Enhancing the NMR signals of plant oil components using hyperpolarisation relayed proton exchange.

In this work, the limited sensitivity of magnetic resonance is addressed by using the hyperpolarisation method relayed signal amplification by reversible exchange (SABRE-Relay) to transfer latent magnetism from -hydrogen, a readily isolated spin isomer of hydrogen gas, to components of key plant oils such as citronellol, geraniol, and nerol. This is achieved relayed polarisation transfer in which an [Ir(H)(IMes)(NHR)]Cl type complex produces hyperpolarised NHR free in solution, before labile proton exchange between the hyperpolarisation carrier (NHR) and the OH-containing plant oil component generates enhanced NMR signals for the latter. Consequently, up to 200-fold H (0.

Recent Progress in Polyaniline and its Composites for Supercapacitors.

Polyaniline (PANI) has piqued the interest of nanotechnology researchers due to its potential as an electrode material for supercapacitors. Despite its ease of synthesis and ability to be doped with a wide range of materials, PANI's poor mechanical properties have limited its use in practical applications. To address this issue, researchers investigated using PANI composites with materials with highly specific surface areas, active sites, porous architectures, and high conductivity.

Low Overpotential Electrochemical Reduction of CO to Ethanol Enabled by Cu/CuO Nanoparticles Embedded in Nitrogen-Doped Carbon Cuboids.

The electrochemical conversion of CO into value-added chemicals is a promising approach for addressing environmental and energy supply problems. In this study, electrochemical CO catalysis to ethanol is achieved using incorporated Cu/CuO nanoparticles into nitrogenous porous carbon cuboids. Pyrolysis of the coordinated Cu cations with nitrogen heterocycles allowed Cu nanoparticles to detach from the coordination complex but remain dispersed throughout the porous carbon cuboids.

Semi-automated EPR system for direct monitoring the photocatalytic activity of TiO suspension using TEMPOL model compound.

The photocatalytic activity of TiO nanoparticles in aqueous solutions is commonly evaluated by monitoring the rate of methylene blue bleaching and phenols degradation, but both substrates suffer from many drawbacks, e.g., the high capacity of dark adsorption, self-degradation, and photosensitization.

Isolation of New Constituents from Whole Plant of of Saudi Origin.

This work describes the first report of the known glycosidic constituents β-sitosterol-3--β-d-glucoside-6'-palmitate (), β-sitosterol-3--β-d-glucoside (), momor-cerebroside I (), phytolacca cerebroside (), 1,2-di--palmitoyl-3--(6-sulfoquinovopyranosyl)-glycerol (), isorhamnetin-3-robinobioside (), and isorhamnetin-3-rutinoside () from the plant grown in the eastern region of Saudi Arabia. The structures of the isolated compounds were elucidated from extensive 1D and 2D nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and chemical analyses. Compound is reported for the first time from the Amaranthaceae family.

Tuning of pH enables carbon-13 hyperpolarization of oxalates by SABRE.

Nuclear spin hyperpolarization transforms typically weak NMR responses into strong signals paving the way for low-gamma nuclei detection within practical time-frames. SABRE (Signal Amplification by Reversible Exchange) is a particularly popular hyperpolarization technique due to its simplicity but the pool of molecules it can polarize is limited. The recent advancement in the form of co-ligands has made SABRE applicable towards molecules with O-donor sites pyruvate, a key step towards its potential clinical application.

Electron and proton magnetic resonance spectroscopic investigation of anthracene oxidation.

The work reports a method for monitoring anthracene radical-mediated oxidation reactions using electron paramagnetic resonance (EPR) spectroscopy. The formation of anthracene dimer product was well-defined using H-NMR and H-H correlation spectroscopy (COSY). Unrestricted 3-21G/B3LYP DFT was used to estimate radical hyperfine spacing (hfs), then to identify the characteristic EPR-spin transitions of anthracene radical intermediate.

Conformational analysis and concentration detection of linuron: Spectroscopic NMR and SERS study.

Linuron is a commonly used organic herbicide which is used in plant growth control. Due to its potential health concerns, the characterization and monitoring of linuron have been a subject of several studies. In this work, we employed nuclear magnetic resonance (NMR) and Raman spectroscopic techniques supported with the density functional theory (DFT) to investigate the conformational behavior and electronic aspects of linuron.

New Constituents from the Leaves of Date Palm ( L.) of Saudi Origin.

The phytochemical analysis of the butanolic extract from the leaves of date palm of Saudi origin resulted in the isolation of three major constituents, oleanolic acid (), vanillyl alcohol (), and β-sitosterol-3--β-d-glucoside (), which had not been isolated from this plant or previously reported. Together, compounds and account for 1.0% of the butanol extract, which represents 0.

