- 3D cage Cofs: A dynamic three-dimensional covalent organic framework with high-connectivity organic cage nodes
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Three-dimensional (3D) covalent organic frameworks (COFs) are rare because there is a limited choice of organic building blocks that offer multiple reactive sites in a polyhedral geometry. Here, we synthesized an organic cage molecule (Cage-6NH2) that was used as a triangular prism node to yield the first cage-based 3D COF, 3D-CageCOF-1. This COF adopts an unreported 2-fold interpenetrated acs topology and exhibits reversible dynamic behavior, switching between a small-pore (sp) structure and a large-pore (lp) structure. It also shows high CO2 uptake and captures water at low humidity (40%). This demonstrates the potential for expanding the structural complexity of 3D COFs by using organic cages as the building units.
- Chen, Linjiang,Clowes, Rob,Cooper, Andrew I.,Cui, Peng,Little, Marc A.,Wang, Xue,Zhu, Qiang
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- Rigid chain ribbon-like metallopolymers
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A set of new copolymers is here reported in which the repeating units are connected each other through Cu(II) metal centers. The coordination link is based on the bis-chelating properties of salicylaldiminate groups of two different monomers. Due to their chemical structure, the two monomers afford, respectively, flexible and rigid repeating units in the metallocopolymers constitution upon coordination to copper centers. All the copolymers were soluble and easily processable. As shown by XRD analysis, rigid units' rich copolymers adopt a ribbon-like structure in solid state in which highly planar strands of polymer stack thanks to π-π interactions, similarly to the polymer composed exclusively by rigid units. This behavior can be justified assuming the existence of a partial block character in copolymer constitution where long sequences of rigid units are alternated to sequences of flexible units. This assumption is supported also by DSC and UV-Vis analysis.
- Carella, Antonio,Borbone, Fabio,Roviello, Giuseppina,Caruso, Ugo,Ferone, Claudio,Ricciotti, Laura,Pirozzi, Beniamino,Persico, Paola,Schieroni, Alberto Giacometti,Roviello, Antonio
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- A novel bifunctional-group salamo-like multi-purpose dye probe based on ESIPT and RAHB effect: Distinction of cyanide and hydrazine through optical signal differential protocol
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A novel bifunctional-group multi-purpose dye probe p-TNS has been designed and synthesized. The probe p-TNS has unique excited-state intramolecular proton transfer (ESIPT) and resonance-assisted hydrogen bonding (RAHB) coupled system, was confirmed to detect cyanide and hydrazine by blocking the ESIPT effect. Cyanide can change the fluorescence of the solution from bright green to orange-red (116 nm Stokes shift), while hydrazine causes the bright green fluorescence to be quenched. The recognition mechanism of the probe p-TNS to CN? and N2H4 was proposed reasonably through spectral characterizations and theoretical calculations. Combined with theoretical calculations, it was speculated that the solvent dependence may be caused by the ICT effect in the molecule. The probe p-TNS could be prepared into test strips for the detection of cyanide and hydrazine. In addition, the probe molecule can also be used to detect trace amounts of cyanide in agricultural products, and respond to gaseous hydrazine by direct contact, indicating that the probe p-TNS has good practical application prospects. Therefore, this molecular framework provides a new way of thinking about detecting multiple target substances.
- Chen, Zhuang-Zhuang,Deng, Yun-Hu,Zhang, Ting,Dong, Wen-Kui
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- Photochromism and proton transfer reaction cycle of new internally H-bonded Schiff bases
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A family of new Schiff bases, derivatives of hydroquinone, has been synthesized. Their synthesis, spectroscopy and photophysics are reported. Two molecules, having one or two internal H-bonds, reveal photochromic properties. Two transients absorbing in the visible have been detected and kinetically separated: one, with lifetime ≈ 300 ps, λmax = 570 nm, was assigned as the Sl → Sn absorption of the primary product of single proton transfer, the second, with lifetime 1.2 ms, λmax = 540 nm, was interpreted as the photochromic modification of the molecule.
