52382-48-6Relevant academic research and scientific papers
Modulating the photoluminescence of bridged silsesquioxanes incorporating Eu3+-complexed n, n′-diureido-2,2′-bipyridine isomers: Application for luminescent solar concentrators
Graffion, Julien,Cattoen, Xavier,Wong Chi Man, Michel,Fernandes, Vasco R.,Andre, Paulo S.,Ferreira, Rute A. S.,Carlos, Luis D.
, p. 4773 - 4782 (2011)
Two new urea-bipyridine derived bridged organosilanes (P5 and P6) have been synthesized and their hydrolysis-condensation under nucleophilic catalysis in the presence of Eu3+ salts led to luminescent bridged silsesquioxanes (M5-Eu and M6-Eu). An important loading of Eu3+ (up to 11% w) can be obtained for the material based on the 6,6′-isomer. Indeed the photoluminescence properties of these materials, that have been investigated in depth (photoluminescence (PL), quantum yield, lifetimes), show a significantly different complexation mode of the Eu3+ ions for M6-Eu, compared with M4-Eu (obtained from the already-reported 4,4′-isomer) and M5-Eu. Moreover, M6-Eu exhibits the highest absolute emission quantum yield value (0.18 ± 0.02) among these three materials. The modification of the sol composition upon the addition of a malonamide derivative led to similar luminescent features but with an increased quantum yield (0.26 ± 0.03). In addition, M6-Eu can be processed as thin films by spin-coating on glass substrates, leading to plates coated by a thin layer (～54 nm) of Eu3+-containing hybrid silica exhibiting one of the highest emission quantum yields reported so far for films of Eu 3+-containing hybrids (0.34 ± 0.03) and an interesting potential as new luminescent solar concentrators (LSCs) with an optical conversion efficiency of ～4%. The ratio between the light guided to the film edges and the one emitted by the surface of the film was quantified through the mapping of the intensity of the red pixels (in the RGB color model) from a film image. This quantification enabled a more accurate estimation of the transport losses due to the scattering of the emitted light in the film (0.40), thereby correcting the initial optical conversion efficiency to a value of 1.7%.
Covalent Organic Frameworks Enabling Site Isolation of Viologen-Derived Electron-Transfer Mediators for Stable Photocatalytic Hydrogen Evolution
Mi, Zhen,Zhou, Ting,Weng, Weijun,Unruangsri, Junjuda,Hu, Ke,Yang, Wuli,Wang, Changchun,Zhang, Kai A. I.,Guo, Jia
, p. 9642 - 9649 (2021/03/16)
Electron transfer is the rate-limiting step in photocatalytic water splitting. Viologen and its derivatives are able to act as electron-transfer mediators (ETMs) to facilitate the rapid electron transfer from photosensitizers to active sites. Nevertheless, the electron-transfer ability often suffers from the formation of a stable dipole structure through the coupling between cationic-radical-containing viologen-derived ETMs, by which the electron-transfer process becomes restricted. Herein, cyclic diquats, a kind of viologen-derived ETM, are integrated into a 2,2′-bipyridine-based covalent organic framework (COF) through a post-quaternization reaction. The content and distribution of embedded diquat-ETMs are elaborately controlled, leading to the favorable site-isolated arrangement. The resulting materials integrate the photosensitizing units and ETMs into one system, exhibiting the enhanced hydrogen evolution rate (34600 μmol h?1 g?1) and sustained performances when compared to a single-module COF and a COF/ETM mixture. The integration strategy applied in a 2D COF platform promotes the consecutive electron transfer in photochemical processes through the multi-component cooperation.
