00619nas a2200181 4500008004100000022001400041245009000055210006900145260000800214300000900222490000700231653000900238653001600247653001600263100001900279700002000298856011900318 2014 eng d a2053-273300aConstruction of highly crystalline ultraporous covalent organic frameworks in seconds0 aConstruction of highly crystalline ultraporous covalent organic  cAPR aC4560 v7010aCOFs10aCrystalline10aUltraporous1 aKarak, Suvendu1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/construction-highly-crystalline-ultraporous-covalent-organic-frameworks-seconds01821nas a2200241 4500008004100000022001400041245010700055210006900162260011000231300001600341490000600357520090000363100002301263700002401286700001901310700002901329700001701358700001901375700001801394700002201412700002001434856012501454 2015 eng d a2050-748800aPore surface engineering in porous, chemically stable covalent organic frameworks for water adsorption0 aPore surface engineering in porous chemically stable covalent or aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcNOV a23664-236690 v33 a

Herein, we have explored the possibility of a class of covalent organic frameworks (COFs) as water adsorbing materials. We have selected, synthesized 12 chemically stable functionalized Schiff base COFs and thoroughly studied their water uptake behaviour. Further, a deep understanding was developed with these COFs towards the effects of condensation pressure of water and hydrophilic/hydrophobic groups present in the COF pores on water absorption capacity and ultimately, their recyclability. Among all reported COFs, TpPa-1 shows the highest water uptake of 30 wt% (368 cm(3) g(-1); 17 mmol g(-1)) at P/P-0 = 0.3, which is also comparable with the recently reported carbon materials and few well known MOFs. This study also reveals that the overall water uptake of COFs can be tuned systematically based on chemical functionality and pore size in a wider window of relative pressures.