- Grabowska,Kownacki,Karpiuk,Dobrin,Kaczmarek
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- Synergistic Effect of Covalent Bonding and Physical Encapsulation of Sulfur in the Pores of a Microporous COF to Improve Cycling Performance in Li-S Batteries
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Lithium-sulfur batteries stands out as a promising technology for energy storage owing to a combination of favorable characteristics including a high theoretical gravimetric capacity, energy density, inexpensive character, and environmental benignity. Covalent organic frameworks (COFs) are a rapidly developing family of functional nanostructures which combine porosity and crystallinity, and which have been already used in these kinds of batteries to build sulfur electrodes, by embedding sulfur into porous COFs in order to enhance cycle lifetimes. In this contribution, this is taken one step forward and a COF endowed with vinyl groups is used, in order to graft sulfur to the COF skeleton through inverse vulcanization. The main aim of the article is to show the synergistic effect of covalent bonding and physical encapsulation of sulfur in the pores of the COF in order to alleviate the fatal redox shuttling process, to improve the cycling performance, and to provide faster ion diffusion pathways. In addition, it is shown how the material with covalently-bound S provides better electrochemical performance under demanding and/or changeable charge conditions than a parent analogue material with sulfur physically confined, but without covalent linkage.
- Royuela, Sergio,Almarza, Joaquín,Manche?o, María J.,Pérez-Flores, Juan C.,Michel, Enrique G.,Ramos, María M.,Zamora, Félix,Ocón, Pilar,Segura, José L.
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- Multistep solid-state organic synthesis of carbamate-linked covalent organic frameworks
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Herein, we demonstrate the first example of a multistep solid-state organic synthesis, in which a new imine-linked two-dimensional covalent organic framework (COF-170, 1) was transformed through three consecutive postsynthetic modifications into porous, crystalline cyclic carbamate and thiocarbamate-linked frameworks. These linkages are previously unreported and inaccessible through de novo synthesis. While not altering the overall connectivity of the framework, these chemical transformations induce significant conformational and structural changes at each step, highlighting the key importance of noncovalent interactions and conformational flexibility to COF crystallinity and porosity. These transformations were assessed using 15N multiCP-MAS NMR spectroscopy, providing the first quantitation of yields in COF postsynthetic modification reactions, as well as of amine defect sites in imine-linked COFs. This multistep COF linkage postsynthetic modification represents a significant step toward bringing the precision of organic solution-phase synthesis to extended solid-state compounds.
- Lyle, Steven J.,Osborn Popp, Thomas M.,Waller, Peter J.,Pei, Xiaokun,Reimer, Jeffrey A.,Yaghi, Omar M.
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- Metalloporphyrin and Ionic Liquid-Functionalized Covalent Organic Frameworks for Catalytic CO2Cycloaddition via Visible-Light-Induced Photothermal Conversion
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We report the construction of a porphyrin and imidazolium-ionic liquid (IL)-decorated and quinoline-linked covalent organic framework (COF, abbreviated as COF-P1-1) via a three-component one-pot Povarov reaction. After post-synthetic metallization of COF-P1-1 with Co(II) ions, the metallized COF-PI-2 is generated. COF-PI-2 is chemically stable and displays highly selective CO2 adsorption and good visible-light-induced photothermal conversion ability (ΔT = 26 °C). Furthermore, the coexistence of Co(II)-porphyrin and imidazolium-IL within COF-PI-2 has guaranteed its highly efficient activity for CO2 cycloaddition. Of note, the needed thermal energy for the reactions is derived from the photothermal conversion of the Co(II)-porphyrin COF upon visible-light irradiation. More importantly, the CO2 cycloaddition herein is a "window ledge"reaction, and it can proceed smoothly upon natural sunlight irradiation. In addition, a scaled-up CO2 cycloaddition can be readily achieved using a COF-PI-2@chitosan aerogel-based fixed-bed model reactor. Our research provides a new avenue for COF-based greenhouse gas disposal in an eco-friendly and energy- and source-saving way.
