Single-atom Pd catalyst anchored on Zr-based metal-organic polyhedra for Suzuki-Miyaura cross coupling reactions in aqueous media

The challenge for single-atom catalysts in various C-C cross coupling reaction exists in the development of solid supporting materials.It has been desired tofind a supporting material designed in molecular level to anchor a single-atom catalyst and provide high degree of dispersion and substrate access in aqueous media.Here,we prepared discrete cages of metal-organic polyhedra anchoring single Pd atom(MOP-BPY(Pd))and successfully performed a Suzuki-Miyaura cross coupling reaction with various substrates in aqueous media.It was revealed that each tetrahedral cage of MOP-BPY(Pd)has 4.5 Pd atoms on average and retained its high degree of dispersion up to 3 months in water.The coupling efficiencies of the Suzuki-Miyaura cross coupling reaction exhibited more than 90.0%for various substrates we have tested in the aqueous media,which is superior to those of the molecular Pd complex and metal-organic framework(MOF)anchoring Pd atoms.Moreover,MOP-BPY(Pd)was successfully recovered and recycled without performance degradation.     

Combining metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs):Emerging opportunities for new materials and applications

In the past decades,metal-organic frameworks(MOFs)and covalent organic frameworks(COFs)basically enjoy the coordination chemistry and covalent chemistry,respect...     

A new metal-organic crystal: Potassium thiourea chloride

The growth and characterization of a new nonlinear metal-organic crystal, potassium thiourea chloride (PTC), is reported. The growth of single crystals of PTC was accomplished by the slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirms the crystal structure. The FT-IR analysis confirms the presence of sulfur to potassium bonds in the complex. From the optical spectrum PTC has a good optical transmission in the entire visible region, which is an essential requirement for a nonlinear crystal.     

Rational tuning of thorium-organic frameworks by reticular chemistry for boosting radionuclide sequestration

The reticular chemistry strategy presents a powerful molecule-design tool to tailor the physical and chemical properties of metal-organic framework(MOF).In this work,we for the first time investigated the effect of organic ligands on the radionuclide sequestration(TcO₄^-)of thorium-organic framework.Through a coordination modulation technique,two novel isoreticular thorium-organic frameworks,namely Th-MOF-67 and Th-MOF-68,were obtained.Relative to the antetype MOF of Th-MOF-66 that shows extremely low uptake of ReO₄^-(a chemical surrogate of radioactive TcO₄^-),the isoreticular MOFs of Th-MOF-67 and Th-MOF-68 enable ultrahigh uptake of ReO₄^-,giving an impressively 36.8-fold or 56-fold enhancement,respectively.The adsorption capacity of Th-MOF-68 is as high as 560 mg/g,exceeding most reported adsorbents for such use.The mechanism for such exceptional outstanding performance,as unveiled by both the single crystal X-ray diffraction and theoretical calculation,is due to coordination interaction for Th-MOF-67,when a tetrazolate ligand was used,or a combined effect from both coordination interaction and anion-exchange for Th-MOF-68,if using a triazolate ligand.     

Product design in less industrialized economies: constraints and opportunities in Kenya

The ability for an economy to design useful products is tied to its productivity, thus economic growth and the population’s standards of living. This paper investigates product design strategies and processes in Kenya in the country’s informal, formal, and non-governmental sectors. In analyzing Kenyan 200+ products, patterns emerged to delineate four approaches to the detailed design acquisition of common-use products: imitated design, imported design, basic original design, and specialty design. A vast majority of product designs, 54 of 55 tracked in this research, originate outside the country or were imitated from imported products. Across sectors, there is emphasis on the detailed design and manufacturing phases of the design process. Factors specific to less industrialized economies (LIEs) like Kenya, such as corruption and an inadequate infrastructure, limit design activities relative to more industrialized economies. Design constraints observed in Kenya are believed to be similar to other economies at the same levels of industrialization. For product design to sustainably support economic development in LIEs, it is imperative that design process be consistent with local conditions and be user-centric in approach.

Growth and characterization of a new metal-organic crystal: potassium thiourea bromide

The growth and characterization of a new nonlinear metal-organic crystal, potassium thiourea bromide (PTB) is reported. The growth of single crystals of PTB was accomplished by slow evaporation method. The grown crystals were characterized by EDAX, X-ray powder diffraction and IR techniques. PTB crystallizes in tetragonal system and the complex formation is established by metal–sulfur bonds. PTB has good optical transmission in the entire visible region, which is an essential requirement for a nonlinear crystal.     