1 aBiswal, Bishnu, P.1 aKandambeth, Sharath1 aChandra, Suman1 aShinde, Digambar, Balaji1 aBera, Saibal1 aKarak, Suvendu1 aGarai, Bikash1 aKharul, Ulhas, K.1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/pore-surface-engineering-porous-chemically-stable-covalent-organic-frameworks-water-001171nas a2200205 4500008004100000245009300041210006900134260000800203300001400211490000700225520047500232100001900707700001800726700001700744700002200761700002500783700001700808700002000825856012000845 2017 eng d00aInterplaying anions in a supramolecular metallohydrogel to form metal organic frameworks0 aInterplaying anions in a supramolecular metallohydrogel to form  cAPR a3705-37080 v533 aThe remarkable effect of anions on the transition from supramolecular gels to crystalline phases has been described. An amino acid-based metallohydrogel was transformed into different metal-organic frameworks through the selective picking of anions. The metallohydrogel and the resulting metal-organic frameworks (MOFs) were thoroughly characterized. The results demonstrated controlled access over the binding of a particular anion to selectively form a particular MOF.1 aKarak, Suvendu1 aKumar, Sushil1 aBera, Saibal1 aDiaz, David, Diaz1 aBanerjee, Subhrashis1 aVanka, Kumar1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/interplaying-anions-supramolecular-metallohydrogel-form-metal-organic-frameworks01769nas a2200193 4500008004100000245006200041210005600103260000800159300001400167490000700181520119000188100002001378700001901398700001801417700001501435700001701450700001901467856008901486 2018 eng d00aAccess to silicon(II)- and germanium(II)-indium compounds0 aAccess to siliconII and germaniumIIindium compounds cAPR a1206-12130 v373 aDespite the remarkable ability of N-heterocyclic silylene to act as a Lewis base and form stable Lewis adducts with group 13 elements such as boron, aluminum, and gallium, there has been no such comparable investigation with indium and the realization of a stable silylene-indium complex has still remained elusive. Similarly, a germylene-indium complex is also presently unknown. We describe herein the reactions of [PhC(NtBu)(2)SiN-(SiMe3)(2)] (1) and [PhC(NtBu)(2)GeN(SiMe3)(2)] (4) with InCl3 and InBr3 that have resulted in the first silylene-indium complexes, [PhC(NtBu)(2)Si{N(SiMe3)(2)}-> InCl3] (2) and [PhC(NtBu)(2)Si{N(SiMe3)(2)}-> InBr3] (3), as well as the first germylene-indium complexes, [PhC(NtBu)(2)Ge{N(SiMe3)(2)}-> InCl3] (5) and [PhC(NtBu)(2)Ge{N(SiMe3)(2)}-> InBr3] (6). The solid-state structures of all species have been validated by single-crystal X-ray diffraction studies. Note that 5 and 6 are the first structurally characterized organometallic compounds that feature a Ge-In single bond (apart from the compounds in Zintl phases). Theoretical calculations reveal that the Si(II)-> In bonds in 2 and 3 and the Ge(II)-> In bonds in 5 and 6 are dative bonds.1 aPahar, Sanjukta1 aKarak, Suvendu1 aPait, Moumita1 aRaj, Vipin1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/access-siliconii-and-germaniumii-indium-compounds02283nas a2200229 4500008004100000245009200041210006900133260000800202300001600210490000700226520149400233100002201727700002701749700001901776700002401795700002101819700002101840700002401861700002401885700002001909856012401929 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 uhttps://library.ncl.res.in/content/convergent-covalent-organic-framework-thin-sheets-flexible-supercapacitor-electrodes01783nas a2200229 4500008004100000245009500041210006900136260000800205300001700213490000800230520100100238100001801239700001701257700002201274700001701296700002201313700002801335700001901363700002401382700002001406856012701426 2018 eng d00aInterlayer hydrogen-bonded covalent organic frameworks as high-performance supercapacitors0 aInterlayer hydrogenbonded covalent organic frameworks as highper cSEP a 10941-109450 v1403 aCovalent organic frameworks (COFs) have emerged as promising electrode materials in supercapacitors (SCs). However, their insoluble powder-like nature, poor capacitive performance in pristine form, integrated with inferior electrochemical stability is a primary concern for their long-term use in electrochemical devices. Keeping this in perspective, herein we report a redox active and hydrogen bonded COF with ultrahigh stability in conc. H2SO4 (18 M), conc. HCl (12 M) and NaOH (9 M). The as-synthesized COF fabricated as thin sheets were efficiently employed as a free-standing supercapacitor electrode material using 3 M aq. H2SO4 as an electrolyte. Moreover, the pristine COF sheet showcased outstanding areal capacitance 1600 mF cm(-2) (gravimetric 169 F g(-1)) and excellent cyclic stability (>100 000) without compromising its capacitive performance or Coulombic efficiency. Moreover, as a proof-of-concept, a solid-state supercapacitor device was also assembled and subsequently tested.1 aHalder, Arjun1 aGhosh, Meena1 aKhayum, Abdul, M.1 aBera, Saibal1 aAddicoat, Matthew1 aSasmal, Himadri, Sekhar1 aKarak, Suvendu1 aKurungot, Sreekumar1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/interlayer-hydrogen-bonded-covalent-organic-frameworks-high-performance-supercapacitors02071nas a2200217 4500008004100000022001400041245013800055210006900193260000800262300001400270490000700284520129100291100001701582700002201599700001901621700001801640700002801658700002001686700002001706856012701726 2018 eng d a0897-475600aMultistimuli-responsive interconvertible low-molecular weight metallohydrogels and the in situ entrapment of CdS quantum dots therein0 aMultistimuliresponsive interconvertible lowmolecular weight meta cJUL a4755-47610 v303 a

Two low molecular weight metallohydrogels (ZALA and CALA) have been synthesized from an amino-acid based ligand precursor (LA) and two different metal salts [zinc acetate dihydrate (ZA) and cadmium acetate dihydrate (CA), respectively. These two hydrogels show a unique chemically stimulated interconversion to each other via a reversible gel-sol gel pathway. This programmable gel-sol reversible system satisfies logic operations of a basic Boolean logic (INHIBIT) gate. Also, these hydrogels can be degraded into different MOF phases at room temperature spontaneously or in the presence of chloride and bromide salts (NaCl and NaBr.). CdS quantum dots can be grown inside the CALA gel matrix (CdS@CALA) in the presence of small amount of Na2S. This CdS doped gel exhibits time dependent tunable emission (white to yellow to orange) as a consequence of a slow agglomeration process of the entrapped quantum dots inside the gel matrix. This luminescence property also reflects the corresponding gel derived MOFs (obtained either by self-degradation of CdS@CALA or via anion induction) as well. This, to the best of our knowledge, is probably the simplest way to make a CdS quantum dot based composite material where CdS is entrapped within the gel and the gel-derived MOF matrix.