- Ding, Luo-Gang,Yao, Bing-Jian,Wu, Wen-Xiu,Yu, Zhi-Gao,Wang, Xiao-Yu,Kan, Jing-Lan,Dong, Yu-Bin
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p. 12591 - 12601
(2021/08/24)
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- Designing Nonfullerene Acceptors with Oligo(Ethylene Glycol) Side Chains: Unraveling the Origin of Increased Open-Circuit Voltage and Balanced Charge Carrier Mobilities
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Despite the recent rapid development of organic solar cells (OSCs), the low dielectric constant (?r=3–4) of organic semiconducting materials limits their performance lower than inorganic and perovskite solar cells. In this work, we introduce oligo(ethylene glycol) (OEG) side chains into the dicyanodistyrylbenzene-based non-fullerene acceptors (NIDCS) to increase its ?r up to 5.4. In particular, a NIDCS acceptor bearing two triethylene glycol chains (NIDCS-EO3) shows VOC as high as 1.12 V in an OSC device with a polymer donor PTB7, which is attributed to reduced exciton binding energy of the blend film. Also, the larger size grain formation with well-ordered stacking structure of the NIDCS-EO3 blend film leads to the increased charge mobility and thus to the improved charge mobility balance, resulting in higher JSC, FF, and PCE in the OSC device compared to those of a device using the hexyl chain-based NIDCS acceptor (NIDCS-HO). Finally, we fabricate NIDCS-EO3 devices with various commercial donors including P3HT, DTS-F, and PCE11 to show higher photovoltaic performance than the NIDCS-HO devices, suggesting versatility of NIDCS-EO3.
- Cui, Junjie,Park, Jung-Hwa,Kim, Dong Won,Choi, Min-Woo,Chung, Hae Yeon,Kwon, Oh Kyu,Kwon, Ji Eon,Park, Soo Young
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supporting information
p. 2481 - 2488
(2021/07/26)
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- Humidity Sensing through Reversible Isomerization of a Covalent Organic Framework
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Here we report that a covalent organic framework (COF), which contains 2,5-di(imine)-substituted 1,4-dihydroxybenzene (diiminol) moieties, undergoes color changes in the presence of solvents or solvent vapor that are rapid, passive, reversible, and easily detectable by the naked eye. A new visible absorption band appears in the presence of polar solvents, especially water, suggesting reversible conversion to another species. This reversibility is attributed to the ability of the diiminol to rapidly tautomerize to an iminol/cis-ketoenamine and its inability to doubly tautomerize to a diketoenamine. Density functional theory (DFT) calculations suggest similar energies for the two tautomers in the presence of water, but the diiminol is much more stable in its absence. Time-dependent DFT calculations confirm that the iminol/cis-ketoenamine absorbs at longer wavelength than the diiminol and indicate that this absorption has significant charge-transfer character. A colorimetric humidity sensing device constructed from an oriented thin film of the COF responded quickly to water vapor and was stable for months. These results suggest that tautomerization-induced electronic structure changes can be exploited in COF platforms to give rapid, reversible sensing in systems that exhibit long-term stability.
- Jhulki, Samik,Evans, Austin M.,Hao, Xue-Li,Cooper, Matthew W.,Feriante, Cameron H.,Leisen, Johannes,Li, Hong,Lam, David,Hersam, Mark C.,Barlow, Stephen,Brédas, Jean-Luc,Dichtel, William R.,Marder, Seth R.
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p. 783 - 791
(2020/02/20)
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- Photocatalytic Molecular Oxygen Activation by Regulating Excitonic Effects in Covalent Organic Frameworks
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Excitonic effects caused by Coulomb interactions between electrons and holes play subtle and significant roles on photocatalysis, yet have been long ignored. Herein, porphyrinic covalent organic frameworks (COFs, specifically DhaTph-M), in the absence or presence of different metals in porphyrin centers, have been shown as ideal models to regulate excitonic effects. Remarkably, the incorporation of Zn2+ in the COF facilitates the conversion of singlet to triplet excitons, whereas the Ni2+ introduction promotes the dissociation of excitons to hot carriers under photoexcitation. Accordingly, the discriminative excitonic behavior of DhaTph-Zn and DhaTph-Ni enables the activation of O2 to 1O2 and O2?-, respectively, under visible light irradiation, resulting in distinctly different activity and selectivity in photocatalytic terpinene oxidation. Benefiting from these results, DhaTph-Ni exhibits excellent photocatalytic activity in O2?-engaged hydroxylation of boronic acid, while DhaTph-Zn possesses superior performance in 1O2-mediated selective oxidation of organic sulfides. This work provides in-depth insights into molecular oxygen activation and opens an avenue to the regulation of excitonic effects based on COFs.
