Pub Date : 2021-09-30DOI: 10.33774/chemrxiv-2021-qtfg0
Kyle Groden, Fernando D Vila, Li Li, Simon Bare, Susannah Scott, Jean-Sabin McEwen
The X-ray absorption near edge structure (XANES) can provide uniquely detailed information on the coordination environments of important Ga-containing materials with unknown structures, including catalytically-active materials. In this study, the Ga K-edge XANES was simulated using first principles-based methods for seven molecular Ga complexes, as well b-Ga2O3, in order to explore the chemical origins of the experimentally observed features. The theoretical spectra were computed using FEFF, CASTEP and StoBE, in order to assess the sensitivity of the results to the computational approach. While the XANES features depend on the Ga coordination environment, they are also sensitive to the electronegativity of the ligands and the symmetry at Ga. The white line position responds to changes in both the core state (due to differential screening) and the valence “p” states (arising from differences in ligand coordination).
{"title":"First Principles Approach to Extracting Chemical Information from X-Ray Absorption Near-Edge Spectra of Ga-Containing Materials","authors":"Kyle Groden, Fernando D Vila, Li Li, Simon Bare, Susannah Scott, Jean-Sabin McEwen","doi":"10.33774/chemrxiv-2021-qtfg0","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-qtfg0","url":null,"abstract":"The X-ray absorption near edge structure (XANES) can provide uniquely detailed information on the coordination environments of important Ga-containing materials with unknown structures, including catalytically-active materials. In this study, the Ga K-edge XANES was simulated using first principles-based methods for seven molecular Ga complexes, as well b-Ga2O3, in order to explore the chemical origins of the experimentally observed features. The theoretical spectra were computed using FEFF, CASTEP and StoBE, in order to assess the sensitivity of the results to the computational approach. While the XANES features depend on the Ga coordination environment, they are also sensitive to the electronegativity of the ligands and the symmetry at Ga. The white line position responds to changes in both the core state (due to differential screening) and the valence “p” states (arising from differences in ligand coordination).","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69679056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-29DOI: 10.33774/chemrxiv-2021-w299m
M. Stasi, Alba Monferrer i Sureda, Leon Babl, Sreekar Wunnava, Christina F. Dirscherl, D. Braun, P. Schwille, Hendrik Dietz, J. Boekhoven
Molecular machines, such as ATPases or motor proteins, couple the catalysis of a chemical reaction, most commonly hydrolysis of nucleotide triphosphates, to their conformational change. In essence, they continuously convert a chemical fuel to drive their motion. An outstanding goal of nanotechnology remains to synthesize a nanomachine with similar functions, precision, and speed. The field of DNA nan- otechnology has given rise to the engineering precision required for such a device. Simultaneously, the field of systems chemistry developed fast chemical reaction cycles that convert fuel to change the function of molecules. In this work, we thus combined a fast, chemical reaction cycle with the precision of DNA nanotechnology to yield kinetic control over the conformational state of a DNA hairpin. Future work on such systems will result in fast and precise DNA nanodevices.
