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Modulation by Amino Acids: Toward Superior Control in the Synthesis of Zirconium Metal–Organic Frameworks

  • Gutov, Oleksii V.
  • Molina, Sonia
  • Escudero-Adan, Eduardo C.
  • Shafir, Alexandr
<p> The synthesis of zirconium metal&ndash;organic frameworks (Zr MOFs) modulated by various amino acids, including <span class="smallCaps">l</span>-proline, glycine, and <span class="smallCaps">l</span>-phenylalanine, is shown to be a straightforward approach toward functional-group incorporation and particle-size control. High yields in Zr-MOF synthesis are achieved by employing 5 equivalents of the modulator at 120&thinsp;&deg;C. At lower temperatures, the method provides a series of Zr MOFs with increased particle size, including many suitable for single-crystal X-ray diffraction studies. Furthermore, amino acid modulators can be incorporated at defect sites in Zr MOFs with an amino acid/ligand ratio of up to 1:1, depending on the ligand structure and reaction conditions. The MOFs obtained through amino acid modulation exhibit an improved CO<sub><font size="2">2</font></sub>-capture capacity relative to nonfunctionalized materials.</p>
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The emergence of sulfoxide and iodonio- based redox arylation as a synthetic tool

  • Shafir, Alexandr
<p> <span style="margin: 0px; line-height: 107%; font-family: &quot;Calibri&quot;,sans-serif; font-size: 11pt;"><font color="#000000">This digest highlights the emergence of the directed metal-free arylation approach employing simple sulfoxide and hypervalent aryliodane. These new processes are characterized by an unusual, and synthetically attractive, retention of the reduced -SR and iodine fragment ortho to the newly formed C-C bond. Although the development of the sulfur- and iodane-based methods have occurred independently, it is becoming increasingly obvious that the two processes are highly analogous in terms of the mechanism and the substrate scope. Indeed, both types of reaction are proposed to occur via a [3,3]-sigmatropic Claisen-type rearrangement, and have been carried out on closely related families of substrates. The digest covers the progress made in 2011-2015 both in the sulfoxide-based methods and in the iodane-based reaction. The ultimate goal is to a) highlight the synthetic potential of the approach; b) offer, for the first time, a unified vision of the two processes</font></span></p>
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Hypervalent Activation as Key Step for Dehydrogenative ortho C-C Coupling of Iodoarenes

  • Wu, Yichen
  • Arenas, Ismael
  • Broomfield, Lewis
  • Martin, Eddy
  • Shafir, Alexandr
<p> Building on earlier results, a direct metal-free &alpha;- arylation of substituted cyclic 1,3-diones using ArI(O<sub><font size="2">2</font></sub>CCF<sub><font size="2">3</font></sub>)<sub><font size="2">2</font></sub> reagents has been developed; unlike other arylative approaches, the arylated products retain the iodine substituent <em>ortho</em> to the newly formed C-C bond. The mechanism is explored by using DFT calculations, which show a vanishingly small activation barrier for the C-C bond-forming step. In fact, taking advantage of an efficient in situ hypervalent activation, the iodoarenes are shown to undergo a cross- dehydrogenative C-C coupling at the C-H <em>ortho</em> to the iodine. When Oxone is used as terminal oxidant, the process is found to benefit from a rapid initial formation of the hypervalent ArI(OR)<sub><font size="2">2</font></sub> species and the sulfate-accelerated final coupling with a ketone. This method complements the <em>ipso</em> selectivity obtained in the metal-catalyzed &alpha;-arylation of carbonyl compounds.</p>
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The mechanism of CO2 hydration: a porous metal oxide nanocapsule catalyst can mimic the biological carbonic anhydrase role

  • Bandeira, Nuno A. G.
  • Garai, Somenath
  • Muller, Achim
  • Bo, Carles
<p> The mechanism for the hydration of CO2 within a Keplerate nanocapsule is presented. A network of hydrogen bonds across the water layers in the first metal coordination sphere facilitates the proton abstraction and nucleophilic addition of water. The highly acidic properties of the polyoxometalate cluster are crucial for explaining the catalysed hydration.<br /> <br /> &nbsp;</p>
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Decreasing Charge Losses in Perovskite Solar Cells Through the mp-TiO2/MAPI Interface Engineering