N hyperpolarisation of the antiprotozoal drug ornidazole by Signal Amplification By Reversible Exchange in aqueous medium.

Signal amplification by reversible exchange (SABRE) offers a cost-effective route to boost nuclear magnetic resonance (NMR) signal by several orders of magnitude by employing readily available para-hydrogen as a source of hyperpolarisation. Although H spins have been the natural choice of SABRE hyperpolarisation since its inception due to its simplicity and accessibility, limited spin lifetimes of H makes it harder to employ them in a range of time-dependent NMR experiments. Heteronuclear spins, for example, C and N, in general have much longer T lifetimes and thereby are found to be more suitable for hyperpolarised biological applications as demonstrated previously by para-hydrogen induced polarisation (PHIP) and dynamic nuclear polarisation (DNP).

Optimisation of pyruvate hyperpolarisation using SABRE by tuning the active magnetisation transfer catalyst.

Hyperpolarisation techniques such as signal amplification by reversible exchange (SABRE) can deliver NMR signals several orders of magnitude larger than those derived under Boltzmann conditions. SABRE is able to catalytically transfer latent magnetisation from -hydrogen to a substrate in reversible exchange temporary associations with an iridium complex. SABRE has recently been applied to the hyperpolarisation of pyruvate, a substrate often used in many MRI studies.

Rapid C NMR hyperpolarization delivered from -hydrogen enables the low concentration detection and quantification of sugars.

Monosaccharides, such as glucose and fructose, are important to life. In this work we highlight how the rapid delivery of improved C detectability for sugars by nuclear magnetic resonance (NMR) can be achieved using the -hydrogen based NMR hyperpolarization method SABRE-Relay (Signal Amplification by Reversible Exchange-Relay). The significant C signal enhancements of 250 at a high field of 9.

Relayed hyperpolarization from -hydrogen improves the NMR detectability of alcohols.

The detection of alcohols by magnetic resonance techniques is important for their characterization and the monitoring of chemical change. Hyperpolarization processes can make previously inpractical measurements, such as the determination of low concentration intermediates, possible. Here, we investigate the SABRE-Relay method in order to define its key characteristics and improve the resulting H NMR signal gains which subsequently approach 10 per proton.

Hyperpolarising Pyruvate through Signal Amplification by Reversible Exchange (SABRE).

Hyperpolarisation methods that premagnetise agents such as pyruvate are currently receiving significant attention because they produce sensitivity gains that allow disease tracking and interrogation of cellular metabolism by magnetic resonance. Here, we communicate how signal amplification by reversible exchange (SABRE) can provide strong C pyruvate signal enhancements in seconds through the formation of the novel polarisation transfer catalyst [Ir(H) (η -pyruvate)(DMSO)(IMes)]. By harnessing SABRE, strong signals for [1- C]- and [2- C]pyruvate in addition to a long-lived singlet state in the [1,2- C ] form are readily created; the latter can be observed five minutes after the initial hyperpolarisation step.

Catalyst-Substrate Effects on Biocompatible SABRE Hyperpolarization.

The hyperpolarization technique, Signal Amplification by Reversible Exchange (SABRE), has the potential to improve clinical diagnosis by making molecular magnetic resonance imaging in vivo a reality. Essential to this goal is the ability to produce a biocompatible bolus for administration. We seek here to determine how the identity of the catalyst and substrate affects the cytotoxicity by in vitro study, in addition to reporting how the use of biocompatible solvent mixtures influence the polarization transfer efficiency.

Fine-tuning the efficiency of para-hydrogen-induced hyperpolarization by rational N-heterocyclic carbene design.

Iridium N-heterocyclic carbene (NHC) complexes catalyse the para-hydrogen-induced hyperpolarization process, Signal Amplification by Reversible Exchange (SABRE). This process transfers the latent magnetism of para-hydrogen into a substrate, without changing its chemical identity, to dramatically improve its nuclear magnetic resonance (NMR) detectability. By synthesizing and examining over 30 NHC containing complexes, here we rationalize the key characteristics of efficient SABRE catalysis prior to using appropriate catalyst-substrate combinations to quantify the substrate's NMR detectability.

Quantification of hyperpolarisation efficiency in SABRE and SABRE-Relay enhanced NMR spectroscopy.

para-Hydrogen (p-H) induced polarisation (PHIP) is an increasingly popular method for sensitivity enhancement in NMR spectroscopy. Its growing popularity is due in part to the introduction of the signal amplification by reversible exchange (SABRE) method that generates renewable hyperpolarisation in target analytes in seconds. A key benefit of PHIP and SABRE is that p-H can be relatively easily and cheaply produced, with costs increasing with the desired level of p-H purity.

