@article {45391, title = {Interlayer hydrogen-bonded covalent organic frameworks as high-performance supercapacitors}, journal = {Journal of the American Chemical Society}, volume = {140}, year = {2018}, month = {SEP}, pages = { 10941-10945}, type = {Article}, abstract = {Covalent 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.}, doi = {10.1021/jacs.8b06460}, author = {Halder, Arjun and Ghosh, Meena and Khayum, Abdul M. and Bera, Saibal and Addicoat, Matthew and Sasmal, Himadri Sekhar and Karak, Suvendu and Kurungot, Sreekumar and Banerjee, Rahul} } @article {44375, title = {Ultrastable imine-based covalent organic frameworks for sulfuric acid recovery: an effect of interlayer hydrogen bonding}, journal = {Angewandte Chemie-International Edition}, volume = {57}, year = {2018}, month = {MAY}, pages = {5797-5802}, abstract = {A 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)).}, doi = {10.1002/anie.201802220}, author = {Halder, Arjun and Karak, Suvendu and Addicoat, Matthew and Bera, Saibal and Chakraborty, Amit and Kunjattu, Shebeeb H. and Pachfule, Pradip and Heine, Thomas and Banerjee, Rahul} } @article {46162, title = {Porosity switching in polymorphic porous organic cages with exceptional chemical stability}, journal = {Angewandte Chemie-International Edition}, volume = {58}, year = {2019}, month = {MAR}, pages = {4243-4247}, type = {Article}, abstract = {

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.

}, keywords = {chemical stability, Morphology, organic cages, polymorphism, porosity switching}, issn = {1433-7851}, doi = {10.1002/anie.201813773}, author = {Bera, Saibal and Dey, Kaushik and Pal, Tapan K. and Halder, Arjun and Tothadi, Srinu and Karak, Suvendu and Addicoat, Matthew and Banerjee, Rahul} } @article {46134, title = {Triazine functionalized porous covalent organic framework for photo-organocatalytic E-Z isomerization of olefins}, journal = {Journal of the American Chemical Society}, volume = {141}, year = {2019}, month = {APR }, pages = {6152-6156}, type = {Article}, abstract = {

Visible light-mediated photocatalytic organic transformation has drawn significant attention as an alternative process for replacing thermal reactions. Although precious metal/organic dyes based homogeneous photocatalysts have been developed, their toxic and nonreusable nature makes them inappropriate for large-scale production. Therefore, we have synthesized a triazine and a keto functionalized nonmetal based covalent organic framework (TpTt) for heterogeneous photo catalysis. As the catalyst shows significant absorption of visible light, it has been applied for the photocatalytic uphill conversion of trans-stilbene to cis-stilbene in the presence of blue light-emitting diodes with broad substrate scope via an energy transfer process.

}, issn = {0002-7863}, doi = {10.1021/jacs.9b01891}, author = {Bhadra, Mohitosh and Kandambeth, Sharath and Sahoo, Manoj K. and Addicoat, Matthew and Balaraman, Ekambaram and Banerjee, Rahul} } @article {46231, title = {Weak intermolecular interactions in covalent organic framework-carbon nanofiber based crystalline yet flexible devices}, journal = {ACS Applied Materials \& Interfaces}, volume = {11}, year = {2019}, month = {AUG}, type = {Article}, abstract = {

The redox-active and porous structural backbone of covalent organic frameworks (COFs) can facilitate high-performance electrochemical energy storage devices. However, the utilities of such 2D materials as supercapacitor electrodes in advanced self-charging power-pack systems have been obstructed due to the poor electrical conductivity and subsequent indigent performance. Herein, we report an effective strategy to enhance the electrical conductivity of COF thin sheets through the in situ solid-state inclusion of carbon nanofibers (CNF) into the COF precursor matrix. The obtained COF-CNF hybrids possess a significant intermolecular π{\textperiodcentered}{\textperiodcentered}{\textperiodcentered}π interaction between COF and the graphene layers of the CNF. As a result, these COF-CNF hybrids (DqTp-CNF and DqDaTp-CNF) exhibit good electrical conductivity (0.25 {\texttimes} 10{\textendash}3\ S cm{\textendash}1), as well as high performance in electrochemical energy storage (DqTp-CNF: 464 mF cm{\textendash}2\ at 0.25 mA cm{\textendash}2). Also, the fabricated, mechanically strong quasi-solid-state supercapacitor (DqDaTp-CNF SC) delivered an ultrahigh device capacitance of 167 mF cm{\textendash}2\ at 0.5 mA cm{\textendash}2. Furthermore, we integrated a monolithic photovoltaic self-charging power pack by assembling DqDaTp-CNF SC with a perovskite solar cell. The fabricated self-charging power pack delivered excellent performance in the areal capacitance (42 mF cm{\textendash}2) at 0.25 mA cm{\textendash}2\ after photocharging for 300 s.

