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This study examines the differences in using two primary methods for adsorbing TMPO onto acid catalysts and their influence on the NMR spectra of TMPO-loaded zeolites. The findings show that TMPO molecules interact with both Brønsted and Lewis acid sites, and that the amount of (TMPO)2H+ dimers formed increases with the amount of TMPO added. The use of dichloromethane as a solvent inhibits the formation of dimers and crystalline TMPO but may lead to inaccurate estimations of acid site strength and quantification due to interactions with residual solvent molecules. The gas-phase method is preferred for adsorbing TMPO onto zeolites, but caution is needed to avoid forming a high number of dimers that make interpretation of the NMR spectra challenging. published

[Abstract] In the periodical system, the lanthanides (the 15 elements in the periodic table between barium and hafnium) are unique in the sense that their trivalent cations have their valence electrons hidden behind the 5s and 5p electrons. They show a gradual decrease in ionic radius with increasing atomic number (also known as the lanthanide contraction). The resulting steric effects determine to a large extent the geometries of complexes of these ions. Here, we discuss these effects, particularly upon the properties of the complexes in aqueous solution, for selected families of Ln3+-complexes of oxycarboxylate and aminocarboxylate ligands. The physical properties of the cations are very different, which is very useful for the elucidation of the configuration, conformation and the dynamics of the complexes by X-ray techniques, NMR spectroscopy, and optical techniques. Often the structural analysis is assisted by computational methods.

Alzheimer's disease (AD) is the most common chronic neurodegenerative disorder leading to progressive and irreversible decline of cognitive functions. Together with neurofibrillary tangles, the formation of brain extracellular plaques containing amyloid-β peptides is a major neuropathological hallmark associated with AD. The development of clinical imaging techniques for early detection of AD is a primary health objective. We present here an overview of recent progress in the chemistry of molecular probes for the in vivo MRI detection of Aβ deposits in the brain to improve early diagnosis of AD.

Three triaza macrocyclic ligands, H6NOTP (1,4,7-triazacyclononane-N,N′,N″-trimethylene phosphonic acid), H4NO2AP (1,4,7-triazacyclononane-N-methylenephosphonic acid-N′,N″-dimethylenecarboxylic acid), and H5NOA2P (1,4,7-triazacyclononane-N,N′-bis(methylenephosphonic acid)-N″-methylene carboxylic acid), and their gallium(III) chelates were studied in view of their potential interest as scintigraphic and PET (Positron Emission Tomography) imaging agents. A 1H, 31P and 71Ga multinuclear NMR study gave an insight on the structure, internal dynamics and stability of the chelates in aqueous solution. In particular, the analysis of 71Ga NMR spectra gave information on the symmetry of the Ga3+ coordination sphere and the stability of the chelates towards hydrolysis. The 31P NMR spectra afforded information on the protonation of the non-coordinated oxygen atoms from the pendant phosphonate groups and on the number of species in solution. The 1H NMR spectra allowed the analysis of the structure and the number of species in solution. 31P and 1H NMR titrations combined with potentiometry afforded the measurement of the protonation constants (log KHi) and the microscopic protonation scheme of the triaza macrocyclic ligands. The remarkably high thermodynamic stability constant (log KGaL =34.44 (0.04) and stepwise protonation constants of Ga (NOA2P)2− were determined by potentiometry and 69Ga and 31P NMR titrations. Biodistribution and gamma imaging studies have been performed on Wistar rats using the radiolabeled 67Ga(NO2AP)− and 67Ga (NOA2P)2−chelates, having both demonstrated to have renal excretion. The correlation of the molecular properties of the chelates with their pharmacokinetic properties has been analysed., The authors thank the financial support from the Fundação para a Ciência e Tecnologia (F.C.T., Portugal, projects RREQ/481/QUI/2006 and RECI/QEQ-QFI/0168/2012), the Rede Nacional de RMN (RNRMN), the Hungarian Scientific Research Fund (OTKA grants K-109029 and K-120224), the János Bolyai Research Scholarship (Gy.T.) of the Hungarian Academy of Sciences and the EU COST Action TD1004 “Theragnostics Imaging and Therapy”. The research was also supported by the EU and co-financed by the European Regional Development Fund (FEDER) under the projects CENTRO-07-CT62-FEDER) and GINOP-2.3.2-15-2016-00008., info:eu-repo/semantics/publishedVersion

