@article { ISI:000297609100003, title = {Porous nitrogen rich cadmium-tetrazolate based metal organic framework (MOF) for H-2 and CO2 uptake}, journal = {Crystal Growth \& Design}, volume = {11}, number = {12}, year = {2011}, month = {DEC}, pages = {5176-5181}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The highly porous nitrogen rich metal organic framework [Cd-3(4-TP)(6)] (Cd-4TP-1) was synthesized solvothermally from the predesigned organic building block 4-tetrazole pyridine (4-TP) and Cd(II) as metal center using DMF as solvent. Cd-4TP-1 has a three-dimensional porous architecture where all the binding sites of Cd(II) are exclusively occupied by the nitrogen atoms from the mu(2)-tetrazolyl group or the pyridyl functionality of the 4-TP ligands. Cd-4TP-1 has Brunauer-Emmett-Teller (BET) and Langmuir surface areas of 472.2 and 728.6 m(2)/g, respectively, and shows 1.1 wt \% H-2 (77 K) and 2.7 mmol/g CO2 uptake (273 K).

}, issn = {1528-7483}, doi = {10.1021/cg201054f}, author = {Pachfule, Pradip and Banerjee, Rahul} } @article { ISI:000303366000001, title = {Polymorphs, salts, and cocrystals: what{\textquoteright}s in a name?}, journal = {Crystal Growth \& Design}, volume = {12}, number = {5}, year = {2012}, month = {MAY}, pages = {2147-2152}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The December 2011 release of a draft United States Food and Drug Administration (FDA) guidance concerning regulatory classification of pharmaceutical cocrystals of active pharmaceutical ingredients (APIs) addressed two matters of topical interest to the crystal engineering and pharmaceutical science communities: (1) a proposed definition of cocrystals; (2) a proposed classification of pharmaceutical cocrystals as dissociable {\textquoteleft}{\textquoteleft}API-excipient{\textquoteright}{\textquoteright} molecular complexes. The Indo U.S. Bilateral Meeting sponsored by the Indo-U.S. Science and Technology Forum titled The Evolving Role of Solid State Chemistry in Pharmaceutical Science was held in Manesar near Delhi, India, from February 2-4, 2012. A session of the meeting was devoted to discussion of the FDA guidance draft. The debate generated strong consensus on the need to define cocrystals more broadly and to classify them like salts. It was also concluded that the diversity of API crystal forms makes it difficult to classify solid forms into three categories that are mutually exclusive. This perspective summarizes the discussion in the Indo-U.S. Bilateral Meeting and includes contributions from researchers who were not participants in the meeting.

