Energy band-gap engineering of conjugated microporous polymers via acidity-dependent in situ cyclization

Conjugated microporous polymers (CMPs) offer a unique structure integrating π- conjugated backbone into a porous network for the simultaneous transport of charges and materials. However, tuning electronic properties of CMPs so far has been limited to an approach of varying the monomers, and the precious metal catalysts are inevitably needed for the C–C coupling reaction. Here, we present a powerful strategy to synthesize CMPs and precisely tune their optical band gap and surface area through metal-free in situ cyclization reaction controlled by the acid strength of acid catalysts. Notably, the optical band gap of CMPs showed a linear relationship with the pKa of acid catalysts, which provides us with the ability to obtain the desired band gap between 2.07 and 3.35 eV, falling in the range of the visible solar spectrum. Moreover, CMPs exhibited excellent textural properties such as microporosity and high specific surface area

Bimetallic metal organic frameworks with precisely positioned metal centers for efficient H2 storage

We demonstrated that the ratio and position of two different metal ions, Pd and Cu, can be precisely controlled within MOFs through predesigned metal clusters. These MOF structures incorporating Pd–Cu paddle wheel units were synthesised simply by reacting Pd–Cu acetate metal clusters and tritopic organic linkers at room temperature. Pd–Cu open metal sites were found to be uniformly distributed throughout the MOFs with a ca. 1 : 1 ratio. The incorporation of Pd into the MOF structure also led to enhanced affinity towards H2 with Qst values up to 8.9 kJ mol−1

A general approach to composites containing nonmetallic fillers and liquid gallium

We report a versatile method to make liquid metal composites by vigorously mixing gallium (Ga) with non-metallic particles of graphene oxide (G-O), graphite, diamond, and silicon carbide that display either paste or putty-like behavior depending on the volume fraction. Unlike Ga, the putty-like mixtures can be kneaded and rolled on any surface without leaving residue. By changing temperature, these materials can be stiffened, softened, and, for the G-O-containing composite, even made porous. The gallium putty (GalP) containing reduced G-O (rG-O) has excellent electromagnetic interference shielding effectiveness. GalP with diamond filler has excellent thermal conductivity and heat transfer superior to a commercial liquid metal-based thermal paste. Composites can also be formed from eutectic alloys of Ga including Ga-In (EGaIn), Ga-Sn (EGaSn), and Ga-In-Sn (EGaInSn or Galinstan). The versatility of our approach allows a variety of fillers to be incorporated in liquid metals, potentially allowing filler-specific "fit for purpose" materials

Novel Molecular Building Blocks Based on the Boradiazaindacene Chromophore: Applications in Fluorescent Metallosupramolecular Coordination Polymers

We designed and synthesized novel boradiazaindacene (Bodipy) derivatives that are appropriately functionalized for metal-ion-mediated supramolecular polymerization. Thus, ligands for 2-terpyridyl-, 2,6-terpyridyl-. and bipyridyl-functionalized Bodipy dyes were synthesized through Sonogashira couplings. These fluorescent building blocks are responsive to metal ions in a stoichiometry-dependent manner. Octahedral coordinating metal ions such as Zn-II result in polymerization at a stoichiometry corresponding to two terpyridyl ligands to one Zn-II ion. However, at increased metal ion concentrations, the dynamic equilibria are re-established in such a way that the monomeric metal complex dominates. The position of equilibria can easily be monitored by H-1 NMR and fluorescence spectroscopies. As expected, although open-shell Fe-II ions form similar complex structures, these cations quench the fluorescence emission of all four functionalized Bodipy ligands

Thinking Outside the Cage: Controlling the Extrinsic Porosity and Gas Uptake Properties of Shape-Persistent Molecular Cages in Nanoporous Polymers

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 (SA_BET = 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 (<i>Q</i>_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 <i>Q</i>_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

Metal-Organic Framework Integrated Anodes for Aqueous Zinc-Ion Batteries

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

Autonomous Shuttling Driven by an Oscillating Reaction: Proof of Principle in a Cucurbit[7]uril-Bodipy Pseudorotaxane

A bipyridinium dication-substituted Bodipy fluorophore, with a terminal carboxylic acid function, provides two alternative stations for cucurbit[7]uril. Changing pH from basic to acidic results in shuttling of the cucurbit[7]uril from one station to another. In addition, this shuttling is accompanied by a change in the emissive properties of the Bodipy dye, which is only observed in the presence of cucurbit[7]uril. More striking, is a demonstration of autonomous shuttling of the pseudorotaxane system in an oscillating pH system

Tetrastyryl-BODIPY-Based Dendritic Light Harvester and Estimation of Energy Transfer Efficiency

Versatile BODIPY dyes can be transformed into bright near-IR-emitting fluorophores by quadruple styryl substitutions. When clickable functionalities on the styryl moieties are inserted, an efficient synthesis of a light harvester is possible. In addition, clear spectral evidence is presented showing that, in dendritic light harvesters, calculations commonly based on quantum yield or emission lifetime changes of the donor are bound to yield large overestimations of energy transfer efficiency

Synthesis of Porous Covalent Quinazoline Networks (CQNs) and Their Gas Sorption Properties

The development of different classes of porous polymers by linking organic molecules using new chemistries still remains a great challenge. Herein, we introduce for the first time the synthesis of covalent quinazoline networks (CQNs) using an ionothermal synthesis protocol. Zinc chloride (ZnCl2) was used as the solvent and catalyst for the condensation of aromatic ortho-aminonitriles to produce tricycloquinazoline linkages. The resulting CQNs show a high porosity with a surface area up to 1870 m2 g&amp;#8722;1. Varying the temperature and the amount of catalyst enables us to control the surface area as well as the pore size distribution of the CQNs. Furthermore, their high nitrogen content and significant microporosity make them a promising CO2 adsorbent with a CO2 uptake capacity of 7.16 mmol g&amp;#8722;1 (31.5 wt %) at 273 K and 1 bar. Because of their exceptional CO2 sorption properties, they are promising candidates as an adsorbent for the selective capture of CO2 from flue gas

Autonomous Shuttling Driven by an Oscillating Reaction: Proof of Principle in a Cucurbit[7]uril-Bodipy Pseudorotaxane

A bipyridinium dication-substituted Bodipy fluorophore, with a terminal carboxylic acid function, provides two alternative stations for cucurbit[7]uril. Changing pH from basic to acidic results in shuttling of the cucurbit[7]uril from one station to another. In addition, this shuttling is accompanied by a change in the emissive properties of the Bodipy dye, which is only observed in the presence of cucurbit[7]uril. More striking, is a demonstration of autonomous shuttling of the pseudorotaxane system in an oscillating pH system