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Layered double hydroxides (LDHs) have attracted much attention for the oxygen evolution reaction (OER) in electrochemical water splitting. In this work, we use a two-dimensional (2D) MOF transformation strategy to synthesize FeNi layered double hydroxides (FeNi LDHs). 2D FeNi Hofmann MOFs ([Fe(L)2Ni(CN)4]) with a similar structure but different ligands (L = py, ISOQ) are synthesized as precursors. Accordingly, hydrolysis transformation assisted by NaBH4 leads to the growth of 2D FeNi-LDH nanosheets from 2D Hofmann-MOFs. During hydrolysis, OH− ions preferentially attack the coordination bond of [Fe(L)2Ni(CN)4], which allows FeNi-LDHs to form quickly on the surface of 2D MOFs. This rapid conversion process can effectively avoid the self-accumulation of LDHs. The hydrogen bubbles produced by NaBH4 can also inhibit the self-stacking of LDHs, which expose ample active species for the OER. Meanwhile, the synergistic effect between Fe and Ni contributes to the outstanding OER performance of FeNi-py-LDH, which shows an overpotential of 238 mV at 10 mA cm−2, a Tafel slope of 22 mV dec−1 and an excellent stability for 15 h. This work provides a universal synthesis method for ultra-thin FeNi-LDHs, which avoids the self-stacking of nanosheets and offers new insights into the OER. [ABSTRACT FROM AUTHOR]

High-quality CoP nanorings (CoP NRs) are easily achieved using a phosphorating treatment of CoOOH nanorings, and reveal high activity towards the hydrogen evolution reaction and the nitrate electrocatalytic reduction reaction due to substantial coordinately unsaturated active sites, a high surface area, and available mass transfer pathways. Consequently, the CoP NRs can achieve a faradaic efficiency of 97.1% towards NO3−-to-NH3 conversion and provide an NH3 yield of 30.1 mg h−1 mg−1cat at a −0.5 V potential. [ABSTRACT FROM AUTHOR]

Holey CoOOH nanosheets (CoOOH HNSs) are easily synthesized by a successive coordination–oxidation–hydrolysis strategy. The CoOOH HNSs possess a large surface area, numerous pores, and substantial edge atoms with excellent electroactivity towards the oxygen evolution reaction in alkaline solution. The overpotential of 305 mV at 10 mA cm−2 for the CoOOH HNSs exceeds that of most monometallic Co-based electrocatalysts. [ABSTRACT FROM AUTHOR]

In extremely low-temperature environments such as aerospace and polar regions, advanced elastic thermal insulation materials are urgently needed but their development is challenging, as traditional elastic insulators are completely "frozen", lose elasticity and become brittle. Herein, we proposed a novel structural elastic strategy to create an ultralow-temperature elastic polymer aerogel with highly oriented thin nanosheets and hierarchically honeycomb-like architectures from low-cost raw materials. This approach endowed the polymer aerogel with superelasticity and high strength at liquid nitrogen temperature (−196 °C), where the aerogel can bear more than 10 000 times its weight and repeatedly recover to its original size after force removal. The underlying structural elastic mechanism was revealed by finite element simulation calculation. The resultant robust aerogel also displayed an excellent extreme-condition thermal insulation, which could maintain a pleasant interior environment with small temperature changes under harsh external environments from liquid nitrogen to fire scenarios. It combined the great features of ultralow-temperature superelasticity with high mechanical strength, excellent thermal insulation under extremely harsh conditions, fire retardancy, and performance stability. These results provide new insights and general methods for the development of advanced super-elastic polymeric insulators with high strength at ultralow temperatures. [ABSTRACT FROM AUTHOR]

The controllable synthesis of highly stable porous metal–organic frameworks (MOFs) with targeted functions is urgently needed but still challenging up to now. In this work, we report the latest achievement in our continuous quest for robust 9-connected (9-c) MOFs based on [M3(O/OH)(COO)6(pyridine)3] building blocks. Different from the reported nets (ncb, xmz and pacs-MOFs) constructed from integrated or separated carboxylate and pyridine ligands, our metal–organic linker (MOL) strategy led to the discovery of six fascinating 9-c MOFs (SNNU-51–56) showing two types of completely new topological nets generated by cis, trans-coordination isomerism. As expected from highly connected architectures and the absence of open metal sites, all these MOFs show high thermal and moisture stability. They can even retain their frameworks after being treated at different pH values for 24 h. Furthermore, SNNU-51–56 not only inherit the excellent gas uptake performance of robust 9-c MOFs, but also exhibit extremely high CH4 separation from CO2, C2H2 and C2H4. Together with robust frameworks, the effective inner-cluster redox process in [M3(OH)(COO)6(pyridine)3] (M = Fe, Co and Ni) units makes SNNU-51–56 high-performance electrochemical pseudocapacitor materials. The asymmetric supercapacitor (ASC) fabricated with the SNNU-52 positive electrode and activated carbon (AC) negative electrode can be reversibly charged/discharged in a working voltage range of 0–1.6 V in 2 M KOH aqueous electrolyte for application in practical energy storage devices, and two serially connected ASCs can continuously light a light emitting diode. In all, greater control over the MOF structure, excellent thermal and chemical stability, and superb metal compatibility make [M3(O/OH)(COO)6(pyridine)3] clusters an ideal building block to design multifunctional MOF materials in the future. [ABSTRACT FROM AUTHOR]