}, issn = {1528-7483}, doi = {10.1021/cg3002948}, author = {Aitipamula, Srinivasulu and Banerjee, Rahul and Bansal, Arvind K. and Biradha, Kumar and Cheney, Miranda L. and Choudhury, Angshuman Roy and Desiraju, Gautam R. and Dikundwar, Amol G. and Dubey, Ritesh and Duggirala, Nagakiran and Ghogale, Preetam P. and Ghosh, Soumyajit and Goswami, Pramod Kumar and Goud, N. Rajesh and Jetti, Ram R. K. R. and Karpinski, Piotr and Kaushik, Poonam and Kumar, Dinesh and Kumar, Vineet and Moulton, Brian and Mukherjee, Arijit and Mukherjee, Gargi and Myerson, Allan S. and Puri, Vibha and Ramanan, Arunachalam and Rajamannar, T. and Reddy, C. Malla and Rodriguez-Hornedo, Nair and Rogers, Robin D. and Row, T. N. Guru and Sanphui, Palash and Shan, Ning and Shete, Ganesh and Singh, Amit and Sun, Changquan C. and Swift, Jennifer A. and Thaimattam, Ram and Thakur, Tejender S. and Thaper, Rajesh Kumar and Thomas, Sajesh P. and Tothadi, Srinu and Vangala, Venu R. and Variankaval, Narayan and Vishweshwar, Peddy and Weyna, David R. and Zaworotko, Michael J.} } @article { ISI:000306942300059, title = {Polymorphs, salts and cocrystals: what{\textquoteright}s in a name? (vol 12, pg 2147, 2012)}, journal = {Crystal Growth \& Design}, volume = {12}, number = {8}, year = {2012}, month = {AUG}, pages = {4290-4291}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, issn = {1528-7483}, doi = {10.1021/cg300704b}, author = {Aitipamula, Srinivasulu and Banerjee, Rahul and Bansal, Arvind K. and Biradha, Kumar and Cheney, Miranda L. and Choudhury, Angshuman Roy and Desiraju, Gautam R. and Dikundwar, Amol G. and Dubey, Ritesh and Duggirala, Nagakiran and Ghogale, Preetam P. and Ghosh, Soumyajit and Goswami, Pramod Kumar and Goud, N. Rajesh and Jetti, Ram R. K. R. and Karpinski, Piotr and Kaushik, Poonam and Kumar, Dinesh and Kumar, Vineet and Moulton, Brian and Mukherjee, Arijit and Mukherjee, Gargi and Myerson, Allan S. and Puri, Vibha and Ramanan, Arunachalam and Rajamannar, T. and Reddy, C. Malla and Rodriguez-Hornedo, Nair and Rogers, Robin D. and Row, T. N. Guru and Sanphui, Palash and Shan, Ning and Shete, Ganesh and Singh, Amit and Sun, Changquan C. and Swift, Jennifer A. and Thaimattam, Ram and Thakur, Tejender S. and Thaper, Rajesh Kumar and Thomas, Sajesh P. and Tothadi, Srinu and Vangala, Venu R. and Vishweshwar, Peddy and Weyna, David R. and Zaworotko, Michael J.} } @article { ISI:000311522500055, title = {Porous ZnO nanorod for targeted delivery of doxorubicin: in vitro and in vivo response for therapeutic applications}, journal = {Journal of Materials Chemistry}, volume = {22}, number = {45}, year = {2012}, month = {DEC}, pages = {24145-24154}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Cancer cell specific targeted delivery (TDD) by porous nanocarrier is on a high role. Here in a simple route for the synthesis of porous ZnO nanorods (ZnO) has been demonstrated. ZnO expressed very high surface area of 305.14 m(2) g(-1) (S-BET) and uniformly distributed pores of 5 nm. In continuation ZnO has been fabricated with 3-aminophosphonic acid followed by folic acid to yield folate conjugated porous ZnO nanorod (ZnO-FA). High surface area, uniformly distributed pores on its surface make the nanocarrier suitable for high drug loading (88\%) of the anticancer drug doxorubicin (DOX). A pH triggered drug release was observed with minimum release in pathophysical conditions. In vitro efficacy of DOX loaded ZnO-FA (ZnO-FA-DOX) has been evaluated against breast cancer cells MDA-MB-231, which is not possible alone by DOX or ZnO-FA. Targeted scaffold with pendant -NH2 group has been covalently bonded with fluorescent dye (RITC) for cellular uptake and imaging studies in MDA-MB-231 cells; the possible pathway for cancer regression has also been evaluated. Even in vivo acute and intravenous toxicological evaluation on murine model system complemented biocompatibility of ZnO-FA in TDD. All together we have collaged a template free synthesis of porous ZnO nanorod, successful targeting on to cancer cells, high drug loading, pH triggered drug release, in vitro efficacy of ZnO-FA-DOX against MDA-MB-231 cells and in vivo compatibility as well. We envisioned the future prospect of porous ZnO nanostructures in TDD.