{"title":"Regulating the dynamic folding of a DNA hairpin at the expense of a small, molecular fuel","authors":"M. Stasi, Alba Monferrer i Sureda, Leon Babl, Sreekar Wunnava, Christina F. Dirscherl, D. Braun, P. Schwille, Hendrik Dietz, J. Boekhoven","doi":"10.33774/chemrxiv-2021-w299m","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-w299m","url":null,"abstract":"Molecular machines, such as ATPases or motor proteins, couple the catalysis of a chemical reaction, most commonly hydrolysis of nucleotide triphosphates, to their conformational change. In essence, they continuously convert a chemical fuel to drive their motion. An outstanding goal of nanotechnology remains to synthesize a nanomachine with similar functions, precision, and speed. The field of DNA nan- otechnology has given rise to the engineering precision required for such a device. Simultaneously, the field of systems chemistry developed fast chemical reaction cycles that convert fuel to change the function of molecules. In this work, we thus combined a fast, chemical reaction cycle with the precision of DNA nanotechnology to yield kinetic control over the conformational state of a DNA hairpin. Future work on such systems will result in fast and precise DNA nanodevices.","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47808269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-29DOI: 10.33774/chemrxiv-2021-8p816
D. Payne, J. Hynek, J. Labuta, Jonathan P. Hill
Meso-tetrakis-(3,4,5-tris{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}phenyl)porphyrin TEG12PH2 is reported as an ‘omnisoluble’ TPP reference for singlet oxygen (1O2) generation quantum yield (ΦSO) estimation. TEG12PH2 is a highly soluble, nonionic compound possessing excellent 1O2 QY in a wide variety of common solvents, including water. TEG12PH2 was prepared on multigram scale by the 12-way O-alkylation of tetrakis(3,4,5-trihydroxyphenyl)porphyrin using 2-(2-(2-methoxyethoxy)ethoxy)ethyl 4-toluenesulfonate as reaction solvent. The corresponding Zn(II) complex TEG12PZn was also prepared and studied. Its 1O2 QYs in the different solvents studied were found to be 0.86 (acetone), 0.59 (acetonitrile), 0.66 (chloroform), 0.85 (methanol), 0.45 (toluene) and 0.51 (water). TEG12PH2 can be considered a reliable and easy to implement omnisoluble reference compound for the estimation of the 1O2 generating activities of new materials, especially new porphyrinic compounds.
{"title":"Simple Nonionic Omnisoluble Tetraphenylporphyrin for Relative Referencing of Singlet Oxygen Quantum Yield","authors":"D. Payne, J. Hynek, J. Labuta, Jonathan P. Hill","doi":"10.33774/chemrxiv-2021-8p816","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-8p816","url":null,"abstract":"Meso-tetrakis-(3,4,5-tris{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}phenyl)porphyrin TEG12PH2 is reported as an ‘omnisoluble’ TPP reference for singlet oxygen (1O2) generation quantum yield (ΦSO) estimation. TEG12PH2 is a highly soluble, nonionic compound possessing excellent 1O2 QY in a wide variety of common solvents, including water. TEG12PH2 was prepared on multigram scale by the 12-way O-alkylation of tetrakis(3,4,5-trihydroxyphenyl)porphyrin using 2-(2-(2-methoxyethoxy)ethoxy)ethyl 4-toluenesulfonate as reaction solvent. The corresponding Zn(II) complex TEG12PZn was also prepared and studied. Its 1O2 QYs in the different solvents studied were found to be 0.86 (acetone), 0.59 (acetonitrile), 0.66 (chloroform), 0.85 (methanol), 0.45 (toluene) and 0.51 (water). TEG12PH2 can be considered a reliable and easy to implement omnisoluble reference compound for the estimation of the 1O2 generating activities of new materials, especially new porphyrinic compounds.","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41727259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-29DOI: 10.33774/chemrxiv-2021-4942b
P. E. S. Soto Rodriguez, M. Valles, Agostino Romeo, R. Artuch, Samuel Sánchez
Phenylketonuria (PKU) is a metabolic disease resulting from a deficiency in the enzyme phenylalanine hydroxylase, increasing L-Phenylalanine (L-Phe) values in the blood and consequently in the brain. If untreated, PKU leads to neurological damage, which can be prevented by following a diet low in L-Phe. Thus, early detection of PKU in newborns is essential. The disease’s screening and monitoring are centralized in reference centers, which require specialized equipment. However, using these techniques, sample treatment is required before the analysis, and trained personnel must perform and interpret the results. In this work, we present an enzyme-based photometric strategy to measure blood L-Phe. An enzymatic mixture, selective for L-Phe, is immobilized on an UV transparent well, and the amount of consumed co-factor is monitored at 340 nm. Standard plasma and whole blood samples were chosen to pre-validate the sensor. The samples were spiked with an increasing amount of L-Phe, accurately discriminating between physiological and pathological L-Phe concentrations. The strategy can be easily extended to analyzing other samples, such as urine or sweat. The proposed photometric system allows to analyze up to 16 samples simultaneously within a matter of hours. The measurements are relatively fast, versatile, cost-effective, and easy to carry out.