Metal-doped bipyridine linked covalent organic framework films as a platform for photoelectrocatalysts
Harada, Takashi,Hosokawa, Tomoya,Iwase, Kazuyuki,Kamiya, Kazuhide,Nakanishi, Shuji,Tsuchida, Kosei,Tsuji, Masaki
, p. 11073 - 11080 (2021/05/14)
The development of efficient photoenergy conversion systems is highly demanded from the viewpoint of solving energy and environmental problems. Covalent organic frameworks (COFs) have attracted much attention as novel photofunctional materials because of their wide-range visible-light absorption, which is related to their large π-conjugation systems. The other important property of COFs is their ability to support a wide variety of metals via coordinate bonds; metal-doped COFs exhibit various electron-transfer catalytic activities depending on the metal species. Here, we newly synthesized free-standing metal-doped COF films as photoelectrocatalysts and evaluated the photoelectrochemical oxygen reduction reaction (ORR) properties of Cu atoms doped in a COF. The photocurrent corresponding to the ORR started to increase under 670 nm irradiation, and the photocurrent for the Cu-doped COF was five times larger than that for the COF without Cu. The action spectra, fluorescence spectra, and in situ X-ray absorption spectra indicate that the electrons photoexcited in the COF were transferred to oxygen via the Cu atoms. Thus, the Cu atoms coordinated to the COF serve as active catalytic sites for the photoinduced ORR. This journal is
Nickel(ii)-modified covalent-organic framework film for electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF)
Cai, Meng,Ding, Sha,Gibbons, Bradley,Yang, Xiaozhou,Kessinger, Matthew C.,Morris, Amanda J.
, p. 14361 - 14364 (2020/12/01)
Electrochemical oxidation of 5-hydroxymethylfurfural (HMF) is a promising synthetic route for 2,5-furandicarboxylic acid (FDCA) production. Here, we prepared a nickel(ii)-modified covalent-organic framework (COF) film TpBpy-Ni@FTO for HMF electrooxidation. With a high conversion of HMF (96%), TpBpy-Ni@FTO afforded a 58% FDCA yield. This work underlines the great potential of COF-based materials in electrocatalysis.
Synthesis of Pd@graphene oxide framework nanocatalyst with enhanced activity in Heck-Mizoroki cross-coupling reaction
Shekarizadeh, Arezoo,Azadi, Roya
, (2020/05/22)
A new method was developed for producing a catalyst involving a Pd nanoparticle (NP) embedded in a graphene oxide framework (Pd@GOF) with ordered macro- and mesoporous structures. First, 5,5′-diamino-2,2′-bipyridine was selected as cross-linking for covalent modification of GO nanosheets to prepare a three-dimensional (3D) framework with interlayer spaces in which well-dispersed and ultra-small Pd NPs in situ grew and embedded the framework. The synthesized nanopores 3D Pd@GOF can act as nanoreactors to help the reaction substrates thoroughly come into contact with the surface of Pd NPs, thereby exhibiting high activity toward the Heck reaction, rarely reported concerning Pd NPs supported on one-side functionalized graphene. The Pd@GOF catalyst can be used 10 times without any significant loss in the catalytic activity, confirming the long-term stability of this catalyst. Therefore, the covalently assembled GOF was proposed as a universal platform for hosting noble metal NPs to construct the desired metal@GOF nanocatalyst with improved activity and stability that can be used in a broad range of practical applications.
Flexibility Matters: Cooperative Active Sites in Covalent Organic Framework and Threaded Ionic Polymer
Sun, Qi,Aguila, Briana,Perman, Jason,Nguyen, Nicholas,Ma, Shengqian
, p. 15790 - 15796 (2016/12/16)
The combination of two or more reactive centers working in concert on a substrate to facilitate the reaction is now considered state of the art in catalysis, yet there still remains a tremendous challenge. Few heterogeneous systems of this sort have been exploited, as the active sites spatially separated within the rigid framework are usually difficult to cooperate. It is now shown that this roadblock can be surpassed. The underlying principle of the strategy presented here is the integration of catalytic components with excellent flexibility and porous heterogeneous catalysts, as demonstrated by the placement of linear ionic polymers in close proximity to surface Lewis acid active sites anchored on the walls of a covalent organic framework (COF). Using the cycloaddition of the epoxides and CO2 as a model reaction, dramatic activity improvements have been achieved for the composite catalysts in relation to the individual catalytic component. Furthermore, they also clearly outperform the benchmark catalytic systems formed by the combination of the molecular organocatalysts and heterogeneous Lewis acid catalysts, while affording additional recyclability. The extraordinary flexibility and enriched concentration of the catalytically active moieties on linear polymers facilitate the concerted catalysis, thus leading to superior catalytic performance. This work therefore uncovers an entirely new strategy for designing bifunctional catalysts with double-activation behavior and opens a new avenue in the design of multicapable systems that mimic biocatalysis.