Growth and characterization of a new metal-organic crystal: Potassium thiourea iodide

Single crystals of potassium thiourea iodide (PTI), a semiorganic nonlinear optical crystal, have been grown from low temperature solution growth method by a slow evaporation technique at room temperature. Single crystal X-ray diffraction pattern and FTIR spectrum analysis has confirmed the formation of the new crystal. PTI has good optical transmission in the entire visible region, which is an essential requirement for a nonlinear crystal.     

Seventy-five years of superplasticity: historic developments and new opportunities

On this seventy-fifth anniversary of the first scientific report of true superplastic flow, it is appropriate both to look back and examine the major developments that established the present understanding of superplasticity and to look to the future to the new opportunities that are made possible by new processing techniques, based on the application of severe plastic deformation, that permit the production of fully dense bulk materials with submicrometer or nanometer grain sizes. This review proposes a minor modification to the present definition of superplasticity, it provides an overview of the current understanding of the flow of superplastic metals and ceramics and then it examines, and gives examples of, the new possibilities that are now available for achieving exceptional superplastic behavior.     

Lithium batteries: a new tool in solid state chemistry

Lithium batteries are being intensively studied owing to the considerable challenge they represent for applications. From a fundamental point of view, the shape of the charge/discharge curves gives information on all the structural and physical properties modifications which occur during the intercalation/deintercalation process. Moreover, the electrochemical reaction is a way of synthesising metastable materials which cannot be obtained by classical methods. The ease of monitoring very accurately either the cell voltage (oxidation state of the material) or the number of electrons transferred (lithium content in the material) makes lithium batteries a new very convenient tool for the solid state chemist. Typical examples are presented.     

Applying reticular synthesis to the design of Cu-based MOFs with mechanically interlocked linkers

The concept of“robust dynamics”describes the incorporation of mechanically interlocked molecules(MIMs)into metal-organic framework(MOF)materials such that large amplitude motions(e.g.,rotation or translation of a macrocycle)can occur inside the free volume pore of the MOF.To aid in the preparation of such materials,reticular synthesis was used herein to design rigid molecular building blocks with predetermined ordered structures starting from the well-known MOF NOTT-101.New linkers were synthesized that have a T-shape,based on a triphenylene tetra-carboxylate strut,and their incorporation into Cu(II)-based MOFs was investigated.The single-crystal structures of three new MOFs,UWCM-12(fof),β-UWCM-13(loz),UWCM-14(lil),with naked T-shaped linkers were determined;β-UWCM-13 is the first reported example of the loz topology.A fourth MOF,UWDM-14(lil)is analogous to UWCM-14(lil)but contains a[2]rotaxane linker.Variable-temperature,²H solid-state NMR was used to probe the dynamics of a 24-membered macrocycle threaded onto the MOF skeleton.     

Fibre reinforced concrete: new design perspectives

Although the use of Fibre Reinforced Concrete (FRC) for structural applications is continuously increasing, it is still limited with respect to its potentials, mainly due to the lack of International Building Codes for FRC structural elements. Within fib (Féderation Internationale du Béton), the Special Activity Group 5 is preparing a New fib Model Code that aims to update the previous CEB-FIP Model Code 90, published in 1993, that can be considered as the reference document for Eurocode 2. The New Model Code includes several innovations and addresses among other topics, new materials for structural design. In this respect, FRC will be introduced. The Technical Groups fib TG 8.3 “Fibre reinforced concrete” and fib TG 8.6 “Ultra high performance FRC” are preparing some sections of the New Model Code, including regular and high performance FRC. This paper aims to briefly explain the main concepts behind the structural rules for FRC structural design.     

Photothermoelectric converter: A new design concept

A new concept of the photothermoelectric converter (PTEC) is proposed, which is free of the main disadvantages (overheating of the photocell and insufficient heat flux in the thermocell) of the existing schemes. The problems are solved using a PTEC scheme with a narrowband optical filter, which transmits radiation with the optimum spectrum to the photocells and directs optimum heat flux to the thermocell.