1 aBera, Saibal1 aChakraborty, Amit1 aKarak, Suvendu1 aHalder, Arjun1 aChatterjee, Soumyajyoti1 aSaha, Subhadeep1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/multistimuli-responsive-interconvertible-low-molecular-weight-metallohydrogels-and-situ02353nas a2200169 4500008004100000245008000041210006900121260000800190300001400198490000800212520177300220100001901993700001802012700002102030700002002051856011202071 2018 eng d00aPorosity prediction through hydrogen bonding in covalent organic frameworks0 aPorosity prediction through hydrogen bonding in covalent organic cAPR a5138-51450 v1403 aEasy and bulk-scale syntheses of two-dimensional (2D) covalent organic frameworks (COFs) represent an enduring challenge in material science. Concomitantly, the most critical aspect is to precisely control the porosity and crystallinity of these robust structures. Disparate complementary approaches such as solvothermal synthesis have emerged recently and are fueled in part by the usage of different modulators and acids that have enriched the COF library. Yet, the fundamental understanding of the integral processes of 2D COF assembly, induding their growth from nucleating sites and the origin of periodicity, is an intriguing chemical question that needs to be answered. To address these cardinal questions, a green and easy-to-perform approach of COF formation has been delineated involving acid-diamine salt precursors. The role of hydrogen bonding [d(av)(N-amine-H center dot center dot center dot O-acid); d(av) signifies the average N-amine-H center dot center dot center dot O-acid distances, i.e., the average distance from the H atom of the amine to the O atom of the acid] present in the acid-diamine salts in improving the COFs' crystallinity and porosity has further been decoded by thorough crystallographic analyses of the salt molecules. What is particularly noteworthy is that we have established the hydrogen-bonding distances d(av)(N-amine-H center dot center dot center dot O-acid) in the acid-diamine salts that are pivotal in maintaining the reversibility of the reaction, which mainly facilitates highly crystalline and porous COF formation. Moreover, this reactant-structure to the product-quality relationship has further been utilized for the synthesis of highly crystalline and porous COFs that are unattainable by other synthetic means.1 aKarak, Suvendu1 aKumar, Sushil1 aPachfule, Pradip1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/porosity-prediction-through-hydrogen-bonding-covalent-organic-frameworks01779nas a2200205 4500008004100000245008700041210006900128260000800197300001600205490000700221520107100228100002001299700002801319700002201347700002401369700001901393700001801412700002401430856011901454 2018 eng d00aSuperprotonic conductivity in flexible porous covalent organic framework membranes0 aSuperprotonic conductivity in flexible porous covalent organic f cAUG a10894-108980 v573 a

Poor mechanical stability of the polymer electrolyte membranes (PEMs) remains one of the bottlenecks towards improving the performance of the proton exchange membrane (PEM) fuel cells. The present work proposes a unique way to utilize crystalline covalent organic frameworks (COFs) as a self‐standing, highly flexible membrane to further boost the mechanical stability of the material without compromising its innate structural characteristics. The as‐synthesized p‐toluene sulfonic acid loaded covalent organic framework membranes (COFMs) showing the highest proton conductivity amongst all crystalline porous organic polymeric materials reported till date, as high as 7.8 x 10‐2 S cm‐1, have been further tested under real PEM operating conditions to ascertain their practical utilization as proton exchange membranes. Attainment of 24 mW cm‐2 power density, which is the highest among COFs and MOFs, highlights the possibilityof using a COF membrane over the other state‐of‐the‐art crystalline porous polymeric materials reported to date.