{"title":"A preclinical biosensor for detecting phenylalanine photometrically in plasma and whole blood samples","authors":"P. E. S. Soto Rodriguez, M. Valles, Agostino Romeo, R. Artuch, Samuel Sánchez","doi":"10.33774/chemrxiv-2021-4942b","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-4942b","url":null,"abstract":"Phenylketonuria (PKU) is a metabolic disease resulting from a deficiency in the enzyme phenylalanine hydroxylase, increasing L-Phenylalanine (L-Phe) values in the blood and consequently in the brain. If untreated, PKU leads to neurological damage, which can be prevented by following a diet low in L-Phe. Thus, early detection of PKU in newborns is essential. The disease’s screening and monitoring are centralized in reference centers, which require specialized equipment. However, using these techniques, sample treatment is required before the analysis, and trained personnel must perform and interpret the results. In this work, we present an enzyme-based photometric strategy to measure blood L-Phe. An enzymatic mixture, selective for L-Phe, is immobilized on an UV transparent well, and the amount of consumed co-factor is monitored at 340 nm. Standard plasma and whole blood samples were chosen to pre-validate the sensor. The samples were spiked with an increasing amount of L-Phe, accurately discriminating between physiological and pathological L-Phe concentrations. The strategy can be easily extended to analyzing other samples, such as urine or sweat. The proposed photometric system allows to analyze up to 16 samples simultaneously within a matter of hours. The measurements are relatively fast, versatile, cost-effective, and easy to carry out.","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48954102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-29DOI: 10.33774/chemrxiv-2021-0np10
J. Shaw, David A. Gutierrez, J. Fettinger, K. Ando, K. Houk
The Lewis acid catalyzed addition of prochiral E and Z allyl nucleophiles to chiral -alkoxy N-tosyl imines is described. Alkene geometry is selectively transferred to the newly formed carbon-carbon bond, resulting in stereochemical control of C2, C3, and C4 of the resulting 2-alkoxy-3-N-tosyl-4-alkyl-5-hexenes. The C3 and C4 diastereoselectivity (dr) is influenced by the geometry of the alkene, size of N-sulfonyl substituent, and steric bulk of the substituted -alkoxy ether group. This work demonstrates that three of the four possible diastereomers can be synthesized in high diastereoselectivity and high yields using the current methods. A mechanistic computational analysis to elucidate the high selectivity is also presented.
{"title":"Diastereoselective Addition of Prochiral Nucleophilic Alkenes to a-Chiral N-Sulfonyl Imines","authors":"J. Shaw, David A. Gutierrez, J. Fettinger, K. Ando, K. Houk","doi":"10.33774/chemrxiv-2021-0np10","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-0np10","url":null,"abstract":"The Lewis acid catalyzed addition of prochiral E and Z allyl nucleophiles to chiral -alkoxy N-tosyl imines is described. Alkene geometry is selectively transferred to the newly formed carbon-carbon bond, resulting in stereochemical control of C2, C3, and C4 of the resulting 2-alkoxy-3-N-tosyl-4-alkyl-5-hexenes. The C3 and C4 diastereoselectivity (dr) is influenced by the geometry of the alkene, size of N-sulfonyl substituent, and steric bulk of the substituted -alkoxy ether group. This work demonstrates that three of the four possible diastereomers can be synthesized in high diastereoselectivity and high yields using the current methods. A mechanistic computational analysis to elucidate the high selectivity is also presented.","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48267473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-29DOI: 10.33774/chemrxiv-2021-3zxh4
Tim Bernges, R. Hanus, Bjöern Wankmiller, Kazuki Imasato, Siqi Lin, M. Ghidiu, Marius Gerlitz, M. Peterlechner, S. Graham, G. Hautier, Y. Pei, Michael Ryan Hansen, G. Wilde, G. J. Snyder, Janine George, M. Agne, W. Zeier
Ultra-low lattice thermal conductivity as often found in superionic compounds is greatly beneficial for thermoelectric performance, however, a high ionic conductivity can lead to device degradation. Conversely, high ionic conductivities are searched for materials in solid-state battery applications. It is commonly thought that ionic transport induces low thermal conductivity and that ion and thermal transport are not completely independent properties of a material. However, no direct comparison or underlying physical relationship has been shown between the two. Here we establish that ionic transport can be varied independent of thermal transport in Ag+ superionic conductors, even though both phenomena arise from atomic vibrations. Thermal conductivity measurements, in conjunction with two-channel lattice dynamics modeling, reveals that the vast majority of Ag+ vibrations have non-propagating diffuson-like character, which provides a rational for how these two transport properties can be independent. Our results provide conceptually novel lattice dynamical insights to ionic transport and confirm that ion transport is not a requirement for ultra-low thermal conductivity. Consequently, this work bridges the fields of solid state ionics and thermal transport, thus providing design strategies for functional ionic conducting materials from a vibrational perspective.
