02868nas a2200265 4500008004100000022001400041245015400055210006900209260000900278300001600287490000700303520188300310653002502193653003102218653003002249653002802279653002502307100002602332700002202358700002102380700002102401700002802422700003002450856012202480 2019 eng d a1944-824400aCu/Cu2O nanoparticles supported on a phenol-pyridyl COF as a heterogeneous catalyst for the synthesis of unsymmetrical diynes via glaser-hay coupling0 aCuCu2O nanoparticles supported on a phenolpyridyl COF as a heter cMAY  a15670-156790 v113 a

Covalent organic frameworks (COFs) are a new class of porous crystalline polymers with a modular construct that favors fiinctionalization. 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 (similar to 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: similar to 4S-50; turn over number: similar to 17S-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.

10aCopper nanoparticles10aCovalent organic framework10aGlaser-Hay heterocoupling10aheterogeneous catalysis10aunsymmetrical diynes1 aChakraborty, Debanjan1 aNandi, Shyamapada1 aMullangi, Dinesh1 aHaldar, Sattwick1 aVinod, Chathakudath, P.1 aVaidhyanathan, Ramanathan uhttps://library.ncl.res.in/content/cucu2o-nanoparticles-supported-phenol-pyridyl-cof-heterogeneous-catalyst-synthesis02285nas a2200313 4500008004100000022001400041245011700055210006900172260000900241300001400250490000600264520120100270653002701471653003101498653002701529653002801556653001901584653001901603100002001622700002901642700002101671700002601692700002101718700001801739700002801757700002501785700003001810856013101840 2020 eng d a2574-097000aNanoporous covalent organic framework embedded with Fe/Fe3O4 nanoparticles as air-stable low-density nanomagnets0 aNanoporous covalent organic framework embedded with FeFe3O4 nano cSEP  a9088-90960 v33 a

Covalent organic frameworks (COFs) made of light atoms such as H, C, N, and O with a significant void-to-framework ratio are excellent low-density supports for nanoparticles (nPs). Their framework can be precoded with heteroatoms to ensure binding with metallic nanoclusters. With these advantages, if controlled amounts of magnetic nPs are anchored to them, they can yield low-density organic-inorganic nanomagnets. Their organic nature facilitates fusion with bulk materials such as paper/textile to enable bulk composites with well-dispersed low-density magnets, which have potential for defense and next-generation aviation applications. Herein, we have grown small Fe/Fe3O4 nPs (5-18 wt %) inside a COF. Interestingly, 300 mg of this organic-inorganic framework material (containing 50 mg of nPs) can lift a vial of similar to 15,000 mg (300 times heavier). Also, the hydrophobic COF wraps around the Fe/Fe3O4 nanocluster retaining its room-temperature magnetic character even after 1 year, while the naked nPs lose it within a few days because of air oxidation. Bulk composites with paper and polymers have been made using this low-density Fe-COF to demonstrate their processability.

10aair-stable nanomagnets10aCovalent organic framework10aFe/Fe3O4 nanoparticles10alow-density nanomagnets10amagnetic rayon10ananoporous COF1 aKushwaha, Rinku1 aKaleeswaran, Dhananjayan1 aHaldar, Sattwick1 aChakraborty, Debanjan1 aMullangi, Dinesh1 aBorah, Aditya1 aVinod, Chathakudath, P.1 aMurugavel, Ramaswamy1 aVaidhyanathan, Ramanathan uhttps://library.ncl.res.in/content/nanoporous-covalent-organic-framework-embedded-fefe3o4-nanoparticles-air-stable-low-density02844nas a2200301 4500008004100000245017400041210006900215260000900284300001400293490000600307520174100313653001202054653001402066653003102080653002802111653001802139653002402157100003702181700002002218700001802238700002202256700002202278700002602300700003602326700003002362700001802392856013202410 2022 eng d00aSynergistic electronic effects in AuCo nanoparticles stabilized in a triazine-based covalent organic framework: a catalyst for methyl orange and methylene blue reduction0 aSynergistic electronic effects in AuCo nanoparticles stabilized  cAPR  a4744-47530 v53 a

Developing stable active catalysts for reducing water-soluble pollutants is a desirable target. In this pursuit, we have functionalized covalent organic frameworks (COFs) with gold (Au) and cobalt (Co) nanoparticles via a one-step aqueous synthesis process, and their catalytic activity in reducing methyl orange and methylene blue is examined. Operando absorbance measurements of methyl orange (anionic dye) reduction revealed AuCoCOF (1.3 Au/1.0 Co) to have superior kinetics over many other catalysts, which typically require additional external stimuli (e.g., photons) and higher catalyst loadings. After confirming the homogeneous dispersion of the nanoparticles on the COF support using three-dimensional (3D) tomography and material stability through powder X-ray diffraction (PXRD), infrared (IR), and thermal studies, we investigated their redox activity. Cyclic voltammetry (CV) confirmed the involvement of both metals in the redox process, while spectroelectrochemical measurements show that their activity and kinetics remain unaltered by an applied potential. Solid-state UV measurements reveal that the neat COF is a semiconductor with a large band gap (2.8 eV), which is substantially lowered when loaded with cobalt nanoparticles (2.2 eV for CoCOF). The electronic synergy between Au and Co nanoparticles further reduces the band gap of AuCoCOF (1.9 eV). Thus, there is a definite advantage in doping non-noble metal nanoparticles into a noble metal lattice and nanoconfining them into a porous COF support. Our study highlights the significance of bimetallic COF-supported nanocatalysts, wherein one can engage each component toward targeted applications that demand redox activity with favorable kinetics.

10aAuCoCOF10aband gaps10aCovalent organic framework10amethyl orange reduction10aNanoparticles10aUV-vis spectroscopy1 aDevulapalli, Venkata, Swaroopa D1 aKushwaha, Rinku1 aOvalle, Edwin1 aSingh, Himan, Dev1 aShekhar, Pragalbh1 aChakraborty, Debanjan1 aVinod, Chathakudath, Prabhakara1 aVaidhyanathan, Ramanathan1 aBorguet, Eric uhttps://library.ncl.res.in/content/synergistic-electronic-effects-auco-nanoparticles-stabilized-triazine-based-covalent-organic