aromatic groups, which via columnar π-π stacking order into a periodic 3D structure (Scheme S1, Supporting Information). Their modular construct and ordered porosity makes them find use in diverse applications Here we are seeking application of 2D COFs in metal-ion batteries, which are typically made of electrodes with layered structures, for example, graphite as anode and LiCoO 2 as cathode. Owing to their graphite resembling structure, COF can serve as anode. Since their initial discovery, many 2D materials with comparable layered structures have been explored as lithium insertion-deinsertion materials. [28][29][30][31][32][33][34][35][36][37][38][39] Some of the highly desirable characteristics of a superior anode material include moderate to high surface accessibility to ensure maximum charge storage per unit area, and the other is the hierarchical porosity for favorable kinetics. Exfoliation enhances surface accessibility and active site creation in such 2D materials. [40][41][42][43][44][45][46][47][48] In this regard, COFs could have much more to offer. [49][50][51] Exfoliation in any 2D material is largely dependent on the interlayer forces holding them. Typically, the COF layers are held together by interlayer π-π interactions or in some cases via additional hydrogen bonding. [52,53] However, unlike graphite, the layers of COF are not built from fused aromatic rings. In their optimized Covalent organic framework (COF) can grow into self-exfoliated nanosheets. Their graphene/graphite resembling microtexture and nanostructure suits electrochemical applications. Here, covalent organic nanosheets (CON) with nanopores lined with triazole and phloroglucinol units, neither of which binds lithium strongly, and its potential as an anode in Li-ion battery are presented. Their fibrous texture enables facile amalgamation as a coin-cell anode, which exhibits exceptionally high specific capacity of ≈720 mA h g −1 (@100 mA g −1 ). Its capacity is retained even after 1000 cycles. Increasing the current density from 100 mA g −1 to 1 A g −1 causes the specific capacity to drop only by 20%, which is the lowest among all high-performing anodic COFs. The majority of the lithium insertion follows an ultrafast diffusion-controlled intercalation (diffusion coefficient, D Li + = 5.48 × 10 −11 cm 2 s −1 ). The absence of strong Liframework bonds in the density functional theory (DFT) optimized structure supports this reversible intercalation. The discrete monomer of the CON shows a specific capacity of only 140 mA h g −1 @50 mA g −1 and no sign of lithium intercalation reveals the crucial role played by the polymeric structure of the CON in this intercalation-assisted conductivity. The potentials mapped using DFT suggest a substantial electronic driving-force for the lithium intercalation. The findings underscore the potential of the designer CON as anode material for Li-ion batteries. Lithium Storage

The ordered modular structure of a covalent organic framework (COF) facilitates the selective incorporation of electronically active segments that can be tuned to function cooperatively. This designability inspires developing COFbased single-source white light emitters, required in nextgeneration solid-state lighting. Here, we present a new anthracene-resorcinol-based COF exhibiting white light emission. The keto−enol tautomers present in the COF give rise to dual emission, which can be tuned by the O-donor and Ndonor solvents. Importantly, when suspended in a solid polymer matrix, this dual emission is retained as both tautomers coexist. A mere 0.32 wt % loading of the COF in poly(methyl methacrylate) (PMMA) gives a solvent-free film with intense white light emission (CIE coordinates (0.35, 0.36)). From steady-state and time-resolved studies, the mechanism of the white light emission has been unambiguously assigned to fluorescence, with the blue emission originating from the π-stacked columns of anthracene, and the mixture of red and green from the keto−enol tautomerized resorcinol units. The study introduces the COF as a new class of readily processable, single-source white light emitter.

Metal-organic frameworks (MOFs) have attracted significant attention as solid sorbents in gas separation processes for low-energy postcombustion CO capture. The parasitic energy (PE) has been put forward as a holistic parameter that measures how energy efficient (and therefore cost-effective) the CO capture process will be using the material. In this work, we present a nickel isonicotinate based ultramicroporous MOF, 1 [Ni-(4PyC)·DMF], that has the lowest PE for postcombustion CO capture reported to date. We calculate a PE of 655 kJ/kg CO, which is lower than that of the best performing material previously reported, Mg-MOF-74. Further, 1 exhibits exceptional hydrolytic stability with the CO adsorption isotherm being unchanged following 7 days of steam-treatment (>85% RH) or 6 months of exposure to the atmosphere. The diffusion coefficient of CO in 1 is also 2 orders of magnitude higher than in zeolites currently used in industrial scrubbers. Breakthrough experiments show that 1 only loses 7% of its maximum CO capacity under humid conditions.

