Full suppression of proton–proton couplings in pure shift HSQC spectra simplifies their analysis, as demonstrated for high precision RDC measurements.

Abstract The COSY experiment is an essential homonuclear 2D NMR for the assignment of resonances. Its multiplet line shape, however, often overly complicated, potentially leads to signal intensity losses, and responsible long minimum overall acquisition times. Herein, we present CLIP‐COSY, a COSY‐type yielding clean in‐phase peaks. It can be recorded within few minutes benefits from enhanced intensities most cross‐peaks. In combination with non‐uniform sampling, times further reduced,...

Abstract NMR offers many possibilities in chemical analysis, structural investigations, and medical diagnostics. Although it is broadly used, one of spectroscopies main drawbacks low sensitivity. Hyperpolarization techniques enhance signals by more than four orders magnitude allowing the design new contrast agents. Parahydrogen induced polarization that utilizes para ‐hydrogen's singlet state to create enhanced particular interest since allows produce molecular imaging agents within seconds....

Peptides and proteins, that have the tendency to form aggregates, are often discussed in context of Alz-heimer’s, Huntington’s, or Parkinson’s disease. However, studying aggregation processes is inherently challenging due diversity aggregate size geometry lack control over process space time. Here, we present a small, synthetic peptide, for which can be controlled reversibly with light within seconds. Specifically, by incorporating photoswitchable unnatural amino acids into sequence...

We report broadband proton-decoupled CLIP/CLAP-HSQC experiments for the accurate determination of one-bond heteronuclear couplings and, by extension, reliable measurement small residual dipolar coupling constants. The combination an isotope-selective BIRD((d)) filter module with a non-selective (1)H inversion pulse is employed to refocus proton-proton evolution prior acquisition brief chunks free induction decay that are subsequently assembled reconstruct fully-decoupled signal evolution. As...

<italic>In situ</italic> irradiation NMR spectroscopy allows for the distinction and quantification of different photoisomers.

We report on a detailed NMR spectroscopic study of the catalyst-substrate interaction highly enantioselective oligopeptide catalyst that is used for kinetic resolution trans-cycloalkane-1,2-diols via monoacylation. The extraordinary selectivity has been rationalized by molecular dynamics as well density functional theory (DFT) computations. Herein we describe conformational analysis organocatalyst studied combination nuclear Overhauser effect (NOE) and residual dipolar coupling (RDC)-based...

Nuclear magnetic resonance is usually drastically limited by its intrinsically low sensitivity: Only a few spins contribute to the overall signal. To overcome this limitation, hyperpolarization methods were developed that increase signals several times beyond normal/thermally polarized signals. The ideal case would be universal approach can signal enhance complete sample of interest in solution detection sensitivity. Here, we introduce combination para-hydrogen enhanced with phenomenon...

A new method is proposed that allows broadband homonuclear decoupled CLIP/CLAP-HSQC NMR spectra to be acquired at virtually no extra cost in measurement time.

Hyperpolarization techniques hold the promise to improve sensitivity of magnetic resonance imaging (MRI) contrast agents by over 10 000-fold. Among these techniques, para-hydrogen induced polarization (PHIP) allows for generating within seconds. Typical hyperpolarized are traceable 2-3 minutes only, thus prolonging tracking-times holds great importance development new ways diagnose and monitor diseases. Here, we report on design perdeuterated 15N-containing molecules with longitudinal...

NMR techniques incorporating pure shift methods to improve signal resolution have recently attracted much attention, owing their potential use in studies of increasingly complex molecular systems. Extraction frequencies from these simplified spectra enables easier structure determination, but only a few the presented provide structural parameters derived integral measurements. In particular, for quantification nuclear Overhauser effect (NOE) it is highly desirable utilize where overlap...

