Zinc‐based batteries have a high capacity and are safe, cost‐effective, environmentally‐friendly, and capable of scalable production. However, dendrite formation and poor reversibility hinder their ...performance. Metal‐organic framework (MOF)‐based Zn anodes are made by wet chemistry to address these issues. These MOF‐based anodes exhibit high efficiency during Zn plating‐stripping and prevent dendrite formation, as shown by ex situ SEM analysis. The practicality of the MOF‐based anodes is demonstrated in aqueous Zn ion batteries, which show improved performance including specific capacity, cycle life, and safety relative to the pristine Zn anode due to their hydrophilic and porous surface. These results, along with the easy scalability of the process, demonstrate the high potential of MOF‐modified Zn anodes for use in dendrite‐free, higher‐performance, Zn‐based energy storage systems.
Metal–organic framework (MOF) integrated Zn metal anodes are designed for next‐generation dendrite‐free Zn‐based batteries. These anodes have hydrophilic and porous surfaces that facilitate Zn2+ ion diffusion and the production of a uniform charge distribution. These novel MOF‐integrated Zn anodes outperform existing Zn anodes and have great potential for use in large‐scale energy storage systems.
A covalent triazine framework (CTF) with embedded polymeric sulfur and a high sulfur content of 62 wt % was synthesized under catalyst‐ and solvent‐free reaction conditions from 1,4‐dicyanobenzene ...and elemental sulfur. Our synthetic approach introduces a new way of preparing CTFs under environmentally benign conditions by the direct utilization of elemental sulfur. The homogeneous sulfur distribution is due to the in situ formation of the framework structure, and chemical sulfur impregnation within the micropores of CTF effectively suppresses the dissolution of polysulfides into the electrolyte. Furthermore, the triazine framework facilitates electron and ion transport, which leads to a high‐performance lithium–sulfur battery.
Elemental stabilization: A covalent triazine framework (CTF) with chemically embedded polymeric sulfur (S‐CTF) was synthesized under catalyst‐ and solvent‐free reaction conditions from 1,4‐dicyanobenzene and elemental sulfur. This material was used as a robust cathode for high‐performance lithium–sulfur batteries with very good cycling stabilities.
We present an efficient strategy for the preparation of conjugated microporous polymers incorporating pillar5arenes (P5-CMPs) with surface areas up to 400 m2 g–1 via Pd-catalyzed ...Sonogashira–Hagihara cross-coupling reaction of triflate functionalized pillar5arene with 1,4-diethynylbenzene and 4,4′-diethynyl-1,1′-biphenyl linkers. In an effort to transfer intrinsic properties of pillar5arene, that is its ability to form strong host–guest complexes with linear hydrocarbons in solution, into the solid-state, we investigated the affinity of P5-CMPs toward propane gas. Unlike previously reported porous solids, which showed isosteric heats of adsorption (Q st) for propane in the range of 32.9–36.9 kJ mol–1 at zero coverage and increasing Q st with rising loading due to intermolecular interactions between propane molecules, we observed very high Q st values up to 53 kJ mol–1 at zero coverage, which gradually decreased to ∼35 kJ mol–1 with increasing loadings. This observation indicates strong supramolecular host–guest complexation between propane and pillar5arene via multiple C–H/π interactions, i.e., “macrocyclic effect” arising from the ideal size match of kinetic diameter of propane to the cavity of pillar5arene. This approach also allowed us to introduce thermodynamic selectivity for the separation of saturated hydrocarbons with low polarizability. High affinity of P5-CMPs for propane facilitated its efficient breakthrough separation from a simulated natural gas mixture (methane:propane, 9:1) at 298 K.
We present a new strategy to introduce local-order into amorphous nanoporous polymers using shape-persistent organic cage compounds as molecular building blocks in the synthesis of porous cage ...frameworks (pCAGEs) without any metal catalyst under environmentally benign conditions. We have demonstrated that by varying the size and dimension of the organic linkers extrinsic porosity of organic cages within nanoporous polymers can be controlled, thus allowing us to tune the surface area and gas uptake properties of amorphous pCAGEs. pCAGEs (SABET = 628.7–844.3 m2 g–1) revealed significantly high CO2 uptake capacities (up to 4.21 mmol g–1 at 1 bar, 273 K) with prominent CO2/N2 IAST selectivities (up to 100). Unlike previously reported triazine-based polymers, pCAGEs showed exceptional isosteric heats of adsorption (Q st) values up to 42.9 kJ mol–1 for CO2 at high loading. We attribute the high affinity of CAGE toward CO2 to the presence of a “cage effect” arising from ultramicroporosity (intrinsic porosity) of CAGE monomers. To prove the cage effect, we have synthesized a control polymer incorporating half-CAGEs as monomeric units. The resulting polymer showed substantially lower Q st values compared to the CAGE and pCAGEs indicating the presence of the cage effect. In addition, the control over the surface area in the case of control polymer was lost completely, thus showing the importance of CAGE monomers as building blocks and the resulting local-order.