Presented herein is a magnesium–organic framework (SNNU-88) incorporated with active hydroquinone groups, which exhibits not only remarkable semiconductor sensing for traces of ammonia vapor (5–100 ppm), but also extra-high fluorescence response to liquid NH3·H2O through an unusual turn-off (0–1.5 ppm) and turn-on (3.0–100 ppm) luminescence sensing mechanism at room temperature. Such bifunctional quantitative ammonia detection together with the extraordinary sensitivity and selectivity, fast response, and good reusability makes SNNU-88 one of the most powerful ammonia sensors. [ABSTRACT FROM AUTHOR]

A porous MOF platform (SNNU-65s) formed by creatively combining paddle-wheel-like [Cu2(COO)4] and trigonal prismatic [M3(μ3-O)(COO)6] building blocks was designed herein. The mixed and high-density open metal sites and the OH-functionalized pore surface promote SNNU-65s to exhibit ultra-high C2H2 uptake and separation performance. Impressively, SNNU-65-Cu-Ga stands out for the highest C2H2/CO2 (18.7) and C2H2/CH4 (120.6) selectivity among all the reported MOFs at room temperature. [ABSTRACT FROM AUTHOR]

Reported herein is the new application of ionothermal synthesis for inorganic optical materials. Under ionothermal conditions with different imidazolium ionic liquids, novel quaternary heterometallic frameworks based on [Pb4(OH)4] cubane and [CuCl4] or [CuBr4] chains and [Cu2I6] binuclear clusters have been successfully produced. Simple chlorine, bromine and iodine replacement leads to not only the space group change (tetragonal I41/acd for 1 and 2, and orthorhombic Fddd for 3) but also the topological net transformation (8,12-net for 1 and 2, and 6,6-net for 3). Notably, compounds 1, 2 and 3 all show tunable solid-state semiconducting and luminescence properties. [ABSTRACT FROM AUTHOR]

The synthetic design of new porous open-framework materials with pre-designed pore properties for desired applications such as gas adsorption and separation remains challenging. We proposed one such class of materials, rod metal–organic frameworks (rod MOFs), which can be tuned by using rod secondary building units (rod SBUs) with different geometrical and chemical features. Our approach takes advantage of the readily accessible metal–triazolate 1-D motifs as rod SBUs to combine with dicarboxylate ligands to prepare target rod MOFs. Herein we report three such metal–triazolate–dicarboxylate frameworks (SNNU-21, -22 and -23). During the formation of these three MOFs, Cd or Zn ions are firstly connected by 1,2,4-triazole through the N1,N2,N4-mode to form 1-D metal–organic ribbon-like rod SBUs, which further joint four adjacent rod SBUs via eight BDC linkers to give 3-D microporous frameworks. However, tuned by the different NH2 groups from metal–triazolate rod SBUs, different space groups, pore sizes and shapes are observed for SNNU-21–23. All of these rod MOFs show not only remarkable CO2 uptake capacity, but also high CO2 over CH4 and C2-hydrocarbons over CH4 selectivity under ambient conditions. Specially, SNNU-23 exhibits a very high isosteric heat of adsorption (Qst) for C2H2 (62.2 kJ mol−1), which outperforms the values of all MOF materials reported to date including the famous MOF-74-Co. [ABSTRACT FROM AUTHOR]

Two supramolecular isomeric anionic porous coordination frameworks synthesised using ion liquids contain similar linear trinuclear zinc motifs but exhibit quite different (4,7)- and (4,6)-connected topologies. Isomer 1 can degrade methylene blue (MB) effectively under UV-lightirradiation, but isomer 2 showed remarkable visible-light-driven degradation of diverse organic dyes. [ABSTRACT FROM AUTHOR]

A novel 3D microporous metal–organic framework based on tetrahedral Zn4clusters has been synthesized and characterized, which presents an unprecedented (3,6)-connected (4·62)3(43·66·86) topology, and the capability of selective adsorption of CO2. [ABSTRACT FROM AUTHOR]

The unusual 10-connected self-penetrating metal–organic framework based on sixteen-nuclear hybrid cadmium clusters has been constructed using 1,2,4-triazole, SCN−and F−as coligands, which represents the highest-connected uninodal network topology presently known for self-penetrating systems. [ABSTRACT FROM AUTHOR]

