‘Why didn’t we think to do this earlier?’ Chemists thrilled by speedy atomic structures

Warren, Matthew

doi:10.1038/d41586-018-07213-3

Cited by 6 publications

(11 citation statements)

References 4 publications

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“…The structure of PCN-226 was determined by continuous rotation electron diffraction (cRED), 46 , 47 also known as microcrystal electron diffraction (MicroED). 48 As an electrocatalyst for ORR, PCN-226 showed high activity and reaction kinetics, especially as compared to cluster-based MOFs. When applied as electrodes for practical application in a rechargeable Zn-air battery, PCN-226 exhibited a high peak power density of 133 mW cm –2 .…”

Section: Introductionmentioning

confidence: 99%

A Porphyrinic Zirconium Metal–Organic Framework for Oxygen Reduction Reaction: Tailoring the Spacing between Active-Sites through Chain-Based Inorganic Building Units

et al. 2020

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The oxygen reduction reaction (ORR) is central in carbon-neutral energy devices. While platinum group materials have shown high activities for ORR, their practical uses are hampered by concerns over deactivation, slow kinetics, exorbitant cost, and scarce nature reserve. The low cost yet high tunability of metal–organic frameworks (MOFs) provide a unique platform for tailoring their characteristic properties as new electrocatalysts. Herein, we report a new concept of design and present stable Zr-chain-based MOFs as efficient electrocatalysts for ORR. The strategy is based on using Zr-chains to promote high chemical and redox stability and, more importantly, tailor the immobilization and packing of redox active-sites at a density that is ideal to improve the reaction kinetics. The obtained new electrocatalyst, PCN-226, thereby shows high ORR activity. We further demonstrate PCN-226 as a promising electrode material for practical applications in rechargeable Zn-air batteries, with a high peak power density of 133 mW cm –2 . Being one of the very few electrocatalytic MOFs for ORR, this work provides a new concept by designing chain-based structures to enrich the diversity of efficient electrocatalysts and MOFs.

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Section: Introductionmentioning

confidence: 99%

A Porphyrinic Zirconium Metal–Organic Framework for Oxygen Reduction Reaction: Tailoring the Spacing between Active-Sites through Chain-Based Inorganic Building Units

et al. 2020

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“…However, assignment of relative configuration can still be a challenging problem when stereogenic centers are remotely located in the molecule, and hence magnetically disconnected. 9 The advent of NMR in weakly aligning media (chiral or not) allowed made it possible to overcome these hurdles by recovering a small fraction of the orientational (tensorial) information inherent to NMR observables, and therefore establishing angular restrictions on the relative orientation of the associated tensors. 20 Most of the existing examples, some of them involving difficult structural problems, are based on the use of one-bond proton-carbon residual dipolar couplings (( 13 C-1 H)-RDC), noted also as 1 D CH .…”

Section: Introductionmentioning

confidence: 99%

“…21,22 These key heteronuclear dipolar data can be also soundly combined with: (i) long-range 2,3 D CH constant analysis, [23][24][25] (ii) NOE constraints, 22,25 (iii) J HH data, 21,22,26,27 or (iv) even powder Xray diffraction analysis. 9 Moreover, information on relative orientation of non-protonated carbons can be obtained through the use of the 13 C residual chemical shift anisotropy ( 13 C-RCSA). [28][29][30][31][32][33] Although 13 C-RCSAs are much more technically demanding to measure with enough accuracy than RDCs (in particular when very weakly oriented media are used) the associated experimental protocol is somewhat simplified as only 13 C-{ 1 H} 1D NMR spectra need to be measured.…”