{"title":"Diffuson-mediated thermal and ionic transport in superionic conductors","authors":"Tim Bernges, R. Hanus, Bjöern Wankmiller, Kazuki Imasato, Siqi Lin, M. Ghidiu, Marius Gerlitz, M. Peterlechner, S. Graham, G. Hautier, Y. Pei, Michael Ryan Hansen, G. Wilde, G. J. Snyder, Janine George, M. Agne, W. Zeier","doi":"10.33774/chemrxiv-2021-3zxh4","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-3zxh4","url":null,"abstract":"Ultra-low lattice thermal conductivity as often found in superionic compounds is greatly beneficial for thermoelectric performance, however, a high ionic conductivity can lead to device degradation. Conversely, high ionic conductivities are searched for materials in solid-state battery applications. It is commonly thought that ionic transport induces low thermal conductivity and that ion and thermal transport are not completely independent properties of a material. However, no direct comparison or underlying physical relationship has been shown between the two. Here we establish that ionic transport can be varied independent of thermal transport in Ag+ superionic conductors, even though both phenomena arise from atomic vibrations. Thermal conductivity measurements, in conjunction with two-channel lattice dynamics modeling, reveals that the vast majority of Ag+ vibrations have non-propagating diffuson-like character, which provides a rational for how these two transport properties can be independent. Our results provide conceptually novel lattice dynamical insights to ionic transport and confirm that ion transport is not a requirement for ultra-low thermal conductivity. Consequently, this work bridges the fields of solid state ionics and thermal transport, thus providing design strategies for functional ionic conducting materials from a vibrational perspective.","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41516170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-29DOI: 10.33774/chemrxiv-2021-1df6h
F. Genier, Shreyas Pathreeker, Robson L. Schuarca, Mohammad Islam, I. Hosein
Deriving battery grade materials from natural sources is a key element to establishing sustainable energy storage technologies. In this work, we present the use of avocado peels as a sustainable source for conversion into hard carbon based anodes for sodium ion batteries. The avocado peels are simply washed and dried then proceeded to a high temperature conversion step. Materials characterization reveals conversion of the avocado peels in high purity, highly porous hard carbon powders. When prepared as anode materials they show to the capability to reversibly store and release sodium ions. The hard carbon-based electrodes exhibit excellent cycling performance, namely, a reversible capacity of 352.55 mAh/g at 0.05 A/g, rate capability up to 86 mAh/g at 3500 mA/g, capacity retention of >90%, and 99.9% coulombic efficiencies after 500 cycles. This study demonstrates avocado derived hard carbon as a sustainable source that can provide excellent electrochemical and battery performance as anodes in sodium ion batteries.