- Qian, Yunyang,Li, Dandan,Han, Yulan,Jiang, Hai-Long
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p. 20763 - 20771
(2020/12/23)
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- Synthesis of fully-fused bisboron azomethine complexes and their conjugated polymers with solid-state near-infrared emission
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We describe herein a robust π-conjugated molecules with solid-state emission in the near-infrared (NIR) region (ΦF = 0.03-0.06). Initially, the diastereomers of bisboron azomethine complexes having phenyl groups in the same and opposite directions to the π-plane were synthesized. These diastereomers showed emission properties with larger red-shifts (>200 nm) and 10 times larger emission efficiencies than those of the mononuclear complex. Theoretical calculation data indicate that superior optical properties of the bisboron complexes should be attributable to efficient expansion of the π-conjugated system. In addition, the bisboron compounds and their conjugated polymers exhibited intense NIR emissions even in the solid state. This journal is
- Chujo, Yoshiki,Gon, Masayuki,Nakamura, Masashi,Ohtani, Shunsuke,Tanaka, Kazuo
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supporting information
p. 6575 - 6578
(2020/07/02)
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- Reaction Environment Modification in Covalent Organic Frameworks for Catalytic Performance Enhancement
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Herein, we show how the spatial environment in the functional pores of covalent organic frameworks (COFs) can be manipulated in order to exert control in catalysis. The underlying mechanism of this strategy relies on the placement of linear polymers in the pore channels that are anchored with catalytic species, analogous to outer-sphere residue cooperativity within the active sites of enzymes. This approach benefits from the flexibility and enriched concentration of the functional moieties on the linear polymers, enabling the desired reaction environment in close proximity to the active sites, thereby impacting the reaction outcomes. Specifically, in the representative dehydration of fructose to produce 5-hydroxymethylfurfural, dramatic activity and selectivity improvements have been achieved for the active center of sulfonic acid groups in COFs after encapsulation of polymeric solvent analogues 1-methyl-2-pyrrolidinone and ionic liquid.
- Sun, Qi,Tang, Yongquan,Aguila, Briana,Wang, Sai,Xiao, Feng-Shou,Thallapally, Praveen K.,Al-Enizi, Abdullah M.,Nafady, Ayman,Ma, Shengqian
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p. 8670 - 8675
(2019/05/07)
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- Perylene-based covalent organic frameworks for acid vapor sensing
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Traditionally, the properties and functions of covalent organic frameworks (COFs) are defined by their constituting building blocks, while the chemical bonds that connect the individual subunits have not attracted much attention as functional components of the final material. We have developed a new series of dual-pore perylene-based COFs and demonstrated that their imine bonds can be protonated reversibly, causing significant protonation-induced color shifts toward the near-infrared, while the structure and crystallinity of the frameworks are fully retained. Thin films of these COFs are highly sensitive colorimetric acid vapor sensors with a detection limit as low as 35 μg L-1 and a response range of at least 4 orders of magnitude. Since the acidochromism in our COFs is a cooperative phenomenon based on electronically coupled imines, the COFs can be used to determine simultaneously the concentration and protonation strength of nonaqueous acid solutions, in which pH electrodes are not applicable, and to distinguish between different acids. Including the imine bonds as function-determining constituents of the framework provides an additional handle for constructing multifunctional COFs and extending the range of their possible applications.
