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Different profiles of soil phosphorous compounds depending on tree species and availability of soil phosphorus in a tropical rainforest in French Guiana. BMC PLANT BIOLOGY 2024; 24:278. [PMID: 38609866 PMCID: PMC11010349 DOI: 10.1186/s12870-024-04907-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/13/2024] [Indexed: 04/14/2024]
Abstract
BACKGROUND The availability of soil phosphorus (P) often limits the productivities of wet tropical lowland forests. Little is known, however, about the metabolomic profile of different chemical P compounds with potentially different uses and about the cycling of P and their variability across space under different tree species in highly diverse tropical rainforests. RESULTS We hypothesised that the different strategies of the competing tree species to retranslocate, mineralise, mobilise, and take up P from the soil would promote distinct soil 31P profiles. We tested this hypothesis by performing a metabolomic analysis of the soils in two rainforests in French Guiana using 31P nuclear magnetic resonance (NMR). We analysed 31P NMR chemical shifts in soil solutions of model P compounds, including inorganic phosphates, orthophosphate mono- and diesters, phosphonates, and organic polyphosphates. The identity of the tree species (growing above the soil samples) explained > 53% of the total variance of the 31P NMR metabolomic profiles of the soils, suggesting species-specific ecological niches and/or species-specific interactions with the soil microbiome and soil trophic web structure and functionality determining the use and production of P compounds. Differences at regional and topographic levels also explained some part of the the total variance of the 31P NMR profiles, although less than the influence of the tree species. Multivariate analyses of soil 31P NMR metabolomics data indicated higher soil concentrations of P biomolecules involved in the active use of P (nucleic acids and molecules involved with energy and anabolism) in soils with lower concentrations of total soil P and higher concentrations of P-storing biomolecules in soils with higher concentrations of total P. CONCLUSIONS The results strongly suggest "niches" of soil P profiles associated with physical gradients, mostly topographic position, and with the specific distribution of species along this gradient, which is associated with species-specific strategies of soil P mineralisation, mobilisation, use, and uptake.
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Hyperpolarization-Enhanced NMR Spectroscopy of Unaltered Biofluids Using Photo-CIDNP. Anal Chem 2024; 96:102-109. [PMID: 38109875 PMCID: PMC10782414 DOI: 10.1021/acs.analchem.3c03215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/20/2023]
Abstract
The direct and unambiguous detection and identification of individual metabolite molecules present in complex biological mixtures constitute a major challenge in (bio)analytical research. In this context, nuclear magnetic resonance (NMR) spectroscopy has proven to be particularly powerful owing to its ability to provide both qualitative and quantitative atomic-level information on multiple analytes simultaneously in a noninvasive manner. Nevertheless, NMR suffers from a low inherent sensitivity and, moreover, lacks selectivity regarding the number of individual analytes to be studied in a mixture of a myriad of structurally and chemically very different molecules, e.g., metabolites in a biofluid. Here, we describe a method that circumvents these shortcomings via performing selective, photochemically induced dynamic nuclear polarization (photo-CIDNP) enhanced NMR spectroscopy on unmodified complex biological mixtures, i.e., human urine and serum, which yields a single, background-free one-dimensional NMR spectrum. In doing this, we demonstrate that photo-CIDNP experiments on unmodified complex mixtures of biological origin are feasible, can be performed straightforwardly in the native aqueous medium at physiological metabolite concentrations, and act as a spectral filter, facilitating the analysis of NMR spectra of complex biofluids. Due to its noninvasive nature, the method is fully compatible with state-of-the-art metabolomic protocols providing direct spectroscopic information on a small, carefully selected subset of clinically relevant metabolites. We anticipate that this approach, which, in addition, can be combined with existing high-throughput/high-sensitivity NMR methodology, holds great promise for further in-depth studies and development for use in metabolomics and many other areas of analytical research.
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3
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(Bio)Functionalisation of Metal-Organic Polyhedra by Using Click Chemistry. Chemistry 2023; 29:e202301945. [PMID: 37523177 DOI: 10.1002/chem.202301945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/24/2023] [Accepted: 07/30/2023] [Indexed: 08/01/2023]
Abstract
The surface chemistry of Metal-Organic Polyhedra (MOPs) is crucial to their physicochemical properties because it governs how they interact with external substances such as solvents, synthetic organic molecules, metal ions, and even biomolecules. Consequently, the advancement of synthetic methods that facilitate the incorporation of diverse functional groups onto MOP surfaces will significantly broaden the range of properties and potential applications for MOPs. This study describes the use of copper(I)-catalysed, azide-alkyne cycloaddition (CuAAC) click reactions to post-synthetically modify the surface of alkyne-functionalised cuboctahedral MOPs. To this end, a novel Rh(II)-based MOP with 24 available surface alkyne groups was synthesised. Each of the 24 alkyne groups on the surface of the "clickable" Rh-MOP can react with azide-containing molecules at room temperature, without compromising the integrity of the MOP. The wide substrate catalogue and orthogonal nature of CuAAC click chemistry was exploited to densely functionalise MOPs with diverse functional groups, including polymers, carboxylic and phosphonic acids, and even biotin moieties, which retained their recognition capabilities once anchored onto the surface of the MOP.
