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Joseph V. Handy Yuting Luo Justin L. Andrews Dr. Nattamai Bhuvanesh Prof. Dr. Sarbajit Banerjee 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(38):16527-16534
The diffusion pathways of Li-ions as they traverse cathode structures in the course of insertion reactions underpin many questions fundamental to the functionality of Li-ion batteries. Much current knowledge derives from computational models or the imaging of lithiation behavior at larger length scales; however, it remains difficult to experimentally image Li-ion diffusion at the atomistic level. Here, by using topochemical Li-ion insertion and extraction to induce single-crystal-to-single-crystal transformations in a tunnel-structured V2O5 polymorph, coupled with operando powder X-ray diffraction, we leverage single-crystal X-ray diffraction to identify the sequence of lattice interstitial sites preferred by Li-ions to high depths of discharge, and use electron density maps to create a snapshot of ion diffusion in a metastable phase. Our methods enable the atomistic imaging of Li-ions in this cathode material in kinetic states and provide an experimentally validated angstrom-level 3D picture of atomic pathways thus far only conjectured through DFT calculations. 相似文献
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Synthesis and Reversible Hydration of a Pseudoprotein,a Fully Organic Polymeric Desiccant by Multiple Single‐Crystal‐to‐Single‐Crystal Transformations 下载免费PDF全文
Raja Mohanrao Prof. Dr. Kana M. Sureshan 《Angewandte Chemie (International ed. in English)》2018,57(38):12435-12439
A diphenylalanine derivative, N3‐Phe‐Phe‐NHCH2CCH, was designed for topochemical azide–alkyne cycloaddition (TAAC) polymerization. This dipeptide adopted β‐sheet arrangement as designed, in its crystals, but the azide and alkyne were not fitly aligned for their topochemical reaction. However, the voids present around these groups allowed them to attain a reactive geometry upon heating and their consequent TAAC polymerization to a pseudoprotein in a single‐crystal‐to‐single‐crystal (SCSC) fashion. This motion led to the creation of channels in the product crystal and it absorbed water from the surroundings to fill these channels as H‐bonded water wire. The pseudoprotein undergo reversible hydration/dehydration in SCSC fashion many times under mild conditions: hydration at low relative humidity and dehydration at low temperature. Vapor sorption analyses suggest that this fully organic polymer might be useful as an energy‐efficient desiccant material for controlling indoor humidity. 相似文献
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Synthesis of Triazole‐linked Homonucleoside Polymers through Topochemical Azide–Alkyne Cycloaddition 下载免费PDF全文
Atchutarao Pathigoolla Prof. Dr. Kana M. Sureshan 《Angewandte Chemie (International ed. in English)》2014,53(36):9522-9525
There is a great deal of interest in developing stable modified nucleic acids for application in diverse fields. Phosphate‐modified DNA analogues, in which the phosphodiester group is replaced with a surrogate group, are attractive because of their high stability and resistance to nucleases. However, the scope of conventional solution or solid‐phase DNA synthesis is limited for making DNA analogues with unnatural linkages. Other limitations associated with conventional synthesis include difficulty in making larger polymers, poor yield, incomplete reaction, and difficult purification. To circumvent these problems, a single‐crystal‐to‐single‐crystal (SCSC) synthesis of a 1,5‐triazole‐linked polymeric ssDNA analogue from a modified nucleoside through topochemical azide–alkyne cycloaddition (TAAC) is reported. This is the first solvent‐free, catalyst‐free synthesis of a DNA analogue that proceeds in quantitative yield and does not require any purification. 相似文献
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Kuntrapakam Hema Rajesh G. Gonnade Kana M. Sureshan 《Angewandte Chemie (International ed. in English)》2020,59(7):2897-2903