- Ascherl, Laura,Evans, Emrys W.,Gorman, Jeffrey,Orsborne, Sarah,Bessinger, Derya,Bein, Thomas,Friend, Richard H.,Auras, Florian
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supporting information
p. 15693 - 15699
(2019/10/14)
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- Experimental and theoretical insights into molecular and solid-state properties of isomeric Bis(salicylaldehydes)
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A series of five bis(salicylaldehydes), including four isomeric compounds based on a benzene scaffold and a closely related naphthalene derivative, were investigated in order to elucidate the impact of resonance effects and intramolecular hydrogen bonds (HBs) on the macroscopic properties of these systems. Density functional theory (DFT) computations revealed important differences between isomers on the molecular level, which was reflected in different charge distributions, aromatic C-C bond orders, and aromaticity characters. The consequences of these features were evidenced by the UV-vis absorption spectra: for 1,3-diformyl-4,6-dihydroxybenzene (2), the longest wavelength absorption band is observed at 285 nm, while its isomers 1,4-diformyl-2,5-dihydroxybenzene (1), 1,4-diformyl-2,3-dihydroxybenzene (3), and 1,2-diformyl-3,6-dihydroxybenzene (4) are characterized by absorption in the visible range (379-407 nm). The specificity of 2 results from simultaneous lowering and elevation of HOMO and LUMO energy levels, respectively. We have found that the HOMO/LUMO energy variations follow trends observed in isomeric dihydroxybenzenes (HOMO) and phthalaldehydes (LUMO), and these effects operate separately to some extent. Furthermore, theoretical calculations indicate that the UV-vis spectral properties of bis(salicylaldehydes) are directly transferable to the corresponding bis(salicylaldimines) and their boron complexes. Finally, the influence of structural and molecular stabilization effects was analyzed by means of X-ray structural analysis and periodic DFT computations.
- Durka, Krzysztof,Górski, Bartosz,B?ocki, Krzysztof,Urban, Mateusz,Wo?niak, Krzysztof,Barbasiewicz, Micha?,Luliński, Sergiusz
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p. 8674 - 8689
(2019/10/11)
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- Covalent organic frameworks: Efficient, metal-free, heterogeneous organocatalysts for chemical fixation of CO2 under mild conditions
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The cycloaddition of CO2 to epoxides to form cyclic carbonates is very promising and does not generate any side products. Metal-free, heterogeneous organocatalysts offer an environmentally friendly alternative to traditional metal-based catalysts. Herein two triazine-based covalent organic frameworks (COF-JLU6 and COF-JLU7) were successfully synthesized under solvothermal conditions. The structural and chemical properties of COFs were fully characterized by using powder X-ray diffraction analysis, structural simulation, Fourier transform infrared spectroscopy, 13C solid-state NMR spectroscopy, electron microscopy, thermogravimetric analysis and nitrogen adsorption. The two COF materials combine mesopores, high crystallinity and good stability, as well as a large number of hydroxy groups in the pore walls. They possess a high Brunauer-Emmett-Teller (BET) specific surface area up to 1390 m2 g-1 and a large pore volume of 1.78 cm3 g-1. The COF-JLU7 displays a high CO2 uptake of 151 mg g-1 at 273 K and 1 bar. Importantly, COF-JLU7 was found to be a highly effective catalyst to convert CO2 into cyclic carbonate through the cycloaddition reaction with epoxides under mild conditions. The effect of reaction parameters, such as reaction temperature, reaction time and CO2 pressure, on the catalytic performance was also investigated in detail. Moreover, the new framework-based catalyst can be recovered and reused five times without a significant loss of catalytic efficiency.
- Zhi, Yongfeng,Shao, Pengpeng,Feng, Xiao,Xia, Hong,Zhang, Yumin,Shi, Zhan,Mu, Ying,Liu, Xiaoming
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p. 374 - 382
(2018/01/12)
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- Stack the Bowls: Tailoring the Electronic Structure of Corannulene-Integrated Crystalline Materials
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We report the first examples of purely organic donor–acceptor materials with integrated π-bowls (πBs) that combine not only crystallinity and high surface areas but also exhibit tunable electronic properties, resulting in a four-orders-of-magnitude conductivity enhancement in comparison with the parent framework. In addition to the first report of alkyne–azide cycloaddition utilized for corannulene immobilization in the solid state, we also probed the charge transfer rate within the Marcus theory as a function of mutual πB orientation for the first time, as well as shed light on the density of states near the Fermi edge. These studies could foreshadow new avenues for πB utilization for the development of optoelectronic devices or a route for highly efficient porous electrodes.