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4
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Synthesis of C 60 /[10]CPP-Catenanes by Regioselective, Nanocapsule-Templated Bingel Bis-Addition. Angew Chem Int Ed Engl 2023; 62:e202309393. [PMID: 37607866 DOI: 10.1002/anie.202309393] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/20/2023] [Accepted: 08/21/2023] [Indexed: 08/24/2023]
Abstract
The addition of two unsymmetric malonate esters to the Buckminster fullerene C60 can lead to 22 spectroscopically distinguishable isomeric products and therefore represents a formidable synthesis challenge. In this work, we achieve 87 % selectivity for the formation of a single (in,out-trans-3) isomer by combining three approaches: (i) we use a starting material, in which the two malonates are covalently connected (tether approach); (ii) we form the strong supramolecular complex of C60 with the shape-persistent [10]CPP macrocycle (template approach) and (iii) we embed this complex further within a self-assembled nanocapsule (shadow mask approach). Variation of the spacer chain shed light on the limitations of the approach and the ring dynamics in the unusual [2]catenanes were studied in silico with atomistic resolution. This work significantly widens the scope of mechanically interlocked architectures comprising cycloparaphenylenes (CPP).
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Synthesis and characterization of highly diluted polyanionic iron(II) spin crossover systems. STAR Protoc 2023; 4:102394. [PMID: 37392390 PMCID: PMC10338372 DOI: 10.1016/j.xpro.2023.102394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/20/2023] [Accepted: 05/31/2023] [Indexed: 07/03/2023] Open
Abstract
Spin crossover (SCO) complexes, through their reversible spin transition under external stimuli, can work as switchable memory materials. Here, we present a protocol for the synthesis and characterization of a specific polyanionic iron SCO complex and its diluted systems. We describe steps for its synthesis and the determination of crystallographic structure of the SCO complex in diluted systems. We then detail a range of spectroscopic and magnetic techniques employed to monitor the spin state of the SCO complex in both diluted solid- and liquid-state systems. For complete details on the use and execution of this protocol, please refer to Galán-Mascaros et al.1.
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Biocatalytic Synthesis of Homochiral 2-Hydroxy-4-butyrolactone Derivatives by Tandem Aldol Addition and Carbonyl Reduction. ACS Catal 2023; 13:5348-5357. [PMID: 37123603 PMCID: PMC10127515 DOI: 10.1021/acscatal.3c00367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/09/2023] [Indexed: 04/08/2023]
Abstract
Chiral 2-hydroxy acids and 2-hydroxy-4-butyrolactone derivatives are structural motifs often found in fine and commodity chemicals. Here, we report a tandem biocatalytic stereodivergent route for the preparation of these compounds using three stereoselective aldolases and two stereocomplementary ketoreductases using simple and achiral starting materials. The strategy comprises (i) aldol addition reaction of 2-oxoacids to aldehydes using two aldolases from E. coli, 3-methyl-2-oxobutanoate hydroxymethyltransferase (KPHMT Ecoli ), 2-keto-3-deoxy-l-rhamnonate aldolase (YfaU Ecoli ), and trans-o-hydroxybenzylidene pyruvate hydratase-aldolase from Pseudomonas putida (HBPA Pputida ) and (ii) subsequent 2-oxogroup reduction of the aldol adduct by ketopantoate reductase from E. coli (KPR Ecoli ) and a Δ1-piperidine-2-carboxylate/Δ1-pyrroline-2-carboxylate reductase from Pseudomonas syringae pv. tomato DSM 50315 (DpkA Psyrin ) with uncovered promiscuous ketoreductase activity. A total of 29 structurally diverse compounds were prepared: both enantiomers of 2-hydroxy-4-butyrolactone (>99% ee), 21 2-hydroxy-3-substituted-4-butyrolactones with the (2R,3S), (2S,3S), (2R,3R), or (2S,3R) configuration (from 60:40 to 98:2 dr), and 6 2-hydroxy-4-substituted-4-butyrolactones with the (2S,4R) configuration (from 87:13 to 98:2 dr). Conversions of aldol adducts varied from 32 to 98%, while quantitative conversions were achieved by both ketoreductases, with global isolated yields between 20 and 45% for most of the examples. One-pot one-step cascade reactions were successfully conducted achieving isolated yields from 30 to 57%.
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7
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Using nuclear magnetic resonance urine metabolomics to develop a prediction model of early stages of renal disease in subjects with type 2 diabetes. J Pharm Biomed Anal 2022; 219:114885. [DOI: 10.1016/j.jpba.2022.114885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 06/01/2022] [Accepted: 06/08/2022] [Indexed: 12/01/2022]
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8
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C sp2-H Amination Reactions Mediated by Metastable Pseudo- Oh Masked Aryl-Co III-nitrene Species. Inorg Chem 2022; 61:14075-14085. [PMID: 35997604 PMCID: PMC9455280 DOI: 10.1021/acs.inorgchem.2c02111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Cobalt-catalyzed C–H amination via M-nitrenoid
species is
spiking the interest of the research community. Understanding this
process at a molecular level is a challenging task, and here we report
a well-defined macrocyclic system featuring a pseudo-Oh aryl-CoIII species that
reacts with aliphatic azides to effect intramolecular Csp2–N bond formation. Strikingly, a putative aryl-Co=NR
nitrenoid intermediate species is formed and is rapidly trapped by
a carboxylate ligand to form a carboxylate masked-nitrene, which functions
as a shortcut to stabilize and guide the reaction to productive intramolecular
Csp2–N bond formation. On one hand, several intermediate
species featuring the Csp2–N bond formed have been
isolated and structurally characterized, and the essential role of
the carboxylate ligand has been proven. Complementarily, a thorough
density functional theory study of the Csp2–N bond
formation mechanism explains at the molecular level the key role of
the carboxylate-masked nitrene species, which is essential to tame
the metastability of the putative aryl-CoIII=NR
nitrene species to effectively yield the Csp2–N
products. The solid molecular mechanistic scheme determined for the
Csp2–N bond forming reaction is fully supported
by both experimental and computation complementary studies. A well-defined pseudo-Oh aryl-CoIII species reacts
with aliphatic azides
to effect intramolecular Csp2−N bond formation via
a carboxylate masked-CoIII-nitrene, which serves as a shortcut
to guide the reaction to productive Csp2−N bond
formation.
