Simultaneous implementation of resistive switching and rectifying effects in a metal-organic framework with switched hydrogen bond pathway

Resistive random-access memory (RRAM) has evolved as one of the most promising candidates for the next-generation memory, but bistability for information storage, simultaneous implementation of resistive switching and rectification effects, and a better understanding of switching mechanism are still challenging in this field. Herein, we report a RRAM device based on a chiral metal-organic framework (MOF) FJU-23-H2O with switched hydrogen bond pathway within its channels, exhibiting an ultralow set voltage (~0.2 V), a high ON/OFF ratio (~105), and a high rectification ratio (~105). It is not only the first MOF with voltage-gated proton conduction but also the first single material showing both rectifying and resistive switching effects. By single-crystal x-ray diffraction analyses, the mechanism of the resistive switching has been demonstrated.Published versio

Extraordinary separation of acetylene-containing mixtures with microporous metal-organic frameworks with open O donor sites and tunable robustness through control of the helical chain secondary building units

Acetylene separation is a very important but challenging industrial separation task. Here, through the solvothermal reaction of CuI and 5-triazole isophthalic acid in different solvents, two metal–organic frameworks (MOFs, FJU-21 and FJU-22) with open O donor sites and controllable robustness have been obtained for acetylene separation. They contain the same paddle-wheel {Cu₂(COO₂)₄} nodes and metal–ligand connection modes, but with different helical chains as Secondary Building Units (SBUs), leading to different structural robustness for the MOFs. FJU-21 and FJU-22 are the first examples in which the MOFs’ robustness is controlled by adjusting the helical chain SBUs. Good robustness gives the activated FJU-22 a, which has higher surface area and gas uptakes than the flexible FJU-21 a. Importantly, FJU-22 a shows extraordinary separation of acetylene mixtures under ambient conditions. The separation capacity of FJU-22 a for 50:50 C₂H₂/CO₂ mixtures is about twice that of the high-capacity HOF-3 and its actual separation selectivity for C₂H₂/C₂H₄ mixtures containing 1% acetylene is the highest among reported porous materials. Based on first-principles calculations, the extraordinary separation performance of C₂H₂ for FJU-22 a was attributed to hydrogen-bonding interactions between the C₂H₂ molecules with the open O donors on the wall, which provide better recognition ability for C₂H₂ than other functional sites, including open metal sites and amino groups

Multistate structures in a hydrogen-bonded polycatenation non-covalent organic framework with diverse resistive switching behaviors

Abstract The inherent structural flexibility and reversibility of non-covalent organic frameworks have enabled them to exhibit switchable multistate structures under external stimuli, providing great potential in the field of resistive switching (RS), but not well explored yet. Herein, we report the 0D+1D hydrogen-bonded polycatenation non-covalent organic framework (HOF-FJU-52), exhibiting diverse and reversible RS behaviors with the high performance. Triggered by the external stimulus of electrical field E at room temperature, HOF-FJU-52 has excellent resistive random-access memory (RRAM) behaviors, comparable to the state-of-the-art materials. When cooling down below 200 K, it was transferred to write-once-read-many-times memory (WORM) behaviors. The two memory behaviors exhibit reversibility on a single crystal device through the temperature changes. The RS mechanism of this non-covalent organic framework has been deciphered at the atomic level by the detailed single-crystal X-ray diffraction analyses, demonstrating that the structural dual-flexibility both in the asymmetric hydrogen bonded dimers within the 0D loops and in the infinite π–π stacking column between the loops and chains contribute to reversible structure transformations between multi-states and thus to its dual RS behaviors

Rhodium-Catalyzed NH-Indole-Directed C–H Carbonylation with Carbon Monoxide: Synthesis of 6<i>H</i>‑Isoindolo[2,1‑<i>a</i>]indol-6-ones

An efficient synthesis of 6<i>H</i>-isoindolo­[2,1-<i>a</i>]­indol-6-ones through rhodium-catalyzed NH-indole-directed C–H carbonylation of 2-arylindoles with carbon monoxide has been developed. Preliminary mechanistic studies revealed that this reaction proceeds via N–H bond cleavage and subsequent C–H bond cleavage. Reaction monitoring via ESI-MS was used to support the formation of five-membered rhodacycle species in the catalytic cycle

A Flexible Microporous Hydrogen-Bonded Organic Framework for Gas Sorption and Separation

A microporous three-dimensional hydrogen-bonded organic framework (HOF-5) has been constructed from a new organic linker 4,4′,4″,4‴-tetra­(2,4-diamino-1,3,5-triazin-6-yl)­tetraphenylethene. Activated HOF-5a exhibits a stepwise N₂ adsorption isotherm at 77 K, suggesting framework flexibility. The structure of activated HOF-5a has been established by powder X-ray diffraction studies, indicating a significant framework contraction from as-synthesized HOF-5 to activated HOF-5a of ∼21% by volume. HOF-5a shows moderately high porosity with a Brunauer–Emmett–Teller (BET) surface area of 1101 m²/g, and takes up a large amount of acetylene and carbon dioxide under ambient conditions. Powder neutron diffraction studies and theoretical calculations reveal that suitable pore sizes, curvatures, and functional sites collectively enable HOF-5a to encapsulate a high density of carbon dioxide molecules packed in a pseudo-one-dimensional array along the pore channel

CCDC 1421052: Experimental Crystal Structure Determination

OLUGUZ : catena-[(μ-5-(4H-1,2,4-triazol-4-yl)isophthalato)-copper N,N-dimethylacetamide solvate sesquihydrate] Space Group: P b c n (60), Cell: a 12.1311(5)Å b 14.5924(7)Å c 20.4168(10)Å, α 90° β 90° γ 90° Related Article: Zizhu Yao, Zhangjing Zhang, Lizhen Liu, Ziyin Li, Wei Zhou, Yunfeng Zhao, Yu Han, Banglin Chen, Rajamani Krishna, Shengchang Xiang|2016|Chem.-Eur.J.|22|5676|doi:10.1002/chem.201505107,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 1421054: Experimental Crystal Structure Determination

OLUHAG : catena-[(μ-5-(4H-1,2,4-triazol-4-yl)isophthalato)-copper N,N-dimethylformamide solvate sesquihydrate] Space Group: P 21/c (14), Cell: a 10.9121(3)Å b 11.8420(3)Å c 14.5557(5)Å, α 90° β 109.471(3)° γ 90° Related Article: Zizhu Yao, Zhangjing Zhang, Lizhen Liu, Ziyin Li, Wei Zhou, Yunfeng Zhao, Yu Han, Banglin Chen, Rajamani Krishna, Shengchang Xiang|2016|Chem.-Eur.J.|22|5676|doi:10.1002/chem.201505107,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

40-Fold Enhanced Intrinsic Proton Conductivity in Coordination Polymers with the Same Proton-Conducting Pathway by Tuning Metal Cation Nodes

Three isostructural imidazole-cation-templated metal phosphates (<b>FJU-25</b>) are the first examples to demonstrate that the tuning of metal cation nodes can be an efficient strategy to significantly improve the proton conductivity without changing the structure of the proton-conducting pathway