}, issn = {0959-9428}, doi = {10.1039/c2jm35013k}, author = {Mitra, Shouvik and Subia, B. and Patra, Prasun and Chandra, Sourov and Debnath, Nitai and Das, Sumistha and Banerjee, Rahul and Kundu, Subhas C. and Pramanik, Panchanan and Goswami, Arunava} } @article { ISI:000316624600020, title = {POM-catalyzed in situ ligand synthesis for the construction of metal complexes and their use in the formation of coordination polymers}, journal = {Chemphyschem}, volume = {14}, number = {5}, year = {2013}, month = {APR}, pages = {1009-1015}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

Six organicinorganic hybrid materials were synthesized by the in situ oxidation of neocuproine by using MoO3/Na2MoO4 as the catalyst in the presence of Cu(NO3)2. The crystal structures of Mo8-Cu4-PHEN and Mo8-Cu2-5(2PIC) are composed of [Mo8O26]4 polyoxometalate (POM) units, whereas the crystal structure of Mo6-Cu-COPHEN is composed of a [Mo6O19]2 POM unit; both POM units could be considered as the active form of the catalyst. Reaction of the hybrid materials with 1,3,5-benzenetricarboxylic acid (BTC) resulted in the formation of two different coordination polymers (CPs) under different reaction conditions. These CPs, depending on their structural attributes, exhibit distinct differences in the adsorption of H2, CO2, and water. The use of 2-methylpyridine instead of neocuproine does not give any oxidation products under the same reaction conditions due to the incorrect positioning of the methyl group with respect to the CuII center.

}, keywords = {coordination polymers, Copper, N ligands, organicinorganic hybrid composites, polyoxometalates}, issn = {1439-4235}, doi = {10.1002/cphc.201201019}, author = {Dey, Chandan and Banerjee, Rahul} } @article { ISI:000326300200011, title = {Porous carbons from nonporous MOFs: influence of ligand characteristics on intrinsic properties of end carbon}, journal = {Crystal Growth \& Design}, volume = {13}, number = {10}, year = {2013}, month = {OCT}, pages = {4195-4199}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Synthesis of porous carbons on direct carbonization of nonporous Zn-based MOFs has been achieved without using any additional carbon precursor. The effect of ligand nature on the resulting carbon porosity has been studied systematically using the MOFs synthesized from rigid and flexible ligands. The linear relations between Zn/C ratio of the MOF versus surface area of the resulting carbon, micro-porosity versus H-2 uptake achieved in these carbons, and surface area versus specific capacitance of the end carbons have been verified from the gas adsorption, molecular composition, and electrochemical studies, respectively. Cyclic voltammetry and charge-discharge cycling have been carried out to study the capacitive behavior of the carbons. The interdependence of capacitive behavior on the surface area has been analyzed using data derived from N-2 adsorption isotherms and charge-discharge curves. Among the carbons synthesized, C-MOF-2 shows maximal surface area of 1378 m(2)/g with a specific capacitance of 170 F/g at 1 A/g.

}, issn = {1528-7483}, doi = {10.1021/cg401122u}, author = {Aiyappa, Harshitha Barike and Pachfule, Pradip and Banerjee, Rahul and Kurungot, Sreekumar} } @article { ISI:000313263300022, title = {Porous-organic-framework-templated nitrogen-rich porous carbon as a more proficient electrocatalyst than Pt/C for the electrochemical reduction of oxygen}, journal = {Chemistry-A European Journal}, volume = {19}, number = {3}, year = {2013}, month = {JAN}, pages = {974-980}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

Porous nitrogen-rich carbon (POF-C-1000) that was synthesized by using a porous organic framework (POF) as a self-sacrificing host template in a nanocasting process possessed a high degree of graphitization in an ordered structural arrangement with large domains and well-ordered arrays of carbon sheets. POF-C-1000 exhibits favorable electrocatalytic activity for the oxygen-reduction reaction (ORR) with a clear positive shift of about 40 mV in the onset potential compared to that of a traditional, commercially available Pt/C catalyst. In addition, irrespective of its moderate surface area (785 m2?g-1), POF-C-1000 showed a reasonable H2 adsorption of 1.6 wt?\% (77 K) and a CO2 uptake of 3.5 mmol?g-1 (273 K).