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pH‐Triggered Removal of Nitrogenous Organic Micropollutants from Water by Using Metal‐Organic Polyhedra. Chemistry 2022; 28:e202200357. [PMID: 35348255 PMCID: PMC9322004 DOI: 10.1002/chem.202200357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Indexed: 11/09/2022]
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10
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Synthesis of γ-Hydroxy-α-amino Acid Derivatives by Enzymatic Tandem Aldol Addition-Transamination Reactions. ACS Catal 2021; 11:4660-4669. [PMID: 34603828 PMCID: PMC8482765 DOI: 10.1021/acscatal.1c00210] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/20/2021] [Indexed: 12/26/2022]
Abstract
![]()
Three
enzymatic routes toward γ-hydroxy-α-amino acids
by tandem aldol addition–transamination one-pot two-step reactions
are reported. The approaches feature an enantioselective aldol addition
of pyruvate to various nonaromatic aldehydes catalyzed by trans-o-hydroxybenzylidene pyruvate hydratase-aldolase
(HBPA) from Pseudomonas putida. This
affords chiral 4-hydroxy-2-oxo acids, which were subsequently enantioselectively
aminated using S-selective transaminases. Three transamination
processes were investigated involving different amine donors and transaminases:
(i) l-Ala as an amine donor with pyruvate recycling, (ii)
a benzylamine donor using benzaldehyde lyase from Pseudomonas
fluorescens Biovar I (BAL) to transform the benzaldehyde
formed into benzoin, minimizing equilibrium limitations, and (iii) l-Glu as an amine donor with a double cascade comprising branched-chain
α-amino acid aminotransferase (BCAT) and aspartate amino transferase
(AspAT), both from E. coli, using l-Asp as a substrate to regenerate l-Glu. The γ-hydroxy-α-amino
acids thus obtained were transformed into chiral α-amino-γ-butyrolactones,
structural motifs found in many biologically active compounds and
valuable intermediates for the synthesis of pharmaceutical agents.
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11
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Abstract
An efficient, one-step protocol for the enrichment of C84 (up to 86%) directly from a fullerene extract is reported, by utilizing a tetragonal prismatic nanocapsule with a suitable size and shape for selective encapsulation.
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12
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Simultaner enantiospezifischer Nachweis mehrerer Verbindungen in Mischungen mittels NMR‐Spektroskopie. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202011727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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13
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Biocatalytic Construction of Quaternary Centers by Aldol Addition of 3,3-Disubstituted 2-Oxoacid Derivatives to Aldehydes. J Am Chem Soc 2020; 142:19754-19762. [PMID: 33147013 DOI: 10.1021/jacs.0c09994] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The congested nature of quaternary carbons hinders their preparation, most notably when stereocontrol is required. Here we report a biocatalytic method for the creation of quaternary carbon centers with broad substrate scope, leading to different compound classes bearing this structural feature. The key step comprises the aldol addition of 3,3-disubstituted 2-oxoacids to aldehydes catalyzed by metal dependent 3-methyl-2-oxobutanoate hydroxymethyltransferase from E. coli (KPHMT) and variants thereof. The 3,3,3-trisubstituted 2-oxoacids thus produced were converted into 2-oxolactones and 3-hydroxy acids and directly to ulosonic acid derivatives, all bearing gem-dialkyl, gem-cycloalkyl, and spirocyclic quaternary centers. In addition, some of these reactions use a single enantiomer from racemic nucleophiles to afford stereopure quaternary carbons. The notable substrate tolerance and stereocontrol of these enzymes are indicative of their potential for the synthesis of structurally intricate molecules.
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Simultaneous Enantiospecific Detection of Multiple Compounds in Mixtures using NMR Spectroscopy. Angew Chem Int Ed Engl 2020; 59:23615-23619. [PMID: 32959941 DOI: 10.1002/anie.202011727] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Indexed: 01/21/2023]
Abstract
Chirality plays a fundamental role in nature, but its detection and quantification still face many limitations. To date, the enantiospecific analysis of mixtures necessarily requires prior separation of the individual components. The simultaneous enantiospecific detection of multiple chiral molecules in a mixture represents a major challenge, which would lead to a significantly better understanding of the underlying biological processes; for example, via enantiospecifically analysing metabolites in their native environment. Here, we report on the first in situ enantiospecific detection of a thirty-nine-component mixture. As a proof of concept, eighteen essential amino acids at physiological concentrations were simultaneously enantiospecifically detected using NMR spectroscopy and a chiral solvating agent. This work represents a first step towards the simultaneous multicomponent enantiospecific analysis of complex mixtures, a capability that will have substantial impact on metabolism studies, metabolic phenotyping, chemical reaction monitoring, and many other fields where complex mixtures containing chiral molecules require efficient characterisation.