Modified bipyridines: 5,5'-Diamino-2,2'-bipyridine metal complexes assembled into multidimensional networks via hydrogen bonding and π-π stacking interactions
Janiak, Christoph,Deblon, Stephan,Wu, He-Ping,Kolm, Mario J.,Klüfers, Peter,Piotrowski, Holger,Mayer, Peter
, p. 1507 - 1521 (2007/10/03)
A new synthetic route for the synthesis of 5,5'-diamino-2,2-bipyridine (5) based on the coupling of 2-chloro-5-aminopyridine in the presence of NiCl2 x 6 H2O/PPh3/Zn in dimethylformamide is described The reactions of the p
Syntheses of 5,5-disubstituted 2,2'-bipyridines
Janiak, Christoph,Deblon, Stephan,Wu, He-Ping
, p. 3341 - 3352 (2007/10/03)
New and improved syntheses of 5,5'-donor-functionalized 2,2'-bipyridines are reported with the 5,5'-donors being -NH2 (4), -NMe2 (5), -CN (6), and - NCS (7). A new route for 4 and 5 is based on the coupling of 2-chloro-5- amino-pyridine in the presence of NiCl2 · 6 H2O/PPh3/Zn in DMF (NiCRA) · 6 was obtained by a dehydration treatment of 5,5'-dicarboxamide-2,2'- bipyridine with (F3CCO)2O and P4O10. The new ligand 7 is prepared from 4 and SCCl2.
Synthesis and metallation of ferrocenylimines derived from ligating diaminoheteroarenes
Asselin, Catherine M.,Fraser, Greig C.,Hall Jr.,Lindsell, W. Edward,Padias, Anne B.,Preston, Peter N.
, p. 3765 - 3771 (2007/10/03)
A regioisomeric mixture of 1,1′-didodecylferrocenedicarbaldehydes 3 was prepared from the reaction of a regioisomeric mixture of 1,1′-didodecyldilithioferrocenes and dimethylformamide. Three ligating heteroaromatics were synthesized each containing two amino substituents: 5,5′-diamino-2,2′-bipyridine and 5,5″-diamino-2,2′ : 6′,2″-terpyridine were prepared from appropriate dinitro compounds by reduction with palladium on charcoal-hydrazine hydrate. The reaction of 2-cyano-5-nitropyridine and hydrazine hydrate gave an isolable amidine derivative and this was transformed with hydrazine in a separate reaction under more forcing conditions into 3,6-bis(5-amino-2-pyridyl)-1,2-dihydro-1,2,4,5-tetrazine. The latter was converted into the tetrazine by oxidation (2,3-dichlpro-5,6-dicyano-1,4-benzoquinone) and then trifluoroacetylated [(CF3CO)2O] to give the bis(trifluoroacetylamino) derivative. Diels-Alder reaction of the latter with dodec-1-yne afforded 4-n-decyl-3,6-bis[5-(trifluoroacetylamino)-2-pyridyl]pyridazine which was deprotected (K2CO3) to give the corresponding diamine. Bis(ferrocenyl) Schiff bases were prepared from ferrocenecarbaldehyde and the appropriate diamine in either uncatalysed or acid-catalysed condensations. Tetracarbonylmolybdenum complexes were prepared by treating the appropriate diamines with molybdenum hexacarbonyl. Reaction of one of these complexes with ferrocenecarbaldehyde gave a heterobimetallic complex.