The synthesis of a new type of redox‐active covalent triazine framework (rCTF) material, which is promising as an anode for Li‐ion batteries, is reported. After activation, it has a capacity up to ...≈1190 mAh g−1 at 0.5C with a current density of 300 mA g−1 and a high cycling stability of over 1000 discharge/charge cycles with a stable Coulombic efficiency in an rCTF/Li half‐cell. This rCTF has a high rate performance, and at a charging rate of 20C with a current density of 12 A g−1 and it functions well for over 1000 discharge/charge cycles with a reversible capacity of over 500 mAh g−1. By electrochemical analysis and theoretical calculations, it is found that its lithium‐storage mechanism involves multi‐electron redox‐reactions at anthraquinone, triazine, and benzene rings by the accommodation of Li. The structural features and progressively increased structural disorder of the rCTF increase the kinetics of infiltration and significantly shortens the activation period, yielding fast‐charging Li‐ion half and full cells even at a high capacity loading.
A redox‐active covalent triazine framework is used as an anode material for lithium‐ion batteries. The progressive structural deformation through activation provides a larger number of accessible active Li‐storage sites and efficient Li‐ion/electron diffusion, which gives a high specific capacity (≈1190 mAh g−1 over 1500 charge/discharge cycles) and a rate performance of over 500 mAh g−1 at 20C rate.
1,3,5,7-Tetramethyl-Bodipy derivatives undergo Knoevenagel-type condensations with aromatic aldehydes to ultimately yield tetrastyryl-Bodipy derivatives. The resulting dyes absorb and emit strongly ...in the near IR. As the versatility of the Bodipy dyes are fully appreciated, these new tetrastyryl dyes are likely to be featured in a variety of functional supramolecular systems.
We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza14annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N ...= nitrogen) compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10–10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-doped NiTAA-MOF synthesized in this work could find potential applications in areas such as catalase mimics, catalysis, energy storage, and dynamic nuclear polarization-nuclear magnetic resonance (DNP-NMR).
Remarkably versatile chemistry of Bodipy dyes allows the design and straightforward synthesis of multivalent-multitopic derivatives, which, with judicious selection of metal ion−ligand pairs based on ...known affinities, affords control and manipulation of photoinduced electron transfer and internal charge transfer processes as desired. We have demonstrated that metal ions acting as modulators (or inputs, in digital design parlance) can generate absorbance changes in accordance with the operation of a half-adder. In addition, an AND logic gate in the emission mode was delivered using a different binucleating arrangement of ligands. A molecular equivalent of a three-input AND logic gate was also obtained exploiting differential binding affinities of metal ions for different ligands. The results suggest that different metal ions can be used as nonannihilating inputs, selectively targeting various ligands incorporated within a single fluorophore, and with careful design, diverse photophysical processes can be selectively modulated, resulting in a range of signals, useful in molecular logic design, and offering an enticing potential for multianalyte chemosensors.
Two Bodipy derivatives with silyl-protected phenolic functionalities signal fluoride concentrations both in solution and in a poly(methyl methacrylate) matrix. The exact location of the “nascent” ...phenolate group is important. If it is at the meso position, photoinduced electron transfer is triggered; however, if it is in full conjugation via a styryl moiety to the Bodipy core, strong intramolecular charge transfer is triggered, resulting in a large red shift in the absorbance peak. In either case, a selective methodology for fluoride sensing is the invariable result.
Cu complexes as photosensitizers: Photoinduced charge‐transfer dynamics from a copper(I) diimine complex to TiO2 nanoparticles were investigated by combining multiple time‐resolved spectroscopic ...methods. An efficient and ultrafast electron transfer process from the singlet MLCT state was discovered as a result of structural control owing to the flattening of the tetrahedral geometry in the complex and the bulky groups in the ligands.
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