Seven organic-inorganic hybrid solids, namely, [(CdI2)2(L1)2] (1), [(CdBr2)3(L1)2]n(2), [(CdCl2)5(L1)2]n(3), [(CdI2)(L2)]n(4), [(CdBr2)(L3)]n(5), [(CdBr2)2(L4)2]n(6), and [(CdI2)4(L4)4]n(7), have been obtained viathe self-assembly of CdX2(X = Cl, Br or I) with the four structurally related flexible organic ligands 1,2-bis(benzotriazole)ethane (L1), 1,3-bis(benzotriazole)propane (L2), 1,4-bis(benzotriazole)butane (L3) and 1,6-bis(benzotriazole)hexane (L4) under solvothermal conditions. Compound 1presents a binuclear structure with a [Cd2N12C4] 18-membered cycle. In 2, the L1ligands locate alternately on the two sides of the 1-D inorganic chain formed by papilionaceous [Cd2Br2] subunits. The 1-D hexagonal [CdCl2]ngrid inorganic chains in 3are generated by vertex-loss cubane-like [Cd3Cl4] motifs through sharing faces, which are further connected by L1ligands to give a 2-D hybrid layer. For compound 4, the L2ligands and 4-connected Cd centres link each other to give a 1-D single chain. In 5and 6, [Cd2Br4] units are connected by L3and L4to generate a 2-D (4, 4) net and 1-D double chain structure, respectively. Four independent [CdI2] centres and four L4ligands in 7generate an extraordinarily large [Cd4N24C24] 52-membered cycle. The varying structures of 1–7indicate that the spacer length of the bis(benzotriazole)alkane ligands and counter-anions play an essential role in the formation of the framework of the Cd(ii) hybrid materials. Strong π–π stacking interactions between the benzotriazole ligands pack these low-dimensional hybrid chains or layers into high-dimensional supramolecular frameworks. The UV-vis diffuse reflectance spectra and solid state luminescence measurements show that compounds 1–7are potential semiconductor and photoluminescence materials. [ABSTRACT FROM AUTHOR]

The first ionothermal case of the heterometallic iodoplumbate, [CuPb2I2Br(OH)2] (1), was prepared using 1-ethyl-3-methyl imidazolium bromide as a solvent. It exhibits an unprecedented (4,12)-connected topology with [Pb4(OH)4] cubane as the joint points of the helices. [ABSTRACT FROM AUTHOR]

A novel 3D (4,6)-connected topological architecture, obtained under ionothermal conditions by using 1-ethyl-3-methyl imidazolium bromide ([EMI]Br) as solvent and structure-directing agent, presents a non-centrosymmetric polar packing arrangement showing an interesting ferroelectric property. [ABSTRACT FROM AUTHOR]

A porous MOF platform (SNNU-65s) formed by creatively combining paddle-wheel-like [Cu 2 (COO) 4 ] and trigonal prismatic [M 3 (μ 3 -O)(COO) 6 ] building blocks was designed herein. The mixed and high-density open metal sites and the OH-functionalized pore surface promote SNNU-65s to exhibit ultra-high C 2 H 2 uptake and separation performance. Impressively, SNNU-65-Cu-Ga stands out for the highest C 2 H 2 /CO 2 (18.7) and C 2 H 2 /CH 4 (120.6) selectivity among all the reported MOFs at room temperature.

Reported herein is the new application of ionothermal synthesis for inorganic optical materials. Under ionothermal conditions with different imidazolium ionic liquids, novel quaternary heterometallic frameworks based on [Pb 4 (OH) 4 ] cubane and [CuCl 4 ] or [CuBr 4 ] chains and [Cu 2 I 6 ] binuclear clusters have been successfully produced. Simple chlorine, bromine and iodine replacement leads to not only the space group change (tetragonal I41/acd for 1 and 2, and orthorhombic Fddd for 3) but also the topological net transformation (8,12-net for 1 and 2, and 6,6-net for 3). Notably, compounds 1, 2 and 3 all show tunable solid-state semiconducting and luminescence properties.

The synthetic design of new porous open-framework materials with pre-designed pore properties for desired applications such as gas adsorption and separation remains challenging. We proposed one such class of materials, rod metal-organic frameworks (rod MOFs), which can be tuned by using rod secondary building units (rod SBUs) with different geometrical and chemical features. Our approach takes advantage of the readily accessible metal-triazolate 1-D motifs as rod SBUs to combine with dicarboxylate ligands to prepare target rod MOFs. Herein we report three such metal-triazolate-dicarboxylate frameworks (SNNU-21, -22 and -23). During the formation of these three MOFs, Cd or Zn ions are firstly connected by 1,2,4-triazole through the N1,N2,N4-mode to form 1-D metal-organic ribbon-like rod SBUs, which further joint four adjacent rod SBUs via eight BDC linkers to give 3-D microporous frameworks. However, tuned by the different NH 2 groups from metal-triazolate rod SBUs, different space groups, pore sizes and shapes are observed for SNNU-21-23. All of these rod MOFs show not only remarkable CO 2 uptake capacity, but also high CO 2 over CH 4 and C 2 -hydrocarbons over CH 4 selectivity under ambient conditions. Specially, SNNU-23 exhibits a very high isosteric heat of adsorption (Q st ) for C 2 H 2 (62.2 kJ mol -1 ), which outperforms the values of all MOF materials reported to date including the famous MOF-74-Co.