et al., Flavonoids from lemongrass – Cymbopogon citratus (DC.) Stapf – leaves infusion, a commonly consumed beverage for the treatment of inflammatory-related conditions, were investigated in this work. Luteolin O-, C- and O,C-glycosides were isolated and identified by nuclear magnetic resonance, being the cassiaoccidentalin B structure fully characterized for the first time in lemongrass. The anti-inflammatory activity of luteolin and its glycosides was evaluated in lipopolysaccharide-stimulated macrophages. Luteolin glycosides demonstrated less cytotoxicity than luteolin itself. Although glycosylation decreases luteolin anti-inflammatory properties, being higher to C-glycosylation, an inhibitory effect on inflammatory mediator production (nitric oxide and IL-1β) was verified for the luteolin 7-O-β-glucopyranoside, without cytotoxic effects. Therefore, luteolin glycosides from lemongrass infusion are evidenced as a less toxic alternative to current anti-inflammatory drugs with promising use in pharmaceutical and food supplement industries. Additionally, this work establishes structure–activity relationships, which constitutes valuable information in the design of anti-inflammatory luteolin glycosides devoid of toxicity., This work was supported by FEDER/COMPETE (FCOMP-01-0124-FEDER-011096) and Foundation for Science and Technology (FCT), by the projects PTDC/SAU-FCF/105429/2008, PEst-OE/SAU/UI0177/2011 and PEst-C/SAU/LA0001/2011, and by PhD fellowshipsSFRH/BD/46281/2008 and SFRH/BD/72918/2010.

In this work we report a synthetic strategy of amphiphilic DOTA-based chelators bearing a variable size α-alkyl chain at one of the pendant acetate arms (from six to fourteen carbon atoms), compatible with their covalent coupling to amine-bearing biomolecules. The amphiphilic behavior of the micelles-forming Ga(III) chelates (critical micelle concentration), their stability in blood serum and their lipophilicity (logP) were investigated. Biodistribution studies with the 67Ga-labeled chelates were performed in Wistar rats showing a predominant liver uptake with almost no traces of the radiochelates in the body after 24 hours., Fundação para a Ciência e a Tecnologia (FCT)

We report a straightforward and efficient synthetic strategy for the synthesis of three model glycine-arginine-glycine-aspartic-glycine (GRGDG) conjugates based on derivatives of NOTA and of their Ga(III) complexes targeted to the integrin αѵβ₃receptor. 71Ga NMR spectroscopy showed that the Ga(III)-labeled conjugates are highly stable in aqueous solution. The 67Ga-labeled conjugates proved to have high kinetic stability and showed a weak but specific binding to the receptors in a U87MG-glioblastoma cell line., Fundação para a Ciência e a Tecnologia (FCT)

Publisher Summary The first report by Hinckley more than 20 years ago of the use of lanthanide complexes to simplify unresolved proton resonances in low-field nuclear magnetic resonance (NMR) spectra marked the start of the application of the lanthanide-induced shift (LIS) method to a variety of NMR problems. A year later, Morallee et al. presented that the line broadenings induced by the gadolinium(III)-lysozyme complex in the proton resonances of fl-methyl-N-acetylglucosamine could be analyzed in terms of the absolute distance between the Gd(III) ion and various sugar protons. These observations stimulated much interest and activity in the use oflanthanides as NMR shift and relaxation reagents, in applications ranging from qualitative spectral simplification, proof of molecular stereochemistry, and quantitative analysis of dynamic solution structures to the most recent applications in NMR spectroscopy of perfused cells, organs, and intact animals and magnetic resonance imaging (MRI). This chapter describes LIS methodologies and their application to study proteins in solution. The qualitative uses of lanthanides to simplify complex NMR spectra are not mentioned because highfield magnets and two- and three-dimensional methods have eliminated the need for LIS measurements for this purpose. The use of lanthanides as shift and relaxation reagents in organic solutions has been reviewed extensively, as well as well as their applications as NMR structural probes in aqueous solutions, particularly for biological systems including peptides and proteins.