{"title":"Hard Carbon Derived from Avocado Peels as a High-Capacity, High-Performance Anode Material for Sodium-Ion Batteries","authors":"F. Genier, Shreyas Pathreeker, Robson L. Schuarca, Mohammad Islam, I. Hosein","doi":"10.33774/chemrxiv-2021-1df6h","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-1df6h","url":null,"abstract":"Deriving battery grade materials from natural sources is a key element to establishing sustainable energy storage technologies. In this work, we present the use of avocado peels as a sustainable source for conversion into hard carbon based anodes for sodium ion batteries. The avocado peels are simply washed and dried then proceeded to a high temperature conversion step. Materials characterization reveals conversion of the avocado peels in high purity, highly porous hard carbon powders. When prepared as anode materials they show to the capability to reversibly store and release sodium ions. The hard carbon-based electrodes exhibit excellent cycling performance, namely, a reversible capacity of 352.55 mAh/g at 0.05 A/g, rate capability up to 86 mAh/g at 3500 mA/g, capacity retention of >90%, and 99.9% coulombic efficiencies after 500 cycles. This study demonstrates avocado derived hard carbon as a sustainable source that can provide excellent electrochemical and battery performance as anodes in sodium ion batteries.","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48149658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-28DOI: 10.33774/chemrxiv-2021-bhs2k
Joe I Higham, J. Bull
The copper mediated β–C(sp2)–H sulfonylation of benzaldehydes with sulfinate salts is accomplished using β-alanine as a catalytic transient directing group. A broad range of sulfonylated benzaldehydes are prepared us-ing copper fluoride as both copper source and oxidant. Both b-(ortho) and g-(peri)-sulfonylation are demon-strated. Mechanistic studies indicate the turnover limiting step to be a concerted asynchronous C–H cleavage via a Wheland-type transition state.
{"title":"Copper Mediated C(sp2)–H Sulfonylation of Aldehydes using a Catalytic Transient Imine Directing Group","authors":"Joe I Higham, J. Bull","doi":"10.33774/chemrxiv-2021-bhs2k","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-bhs2k","url":null,"abstract":"The copper mediated β–C(sp2)–H sulfonylation of benzaldehydes with sulfinate salts is accomplished using β-alanine as a catalytic transient directing group. A broad range of sulfonylated benzaldehydes are prepared us-ing copper fluoride as both copper source and oxidant. Both b-(ortho) and g-(peri)-sulfonylation are demon-strated. Mechanistic studies indicate the turnover limiting step to be a concerted asynchronous C–H cleavage via a Wheland-type transition state.","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45377218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-28DOI: 10.33774/chemrxiv-2021-brq1h
Hadar Nasi, M. D. di Gregorio, Qiang Wen, L. Shimon, I. Kaplan-Ashiri, T. Bendikov, M. Lahav, M. E. van der Boom
Crystals are among the most challenging materials to design, both at the molecular and macroscopic levels. We show here that metal-organic frameworks, based on tetrahedral pyridyl ligands, can be used as a morpho-logical and structural mold to form a series of other isostructural crystals having different metal ions. The cati-on exchange is versatile, based on the use of diverse first-row metals; it occurs with retention of the morpholo-gy. Different morphologies were obtained by a direct reaction between the ligand and metal salts. An iterative crystal-to-crystal conversion has also been demonstrated by two consecutive cation exchange processes. The primary manganese-based crystals have a complex connectivity characterized by a rare space group (P622). The molecular structure generates two types of homochiral channels that span longitudinally the entire hex-agonal prism. These channels mediate the cation exchange, as indicated by energy-dispersive X-ray spectros-copy combined with scanning electron microscopy measurements on microtome-sectioned crystals. The occur-rence of the observed cation exchange is in excellent agreement with the Irving-Williams series (Mn < Fe < Co < Ni < Cu > Zn) that are associated with the relative stability of the resulting coordination nodes. The overall approach allows for the predictability of the structural properties of rare metal-organic frameworks based on tetrahedral pyridyl ligands at different hierarchies: from elemental composition, molecular packing, and mor-phology to the bulk properties.