}, keywords = {Adsorption, Electrochemistry, fuel cells, oxygen-reduction reaction, porous organic frameworks}, issn = {0947-6539}, doi = {10.1002/chem.201202940}, author = {Pachfule, Pradip and Dhavale, Vishal M. and Kandambeth, Sharath and Kurungot, Sreekumar and Banerjee, Rahul} } @article { ISI:000321431600027, title = {Proton-conducting supramolecular metallogels from the lowest molecular weight assembler ligand: a quote for simplicity}, journal = {Chemistry-A European Journal}, volume = {19}, number = {29}, year = {2013}, month = {JUL}, pages = {9562-9568}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

Oxalic acid has been proven to be the lowest molecular weight organic ligand able to form robust supramolecular metallogel networks in the presence of metal salts. In particular, two novel multifunctional metallogels were readily prepared at room temperature by simple mixing of stock solutions of Cu-II acetate monohydrate or Cu-II perchlorate hexahydrate and oxalic acid dihydrate. Formation of different polymorphs and unprecedented proton conduction under anhydrous conditions were also demonstrated with some of these materials.

}, keywords = {Copper, low-molecular-weight ligands, metallogels, proton conductivity, supramolecular chemistry}, issn = {0947-6539}, doi = {10.1002/chem.201204542}, author = {Saha, Subhadeep and Schoen, Eva-Maria and Cativiela, Carlos and Diaz, David Diaz and Banerjee, Rahul} } @article { ISI:000335720200011, title = {Phosphoric acid loaded azo (-N=N-) based covalent organic framework for proton conduction}, journal = {Journal of the American Chemical Society}, volume = {136}, number = {18}, year = {2014}, month = {MAY}, pages = {6570-6573}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Two new chemically stable functional crystalline covalent organic frameworkds (COFs) (Tp-Azo and Tp-Stb) were synthesized using the Schiff base reaction between triformylphloroglucinol (Tp) and 4,4{\textquoteright}-azodianiline (Azo) or 4,4{\textquoteright}-diaminostilbene (Stb), respectively. Both COFs show the expected keto-enamine form, and high stability toward boiling water, strong acidic, and basic media. H3PO4 doping in Tp-Azo leads to immobilization of the acid within the porous framework, which facilitates proton conduction in both the hydrous (sigma = 9.9 X 10(-4) S cm(-1)) and anhydrous state (sigma = 6.7 X 10(-5) S cm-1). This report constitutes the first emergence of COFs as proton conducting materials.

}, issn = {0002-7863}, doi = {10.1021/ja502212v}, author = {Chandra, Suman and Kundu, Tanay and Kandambeth, Sharath and BabaRao, Ravichandar and Marathe, Yogesh N. and Kunjir, Shrikant M. and Banerjee, Rahul} } @article { ISI:000343686500039, title = {Photocatalytic metal-organic framework from cds quantum dot incubated luminescent metallohydrogel}, journal = {Journal of the American Chemical Society}, volume = {136}, number = {42}, year = {2014}, month = {OCT}, pages = {14845-14851}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Cadmium sulfide (CdS) quantum dots (\<10 nm in size) have been successfully synthesized in situ without any capping agent in a Zn(II)-based low-molecular-weight metallohydrogel (ZAVA). Pristine ZAVA hydrogel shows blue luminescence, but the emission can be tuned upon encapsulation of the CdS quantum dots. Time-dependent tunable emission (white to yellow to orange) of the CdS incubated gel (CdS@ZAVA gel) can be attributed to sluggish growth of the quantum dots inside the gel matrix. Once CdS quantum dots are entrapped, their augmentation can be stopped by converting the gel into xerogel, wherein the quantum dots remains embedded in the solid xerogel matrix. Similar size stabilization of CdS quantum dots can be achieved by means of a unique room-temperature conversion of the CdS incubated ZAVA gel to CdS incubated MOF (CdS@ZAVCl) crystals. This in turn arrests the tunability in emission owing to the restriction in the growth of CdS quantum dots inside xerogel and MOF. These CdS embedded MOFs have been utilized as a catalyst for water splitting under visible light.