- Rice, Allison M.,Dolgopolova, Ekaterina A.,Yarbrough, Brandon J.,Leith, Gabrielle A.,Martin, Corey R.,Stephenson, Kenneth S.,Heugh, Rebecca A.,Brandt, Amy J.,Chen, Donna A.,Karakalos, Stavros G.,Smith, Mark D.,Hatzell, Kelsey B.,Pellechia, Perry J.,Garashchuk, Sophya,Shustova, Natalia B.
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p. 11310 - 11315
(2018/08/11)
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- Pore Environment Control and Enhanced Performance of Enzymes Infiltrated in Covalent Organic Frameworks
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In the drive toward green and sustainable methodologies for chemicals manufacturing, biocatalysts are predicted to have much to offer in the years to come. That being said, their practical applications are often hampered by a lack of long-term operational stability, limited operating range, and a low recyclability for the enzymes utilized. Herein, we show how covalent organic frameworks (COFs) possess all the necessary requirements needed to serve as ideal host materials for enzymes. The resultant biocomposites of this study have shown the ability boost the stability and robustness of the enzyme in question, namely lipase PS, while also displaying activities far outperforming the free enzyme and biocomposites made from other types of porous materials, such as mesoporous silica and metal-organic frameworks, exemplified in the kinetic resolution of the alcohol assays performed. The ability to easily tune the pore environment of a COF using monomers bearing specific functional groups can improve its compatibility with a given enzyme. As a result, the orientation of the enzyme active site can be modulated through designed interactions between both components, thus improving the enzymatic activity of the biocomposites. Moreover, in comparison with their amorphous analogues, the well-defined COF pore channels not only make the accommodated enzymes more accessible to the reagents but also serve as stronger shields to safeguard the enzymes from deactivation, as evidenced by superior activities and tolerance to harsh environments. The amenability of COFs, along with our increasing understanding of the design rules for stabilizing enzymes in an accessible fashion, gives great promise for providing "off the shelf" biocatalysts for synthetic transformations.
- Sun, Qi,Fu, Chung-Wei,Aguila, Briana,Perman, Jason,Wang, Sai,Huang, Hsi-Ya,Xiao, Feng-Shou,Ma, Shengqian
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p. 984 - 992
(2018/02/07)
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- Removal of GenX and Perfluorinated Alkyl Substances from Water by Amine-Functionalized Covalent Organic Frameworks
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Per- and polyfluorinated alkyl substances (PFAS), such as perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS), and ammonium perfluoro-2-propoxypropionate (GenX), contaminate ground and surface waters throughout the world. The cost and performance limitations of current PFAS removal technologies motivate efforts to develop selective and high-affinity adsorbents. Covalent organic frameworks (COFs) are unexplored yet promising adsorbents because of their high surface area and tunable pore sizes. Here we show that imine-linked two-dimensional (2D) COFs bearing primary amines adsorb GenX rapidly at environmentally relevant concentrations. COFs with partial amine incorporation showed the highest capacity and fastest removal, suggesting that the synergistic combination of the polar group and hydrophobic surfaces are responsible for GenX binding. A COF with 28% amine loading also removed more than 90% of 12 out of 13 PFAS. These results demonstrate the promise of COFs for PFAS removal and suggest design criteria for maximizing adsorbent performance.
- Ji, Woojung,Xiao, Leilei,Ling, Yuhan,Ching, Casey,Matsumoto, Michio,Bisbey, Ryan P.,Helbling, Damian E.,Dichtel, William R.
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supporting information
p. 12677 - 12681
(2018/10/15)
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- METHODS FOR IDENTIFYING PROTEINS BY USING SYNTHETIC RECEPTORS
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The invention relates to oligomeric macrocycles and to uses thereof as receptors for recognition of protein post-translational modifications (PTM) or specific motifs in proteins.