Section: Introductionmentioning

confidence: 99%

“…The determination of relative configuration in organic compounds is still a challenging problem because single-crystal X-ray diffraction spectroscopy is, in many cases, not applicable due to the studied compound failing to produce suitable crystals for analysis. Because powder X-ray , diffraction analysis or the very promising molecular sponge methods still present important technical issues, liquid-state nuclear magnetic resonance (NMR) spectroscopy assisted by molecular modeling has become the technique of choice for probing molecular geometry. Classically, the problem of obtaining internuclear distances and bond angles is addressed through the analysis of nuclear Overhauser effect (NOE) experiments , as well as the determination of homonuclear 3 J ( 1 H– 1 H) and heteronuclear 1 J ( 1 H– 13 C) scalar couplings. , New developments in quantitative NOE methods or density functional theory (DFT) predictions of chemical shifts/scalar couplings − further enhance the power of these approaches.…”

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confidence: 99%

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Deuterium Residual Quadrupolar Couplings: Crossing the Current Frontiers in the Relative Configuration Analysis of Natural Products

et al. 2020

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Determination of the 3D structure (configuration and preferred conformation) of complex natural and synthetic organic molecules is a long-standing but still challenging task for chemists, with various implications in pharmaceutical sciences whether or not these substances have specific bioactivities. NMR in aligning media, either lyotropic liquid crystals (LLC) or polymer gels, in combination with molecular modelling is a unique framework to solve complex structural problems whose analytical wealth lies in the establishment of non-local structural correlations. As an alternative to already well-established anisotropic NMR parameters, such as RDCs (residual dipolar couplings) and RCSAs (residual chemical shift anisotropies), it is shown here that deuterium residual quadrupolar couplings ( 2 H-RQCs) can be extracted from 2 H 2D-NMR spectra recorded at natural abundance level in samples oriented in a homopolypeptide LLC (PBLG). These 2 H-RQCs were successfully used to address non-trivial structural problems in organic molecules. The performance and scope of this new tool is examined for two natural chiral compounds of pharmaceutical interest (strychnine and artemisinin). This is the first report in which the 3D structure/relative configuration of complex bioactive molecules is unambiguously determined using only 2 H-RQCs, being in this case at 2 H natural abundance.

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“…Recent developments of fast 3D electron diffraction (3DED) or microcrystal electron diffraction (MicroED) data collection techniques (<5 min) using continuous rotation (denoted cRED here) have made it possible for studying beam sensitive nano-and micrometer-sized crystals 18,[36][37][38][39][40] . Here, we demonstrate the ab initio structure determination of PST-5 using cRED data collected under low-dose condition.…”

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confidence: 99%

3D-3D topotactic transformation in aluminophosphate molecular sieves and its implication in new zeolite structure generation

et al. 2020

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Zeolites have unique pore structures of molecular dimensions and tunable compositions, making them ideal for shape selective catalysis and separation. However, targeted synthesis of zeolites with new pore structures and compositions remains a key challenge. Here, we propose an approach based on a unique 3D-3D topotactic transformation, which takes advantage of weak bonding in zeolites. This is inspired by the structure transformation of PST-5, a new aluminophosphate molecular sieve, to PST-6 by calcination. The structure of nano-sized PST-5 crystals is determined by 3D electron diffraction. We find that the 3D-3D topotactic transformation involves two types of building units where penta-or hexacoordinated Al is present. We apply this approach to several other zeolite systems and predict a series of new zeolite structures that would be synthetically feasible. This method provides a concept for the synthesis of targeted zeolites, especially those which may not be feasible by conventional methods.

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‘Why didn’t we think to do this earlier?’ Chemists thrilled by speedy atomic structures

Cited by 6 publications

References 4 publications

A Porphyrinic Zirconium Metal–Organic Framework for Oxygen Reduction Reaction: Tailoring the Spacing between Active-Sites through Chain-Based Inorganic Building Units

A Porphyrinic Zirconium Metal–Organic Framework for Oxygen Reduction Reaction: Tailoring the Spacing between Active-Sites through Chain-Based Inorganic Building Units

Deuterium Residual Quadrupolar Couplings: Crossing the Current Frontiers in the Relative Configuration Analysis of Natural Products

3D-3D topotactic transformation in aluminophosphate molecular sieves and its implication in new zeolite structure generation

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