The synthesis of crystalline helical polymers of trehalose via topochemical azide–alkyne cycloaddition (TAAC) of a trehalose‐based monomer is presented. An unsymmetrical trehalose derivative having azide and alkyne crystallizes in two different forms having almost similar packing. Upon heating, both the crystals undergo TAAC reaction to form crystalline polymers. Powder X‐ray diffraction (PXRD) studies revealed that the monomers in both the crystals polymerize in a crystal‐to‐crystal fashion; circular dichroism (CD) studies of the product crystals revealed that the formed polymer is helically ordered. This solvent‐free, catalyst‐free polymerization method that eliminates the tedious purification of the polymeric product exemplifies the advantage of topochemical polymerization reaction over traditional solution‐phase polymerization. 相似文献
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Vignesh Athiyarath Kana M. Sureshan 《Angewandte Chemie (International ed. in English)》2020,59(36):15580-15585
To synthesize a fully organic 1D polymer in a novel twist‐stacked topology, we designed a peptide monomer HC≡CCH2‐NH‐Ile‐Leu‐N3, which crystallizes with its molecules H‐bonded along a six‐fold screw axis. These H‐bonded columns pack parallelly such that molecules arrange head‐to‐tail, forming linear non‐covalent chains in planes perpendicular to the screw axis. The chains arrange parallelly to form molecular layers which twist‐stack along the screw axis. Crystals of this monomer, on heating, undergo single‐crystal‐to‐single‐crystal (SCSC) topochemical azide–alkyne cycloaddition (TAAC) polymerization to yield an exclusively 1,4‐triazole‐linked polymer in a twist‐stacked layered topology. This topologically defined polymer shows better mechanical strength and thermal stability than its unordered form, as evidenced by nanoindentation studies and thermogravimetric analysis, respectively. This work illustrates the scope of topochemical polymerizations for synthesizing polymers in pre‐decided topologies. 相似文献
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A Tale of Copper Coordination Frameworks: Controlled Single‐Crystal‐to‐Single‐Crystal Transformations and Their Catalytic CH Bond Activation Properties 下载免费PDF全文
Yifa Chen Prof. Xiao Feng Prof. Xianqiang Huang Zhengguo Lin Xiaokun Pei Siqing Li Jikun Li Shan Wang Rui Li Prof. Bo Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):13894-13899
Metal–organic frameworks (MOFs), as a class of microporous materials with well‐defined channels and rich functionalities, hold great promise for various applications. Yet the formation and crystallization processes of various MOFs with distinct topology, connectivity, and properties remain largely unclear, and the control of such processes is rather challenging. Starting from a 0D Cu coordination polyhedron, MOP‐1, we successfully unfolded it to give a new 1D‐MOF by a single‐crystal‐to‐single‐crystal (SCSC) transformation process at room temperature as confirmed by SXRD. We also monitored the continuous transformation states by FTIR and PXRD. Cu MOFs with 2D and 3D networks were also obtained from this 1D‐MOF by SCSC transformations. Furthermore, Cu MOFs with 0D, 1D, and 3D networks, MOP‐1, 1D‐MOF, and HKUST‐1, show unique performances in the kinetics of the C?H bond catalytic oxidation reaction. 相似文献
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Versatile Tailoring of Paddle‐Wheel ZnII Metal–Organic Frameworks through Single‐Crystal‐to‐Single‐Crystal Transformations 下载免费PDF全文
Tapan K. Pal Dr. Subhadip Neogi Prof. Parimal K. Bharadwaj 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(45):16083-16090
A new tetracarboxylate ligand having short and long arms formed 2D layer ZnII coordination polymer 1 with paddle‐wheel secondary building units under solvothermal conditions. The framework undergoes solvent‐specific single crystal‐to‐single crystal (SC‐SC) transmetalation to produce 1Cu . With a sterically encumbered dipyridyl linker, the same ligand forms non‐interpenetrated, 3D, pillared‐layer ZnII metal–organic framework (MOF) 2 , which takes part in SC‐SC linker‐exchange reactions to produce three daughter frameworks. The parent MOF 2 shows preferential incorporation of the longest linker in competitive linker‐exchange experiments. All the 3D MOFs undergo complete SC‐SC transmetalation with CuII, whereby metal exchange in different solvents and monitoring of X‐ray structures revealed that bulky solvated metal ions lead to ordering of the shortest linker in the framework, which confirms that the solvated metal ions enter through the pores along the linker axis. 相似文献