1 aBanerjee, Rahul1 aSasmal, Himadri, Sekhar1 aHarshitha, B., A.1 aBhange, Siddheshwar1 aKarak, Suvendu1 aHalder, Arjun1 aKurungot, Sreekumar uhttps://library.ncl.res.in/content/superprotonic-conductivity-flexible-porous-covalent-organic-framework-membranes01713nas a2200229 4500008004100000245012500041210006900166260000800235300001400243490000700257520090400264100001801168700001901186700002201205700001701227700002201244700002601266700002101292700001801313700002001331856013201351 2018 eng d00aUltrastable imine-based covalent organic frameworks for sulfuric acid recovery: an effect of interlayer hydrogen bonding0 aUltrastable iminebased covalent organic frameworks for sulfuric  cMAY a5797-58020 v573 aA rapid and scalable synthesis of six new imine-linked highly porous and crystalline COFs is presented that feature exceptionally high chemical stability in harsh environments including conc. H2SO4 (18M), conc. HCl (12M), and NaOH (9M). This is because of the presence of strong interlayer C-H center dot center dot center dot N hydrogen bonding among the individual layers, which provides significant steric hindrance and a hydrophobic environment around the imine (-C=N-) bonds, thus preventing their hydrolysis in such an abrasive environment. These COFs were further converted into porous, crystalline, self-standing, and crack-free COF membranes (COFMs) with extremely high chemical stability for their potential applications for sulfuric acid recovery. The as-synthesized COFMs exhibit unprecedented permeance for acetonitrile (280 Lm(-2) h(-1) bar(-1)) and acetone (260 Lm(-2) h(-1) bar(-1)).1 aHalder, Arjun1 aKarak, Suvendu1 aAddicoat, Matthew1 aBera, Saibal1 aChakraborty, Amit1 aKunjattu, Shebeeb, H.1 aPachfule, Pradip1 aHeine, Thomas1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/ultrastable-imine-based-covalent-organic-frameworks-sulfuric-acid-recovery-effect-interlayer02493nas a2200217 4500008004100000022001400041245014700055210006900202260000900271300001400280490000800294520171100302100001902013700001702032700001702049700001802066700001702084700002702101700002002128856012702148 2019 eng d a0002-786300aInducing disorder in order: hierarchically porous covalent organic framework nanostructures for rapid removal of persistent organic pollutants0 aInducing disorder in order hierarchically porous covalent organi cMAY  a7572-75810 v1413 a

The key factor responsible for fast diffusion and mass transfer through a porous material is the availability of a widely open pore interior having complete accessibility from their surface. However, because of their highly stacked nature, ordered two-dimensional (2D) materials fail to find real-world applicability, as it is difficult to take advantage of their complete structure, especially the inner cores. In this regard, three-dimensional (3D) nanostructures constructed from layered two-dimensional crystallites could prove to be advantageous. However, the real challenge is to cultivate a porous nanostructure with ordered pores where the pores are surrounded by crystalline walls. Herein, a simple yet versatile in situ gas-phase foaming technique has been employed to address these cardinal issues. The use of baking soda leads to the continuous effervescence of CO2 during the crystallization of foam, which creates ripples and fluctuations on the surface of the 2D crystallites. The induction of ordered micropores within the disordered 3D architecture synergistically renders fast diffusion of various guests through the interconnected pore network. The high-density defects in the hierarchically porous structure help in ultrafast adsorption (<10 s) of various pollutants (removal efficiency of 99%) from water, all of which would lead to significant environmental benefit. The pseudo-second-order rate constant for the BPA pollutant is 182.3 g mg(-1) min(-1), which is the highest among all the literature reports to date. The high removal efficiency (highest efficiency of 94% and average efficiency of 70%) of a persistent organic pollutant has been attended for the first time.

1 aKarak, Suvendu1 aDey, Kaushik1 aTorris, Arun1 aHalder, Arjun1 aBera, Saibal1 aKanheerampockil, Fayis1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/inducing-disorder-order-hierarchically-porous-covalent-organic-framework-nanostructures02417nas a2200289 4500008004100000022001400041245009500055210006900150260000800219300001400227490000700241520151000248653002301758653001501781653001801796653001701814653002301831100001701854700001701871700001901888700001801907700001901925700001901944700002201963700002001985856012202005 2019 eng d a1433-785100aPorosity switching in polymorphic porous organic cages with exceptional chemical stability0 aPorosity switching in polymorphic porous organic cages with exce cMAR a4243-42470 v583 a

Porous solids that can be switched between different forms with distinct physical properties are appealing candidates for separation, catalysis, and host-guest chemistry. In this regard, porous organic cages (POCs) are of profound interest because of their solution-state accessibility. However, the application of POCs is limited by poor chemical stability. Synthesis of an exceptionally stable imine-linked (4+6) porous organic cage (TpOMe-CDA) is reported using 2,4,6-trimethoxy-1,3,5-triformyl benzene (TpOMe) as a precursor aldehyde. Introduction of the -OMe functional group to the aldehyde creates significant steric and hydrophobic characteristics in the environment around the imine bonds that protects the cage molecules from hydrolysis in the presence of acids or bases. The electronic effect of the -OMe group also plays an important role in enhancing the stability of the reported POCs. As a consequence, TpOMe-CDA reveals exceptional chemical stability in neutral, acidic and basic conditions, even in 12m NaOH. Interestingly, TpOMe-CDA exists in three different porous and non-porous polymorphic forms (, , and ) with respect to differences in crystallographic packing and the orientation of the flexible methoxy groups. All of the polymorphs retain their crystallinity even after treatment with acids and bases. All the polymorphs of TpOMe-CDA differ significantly in their properties as well as morphology and could be reversibly switched in the presence of an external stimulus.