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31P-NMR Metabolomics Revealed Species-Specific Use of Phosphorous in Trees of a French Guiana Rainforest. Molecules 2020; 25:molecules25173960. [PMID: 32877991 PMCID: PMC7504763 DOI: 10.3390/molecules25173960] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/23/2020] [Accepted: 07/30/2020] [Indexed: 11/16/2022] Open
Abstract
Productivity of tropical lowland moist forests is often limited by availability and functional allocation of phosphorus (P) that drives competition among tree species and becomes a key factor in determining forestall community diversity. We used non-target 31P-NMR metabolic profiling to study the foliar P-metabolism of trees of a French Guiana rainforest. The objective was to test the hypotheses that P-use is species-specific, and that species diversity relates to species P-use and concentrations of P-containing compounds, including inorganic phosphates, orthophosphate monoesters and diesters, phosphonates and organic polyphosphates. We found that tree species explained the 59% of variance in 31P-NMR metabolite profiling of leaves. A principal component analysis showed that tree species were separated along PC 1 and PC 2 of detected P-containing compounds, which represented a continuum going from high concentrations of metabolites related to non-active P and P-storage, low total P concentrations and high N:P ratios, to high concentrations of P-containing metabolites related to energy and anabolic metabolism, high total P concentrations and low N:P ratios. These results highlight the species-specific use of P and the existence of species-specific P-use niches that are driven by the distinct species-specific position in a continuum in the P-allocation from P-storage compounds to P-containing molecules related to energy and anabolic metabolism.
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Evidence of Enantiomers of Spiroglycol. Distinction by Using α,α′-Bis(trifluoromethyl)-9,10-anthracenedimethanol as a Chiral Solvating Agent and by Derivatization with Chiral Acids. J Org Chem 2020; 85:7247-7257. [DOI: 10.1021/acs.joc.0c00578] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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17
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How to measure long-range proton-carbon coupling constants from 1 H-selective HSQMBC experiments. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2020; 58:363-375. [PMID: 32239575 DOI: 10.1002/mrc.4928] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/27/2019] [Accepted: 07/18/2019] [Indexed: 06/11/2023]
Abstract
Heteronuclear long-range scalar coupling constants (n JCH ) are a valuable tool for solving problems in organic chemistry and are especially suited for stereochemical and configurational analyses of small molecules and natural products. This tutorial will focus on the step-by-step implementation of several 2D 1 H frequency selective HSQMBC experiments for the easy and accurate measurement of either the magnitude or both the magnitude and the sign of long-range n JCH couplings. The performance of these experiments will be showcased with several scenarios in a range of different experimental conditions.
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LR-HSQMBC versus LR-selHSQMBC: Enhancing the Observation of Tiny Long-Range Heteronuclear NMR Correlations. JOURNAL OF NATURAL PRODUCTS 2020; 83:1275-1282. [PMID: 32155071 DOI: 10.1021/acs.jnatprod.0c00058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The detection of ultra-long-range (4JCH and higher) heteronuclear connectivities can complement the conventional use of HMBC/HSQMBC data in structure elucidation NMR studies of proton-deficient natural products, where two-bond and three-bond correlations are usually observed. The performance of the selHSQMBC experiment with respect to its broadband HSQMBC counterpart is evaluated. Despite its frequency-selectivity nature, selHSQMBC efficiently prevents any unwanted signal phase and intensity modulations due to passive proton-proton coupling constants typically involved in HSQMBC. As a result, selHSQMBC offers a significant sensitivity enhancement and provides pure in-phase multiplets, improving the detection levels for short- and long-range cross-peaks corresponding to small heteronuclear coupling values. This is particularly relevant for experiments optimized to small nJCH values (2-3 Hz), referred to as LR-selHSQMBC, where key cross-peaks that are not visible in the equivalent broadband LR-HSQMBC spectrum can become observable in optimum conditions.
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19
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Novel Heteroleptic Ruthenium(II) Complexes with 2,2'- Bipyridines Containing a Series of Electron-Donor and Electron-Acceptor Substituents in 4,4'-Positions: Syntheses, Characterization, and Application as Sensitizers for ZnO Nanowire-Based Solar Cells. ACS OMEGA 2020; 5:8097-8107. [PMID: 32309719 PMCID: PMC7161030 DOI: 10.1021/acsomega.0c00243] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
A novel series of complexes of the formula [Ru(4,4'-X2-bpy)2(Mebpy-CN)](PF6)2 (X = -CH3, -OCH3, -N(CH3)2; Mebpy-CN = 4-methyl-2,2'-bipyridine-4'-carbonitrile) have been synthesized and characterized by spectroscopic, electrochemical, and photophysical techniques. Inclusion of the electron-withdrawing substituent -CN at one bpy ligand and different electron-donor groups -X at the 4,4'-positions of the other two bpy ligands produce a fine tuning of physicochemical properties. Redox potentials, electronic absorption maxima, and emission maxima correlate well with Hammett's σp parameters of X. Quantum mechanical calculations are consistent with experimental data. All the complexes can be anchored through the nitrile moiety of Mebpy-CN over ZnO nanowires in dye-sensitized solar cells that exhibit an improvement of light to electrical energy conversion efficiency as the electronic asymmetry increases in the series.