}, doi = {10.1021/acsami.9b08625}, author = {Mohammed, Abdul Khayum and Vijayakumar, Vidyanand and Halder, Arjun and Ghosh, Meena and Addicoat, Matthew and Bansode, Umesh and Kurungot, Sreekumar and Banerjee, Rahul} } @article {46233, title = {Zinc ion interactions in a two-dimensional covalent organic framework based aqueous zinc ion battery}, journal = {Chemical Science}, year = {2019}, month = {AUG}, type = {Article}, abstract = {

The two-dimensional structural features of covalent organic frameworks (COFs) can promote the electrochemical storage of cations like H+, Li+, and Na+\ through both faradaic and non-faradaic processes. However, the electrochemical storage of cations like Zn2+\ ion is still unexplored although it bears a promising divalent charge. Herein, for the first time, we have utilized hydroquinone linked β-ketoenamine COF acting as a Zn2+\ anchor in an aqueous rechargeable zinc ion battery. The charge-storage mechanism comprises of an efficient reversible interlayer interaction of Zn2+\ ions with the functional moieties in the adjacent layers of COF (-182.0 kcal mol-1). Notably, due to the well-defined nanopores and structural organization, a constructed full cell, displays a discharge capacity as high as 276 mA h g-1\ at a current rate of 125 mA g-1.

}, doi = {10.1039/C9SC03052B}, author = {Mohammed, Abdul Khayum and Ghosh, Meena and Vijayakumar, Vidyanand and Halder, Arjun and Nurhuda, Maryam and Kumar, Sushil and Addicoat, Matthew and Kurungot, Sreekumar and Banerjee, Rahul} } @article {46867, title = {Connecting microscopic structures, mesoscale assemblies, and macroscopic architectures in 3D-printed hierarchical porous covalent organic framework foams}, journal = {Journal of the American Chemical Society}, volume = {142}, year = {2020}, month = {MAY }, pages = {8252-8261}, type = {Article}, abstract = {

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.

}, issn = {0002-7863}, doi = {10.1021/jacs.0c00555}, author = {Mohammed, Abdul Khayum and Usgaonkar, Saurabh and Kanheerampockil, Fayis and Karak, Suvendu and Halder, Arjun and Tharkar, Minakshi and Addicoat, Matthew and Ajithkumar, Thalasseril G. and Banerjee, Rahul} } @article {46904, title = {Morphological evolution of two-dimensional porous hexagonal trimesic acid framework}, journal = {ACS Applied Materials \& Interfaces}, volume = {12}, year = {2020}, month = {APR }, pages = {15588-15594}, type = {Article}, abstract = {

Hexagonal single crystal structure (Form II) of trimesic acid (TMA) has been isolated by dissolving the interpenetrated Form I of TMA in tetrahydrofuran. Form II (hexagonal) was converted to Form I (interpenetrated) at room temperature through some intermediate structures. A detailed time-dependent FESEM study shows that the external morphology of Form II (hexagonal) is a hollow hexagonal tube that mimics its crystal structure. The block-shaped (morphology) of Form I (interpenetrated) was converted to the hollow hexagonal tube through some intermediate morphologies which are corresponding to particular crystal structures. Here, we have established a strong correlation between crystal structures with the morphology. These hollow tubes have been employed for Rhodamine B dye adsorption studies and showed an uptake of 82\%, much more significant than Form I (interpenetrated) (39\%) due to the presence of a pore channel in the crystal structure.

}, keywords = {dye adsorption, hollow hexagonal rod, hydrogen-bonded organic framework, morphology evaluation, trimesic acid}, issn = {1944-8244}, doi = {10.1021/acsami.0c01398}, author = {Tothadi, Srinu and Koner, Kalipada and Dey, Kaushik and Addicoat, Matthew and Banerjee, Rahul} }