10achemical stability10aMorphology10aorganic cages10apolymorphism10aporosity switching1 aBera, Saibal1 aDey, Kaushik1 aPal, Tapan, K.1 aHalder, Arjun1 aTothadi, Srinu1 aKarak, Suvendu1 aAddicoat, Matthew1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/porosity-switching-polymorphic-porous-organic-cages-exceptional-chemical-stability02436nas a2200241 4500008004100000022001400041245015800055210006900213260000900282300001400291490000800305520154300313100002801856700002301884700002701907700001901934700001801953700002201971700002201993700003202015700002002047856012702067 2020 eng d a0002-786300aConnecting microscopic structures, mesoscale assemblies, and macroscopic architectures in 3D-printed hierarchical porous covalent organic framework foams0 aConnecting microscopic structures mesoscale assemblies and macro cMAY  a8252-82610 v1423 a

The induction of macro and mesopores into two-dimensional porous covalent organic frameworks (COFs) could enhance the exposure of the intrinsic micropores toward the pollutant environment, thereby, improving the performance. However, the challenge is to build a continuous hierarchically porous macro-architecture of crystalline organic materials in the bulk scale. In this regard, we have strategized a novel synthetic method to create hierarchically porous COF foams consisting of ordered micropores (2-2.2 nm) and disordered meso and macropores (50 nm to 200 mu m) as well as ordered macropores (1.5 mm to 2 cm). Herein, graphene oxide was used for creating disordered macro and mesopores in COF-GO foams. Considering the rheological features of the precursor hydrogel, we could integrate crystalline and porous COF-GO foams into self-supported three-dimensional (3D)-printed objects with the desired shapes and sizes. Therefore, we have engineered the 3D macro-architecture of COF-GO foams into complex geometries keeping their structural order and continuous porosity intact over a range of more than a million (10(-9) m to 10(-3) m). The interconnected 3D openings in these COF-GO foams further enhance the rapid and efficient uptake of organic and inorganic pollutants from water (>95% removal within 30 s). The abundant distribution of interconnected macroporous volume (55%) throughout the COF-GO foam matrix enhances the flow of water (1.13 x 10(-3) m.s(-1)) which results in efficient mass transport and adsorption.

1 aMohammed, Abdul, Khayum1 aUsgaonkar, Saurabh1 aKanheerampockil, Fayis1 aKarak, Suvendu1 aHalder, Arjun1 aTharkar, Minakshi1 aAddicoat, Matthew1 aAjithkumar, Thalasseril, G.1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/connecting-microscopic-structures-mesoscale-assemblies-and-macroscopic-architectures-3d02663nas a2200229 4500008004100000022001400041245013900055210006900194260000900263300001400272490000800286520184200294100002802136700001602164700001902180700002202199700002102221700001902242700002202261700002002283856013002303 2021 eng d a0002-786300aHeterogeneous C-H functionalization in water via porous covalent organic framework nanofilms: a case of catalytic sphere transmutation0 aHeterogeneous CH functionalization in water via porous covalent  cJUN  a8426-84360 v1433 aHeterogeneous catalysis in water has not been explored beyond certain advantages such as recyclability and recovery of the catalysts from the reaction medium. Moreover, poor yield, extremely low selectivity, and active catalytic site deactivation further underrate the heterogeneous catalysis in water. Considering these facts, we have designed and synthesized solution-dispersible porous covalent organic framework (COF) nanospheres. We have used their distinctive morphology and dispersibility to functionalize unactivated C-H bonds of alkanes heterogeneously with high catalytic yield (42-99%) and enhanced regioand stereoselectivity (3 degrees:2 degrees = 105:1 for adamantane). Further, the fabrication of catalyst-immobilized COF nanofilms via covalent self-assembly of catalytic COF nanospheres for the first time has become the key toward converting the catalytically inactive homogeneous catalysts into active and effective heterogeneous catalysts operating in water. This unique covalent self-assembly occurs through the protrusion of the fibers at the interface of two nanospheres, transmuting the catalytic spheres into films without any leaching of catalyst molecules. The catalyst-immobilized porous COF nanofilms' chemical functionality and hydrophobic environment stabilize the high-valent transient active oxoiron(V) intermediate in water and restricts the active catalytic site's deactivation. These COF nanofilms functionalize the unactivated C-H bonds in water with a high catalytic yield (45-99%) and with a high degree of selectivity (cis:trans = 155:1; 3 degrees:2 degrees = 257:1, for cis-1,2-dimethylcyclohexane). To establish this approach's ``practical implementation'', we conducted the catalysis inflow (TON = 424 +/- 5) using catalyst-immobilized COF nanofilms fabricated on a macroporous polymeric support.1 aSasmal, Himadri, Sekhar1 aBag, Saikat1 aChandra, Bittu1 aMajumder, Poulami1 aKuiry, Himangshu1 aKarak, Suvendu1 aGupta, Sayam, Sen1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/heterogeneous-c-h-functionalization-water-porous-covalent-organic-framework-nanofilms-case01978nas a2200301 4500008004100000022001400041245007800055210006900133260000800202300000900210490000700219520105200226100002001278700001801298700002401316700001901340700001901359700001801378700002001396700001601416700002201432700001701454700001901471700003201490700002401522700002001546856011001566 2022 eng d a1755-433000aPorous covalent organic nanotubes and their assembly in loops and toroids0 aPorous covalent organic nanotubes and their assembly in loops an cMAY a507+0 v143 a