  • Marin-Beloqui, Jose Manuel
  • Lanzetta, Luis
  • Palomares, Emilio
<p> <span style="color: rgb(85, 85, 85); font-family: HelveticaNeue, &quot;Helvetica Neue&quot;, HelveticaNeueRoman, HelveticaNeue-Roman, &quot;Helvetica Neue Roman&quot;, texgyreherosregular, Arial, sans-serif; font-size: 14px; text-align: justify;">On the basis of our experience in controlling the recombination kinetics in Dye Sensitized Solar Cells (DSSC) by modifying the mesoporous TiO2&nbsp;(mp-TiO2) interface, we modified the methylammonium lead iodide (MAPI) /mp-TiO2&nbsp;interface with a nanoscopic layer of insulating Al2O3. The effects on device efficiency, the open-circuit voltage (</span><i style="box-sizing: border-box; color: rgb(85, 85, 85); font-family: HelveticaNeue, &quot;Helvetica Neue&quot;, HelveticaNeueRoman, HelveticaNeue-Roman, &quot;Helvetica Neue Roman&quot;, texgyreherosregular, Arial, sans-serif; font-size: 14px; text-align: justify;">V</i><span style="color: rgb(85, 85, 85); font-family: HelveticaNeue, &quot;Helvetica Neue&quot;, HelveticaNeueRoman, HelveticaNeue-Roman, &quot;Helvetica Neue Roman&quot;, texgyreherosregular, Arial, sans-serif; font-size: 14px; text-align: justify;">oc), device reproducibility, and the relationship between the increase in&nbsp;</span><i style="box-sizing: border-box; color: rgb(85, 85, 85); font-family: HelveticaNeue, &quot;Helvetica Neue&quot;, HelveticaNeueRoman, HelveticaNeue-Roman, &quot;Helvetica Neue Roman&quot;, texgyreherosregular, Arial, sans-serif; font-size: 14px; text-align: justify;">V</i><span style="color: rgb(85, 85, 85); font-family: HelveticaNeue, &quot;Helvetica Neue&quot;, HelveticaNeueRoman, HelveticaNeue-Roman, &quot;Helvetica Neue Roman&quot;, texgyreherosregular, Arial, sans-serif; font-size: 14px; text-align: justify;">oc, and the presence of the Al2O3&nbsp;layer is thoroughly discussed and explained. Although in DSSC there is a TiO2&nbsp;conduction band edge shift for Al2O3coated mp-TiO2&nbsp;films, in MAPI perovskite solar cells the charge vs voltage measurements carried out under sun-simulated irradiation conditions show a negligible shift of the exponential charge distribution whether it is measured using PICE (Photo Induced Charge Extraction) or PIDC (Photo Induced Differential Charging). Furthermore, the charge recombination lifetime decreases considerably in the Al2O3-treated samples, which improves the overall efficiency of the device because of the slower rate in the back-electron transfer reactions.</span></p>
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Catalysis under microscope: Unraveling the mechanism of catalyst de- and re-activation in the continuous dimethyl carbonate synthesis from CO2 and met

  • Stoian, Dragos
  • Bansode, Atul
  • Medina, Francesc
  • Urakawa, Atsushi
<p> The high efficiency of 2-cyanopyridine (2-CP) as dehydrating agent in the direct dimethyl carbonate (DMC) synthesis from CO<sub>2</sub> and methanol over CeO<sub>2</sub> catalysts has been recently demonstrated with excellent DMC yields (&gt;90%) in both batch and continuous operations. The catalytic reaction is expected to involve a complex three-phase boundary due to the high boiling points of 2-CP and also 2-picolinamide (2-PA) formed by hydration of 2-CP. The catalyst is also known to deactivate noticeably in the time-scale of days during the continuous operation. The aim of this work is to gain visual information of the catalyst under <em>operando</em> conditions by means of an optically transparent, fused quartz reactor to understand the behavior of catalyst deactivation and to learn about the phase behavior of the reaction mixture. The catalytic tests using the fused quartz reactor could reproduce the results observed in a common stainless steel reactor, and the effects of reaction temperature and pressure (up to 30 bar) were examined in detail to show that there is an optimum condition (30 bar, 120 &deg;C) to achieve the best catalytic performance. The visual inspection was further combined with IR and Raman spectroscopic studies to identify the origin of the catalyst deactivation and establish an efficient catalyst reactivation protocol. Interestingly, not coke but 2-PA surface adsorption was found responsible for the catalyst deactivation. The <em>operando</em> visual inspection evidenced that the surface of the CeO<sub>2</sub> catalyst particles is constantly wet and also coated with some crystallites (likely of 2-PA) during the reaction, whereas the bulk of the CeO<sub>2</sub> particle is still accessible for the reactants and thus available for the reaction.</p>
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Nickel-Catalyzed Carboxylation of Benzylic C−N Bonds with CO2

