02242nas a2200241 4500008004100000022001400041245012400055210006900179260007100248300001600319490000800335520133000343100001901673700002401692700002301716700001801739700002501757700002801782700002501810700001801835700002001853856012701873 2013 eng d a0002-786300aChemically stable multilayered covalent organic nanosheets from covalent organic frameworks via mechanical delamination0 aChemically stable multilayered covalent organic nanosheets from  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV a17853-178610 v1353 a

A series of five thermally and chemically stable functionalized covalent organic frameworks (COFs), namely, TpPa-NO2, TpPa-F-4, TpBD-(NO2)(2), TpBD-Me-2, and TpBD-(OMe)(2) were synthesized by employing the solvothermal aldehyde-amine Schiff base condensation reaction. In order to complete the series, previously reported TpPa-1, TpPa-2, and TpBD have also been synthesized, and altogether, eight COFs were fully characterized through powder X-ray diffraction (PXRD), Fourier transform IR (FT-IR) spectroscopy, C-13 solid-state NMR spectroscopy, and thermogravimetric analysis. These COFs are crystalline, permanently porous, and stable in boiling water, acid (9 N HCl), and base (3 N NaOH). The. synthesized COFs (all eight) were successfully delaminated using a simple, safe, and environmentally friendly mechanical grinding route to transform into covalent organic nanosheets (CONs) and were well characterized via transmission electron microscopy and atomic force microscopy. Further PXRD and FT-IR analyses confirm that these CONs retain their structural integrity throughout the delamination process and also remain stable in aqueous, acidic, and basic media like the parent COFs. These exfoliated CONs have graphene-like layered morphology (delaminated layers), unlike the COFs from which they were synthesized.

1 aChandra, Suman1 aKandambeth, Sharath1 aBiswal, Bishnu, P.1 aLukose, Binit1 aKunjir, Shrikant, M.1 aChaudhary, Minakshi, V.1 aBabaRao, Ravichandar1 aHeine, Thomas1 aBanerjee, Rahul uhttp://library.ncl.res.in/content/chemically-stable-multilayered-covalent-organic-nanosheets-covalent-organic-frameworks-001914nas a2200241 4500008004100000022001400041245007500055210006900130260011000199300001400309490000600323520105000329100001701379700002301396700002401419700001801443700002001461700002601481700001801507700001901525700002001544856010801564 2015 eng d a2041-652000aChemical sensing in two dimensional porous covalent organic nanosheets0 aChemical sensing in two dimensional porous covalent organic nano aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAPR a3931-39390 v63 a

Two new imide-based crystalline, porous, and chemically stable covalent organic frameworks (COFs) (TpBDH and TfpBDH) have been successfully synthesized employing solvothermal crystallization route. Furthermore, thin layered covalent organic nanosheets (CONs) were derived from these bulk COFs by the simple liquid phase exfoliation method. These 2D CONs showcase increased luminescence intensity compared to their bulk counterparts (COFs). Notably, TfpBDH-CONs showcase good selectivity and prominent, direct visual detection towards different nitroaromatic analytes over TpBDH-CONs. Quite interestingly, TfpBDH-CONs exhibit a superior ``turn-on'' detection capability for 2,4,6-trinitrophenol (TNP) in the solid state, but conversely, they also show a ``turn-off'' detection in the dispersion state. These findings describe a new approach towards developing an efficient, promising fluorescence chemosensor material for both visual and spectroscopic detection of nitroaromatic compounds with very low [10(-5) (M)] analyte concentrations.