Carbon nanotubes, and synthetic organic nanotubes more generally, have in recent decades been widely explored for application in electronic devices, energy storage, catalysis and biosensors. Despite noteworthy progress made in the synthesis of nanotubular architectures with well-defined lengths and diameters, purely covalently bonded organic nanotubes have remained somewhat challenging to prepare. Here we report the synthesis of covalently bonded porous organic nanotubes (CONTs) by Schiff base reaction between a tetratopic amine-functionalized triptycene and a linear dialdehyde. The spatial orientation of the functional groups promotes the growth of the framework in one dimension, and the strong covalent bonds between carbon, nitrogen and oxygen impart the resulting CONTs with high thermal and chemical stability. Upon ultrasonication, the CONTs form intertwined structures that go on to coil and form toroidal superstructures. Computational studies give some insight into the effect of the solvent in this assembly process.

1 aKoner, Kalipada1 aKarak, Shayan1 aKandambeth, Sharath1 aKarak, Suvendu1 aThomas, Neethu1 aLeanza, Luigi1 aPerego, Claudio1 aPesce, Luca1 aCapelli, Riccardo1 aMoun, Monika1 aBhakar, Monika1 aAjithkumar, Thalasseril, G.1 aPavan, Giovanni, M.1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/porous-covalent-organic-nanotubes-and-their-assembly-loops-and-toroids01894nas a2200241 4500008004100000022001400041245007900055210006900134260000900203300001600212490000800228520112300236100002001359700001801379700002001397700002301417700002201440700002401462700001901486700001701505700002001522856011001542 2022 eng d a0002-786300aViscoelastic covalent organic nanotube fabric via macroscopic entanglement0 aViscoelastic covalent organic nanotube fabric via macroscopic en cSEP  a16052-160590 v1443 a

Covalent organic nanotubes (CONTs) are one-dimensional porous frameworks constructed from organic building blocks via dynamic covalent chemistry. CONTs are synthesized as insoluble powder that restricts their potential applications. The judicious selection of 2,2'-bipyridine-5,5'-dicarbaldehyde and tetraaminotriptycene as building blocks for TAT-BPy CONTs has led to constructing flexible yet robust and self-standing fabric up to 3 mu m thickness. The TAT-BPy CONTs and TAT-BPy CONT fabric have been characterized by solid-state one-dimensional (1D) C-13 CP-MAS, two-dimensional (2D) C-13-H-1 correlation NMR, 2D H-1-H-1 DQ-SQ NMR, and 2D N-14-H-1 correlation NMR spectroscopy. The mechanism of fabric formation has been established by using high-resolution transmission electron microscopy and scanning electron microscopy techniques. The as-synthesized viscoelastic TAT-BPy CONT fabric exhibits high mechanical strength with a reduced modulus (E-r) of 8 (+/- 3) GPa and hardness (H) of 0.6 (+/- 0.3) GPa. Interestingly, the viscoelastic fabric shows time-dependent elastic depth recovery up to 50-70%.

1 aKoner, Kalipada1 aDas, Susobhan1 aMohata, Shibani1 aDuong, Nghia, Tuan1 aNishiyama, Yusuke1 aKandambeth, Sharath1 aKarak, Suvendu1 aReddy, Malla1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/viscoelastic-covalent-organic-nanotube-fabric-macroscopic-entanglement