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- Efficient symmetrical bidentate dioxime ligand-accelerated homogeneous palladium-catalyzed Suzuki-Miyaura coupling reactions of aryl chlorides
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A series of N,O-bidentate ligands were synthesized using the Vilsmeier-Haack reaction and oximation. 2,5-Dihydroxyterephthalaldehyde dioxime (L8) as an efficient N,O-symmetrical bidentate ligand was prepared from hydroquinone. It was studied as a high activity ligand for palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions. The coupling reactions were performed in the presence of PdCl2 as the catalyst, L8 as the ligand, Na2CO3 as the base, PEG-400 as the PTC and in ethanol/water (1?:?1) as an environmentally benign solvent at 85 °C. Plentiful biaryls were obtained by the optimized reaction with good yields at a low palladium loading of 0.20 mol%.
- Song, Jinyi,Zhao, Hongyan,Liu, Yang,Han, Huatao,Li, Zhuofei,Chu, Wenyi,Sun, Zhizhong
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supporting information
p. 372 - 376
(2016/12/30)
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- Hydrogen-Bonding-Induced Fluorescence: Water-Soluble and Polarity-Independent Solvatochromic Fluorophores
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Fluorophores with emission wavelengths that shift depending on their hydrogen-bonding microenvironment in water would be fascinating tools for the study of biological events. Herein we describe the design and synthesis of a series of water-soluble solvatochromic fluorophores, 2,5-bis(oligoethylene glycol)oxybenzaldehydes (8-11) and 2,5-bis(oligoethylene glycol)oxy-1,4-dibenzaldehydes (14-17), based on a push-pull strategy. Unlike typical examples in this class of fluorophores, the fluorescence properties of these compounds are independent of solvent polarity and become fluorescent upon intermolecular hydrogen-bonding, exhibiting high quantum yields (up to φ = 0.55) and large Stokes shifts (up to 134 nm). Furthermore, their emission wavelengths change depending on their hydrogen-bonding environment. The described fluorophores provide a starting point for unprecedented applications in the fields of chemical biology and medicinal chemistry.
- Okada, Yohei,Sugai, Masae,Chiba, Kazuhiro
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p. 10922 - 10929
(2016/11/29)
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- POLYMERIZABLE COMPOUND, POLYMERIZABLE COMPOSITION, POLYMER, AND OPTICALLY ANISOTROPIC SUBSTANCE
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The present invention relates to: a polymerizable compound represented by a formula (I); a polymerizable composition comprising the polymerizable compound and an initiator; a polymer obtained by polymerizing the polymerizable compound or the polymerizable composition; and an optically anisotropic article comprising the polymer [in the formula, Y1 to Y8 are a chemical single bond, —O—, —O—C(═O)—, —C(═O)—O—, or the like; G1 and G2 are a divalent aliphatic group having 1 to 20 carbon atoms, or the like; Z1 and Z2 are an alkenyl group having 2 to 10 carbon atoms, or the like; A1 is a tetravalent aromatic group, or the like; A2 and A3 are a divalent alicyclic hydrocarbon group having 3 to 30 carbon atoms, or the like; A4 and A5 are a divalent aromatic group having 4 to 30 carbon atoms, or the like; Ax1 and Ax2 are an organic group having 2 to 30 carbon atoms that includes an aromatic ring, or the like; Ay1 and Ay2 are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or the like; Q1 and Q2 are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or the like; and m and n are 0 or 1]. According to the present invention, a polymerizable compound, a polymerizable composition, and a polymer that have a practical low melting point, exhibit excellent solubility in a general-purpose solvent, can be produced at low cost, and can produce an optical film that achieves uniform conversion of polarized light over a wide wavelength band, and also provide an optically anisotropic article.
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- Liquid crystalline bis(N-salicylideneaniline)s: Synthesis and thermal behavior of constitutional isomers
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The first examples of mesogenic bis(N-salicylideneaniline)s (BSANs), wherein two lipophilic (half-disk shaped) entities are interlinked through the dihydroxydiformylbenzene core, were synthesized and characterized. In particular, three constitutional (positional) isomeric BSANs were prepared by the facile twofold condensation of 3,4,5-tris(alkoxy)anilines with 2,3-dihydroxyterephthalaldehyde, 4,6-dihydroxyisophthalaldehyde, and 2,5-dihydroxyterephthalaldehyde and their structures were established by elemental analyses, FT-IR, 1H NMR, and 13C NMR. Proton NMR experiments demonstrated their existence in enol-imine (OH) form solely. Polarizing optical microscopic, differential scanning calorimetric, and powder X-ray diffraction studies evidenced the occurrence of columnar mesomorphism in two sets of isomers.