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An Enantiopure Propeller‐Like Trityl‐Brominated Radical: Bringing Together a High Racemization Barrier and an Efficient Circularly Polarized Luminescent Magnetic Emitter. Chemistry 2020; 26:3776-3781. [DOI: 10.1002/chem.202000098] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Indexed: 11/09/2022]
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Cover Feature: An Enantiopure Propeller‐Like Trityl‐Brominated Radical: Bringing Together a High Racemization Barrier and an Efficient Circularly Polarized Luminescent Magnetic Emitter (Chem. Eur. J. 17/2020). Chemistry 2020. [DOI: 10.1002/chem.202000463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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LR-selHSQMBC: Simultaneous Detection and Quantification of Very Weak Long-Range Heteronuclear NMR Correlations. Chemphyschem 2020; 21:280-283. [PMID: 31951093 DOI: 10.1002/cphc.201901142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/10/2020] [Indexed: 11/08/2022]
Abstract
The optimum detection and accurate measurement of longer-range (4 J and higher) heteronuclear NMR correlations is described. The magnitude and/or the sign of a wide range of large and small long-range couplings can be simultaneously determined for protonated and non-protonated 13 C and 15 N nuclei using the LR-selHSQMBC experiment.
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23
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Synthesis and Structural Determination of New Brassinosteroid 24-Nor-5α-Cholane Type Analogs. Molecules 2019; 24:molecules24244612. [PMID: 31861056 PMCID: PMC6943489 DOI: 10.3390/molecules24244612] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 12/18/2022] Open
Abstract
Natural brassinosteroids possess a 22R, 23R configuration that appears essential for biological activity. It is, therefore, interesting to elucidate if the activity of brassinosteroids with a short side chain depends on the C22 configuration. Herein, we describe the synthesis of new brassinosteroids analogs with 24-norcholane type of side chain and R configuration at C22. The initial reaction is the dihydroxylation of a terminal olefin that leads to S/R epimers. Three different methods were tested in order to evaluate the obtained S/R ratio and the reaction yields. The results indicate that Upjohn dihydroxylation is the most selective reaction giving a 1.0:0.24 S/R ratio, whereas a Sharpless reaction leads to a mixture of 1.0:0.90 S/R with 95% yield. Using the latter mixture and following a previous reported method, benzoylated derivatives and both S and R brassinosteroids analogs were synthesized. All synthesized compounds were completely characterized by NMR spectroscopy, and HRMS of new compounds are also given. In conclusion, a synthetic route for preparation of new analogs of brassinosteroids of 24-norcholane type and R configuration at C22 were described. It is expected that this will help to elucidate if a configuration at C22 is a structural requirement for hormonal growth activity in plants.
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A novel mononuclear complex of 4,4″-azobis-(2,2′-bipyridine) coordinated to tetracyanoruthenium(II) can behave as a “molecular switch”. Polyhedron 2019. [DOI: 10.1016/j.poly.2019.114149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Model-based optimization of the enzymatic aldol addition of propanal to formaldehyde: A first step towards enzymatic synthesis of 3-hydroxybutyric acid. Chem Eng Res Des 2019. [DOI: 10.1016/j.cherd.2019.06.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Electrophilic Iron Catalyst Paired with a Lithium Cation Enables Selective Functionalization of Non‐Activated Aliphatic C−H Bonds via Metallocarbene Intermediates. Angew Chem Int Ed Engl 2019; 58:13904-13911. [DOI: 10.1002/anie.201905986] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 07/19/2019] [Indexed: 12/27/2022]
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Electrophilic Iron Catalyst Paired with a Lithium Cation Enables Selective Functionalization of Non‐Activated Aliphatic C−H Bonds via Metallocarbene Intermediates. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201905986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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28
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Aldolase-Catalyzed Asymmetric Synthesis of N-Heterocycles by Addition of Simple Aliphatic Nucleophiles to Aminoaldehydes. Adv Synth Catal 2019; 361:2673-2687. [PMID: 31680790 PMCID: PMC6813633 DOI: 10.1002/adsc.201801530] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/22/2019] [Indexed: 11/08/2022]
Abstract
Nitrogen heterocycles are structural motifs found in many bioactive natural products and of utmost importance in pharmaceutical drug development. In this work, a stereoselective synthesis of functionalized N-heterocycles was accomplished in two steps, comprising the biocatalytic aldol addition of ethanal and simple aliphatic ketones such as propanone, butanone, 3-pentanone, cyclobutanone, and cyclopentanone to N-Cbz-protected aminoaldehydes using engineered variants of d-fructose-6-phosphate aldolase from Escherichia coli (FSA) or 2-deoxy-d-ribose-5-phosphate aldolase from Thermotoga maritima (DERA Tma ) as catalysts. FSA catalyzed most of the additions of ketones while DERA Tma was restricted to ethanal and propanone. Subsequent treatment with hydrogen in the presence of palladium over charcoal, yielded low-level oxygenated N-heterocyclic derivatives of piperidine, pyrrolidine and N-bicyclic structures bearing fused cyclobutane and cyclopentane rings, with stereoselectivities of 96-98 ee and 97:3 dr in isolated yields ranging from 35 to 79%.