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Vadym V. Kulish Dr. Man‐Fai Ng Oleksandr I. Malyi Prof. Ping Wu Prof. Zhong Chen 《Chemphyschem》2013,14(6):1161-1167
We report a first‐principles investigation of Li adsorption and diffusion in single‐walled Si nanotubes (SWSiNTs) of interest to Li‐ion battery anodes. We calculate Li insertion characteristics in SWSiNTs and compare them with the respective ones in carbon nanotubes (CNTs) and other silicon nanostructures. From our calculations, SWSiNTs show higher reactivity toward the adsorption of Li adatoms than CNTs and Si nanoclusters. Considering the importance of Li kinetics, we demonstrate that the interior of SWSiNTs may serve as a fast Li diffusion channel. The important advantage of SWSiNTs over their carbon analogues is a sevenfold reduction in the energy barrier for the penetration of the Li atoms into the nanotube interior through the sidewalls. This prepossesses easier Li diffusion inside the tube and subsequent utilization of the interior sites, which enhances Li storage capacity of the system. The improvements in both Li uptake and Li mobility over their analogues support the great potential of SWSiNTs as Li‐ion battery anodes. 相似文献
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Yanmin Huang Lu Qiao Yuanzhi Jiang Tingwei He Run Long Fan Yang Lin Wang Xiaojuan Lei Mingjian Yuan Jun Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17998-18006
Metal halide perovskites have emerged as a new generation of X‐ray detector materials. However, large‐sized MAPbI3 single crystals (SCs) still exhibit lower performance than MAPbBr3 SCs in X‐ray detection. DFT (density functional theory) simulations suggest the problem could be overcome by alloying large‐sized cations at the A site. The alloyed process could notably decrease the electron–phonon coupling strength and increase the material defect formation energy. Accordingly, centimeter‐sized alloyed DMAMAPbI3 (DMA=dimethylammonium) and GAMAPbI3 (GA=guanidinium) SCs are obtained. Electrical characterizations confirm the GAMAPbI3 SCs display improved charge collection efficiency. It also exhibits a remarkable reduction of dark current, an important figure of merit for X‐ray detectors. With a judiciously designed device architecture, the overall detector performance confirms GAMAPbI3 SCs as one of the most sensitive perovskite X‐ray detectors to date. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(38):12615-12619
A diphenylalanine derivative, N3‐Phe‐Phe‐NHCH2CCH, was designed for topochemical azide–alkyne cycloaddition (TAAC) polymerization. This dipeptide adopted β‐sheet arrangement as designed, in its crystals, but the azide and alkyne were not fitly aligned for their topochemical reaction. However, the voids present around these groups allowed them to attain a reactive geometry upon heating and their consequent TAAC polymerization to a pseudoprotein in a single‐crystal‐to‐single‐crystal (SCSC) fashion. This motion led to the creation of channels in the product crystal and it absorbed water from the surroundings to fill these channels as H‐bonded water wire. The pseudoprotein undergo reversible hydration/dehydration in SCSC fashion many times under mild conditions: hydration at low relative humidity and dehydration at low temperature. Vapor sorption analyses suggest that this fully organic polymer might be useful as an energy‐efficient desiccant material for controlling indoor humidity. 相似文献
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Nicon Ungur Veaceslav Kulciţki Olga Chetraru Marina Grinco Pavel F. Vlad 《Helvetica chimica acta》2013,96(5):864-871
An efficient one step, retro‐biomimetic procedure for the synthesis of natural products having the atisane structure is described (Scheme 2), natural products which are components of medicinal plants and possess relevant biological activity. Their structures were confirmed by chemical transformations and spectral data. The starting materials were the known ent‐kaur‐16‐en‐19‐oic acid ( 1 ) and ent‐trachyloban‐19‐oic acid ( 2 ), diterpenoids readily available from the waste of sunflower. 相似文献