1 aDas, Gobinda1 aBiswal, Bishnu, P.1 aKandambeth, Sharath1 aVenkatesh, V.1 aKaur, Gagandeep1 aAddicoat, Matthew, A.1 aHeine, Thomas1 aVerma, Sandeep1 aBanerjee, Rahul uhttp://library.ncl.res.in/content/chemical-sensing-two-dimensional-porous-covalent-organic-nanosheets-001492nas a2200217 4500008004100000245007900041210006900120260000800189300001600197490000700213520077400220100001800994700002401012700001901036700002101055700001501076700002501091700002501116700002001141856011301161 2016 eng d00aChemically delaminated free-standing ultrathin covalent organic nanosheets0 aChemically delaminated freestanding ultrathin covalent organic n cDEC a15604-156080 v553 aCovalent organic nanosheets (CONs) are a new class of porous thin two-dimensional (2D) nanostructures that can be easily designed and functionalized and could be useful for separation applications. Poor dispersion, layer restacking, and difficult postsynthetic modifications are the major hurdles that need to be overcome to fabricate scalable CON thin films. Herein, we present a unique approach for the chemical exfoliation of an anthracene-based covalent organic framework (COF) to N-hexylmaleimide-functionalized CONs, to yield centimeter-sized free-standing thin films through layer-by-layer CON assembly at the air-water interface. The thinlayer fabrication technique presented here is simple, scalable, and does not require any surfactants or stabilizing agents.1 aKhayum, Abdul1 aKandambeth, Sharath1 aMitra, Shouvik1 aNair, Sanoop, B.1 aDas, Anuja1 aNagane, Samadhan, S.1 aMukherjee, Rabibrata1 aBanerjee, Rahul uhttp://library.ncl.res.in/content/chemically-delaminated-free-standing-ultrathin-covalent-organic-nanosheets01625nas a2200217 4500008004100000245008300041210006900124260000800193300001200201490000600213520088800219100001901107700003101126700002301157700002401180700002301204700002901227700002101256700002001277856011001297 2016 eng d00aConstructing covalent organic frameworks in water via dynamic covalent bonding0 aConstructing covalent organic frameworks in water via dynamic co cNOV a402-4070 v33 aThe formation of keto-enamine based crystalline, porous polymers in water is investigated for the first time. Facile access to the Schiff base reaction in water has been exploited to synthesize stable porous structures using the principles of Dynamic Covalent Chemistry (DCC). Most credibly, the water-based Covalent Organic Frameworks (COFs) possess chemical as well as physical properties such as crystallinity, surface area and porosity, which is comparable to their solvothermal counterparts. The formation of COFs in water is further investigated by understanding the nature of the monomers formed using hydroxy and non-hydroxy analogues of the aldehyde. This synthetic route paves a new way to synthesize COFs using a viable, greener route by utilization of the DCC principles in conjunction with the keto-enol tautomerism to synthesize useful, stable and porous COFs in water.1 aThote, Jayshri1 aAiyappa, Harshitha, Barike1 aKumar, Raya, Rahul1 aKandambeth, Sharath1 aBiswal, Bishnu, P.1 aShinde, Digambar, Balaji1 aRoy, Neha, Chaki1 aBanerjee, Rahul uhttp://library.ncl.res.in/content/constructing-covalent-organic-frameworks-water-dynamic-covalent-bonding02282nas a2200229 4500008004100000245009200041210006900133260000800202300001600210490000700226520149400233100002201727700002701749700001901776700002401795700002101819700002101840700002401861700002401885700002001909856012301929 2018 eng d00aConvergent covalent organic framework thin sheets as flexible supercapacitor electrodes0 aConvergent covalent organic framework thin sheets as flexible su cAUG a28139-281460 v103 aFlexible supercapacitors in modern electronic equipment require light-weight electrodes, which have a high surface area, precisely integrated redox moieties, and mechanically strong flexible free-standing nature. However, the incorporation of the aforementioned properties into a single electrode remains a great task. Herein, we could overcome these challenges by a facile and scalable synthesis of the convergent covalent organic framework (COF) free-standing flexible thin sheets through solid-state molecular baking strategy. Here, redox-active anthraquinone (Dq) and pi-electron-rich anthracene (Da) are judiciously selected as two different linkers in a beta-ketoenamine-linked two-dimensional (2D) COF. As a result of precisely integrated anthraquinone moieties, COF thin sheet exhibits redox activity. Meanwhile, pi-electron-rich anthracene linker assists to improve the mechanical property of the free-standing thin sheet through the enhancement of noncovalent interaction between crystallites. This binder-free strategy offers the togetherness of crystallinity and flexibility in 2D COF thin sheets. Also, the synthesized porous crystalline convergent COF thin sheets are benefited with crack-free uniform surface and light-weight nature. Further, to demonstrate the practical utility of the material as an electrode in energy-storage systems, we fabricated a solid-state symmetrical flexible COF supercapacitor device using a GRAFOIL peeled carbon tape as the current collector.1 aKhayum, Abdul, M.1 aVijayakumar, Vidyanand1 aKarak, Suvendu1 aKandambeth, Sharath1 aBhadra, Mohitosh1 aSuresh, Karthika1 aAcharambath, Nikhil1 aKurungot, Sreekumar1 aBanerjee, Rahul uhttp://library.ncl.res.in/content/convergent-covalent-organic-framework-thin-sheets-flexible-supercapacitor-electrodes02051nas a2200157 4500008004100000245006600041210006300107260000800170300001400178490000800192520153700200100002401737700001701761700002001778856009501798 2019 eng d00a Covalent organic frameworks: chemistry beyond the structure 0 aCovalent organic frameworks chemistry beyond the structure cFEB a1807-18220 v1413 a

Covalent organic frameworks (COFs) represent a new field of rapidly growing chemical research that takes direct inspiration from diverse covalent bonds existing between atoms. The success of linking atoms in two and three dimensions to construct extended framework structures moved the chemistry of COFs beyond the structures to methodologies, highlighting the possibility of prospective applications. Although structure to property relation in COFs has led to fascinating properties, chemical stability, processability and scalability were some of the important challenges that needed to be overcome for their successful implementation. In this Perspective, we take a closer look at the growth of COFs from mere supramolecular structures to potential industrializable materials.

1 aKandambeth, Sharath1 aDey, Kaushik1 aBanerjee, Rahul uhttp://library.ncl.res.in/content/covalent-organic-frameworks-chemistry-beyond-structure-0