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Practical aspects of the simultaneous collection of COSY and TOCSY spectra. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:S85-S94. [PMID: 30676668 DOI: 10.1002/mrc.4835] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/10/2019] [Accepted: 01/15/2019] [Indexed: 06/09/2023]
Abstract
The practical aspects of some NMR experiments designed for the simultaneous acquisition of 2D COSY and 2D TOCSY spectra are presented and discussed. Several techniques involving afterglow-based, coherence transfer pathway (CTP)-based, and NMR by Ordered Acquisition using 1 H-detection (NOAH)-based strategies for the collection of different free-induction signal decays (FIDs) within the same scan are evaluated and compared. These methods offer a faster recording of these spectra in small-molecule NMR when sensitivity is not a limiting factor, with a reduction in spectrometer time about 45-60% when compared with the conventional sequential acquisition of the parent experiments. It is also shown how the optimized design of an extended three-FID approach yields one COSY and two TOCSY spectra simultaneously by combining CTP and NOAH principles in the same experiment, affording substantial sensitivity enhancements per time unit.
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Simultaneous acquisition of two 2D HSQC spectra with different 13C spectral widths. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 300:1-7. [PMID: 30682692 DOI: 10.1016/j.jmr.2019.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/10/2019] [Accepted: 01/11/2019] [Indexed: 06/09/2023]
Abstract
A time-efficient NMR strategy that involves the interleaved acquisition of two 2D HSQC spectra having different spectral widths in the indirect 13C dimension is presented. We show how the two equivalent coherence transfer pathways involved in sensitivity-enhanced HSQC experiments are managed selectively and detected separately in different FID periods within the same scan. The feasibility of this new SADA-HSQC (Spectral Aliasing in Dually Acquired HSQC) technique is demonstrated by recording simultaneously two complementary datasets, conventional and highly-resolved spectral-aliased 2D HSQC spectra, in a single NMR experiment. Combining the information from both datasets, accurate chemical shift determination and excellent signal dispersion is achieved in a unique measurement using only few t1 increments.
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Broadband homodecoupled time-shared 1H- 13C and 1H- 15N HSQC experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 298:23-30. [PMID: 30502625 DOI: 10.1016/j.jmr.2018.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 11/19/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
The concepts of pure-shift NMR and time-shared NMR are merged in a single experiment. A 13C/15N time-shared version of the real-time BIRD-based broadband homodecoupled HSQC experiment is described. This time-efficient approach affords simultaneously 1H-13C and 1H-15N pure-shift HSQC spectra in a single acquisition, while achieving substantial gains in both sensitivity and spectral resolution. We also present a related 13C/15N-F2-coupled homodecoupled version of the CLIP-HSQC experiment for the simultaneous measurement of 1JCH and 1JNH from the simplified doublets observed along the direct dimension. Finally, a novel J-resolved HSQC experiment has been designed for the simple and automated determination of both 1JCH/1JNH from a 2D J-resolved spectrum.
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32
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Enhancing the utility of 1JCH coupling constants in structural studies through optimized DFT analysis. Chem Commun (Camb) 2019; 55:5781-5784. [DOI: 10.1039/c9cc02469g] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
High accuracy for DFT-predicted 1JCH-couplings can be achieved without ad hoc corrections or empirical scaling by careful selection of the DFT method utilized for geometry optimization and J-coupling calculations.
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33
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Towards perfect NMR: Spin-echo versus perfect-echo building blocks. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:13-29. [PMID: 29927497 DOI: 10.1002/mrc.4776] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/10/2018] [Accepted: 06/12/2018] [Indexed: 06/08/2023]
Abstract
The development of new tools to improve the quality of nuclear magnetic resonance (NMR) spectra is a challenging task. The concept of "perfect NMR" includes the design of robust pulse sequences that allow an investigator to obtain undistorted pure in-phase signals, with pure absorption lineshapes that are free of phase anomalies derived from undesired J modulations. Here, alternative NMR building blocks to the spin-echo that are based on a general double SE module, known as a perfect-echo, are reviewed. Several implementations to minimize/remove unwanted dispersive contributions in homonuclear and heteronuclear NMR experiments are described and illustrated with some examples of broad interest for small molecules.
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Interleaved Dual NMR Acquisition of Equivalent Transfer Pathways in TOCSY and HSQC Experiments. Chemphyschem 2018; 20:356-360. [PMID: 30485623 DOI: 10.1002/cphc.201801034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 11/28/2018] [Indexed: 11/09/2022]
Abstract
A dual NMR data acquisition strategy to handle and detect two active equivalent transfer pathways is presented and discussed. We illustrate the power of this time-efficient approach by collecting two different 2D spectra simultaneously in a single experiment: i) TOCSY or HSQC-TOCSY spectra with different mixing times, ii) F2-13 C-coupled and decoupled HSQC spectra, iii) conventional and pure-shift HSQC spectra, or iv) complementary HSQC and HSQC-TOCSY spectra.