Abstract Wir stellen eine umfassende NMR‐spektroskopische Untersuchung der Katalysator‐Substrat‐Wechselwirkungen eines hochselektiven Oligopeptid‐Katalysators vor, welcher für die kinetische Racematspaltung von trans‐Cycloalkan‐1,2‐diolen via Monoacylierung verwendet wird. Die außerordentliche Selektivität wurde basierend auf Molekulardynamik‐Simulationen sowie DFT‐Rechnungen erklärt. In dieser Arbeit beschreiben wir Konformationsanalyse des Organokatalysators durch Kombination...

Abstract Hydrogenases are widespread metalloenzymes used for the activation and production of molecular hydrogen. Understanding catalytic mechanism hydrogenases can help to establish industrial (bio)catalytic hydrogen conversion. Here we show observation so-far undetectable intermediates [Fe]-hydrogenase in its cycle. We observed these by applying a signal-enhancing NMR technique based on parahydrogen. Molecular occurs as orthohydrogen or parahydrogen, depending nuclear spin state. found...

There has been much debate about the σ‐donor and π‐acceptor properties of N ‐heterocyclic carbenes (NHCs). While a lot synthetic modifications have performed with goal optimizing catalyst to tune reactivity in various transformations (e.g. metathesis), direct methods characterize are still few. We believe that dynamic NMR spectroscopy can improve understanding this aspect. Thus, we investigated intramolecular dynamics metathesis precatalysts bearing two NHCs. chose four systems one identical...

Abstract Nuclear magnetic resonance is usually drastically limited by its intrinsically low sensitivity: Only a few spins contribute to the overall signal. To overcome this limitation, hyperpolarization methods were developed that increase signals several times beyond normal/thermally polarized signals. The ideal case would be universal approach can signal enhance complete sample of interest in solution detection sensitivity. Here, we introduce combination para‐hydrogen enhanced with...

Abstract Molecular hydrogen (H 2 ) is considered an eco-friendly future energy-carrier and alternative to fossil fuel 1 thus, major efforts are directed towards identifying efficient economical catalysts. 2,3 Efficient catalysis used by many microorganisms, some of them producing H from organic materials others consuming it. 4-6 To metabolize , these microorganisms use enzymes called hydrogenases. 7,8 For the development catalysts a detailed analysis catalytic mechanisms such hydrogenases...

Band selective techniques offer the highest sensitivity of all pure shift approaches and thus are best choice for decoupling well-separated 1 H-frequency regions, such as amide- or α-proton region α-peptides. They inept to fully decouple simultaneously, though. Herein, we present a new homonuclear technique, which extends capabilities band using perfect echo principle. This modification allows complete backbone (amide- α-protons) in peptides opens substances with two mutually coupled protons...

Abstract Das COSY ist ein wichtiges homonukleares 2D‐NMR‐Experiment zur Zuordnung von Resonanzen. Die Multiplettstruktur seiner Kreuzsignale jedoch häufig kompliziert, bedingt eine geringe Signalintensität und erfordert lange Aufnahmezeiten. Wir stellen das CLIP‐COSY vor, COSY‐artiges Experiment, reine Inphase‐Signale erzeugt. Es verstärkt die Intensität der meisten kann in wenigen Minuten aufgenommen werden. Durch Kombination mit nicht‐äquidistantem Abtasten (NUS) Messzeit weiter reduziert...

Bimodal molecular probes combining nuclear magnetic resonance (NMR) and fluorescence have been widely studied in basic science, as well clinical research. The investigation of spin phenomena holds promise to broaden the scope available allowing deeper insights into physiological processes. Herein, a class molecules with bimodal character respect singlet states is introduced. Singlet are NMR silent but can be probed indirectly. Symmetric, perdeuterated molecules, which populated by...

NMR-Spektroskopie In der Zuschrift auf S. 15986 ff. bestätigen P. R. Schreiner, C. M. Thiele et al. den postulierten Mechanismus einer enantioselektiven Acylierung mithilfe neuartiger NMR-Experimente. Eine Schlüsselrolle spielen Dispersionswechselwirkungen zwischen Katalysator und Substrat.