  • Moragas, Toni
  • Gaydou, Morgane
  • Martin, Ruben
<p> A user-friendly Ni-catalyzed reductive carboxylation of benzylic C&minus;N bonds with CO<sub>2</sub> is described. This procedure outperforms state-of-the-art techniques for the carboxylation of benzyl electrophiles by avoiding commonly observed parasitic pathways, such as homodimerization or &beta;-hydride elimination, thus leading to new knowledge in cross-electrophile reactions.</p>
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Synthesis and Structural Features of Co(II) and Co(III) Complexes Supported by Aminotrisphenolate Ligand Scaffolds

  • Martín, Carmen
  • Whiteoak, Cristopher J.
  • Martin, Eddy
  • Escudero-Adán, Eduardo C.
  • Galán-Mascarós, José-Ramón
  • Klei, Arjan W.
<p> Co(II) complexes of aminotrisphenolate<br /> ((ArO)3N3&minus;) ligands can be prepared straightforwardly in high<br /> yield. X-ray analysis reveals these complexes to comprise of two<br /> different hemispheres, one containing an anionic Co((ArO)3N)&minus;<br /> and the other a cationic (ArO)3NH+ unit, which are associated<br /> through hydrogen bonding. These Co(II) complexes can be<br /> easily converted into their Co(III) analogues in air in the<br /> presence of suitable bases such as dimethylaminopyridine and<br /> 2,2&prime;-bipyridine, and the structural features and magnetic properties<br /> of these latter compounds are also reported.</p>
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Ni-Catalyzed Carboxylation of Unactivated Alkyl Chlorides with CO2

  • Börjesson, Marino
  • Moragas, Antoni
  • Martin, Ruben
<p> A catalytic carboxylation of unactivated primary, secondary &amp; tertiary alkyl chlorides with CO<sub>2</sub> at atmospheric pressure is described. This protocol represents the first <em>intermolecular </em>cross-electrophile coupling of unactivated alkyl chlorides, thus leading to new knowledge in the cross-coupling arena.</p>
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Managing the Computational Chemistry Big Data problem: the ioChem-BD platform

  • Álvarez-Moreno, M.
  • de Graaf, Coen
  • López, Núria
  • Maseras, Feliu
  • Poblet, Josep Maria
  • . Bo, Carles
<div class="page" title="Page 1"> <div class="section"> <div class="layoutArea"> <div class="column"> <p> <span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11'">We present the </span><span style="font-size: 10.000000pt; font-family: 'AdvOT51c1769e'">ioChem-BD </span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11'">platform (www. iochem-bd.org) as a multiheaded tool aimed to manage large volumes of quantum chemistry results from a diverse group of already common simulation packages. The platform has an extensible structure. The key modules managing the main tasks are to (i) upload of output </span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11+fb'">fi</span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11'">les from common computational chemistry packages, (ii) extract meaningful data from the results, and (iii) generate output summaries in user-friendly formats. A heavy use of the Chemical Mark-up Language (CML) is made in the intermediate </span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11+fb'">fi</span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11'">les used by </span><span style="font-size: 10.000000pt; font-family: 'AdvOT51c1769e'">ioChem-BD</span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11'">. From them and using XSL techniques, we manipulate and transform such chemical data sets to ful</span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11+fb'">fi</span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11'">ll researchers</span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11+20'">&rsquo; </span><span style="font-size: 10.000000pt; font-family: 'AdvOT2e364b11'">needs in the form of HTML5 reports, supporting information, and other research media. </span></p> </div> </div> </div> </div> <p> &nbsp;</p>
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