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Exopolysaccharides from olive brines could reduce the adhesion of ETEC K88 to intestinal epithelial cells. Food Funct 2018; 9:3884-3894. [PMID: 29961784 DOI: 10.1039/c8fo00690c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
This study aims to explore the biological functions of the isolated exopolysaccharides (EPSs) produced during the industrial fermentation of olives against enterotoxigenic E. coli (ETEC) K88. Exopolysaccharides were isolated from five industrial fermenters. Analysis of their monosaccharide composition by GLC revealed that the main components were glucose (27%-50%) and galactose (23%-33%) followed by rhamnose (4-23%) and arabinose (6-17%). The 1H NMR spectrum showed a very similar profile between samples, and a more in-depth analysis revealed the presence of an α-pyranose in the form of α-d-Glcp-(1→) and two different α-furanoses, with chemicals shift values, suggesting the presence of α-d-Glcf and α-d-Galf. Miniaturized in vitro tests demonstrated the ability of EPS samples to attach specifically to ETEC K88 (P < 0.05) with variable intensities. The competition test did not show the ability to block the ETEC K88 adhesion to IPEC-J2 cells; however, in the displacement test, all EPS samples were shown to effectively remove the pathogens attached to the cells (P < 0.01). These results suggest that the EPSs produced during the fermentation of table green olives could interfere with the attachment of opportunistic pathogens onto the intestinal epithelial cells. This would open the possibility of novel functional properties for this traditional Mediterranean fermented food and for the isolated EPSs as candidates for nutraceutics to be used in human and/or animal diets in the prevention and treatment of ETEC diarrhoea.
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Multiplicity-edited 1 H- 1 H TOCSY experiment. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:976-982. [PMID: 29220535 DOI: 10.1002/mrc.4695] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 10/27/2017] [Accepted: 11/28/2017] [Indexed: 06/07/2023]
Abstract
A 1 H-1 H total correlation spectroscopy (TOCSY) experiment incorporating 13 C multiplicity information is proposed. In addition, broadband 1 H homodecoupling in the indirect dimension can be implemented using a perfect BIRD module that affords exclusive 1 H chemical shift evolution with full decoupling of all heteronuclear and homonuclear (including 2 JHH ) coupling constants. As a complement to the normal TOCSY and the recent PSYCHE-TOCSY experiments, this novel multiplicity-edited TOCSY experiment distinguishes between CH/CH3 (phased up) and CH2 (phased down) cross-peaks, which facilitates resonance analysis and assignment.
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37
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Biocatalytic Aldol Addition of Simple Aliphatic Nucleophiles to Hydroxyaldehydes. ACS Catal 2018; 8:8804-8809. [PMID: 30221031 PMCID: PMC6135579 DOI: 10.1021/acscatal.8b02486] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/07/2018] [Indexed: 01/06/2023]
Abstract
Asymmetric aldol addition of simple aldehydes and ketones to electrophiles is a cornerstone reaction for the synthesis of unusual sugars and chiral building blocks. We investigated d-fructose-6-phosphate aldolase from E. coli (FSA) D6X variants as catalysts for the aldol additions of ethanal and nonfunctionalized linear and cyclic aliphatic ketones as nucleophiles to nonphosphorylated hydroxyaldehydes. Thus, addition of propanone, cyclobutanone, cyclopentanone, or ethanal to 3-hydroxypropanal or (S)- or (R)-3-hydroxybutanal catalyzed by FSA D6H and D6Q variants furnished rare deoxysugars in 8-77% isolated yields with high stereoselectivity (97:3 dr and >95% ee).
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Cover Feature: New Vistas in Transmetalation with Discrete “AgCF
3
” Species: Implications in Pd‐Mediated Trifluoromethylation Reactions (Chem. Eur. J. 46/2018). Chemistry 2018. [DOI: 10.1002/chem.201803632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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39
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New Vistas in Transmetalation with Discrete “AgCF
3
” Species: Implications in Pd‐Mediated Trifluoromethylation Reactions. Chemistry 2018; 24:11895-11898. [DOI: 10.1002/chem.201802586] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Indexed: 12/16/2022]
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40
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Isotropic/Anisotropic NMR Editing by Resolution-Enhanced NMR Spectroscopy. Chemphyschem 2018; 19:1024-1029. [PMID: 29384256 DOI: 10.1002/cphc.201800094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Indexed: 11/11/2022]
Abstract
Modern resolution-enhanced NMR techniques can monitor the in situ discrimination of co-existing isotropic and anisotropic contributions of small molecules dissolved in weakly aligning PMMA/CDCl3 media. The simultaneous sign-sensitive determination of accurate Δδiso-aniso (1 H), Δδiso-aniso (13 C) and/or isotropic 1 JCH and anisotropic 1 TCH coupling constants (and consequently 1 H-13 C residual dipolar couplings and 1 H/13 C residual chemical shift anisotropies) can be performed from spectral-aliased heteronuclear single-quantum correlation spectra.
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Current developments in homonuclear and heteronuclear J-resolved NMR experiments. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:230-250. [PMID: 29314247 DOI: 10.1002/mrc.4706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/12/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Two-dimensional J-resolved (Jres) NMR experiments offer a simple, user-friendly spectral representation where the information of coupling constants and chemical shifts are separated into two orthogonal frequency axis. Since its initial proposal 40 years ago, Jres has been the focus of considerable interest both in improving the basic pulse sequence and in its successful application to a wide range of studies. Here, the latest developments in the design of novel Jres pulse schemes are reviewed, mainly focusing on obtaining pure absorption lineshapes, minimizing strong coupling artifacts, and also optimizing sensitivity and experimental measurements. A discussion of several Jres versions for the accurate measurement of a different number of homonuclear (JHH ) and heteronuclear (JCH ) coupling constants is presented, accompanied by some illustrative examples.
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Titelbild: Nucleophile Promiscuity of Engineered Class II Pyruvate Aldolase YfaU from E. Coli
(Angew. Chem. 14/2018). Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201802275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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43
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Cyclometalated gold(iii) complexes: noticeable differences between (N,C) and (P,C) ligands in migratory insertion. Chem Sci 2018; 9:3932-3940. [PMID: 29780525 PMCID: PMC5941201 DOI: 10.1039/c7sc04899h] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 03/21/2018] [Indexed: 12/12/2022] Open
Abstract
Gold(iii) complexes are garnering increasing interest for opto-electronic, therapeutic and catalytic applications.