Ordered nanoporosity in covalent organic framework (COF) offers excellent opportunity for property development. Loading nanoparticles (nPs) onto them is one approach to introducing tailor-made properties into a COF. Here, a COF-Co/Co(OH) composite containing about 16 wt% of <6 nm sized Co/Co(OH) nPs is prepared on a N-rich COF support that catalyzes the release of theoretical equivalence of H from readily available, safe, and cheap NaBH . Furthermore, the released H is utilized for the hydrogenation of nitrile and nitro compounds to amines under ambient conditions in a facile one-pot reaction. The COF "by choice" is built from "methoxy" functionalized dialdehydes which is crucial in enabling the complete retention of the COF structure under the conditions of the catalysis, where the regular Schiff bonds would have hydrolyzed. The N-rich binding pockets in the COF ensure strong nP-COF interactions, which provides stability and enables catalyst recycling. Modeling studies reveal the crucial role played by the COF in exposing the active facets and thereby in controlling the activation of the reducing agent. Additionally, via density functional theory, we provide a rational explanation for how these COFs can stabilize nanoparticles which grow beyond the limiting pore size of the COF and yet result in a truly stable heterogeneous catalyst - a ubiquitous observation. The study underscores the versatility of COF as a heterogeneous support for developing cheap and highly active nonnoble metal catalysts.

Covalent organic frameworks (COFs) are a new class of porous crystalline polymers with a modular construct that favors functionalization. COF pores can be used to grow nanoparticles (nPs) with dramatic size reduction, stabilize them as dispersions, and provide excellent nP access. Embedding substrate binding sites in COFs can generate host–guest synergy, leading to enhanced catalytic activity. In this report, Cu/Cu2O nPs (2–3 nm) are grown on a COF, which is built by linking a phenolic trialdehyde and a triamine through Schiff bonds. Their micropores restrict the nP to exceptionally small sizes (∼2–3 nm), and the pore walls decorated with strategically positioned hydrogen-bonding phenolic groups anchor the substrates via hydrogen-bonding, whereas the basic pyridyl sites serve as cationic species to stabilize the [CuclusterCl2]2– type reactive intermediates. This composite catalyst shows high activity for Glaser–Hay heterocoupling reactions, an essential 1,3-diyne yielding reaction with widespread applicability in organic synthesis and material science. Despite their broad successes in homocoupled products, preparation of unsymmetrical 1,3-diynes is challenging due to poor selectivity. Here, our COF-based Cu catalyst shows elevated selectivity toward heterocoupling product(s) (Cu nP loading 0.0992 mol %; turn over frequency: ∼45–50; turn over number: ∼175–190). The reversible redox activity at the Cu centers has been demonstrated by carrying out X-ray photoelectron spectroscopy on the frozen reactions, whereas the crucial interactions between the substrates and the binding sites in their optimized configurations have been modeled using density functional theory methods. This report emphasizes the utility of COFs in developing a heterogeneous catalyst for a truly challenging organic heterocoupling reaction.

Permanent porosity has been realized in a hydrogen bonded framework formed by a single tripodal tricarboxylic acid molecule. The presence of three phenyl rings linked to a flexible sp(3) nitrogen centre renders a near-propeller shape to the molecule generating an unusual 'non-planar' 3-D framework formed by highly directional planar -COOHHOOC- hydrogen bonds, propagating in all three directions. The material shows exceptional hydrolytic, acidic and thermal stability and has a surface area of 1025 m(2) g(-1). Importantly, it shows preferential adsorption of CO2 over N2 with very high selectivities (350 : 1@1 bar, 303 K). DFT modeling shows the presence of stable T-shaped CO2CO2 dimers within the channels suggesting favorable co-operativity between them.

Fe 2+ is vital to O 2 transportation and photosynthesis regulated by oxidases and reductases. On the other hand, Fe 3+ is detrimental due to its irreversible binding to O 2 . Hence there is a need for selective identification of Fe 3+ from aqueous systems in the presence of Fe 2+ . However, given their close chemical nature, it is not straightforward to differentiate them. Fe 2+ and Fe 3+ are typically sensed and differentiated using magnetic measurements, Mossbauer, X-ray absorption spectroscopy, or EXAFS, which are complex and equipment intensive techniques. In comparison, the fluorescence technique is advantageous in terms of time and accessibility. Although readily available lanthanide salts exhibit fluorescence, they are weak, and to serve as an optical probe, their luminescence has to be enhanced via ligand design. Hence we have designed a chromophoric ligand that can covalently bind to lanthanides and enhance its fluorescence intensity, and it binds selectively to Fe 3+ through its nitrogen centers. It detects Fe 3+ from low concentration (∼100 μM) aqueous solutions, with fast response time (<1 min) and with a detection limit of 3.6 ppm. Importantly, the Fe 3+ adsorbed MOF can be readily reactivated for the next cycle by merely washing with an aqueous ascorbic acid solution and can be used for multiple cycles without any appreciable loss in activity. This makes the Ln-MOF an environmentally benign, cost-effective, scalable, and recyclable probe.

Isostructural azolyl-carboxylate MOFs with acetate modulators giving rise to nitrogen-rich pores lined with methyl groups favor high CO2 capacity via CO2⋯CO2 interactions and provide high stability towards humidity.