}, issn = {0002-7863}, doi = {10.1021/0509019k}, author = {Saha, Subhadeep and Das, Gobinda and Thote, Jayshri and Banerjee, Rahul} } @article {46382, title = {Photochromic metal organic frameworks for inkless and erasable printing}, journal = {Acta Crystallographica A-Foundation and Advances}, volume = {70}, year = {2014}, month = {MAY}, pages = {C110}, type = {Meeting Abstract}, keywords = {Erasable Printing, Inkless Printing, metal organic framework}, issn = {2053-2733}, author = {Garai, Bikash and Banerjee, Rahul} } @article { ISI:000332124800027, title = {Post modification of MOF derived carbon via g-C3N4 entrapment for an efficient metal-free oxygen reduction reaction}, journal = {Chemical Communications}, volume = {50}, number = {25}, year = {2014}, month = {FEB}, pages = {3363-3366}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

High surface area carbon with a nitrogen content of 7.0\% is derived from MOF via in situ g-C3N4 formation. The material shows excellent ORR activity with an onset potential of 0.035 V (vs. Hg/HgO) in alkaline medium apart from high durability and strong disinclination towards methanol crossover.

}, issn = {1359-7345}, doi = {10.1039/c3cc47620k}, author = {Pandiaraj, Sekar and Aiyappa, Harshitha Barike and Banerjee, Rahul and Kurungot, Sreekumar} } @article { ISI:000346189100095, title = {Phosphate enriched polyoxometalate based ionic salts for proton conduction}, journal = {RSC Advances}, volume = {5}, number = {3}, year = {2015}, month = {DEC}, pages = {2333-2337}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A series of [NiMo12O30(PO4)(8)](n-) POM anion and organic cation based ionic composites have been prepared in hydrothermal conditions. The ionic composites with protonated ethylene diamine molecules have been tested for proton conductivity.

}, issn = {2046-2069}, doi = {10.1039/c4ra07598f}, author = {Dey, Chandan and Kundu, Tanay and Aiyappa, Harshitha Barike and Banerjee, Rahul} } @article { ISI:000365205000004, title = {Pore surface engineering in porous, chemically stable covalent organic frameworks for water adsorption}, journal = {Journal of Materials Chemistry A}, volume = {3}, number = {47}, year = {2015}, month = {NOV}, pages = {23664-23669}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

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.

}, issn = {2050-7488}, doi = {10.1039/c5ta07998e}, author = {Biswal, Bishnu P. and Kandambeth, Sharath and Chandra, Suman and Shinde, Digambar Balaji and Bera, Saibal and Karak, Suvendu and Garai, Bikash and Kharul, Ulhas K. and Banerjee, Rahul} } @article { ISI:000371021900071, title = {Photochromic metal-organic frameworks for inkless and erasable printing}, journal = {Chemical Science}, volume = {7}, number = {3}, year = {2016}, month = {DEC}, pages = {2195-2200}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Inkless and erasable printing is the key solution towards a more sustainable paper industry, in terms of reducing paper wastages and the associated environmental hazards from waste paper processing. However, only a few cases have been reported in the literature where inkless printing has been tested in some practical systems. In an attempt to address this solution, we used photochromic metal-organic frameworks (MOFs) and tested their capability as inkless and erasable printing media. The printing was performed using sunlight as the light source on MOF-coated papers. The resulting printing had good resolution and stability, and was capable of being read both by the human eye and smart electronic devices; furthermore, the paper could be reused for several cycles without any significant loss in intensity. Interestingly, different coloured printing with a similar efficiency was achieved by varying the structure of the MOF.