Gold(iii) complexes are garnering increasing interest for opto-electronic, therapeutic and catalytic applications. But so far, very little is known about the factors controlling their reactivity and the very influence of the ancillary ligand. This article reports the first comprehensive study on this topic. The reactivity of a cationic (N,C) gold(iii) complex, namely 1A, towards ethylene has been thoroughly studied and compared with that of the related (P,C) complex 1C. A cationic gold(iii) complex 5A resulting from double insertion of ethylene was selectively obtained. Complex 5A was found to be remarkably stable. It was trapped with chloride and fully characterized. In marked contrast to that observed with 1C, no β-H elimination or linear-to-branched rearrangement of the alkyl chain occurred with 1A. The energy profile for the reactions of 1A with ethylene has been comprehensively investigated computationally, and the influence of the ancillary ligand has been precisely delineated. Because nitrogen is a weaker donor than carbon (and phosphorus), the (N,C) ligand is very electronically dissymmetric, much more than the (P,C) ligand. This makes the two reactive sites at gold quite different, which noticeably influences the competition between migratory insertion and β-H elimination, and actually changes the outcome of the olefin insertion at gold. This study provides valuable insight into the influence of ancillary ligands on gold(iii) reactivity, something critical to further develop Au(iii) and Au(i)/Au(iii) catalysis.
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Cover Picture: Nucleophile Promiscuity of Engineered Class II Pyruvate Aldolase YfaU from E. Coli
(Angew. Chem. Int. Ed. 14/2018). Angew Chem Int Ed Engl 2018. [DOI: 10.1002/anie.201802275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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45
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Nucleophile Promiscuity of Engineered Class II Pyruvate Aldolase YfaU from E. Coli. Angew Chem Int Ed Engl 2018; 57:3583-3587. [PMID: 29363239 DOI: 10.1002/anie.201711289] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 01/09/2018] [Indexed: 11/08/2022]
Abstract
Pyruvate-dependent aldolases exhibit a stringent selectivity for pyruvate, limiting application of their synthetic potential, which is a drawback shared with other existing aldolases. Structure-guided rational protein engineering rendered a 2-keto-3-deoxy-l-rhamnonate aldolase variant, fused with a maltose-binding protein (MBP-YfaU W23V/L216A), capable of efficiently converting larger pyruvate analogues, for example, those with linear and branched aliphatic chains, in aldol addition reactions. Combination of these nucleophiles with N-Cbz-alaninal (Cbz=benzyloxycarbonyl) and N-Cbz-prolinal electrophiles gave access to chiral building blocks, for example, derivatives of (2S,3S,4R)-4-amino-3-hydroxy-2-methylpentanoic acid (68 %, d.r. 90:10) and the enantiomer of dolaproine (33 %, d.r. 94:6) as well as a collection of unprecedented α-amino acid derivatives of the proline and pyrrolizidine type. Conversions varied between 6-93 % and diastereomeric ratios from 50:50 to 95:5 depending on the nucleophilic and electrophilic components.
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Nucleophile Promiscuity of Engineered Class II Pyruvate Aldolase YfaU from E. Coli. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201711289] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
The encapsulation of coordination complexes in a tetragonal prismatic nanocage (1·(BArF)8) built from Zn-porphyrin and macrocyclic Pd-clip-based synthons is described. The functional duality of the guest ligand L1 allows for its encapsulation inside the cage 1·(BArF)8, along with the simultaneous coordination of ZnII, CuII, or FeIII metal ions. Remarkably, the coordination chemistry inside the host-guest adduct L1⊂1·(BArF)8 occurs in both solution solution and solid state. The resulting confined metallocomplexes have been characterized by means of UV-vis, ESI-HRMS, NMR, and EPR techniques. Furthermore, the emission of the Zn-porphyrin fluorophores of 1·(BArF)8 is strongly quenched by the encapsulation of paramagnetic complexes, representing a remarkable example of guest-dependent tuning of the host fluorescence.
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Response to Comment on “Direct Monitoring of Exogenous γ-Hydroxybutyric Acid in Body Fluids by NMR Spectroscopy”: Several Issues to Consider When Quantifying γ-Hydroxybutyric Acid in Biological Matrixes. Anal Chem 2018; 90:1046-1047. [DOI: 10.1021/acs.analchem.7b04473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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49
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Implementing one-shot multiple-FID acquisition into homonuclear and heteronuclear NMR experiments. Chem Commun (Camb) 2018; 54:13507-13510. [DOI: 10.1039/c8cc08065h] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The concept of multiple-FID acquisition (MFA) within the same scan is applied to acquire simultaneously multiple 2D spectra from a single NMR experiment. A discussion on the incorporation of the MFA strategy in homonuclear and heteronuclear pulse sequences is presented. Several novel COSY- and HMBC-type experiments are reported as a time-efficient solution in small-molecule NMR spectroscopy.
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Carboxylate-Assisted Formation of Aryl-Co(III) Masked-Carbenes in Cobalt-Catalyzed C–H Functionalization with Diazo Esters. J Am Chem Soc 2017; 139:14649-14655. [DOI: 10.1021/jacs.7b07880] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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