. These species have strong van der Waals interaction with the zeolite framework demonstrating that their accumulation in the channels of the zeolites leads to deactivation. These results enable understanding of deactivation pathways and open up opportunities for the design of catalysts with improved performances