Iridium α-Carboxyimine Complexes Hyperpolarized with para-Hydrogen Exist in Nuclear Singlet States before Conversion into Iridium Carbonates.

The formation and hyperpolarization of an [Ir(H) (amine)(IMes)(η -imine)]Cl complex that can be created in a hyperpolarized nuclear singlet state is reported. These complexes are formed when an equilibrium mixture of pyruvate, amine (benzylamine or phenylethylamine), and the corresponding imine condensation product, react with preformed [Ir(H) (amine) (IMes)]Cl. These iridium α-carboxyimine complexes exist as two regioisomers differentiated by the position of amine.

Direct and indirect hyperpolarisation of amines using hydrogen.

Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) are two widely used techniques for the study of molecules and materials. Hyperpolarisation methods, such as Signal Amplification By Reversible Exchange (SABRE), turn typically weak magnetic resonance responses into strong signals. In this article we detail how it is possible to hyperpolarise the H, C and N nuclei of a range of amines.

Using hydrogen to hyperpolarize amines, amides, carboxylic acids, alcohols, phosphates, and carbonates.

Hyperpolarization turns weak nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) responses into strong signals, so normally impractical measurements are possible. We use hydrogen to rapidly hyperpolarize appropriate H, C, N, and P responses of analytes (such as NH) and important amines (such as phenylethylamine), amides (such as acetamide, urea, and methacrylamide), alcohols spanning methanol through octanol and glucose, the sodium salts of carboxylic acids (such as acetic acid and pyruvic acid), sodium phosphate, disodium adenosine 5'-triphosphate, and sodium hydrogen carbonate. The associated signal gains are used to demonstrate that it is possible to collect informative single-shot NMR spectra of these analytes in seconds at the micromole level in a 9.

Extending the Scope of F Hyperpolarization through Signal Amplification by Reversible Exchange in MRI and NMR Spectroscopy.

Fluorinated ligands have a variety of uses in chemistry and industry, but it is their medical applications as F-labelled positron emission tomography (PET) tracers where they are most visible. In this work, we illustrate the potential of using F-containing ligands as future magnetic resonance imaging (MRI) contrast agents and as probes in magnetic resonance spectroscopy studies by significantly increasing their magnetic resonance detectability through the signal amplification by reversible exchange (SABRE) hyperpolarization method. We achieve F SABRE polarization in a wide range of molecules, including those essential to medication, and analyze how their steric bulk, the substrate loading, polarization transfer field, pH, and rate of ligand exchange impact the efficiency of SABRE.

Achieving Biocompatible SABRE: An in vitro Cytotoxicity Study.

Production of a biocompatible hyperpolarized bolus for signal amplification by reversible exchange (SABRE) could open the door to simple clinical diagnosis via magnetic resonance imaging. Essential to successful progression to preclinical/clinical applications is the determination of the toxicology profile of the SABRE reaction mixture. Herein, we exemplify the cytotoxicity of the SABRE approach using in vitro cell assays.

Achieving High Levels of NMR-Hyperpolarization in Aqueous Media With Minimal Catalyst Contamination Using SABRE.

Signal amplification by reversible exchange (SABRE) is shown to allow access to strongly enhanced H NMR signals in a range of substrates in aqueous media. To achieve this outcome, phase-transfer catalysis is exploited, which leads to less than 1.5×10  mol dm of the iridium catalyst in the aqueous phase.

Iridium Cyclooctene Complex That Forms a Hyperpolarization Transfer Catalyst before Converting to a Binuclear C-H Bond Activation Product Responsible for Hydrogen Isotope Exchange.

[IrCl(COE)] (1) reacts with pyridine (py) and H to form crystallographically characterized IrCl(H)(COE)(py) (2). 2 undergoes py loss to form 16-electron IrCl(H)(COE)(py) (3), with equivalent hydride ligands. When this reaction is studied with parahydrogen, 1 efficiently achieves hyperpolarization of free py (and nicotinamide, nicotine, 5-aminopyrimidine, and 3,5-lutudine) via signal amplification by reversible exchange (SABRE) and hence reflects a simple and readily available precatayst for this process.

A Ruthenium(II)-Copper(II) Dyad for the Photocatalytic Oxygenation of Organic Substrates Mediated by Dioxygen Activation.

Dioxygen activation by copper complexes is a valuable method to achieve oxidation reactions for sustainable chemistry. The development of a catalytic system requires regeneration of the Cu(I) active redox state from Cu(II). This is usually achieved using extra reducers that can compete with the Cu(II)(O2) oxidizing species, causing a loss of efficiency.