1951-36-6Relevant academic research and scientific papers
3D cage Cofs: A dynamic three-dimensional covalent organic framework with high-connectivity organic cage nodes
Chen, Linjiang,Clowes, Rob,Cooper, Andrew I.,Cui, Peng,Little, Marc A.,Wang, Xue,Zhu, Qiang
, p. 16842 - 16848 (2020)
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.
Rigid chain ribbon-like metallopolymers
Carella, Antonio,Borbone, Fabio,Roviello, Giuseppina,Caruso, Ugo,Ferone, Claudio,Ricciotti, Laura,Pirozzi, Beniamino,Persico, Paola,Schieroni, Alberto Giacometti,Roviello, Antonio
, p. 2412 - 2421 (2014)
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.
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
Chen, Zhuang-Zhuang,Deng, Yun-Hu,Zhang, Ting,Dong, Wen-Kui
, (2021)
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.
Photochromism and proton transfer reaction cycle of new internally H-bonded Schiff bases
Grabowska,Kownacki,Karpiuk,Dobrin,Kaczmarek
, p. 132 - 140 (1997)
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.
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
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.
, p. 12394 - 12404 (2019)
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.
Multistep solid-state organic synthesis of carbamate-linked covalent organic frameworks
Lyle, Steven J.,Osborn Popp, Thomas M.,Waller, Peter J.,Pei, Xiaokun,Reimer, Jeffrey A.,Yaghi, Omar M.
, p. 11253 - 11258 (2019)
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.
Metalloporphyrin and Ionic Liquid-Functionalized Covalent Organic Frameworks for Catalytic CO2Cycloaddition via Visible-Light-Induced Photothermal Conversion
Ding, Luo-Gang,Yao, Bing-Jian,Wu, Wen-Xiu,Yu, Zhi-Gao,Wang, Xiao-Yu,Kan, Jing-Lan,Dong, Yu-Bin
, p. 12591 - 12601 (2021/08/24)
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.
Designing Nonfullerene Acceptors with Oligo(Ethylene Glycol) Side Chains: Unraveling the Origin of Increased Open-Circuit Voltage and Balanced Charge Carrier Mobilities
Cui, Junjie,Park, Jung-Hwa,Kim, Dong Won,Choi, Min-Woo,Chung, Hae Yeon,Kwon, Oh Kyu,Kwon, Ji Eon,Park, Soo Young
supporting information, p. 2481 - 2488 (2021/07/26)
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.
Humidity Sensing through Reversible Isomerization of a Covalent Organic Framework
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.
, p. 783 - 791 (2020/02/20)
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.
Photocatalytic Molecular Oxygen Activation by Regulating Excitonic Effects in Covalent Organic Frameworks
Qian, Yunyang,Li, Dandan,Han, Yulan,Jiang, Hai-Long
, p. 20763 - 20771 (2020/12/23)
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.
