3022-16-0Relevant academic research and scientific papers
Pore environment engineering in metal-organic frameworks for efficient ethane/ethylene separation
Wang, Xun,Niu, Zheng,Al-Enizi, Abdullah M.,Nafady, Ayman,Wu, Yufang,Aguila, Briana,Verma, Gaurav,Wojtas, Lukasz,Chen, Yu-Sheng,Li, Zhong,Ma, Shengqian
supporting information, p. 13585 - 13590 (2019/06/13)
Selective adsorption of trace amounts of C2H6 from bulk C2H4 is a significantly important and extremely challenging task in industry, which requires an adsorbent with specific pore properties. Herein, we describe a strategy for adjusting the pore environment of metal-organic frameworks (MOFs) by introducing different amounts of methyl groups in the channel to enhance the guest-host interaction between C2H6 and the framework. To prove this concept, 2,3,5,6-tetramethylterephthalic acid (TMBDC) was deliberately added to a microporous MOF, Ni(BDC)(DABCO)0.5, affording a series of mixed-ligand materials, Ni(BDC)1-x(TMBDC)x(DABCO)0.5 (x = 0, 0.2, 0.45, 0.71, 1), having different pore environments. Significantly, these mixed-ligand materials demonstrated improved performance in terms of the adsorption capacity of C2H6 and C2H4 with an unprecedented C2H6 uptake of 2.21 mmol g-1 for Ni(TMBDC)(DABCO)0.5 at 0.0625 bar and 298 K. With the best theoretical C2H6/C2H4 selectivity predicted by IAST, Ni(TMBDC)(DABCO)0.5 exhibited effective separation of C2H6/C2H4 (1/15, v/v) and great recyclability in five consecutive adsorption/desorption cycles throughout the breakthrough experiment.
SALE-Ing a MOF-Based “Ship of Theseus.” Sequential Building-Block Replacement for Complete Reformulation of a Pillared-Paddlewheel Metal-Organic Framework
Xu, Yan,Vermeulen, Nicolaas A.,Liu, Yangyang,Hupp, Joseph T.,Farha, Omar K.
supporting information, p. 4345 - 4348 (2016/10/04)
A complete structure and composition evolution of a pillared-paddlewheel metal-organic framework was achieved using a combination of solvent-assisted linker exchange (SALE) and node transmetalation. In this example, each building unit – the di-topic carboxylate strut, the di-topic nitrogen-based pillar, and the di-zinc node – of the original metal-organic framework is replaced in sequential fashion to produce a nickel-based daughter metal-organic framework with entirely different components.
Tuning the electrocatalytic hydrogen evolution reaction promoted by [Mo2O2S2]-based molybdenum cycles in aqueous medium
Hijazi, Akram,Kemmegne-Mbouguen, Justin Claude,Floquet, Sébastien,Marrot, Jér?me,Fize, Jennifer,Artero, Vincent,David, Olivier,Magnier, Emmanuel,Pégot, Bruce,Cadot, Emmanuel
, p. 4848 - 4858 (2013/04/24)
We report the syntheses and characterizations, in the solid state and in solution, of three new cyclic polyoxothiomolybdates self-assembled around 2,5-dimethylterephthalate (DMT) and 2,5-bis(trifluoromethyl)terephthalate (DFMT) ligands, namely [Mo12DMT]2-, [Mo12DFMT] 2- and [Mo16DFMT]2-. A series of these two Mo12-compounds completed by the two Mo12-compounds obtained with 2,3,5,6-tetramethylterephthalate and trimesate ligands offer the opportunity to compare their electro-catalytic properties for reduction of protons into hydrogen. The ability of these compounds to promote the reduction of protons into hydrogen in aqueous medium is evidenced and the influence of the embedded ligand is highlighted, thus allowing proposal of a mechanism for the hydrogen evolution reaction catalyzed by these clusters.
Preparation, 13C NMR/DFT/IGLO study of benzylic mono- and dications, and attempted preparation of a trication
Olah, George A.,Shamma, Tatyana,Burrichter, Arwed,Rasul, Golam,Prakash, G. K. Surya
, p. 12923 - 12928 (2007/10/03)
Substituted benzylic mono- and dications were prepared and investigated by 1H and 13C NMR spectroscopy and DFT/IGLO calculations. Combined experimental and theoretical study suggest that the structure 1a is the major resonance contributor to the 2,4,6-trimethylbenzyl cation 1. Similar results were also found for the 2,4,6-dimethyl-4-tert-butylbenzyl 2 and 2,3,4,5,6- pentamethylbenzyl cation 3. It was found that the structure 4a is the predominant resonance contributor to the overall structure of 2,6- dimethylmesityldiyl dication 4 wherein the dienyl and allylic cation units are insulated from each other. Similar studies indicate structure 5a as the predominant canonical structure for 5-methoxy-2,6-dimethyl-m-xylyldiyl dication 5 wherein the dienyl and oxoallylic cation units are insulated from each other. Attempts to generate the 2,3,5,6-tetramethyl-1,4- dimethylbenzenediyl dication 8 was, however, not successful as were the generation of the 2,4,6-trimethylmesityltriyl trication 10 by ionization of 2,4,6-bis(chloromethyl)-mesitylene. The resulting ion was characterized as a chloromethyl substituted dication 9.
Electron Paramagnetic Resonance Spectra of the Radical Cations of Some Benzocyclobutenes, Benzocyclopentenes and Benzocyclohexenes
Avila, David V.,Davies, Alwyn G.,Li, Elizabeth R.,Ng, Kai M.
, p. 355 - 362 (2007/10/02)
1,2,4,5-Tetrahydrobenzodicyclobutene, 1,2,3,5,6,7-hexahydrobenzodicyclopentene and 1,2,3,4,6,7,8,9-octahydrobenzodicyclohexene, and their dimethyl derivatives, and tetramethylbenzocyclo-butene, -pentene and -hexene have been prepared.All except the first compound have been oxidised to their corresponding radical cations, and the EPR spectra have been analysed by assigning McConnell-type Q-values to the substituents in the benzene ring.It is suggested that the ordering of the orbital energy levels (ΨA above ΨS) in 3,6-dimethylbenzobiscyclobutene and -pentene is a manifestation of the Mills-Nixon effect, and results from rehybridisation of the strained molecular framework.In the radical cations of 5,10-dimethyl-1,2,3,4,6,7,8,9-octahydrobenzodicyclohexene and 5,6,7,8-tetramethyl-1,2,3,4-tetrahydrobenzocyclohexene the total unpaired electron density, as implied by the McConnell type of relationship, appears to be less than unity.Various possible causes of this are examined.
OXIDATION OF HEXAMETHYLBENZENE AND 2,3,4,5,6-PENTAMETHYLBENZYL CATION IN FLUOROSULFONIC ACID
Rudenko, A. P.,Zarubin, M. Ya.,Fedorova, E. M.
, p. 1609 - 1618 (2007/10/02)
The oxidation of hexamethylbenzene in HSO3F-PbO2 takes place with the participation of the 1-H+-1,2,3,4,5,6-hexamethylbenzenonium ion and the intermediate formation of the 2,3,4,5,6-pentamethylbenzyl cation, which is capable of entering into further oxidative transformations leading to substitution of the hydrogen atom in two and three methyl groups.The structure of the final products from the observed transformations were established, and a mechanism is proposed for their formation.