- Hiremath, Uma S.
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p. 3419 - 3423
(2013/07/04)
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- FLUORESCENT NANOPROBE FOR DETECTING HYDROGEN PEROXIDE AND FABRICATION METHOD THEREOF
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The present disclosure relates to a sulfonated benzene compound emitting fluorescence by reaction with hydrogen peroxide, aqueous-dispersed fluorescent nanoprobes applicable for real-time detection of hydrogen peroxide, and a fluorescent nanoprobe fabrication method. The fluorescent nanoprobe contains the following sulfonated benzene compound and water.
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- 2,5-diformylbenzene-1,4-diol: A versatile building block for the synthesis of ditopic redox-active schiff base ligands
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2,5-Diformylbenzene-1,4-diol (5) is a well-suited starting compound for the preparation of ditopic hydroquinone-based ligands. Here, we report an optimized synthesis of 5 which improves the overall yield from published 7 % to 42 %. Three new ditopic Schiff base ligands, 2,5-[iPr2N(CH 2)2N=CH]2-1,4-(OH)2-C 6H2 (8), 2,5-(pyCH2N=CH)2-1,4-(OH) 2-C6H2 (9), and 2,5-[py(CH2) 2N=CH]2-1,4-(OH)2-C6H2 (10), have been synthesized from 5 and structurally characterized by X-ray crystal structure analysis (py = 2-pyridyl).
- Kretz, Tonia,Bats, Jan Willem,Lerner, Hans-Wolfram,Wagner, Matthias
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- Anodic Oxidation of Mono- and Disubstituted 1,4-Dimethoxybenzenes
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The electrochemical oxidation of mono- and disubstituted 1,4-dimethoxybenzene derivatives with zero, one, and two benzylic CH2X groups (X = OAc, Cl, OH) (5a-c and 6a-c) has been carried out by using both constant-current and controlled-potential techniques in methanol and in the presence of different electrolytes and working electrodes. Constant-current electrolysis in KOH-methanol solutions yielded mostly the corresponding 1,4-quinone derivatives from 5a-c and 6b, whereas the disubstituted 1,4-dimethoxybenzenes 6a,c underwent side-chain oxidation to form 2,5-dimethoxyterephthalaldehydes. Upon alteration of the medium from the commonly used basic KOH-methanol to neutral LiClO4-methanol, a new spectrum of products was achieved in most cases, involving novel coupling products from monosubstituted substrates and quinone derivatives from disubstituted ones. Controlled-potential oxidation at the glassy carbon anodes and in a neutral LiClO4-methanol medium led to more complex mixtures of products, namely, polymers and new coupling products from monosubstituted substrates and quinones and side-chain oxidation (or substitution) products from the disubstituted ones. Three new coupling products were isolated and characterized by X-ray measurements.
- Zeng, Cheng-Chu,Becker, James Y.
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p. 1053 - 1059
(2007/10/03)
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- Intramolecular hydrogen bonding and molecular structure of 2,5-dihydroxyterephthalaldehyde and 4,6-dihydroxyisophthalaldehyde: A gas-phase electron diffraction and ab initio molecular orbital study
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The molecular structure of 2,5-dihydroxyterephthalaldehyde has been determined from a joint electron diffraction/ab initio investigation, and the molecular structure of 4,6-dihydroxyisophthalaldehyde has been obtained from ab initio calculations at the MP2/6-31G* level. There is considerable intramolecular hydrogen bonding in these structures manifested by the O...H and O...O distances as well as by the structural changes in the rest of the molecule. These changes are consistent with the notion of resonance-assisted hydrogen bonding. The hydrogen bonding is somewhat stronger in 4,6-dihydroxyisophthalaldehyde than in 2,5-dihydroxyterephthalaldehyde, and this difference may be linked to the difference in the mutual positioning of the interacting formyl and hydroxy groups in these molecules.
- Borisenko, Konstantin B.,Zauer, Karoly,Hargittai, Istvan
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p. 19303 - 19309
(2007/10/03)
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