}, issn = {2041-6520}, doi = {10.1039/c5sc04450b}, author = {Garai, Bikash and Mallick, Arijit and Banerjee, Rahul} } @article {43721, title = {Porous porphyrin organic polymer (PPOP) for visible light triggered hydrogen production}, journal = {Chemical Communications}, volume = {53}, year = {2017}, month = {APR}, pages = {4461-4464}, type = {Article}, chapter = {4461-4464}, abstract = {A visible light active porphyrin-based porous organic polymer having high chemical stability and surface area has been synthesized and its ability to influence the photocatalytic activity of large band gap-TiO2 nanoparticles has been tested. The resultant composite shows improved photocatalytic activity as compared to the parent precursors. This study provides insights into the photosensitizing ability of the polymer in addition to its ability to firmly harbor nanoparticles onto its surface.}, doi = {10.1039/c7cc00879a}, author = {Mukherjee, Gargi and Thote, Jayshri and Aiyappa, Harshitha Barike and Kandambeth, Sharath and Banerjee, Subhrashis and Vanka, Kumar and Banerjee, Rahul} } @article {43732, title = {Predesigned metal-anchored building block for in situ generation of Pd nanoparticles in porous covalent organic framework: application in heterogeneous tandem catalysis}, journal = {ACS Applied Materials \& Interfaces}, volume = {9}, year = {2017}, month = {APR}, pages = {13785-13792}, type = {Article}, abstract = {The development of nanoparticle-polymer-hybrid-based heterogeneous catalysts with high reactivity and good recyclability is highly desired for their applications in the chemical and pharmaceutical industries: Herein, we have developed a novel synthetic strategy by choosing a predesigned metal-anchored building block for in situ generation of metal (Pd) nanoparticles in the stable, porous, and crystalline covalent organic framework (COF), without using conventional reducing agents. In situ generation of Pd nanoparticles in the COF Skeleton is explicitly confirmed{\textquoteright} from PXRD, XPS, TEM images, and N-15 NMR spectral analysis. This hybrid material is found to be an excellent reusable heterogeneous catalyst for the synthesis of biologically and pharmaceutically important 2-substituted benzofurans from 2-bromophencils and terminal alkynes via a tandem process with the turnover number up to 1101. The heterogeneity of the catalytic process is unambiguously verified by a mercury poisoning experiment and leaching test. This hybrid material shows superior catalytic performance compared to commercially available homogeneous as well as heterogeneous Pd catalysts.}, doi = {10.1021/acsami.7b02355}, author = {Bhadra, Mohitosh and Sasmal, Himadri Sekhar and Basu, Arghya and Midya, Siba P. and Kandambeth, Sharath and Pachfule, Pradip and Balaraman, Ekambaram and Banerjee, Rahul} } @article {44399, title = {Porosity prediction through hydrogen bonding in covalent organic frameworks}, journal = {Journal of the American Chemical Society}, volume = {140}, year = {2018}, month = {APR}, pages = {5138-5145}, abstract = {Easy 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{\textquoteright} 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.}, doi = {10.1021/jacs.7b13558}, author = {Karak, Suvendu and Kumar, Sushil and Pachfule, Pradip 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 {48209, title = {Porous covalent organic nanotubes and their assembly in loops and toroids}, journal = {Nature Chemistry}, volume = {14}, year = {2022}, month = {MAY}, pages = {507+}, type = {Article}, abstract = {

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.

}, issn = {1755-4330}, doi = {10.1038/s41557-022-00908-1}, author = {Koner, Kalipada and Karak, Shayan and Kandambeth, Sharath and Karak, Suvendu and Thomas, Neethu and Leanza, Luigi and Perego, Claudio and Pesce, Luca and Capelli, Riccardo and Moun, Monika and Bhakar, Monika and Ajithkumar, Thalasseril G. and Pavan, Giovanni M. and Banerjee, Rahul} }