{"title":"Directing both the Morphology and Packing of Chiral Metal-Organic Frameworks by Cation Exchange Mediated by Nanochannels","authors":"Hadar Nasi, M. D. di Gregorio, Qiang Wen, L. Shimon, I. Kaplan-Ashiri, T. Bendikov, M. Lahav, M. E. van der Boom","doi":"10.33774/chemrxiv-2021-brq1h","DOIUrl":"https://doi.org/10.33774/chemrxiv-2021-brq1h","url":null,"abstract":"Crystals are among the most challenging materials to design, both at the molecular and macroscopic levels. We show here that metal-organic frameworks, based on tetrahedral pyridyl ligands, can be used as a morpho-logical and structural mold to form a series of other isostructural crystals having different metal ions. The cati-on exchange is versatile, based on the use of diverse first-row metals; it occurs with retention of the morpholo-gy. Different morphologies were obtained by a direct reaction between the ligand and metal salts. An iterative crystal-to-crystal conversion has also been demonstrated by two consecutive cation exchange processes. The primary manganese-based crystals have a complex connectivity characterized by a rare space group (P622). The molecular structure generates two types of homochiral channels that span longitudinally the entire hex-agonal prism. These channels mediate the cation exchange, as indicated by energy-dispersive X-ray spectros-copy combined with scanning electron microscopy measurements on microtome-sectioned crystals. The occur-rence of the observed cation exchange is in excellent agreement with the Irving-Williams series (Mn < Fe < Co < Ni < Cu > Zn) that are associated with the relative stability of the resulting coordination nodes. The overall approach allows for the predictability of the structural properties of rare metal-organic frameworks based on tetrahedral pyridyl ligands at different hierarchies: from elemental composition, molecular packing, and mor-phology to the bulk properties.","PeriodicalId":72565,"journal":{"name":"ChemRxiv : the preprint server for chemistry","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43501358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-28DOI: 10.33774/CHEMRXIV-2021-ND0R2
Qin Yiying Zhu Yu Xiang Zichen
The SARS-CoV-2 spike protein uses its receptor-binding domain (RBD) to interact with the angiotensin-converting enzyme 2 (ACE2) receptor on host cells, establishing the first step of SARS-CoV-2 infection. Inhibitors of RBD-ACE2 interaction, therefore, have shown great promise in preventing SARS-CoV-2 infection. Currently known RBD-ACE2 inhibitors are all based on reversible binding and must compete with ACE2 or RBD at the equilibrium. On the other hand, covalent inhibitors, such as those based on sulfur(VI) fluoride exchange (SuFEx) chemistry, can form irreversible chemical bonds with target proteins and offer advantages including higher potency and longer duration of inhibition. Here, we report covalent aptamer inhibitors that can block RBD-ACE2 by forming covalent bonds with RBD. These covalent aptamer inhibitors were developed by equipping known RBD aptamers with multiple SuFEx (mSuFEx) modifications. The mSuFEx-aptamer 6C3-7SF underwent strong covalent bonding with RBD and some of its variants at fast rates (t1/2 = 20 ~ 29 min−1) and induced more efficient RBD-ACE2 inhibition (IC50 = 26 ~ 37 nM) than the original aptamer (IC50 > 200 nM) according to an in vitro enzyme-linked immunosorbent assay (ELISA). The covalent bond formation was highly selective to RBD over human serum albumin (HSA) and ACE2, and could occur efficiently in diluted human serum. Peptide fragmentation analyses of the RBD-6C3-7SF adducts revealed multiple sites of covalent bonding on RBD, including K378, R408, Y422, Y424, Y453, and K458. The surprising R408 suggests that context-specific non-N-terminal arginine could be a new type of targetable residue by SuFEx-based covalent inhibitors, which were never reported as reactive with any non-N-terminal arginine in target proteins. In addition, RBD R408 is responsible for binding with ACE2 N90 glycan, and this arginine is conserved in SARS-CoV-2 variants of concern or interest, suggesting that R408 could be the potential site of interest for developing SuFEx-based covalent inhibitors against threatening SARS-CoV-2 variants. Although the compatibility of mSuFEx-based covalent aptamers in cellular and in vivo systems should be further investigated, our study demonstrated the promise of mSuFEx chemistry in constructing potent covalent aptamers to inhibit important protein-protein interactions (PPIs).
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