(1)H-NMR analysis of the human urinary metabolome in response to an 18-month multi-component exercise program and calcium-vitamin-D3 supplementation in older men

The musculoskeletal benefits of calcium and vitamin-D3 supplementation and exercise have been extensively studied, but the effect on metabolism remains contentious. Urine samples were analyzed by (1)H-NMR spectroscopy from participants recruited for an 18-month, randomized controlled trial of a multi-component exercise program and calcium and vitamin-D3 fortified milk consumption. It was shown previously that no increase in musculoskeletal composition was observed for participants assigned to the calcium and vitamin-D3 intervention, but exercise resulted in increased bone mineral density, total lean body mass, and muscle strength. Retrospective metabolomics analysis of urine samples from patients involved in this study revealed no distinct changes in the urinary metabolome in response to the calcium and vitamin-D3 intervention, but significant changes followed the exercise intervention, notably a reduction in creatinine and an increase in choline, guanidinoacetate, and hypoxanthine (p < 0.001, fold change > 1.5). These metabolites are intrinsically involved in anaerobic ATP synthesis, intracellular buffering, and methyl-balance regulation. The exercise intervention had a marked effect on the urine metabolome and markers of muscle turnover but none of these metabolites were obvious markers of bone turnover. Measurement of specific urinary exercise biomarkers may provide a basis for monitoring performance and metabolic response to exercise regimes.

Modular synthesis of linear Bis- and Tris-monodentate fused [6]Polynorbornane-Based Ligands and their assembly into coordination cages

A modular approach has been developed for the synthesis of rigid linear di- and tritopic ligands based on a fused [6]polynorbornane scaffold. The design provides up to three sites for installing functionality, including both "ends" and a "central" position with the advantage that each region can be independently addressed during synthesis. To illustrate the utility of the approach, both pyridyl and picolyl units were incorporated to provide six new ligands, with centers and ends either matched or mismatched. Indeed, both [M2 L4 ] cages with endohedral functionality and [M3 L4 ] complexes were cleanly produced from these ligands with assembled structures confirmed by using (1) H NMR spectroscopy, HRMS, and molecular modelling.

Controlling the supramolecular architecture of molecular gels with surfactants

Manipulating molecular assembly is significant for achieving materials with desirable performances. In this paper, two nonionic surfactants, Span 20 and Triton X-100, are used to tune the nucleation and fiber growth of a molecular gelator 2,3-di-n-decyloxyanthracene (DDOA). Confocal microscopic images show that Span 20 induces elongation of DDOA spherulites, and promotes fiber side branching. In contrast, Triton X-100 enhances the primary nucleation of DDOA leading to the formation of smaller DDOA spherulites, and promotes fiber tip branching. (1)H NMR investigation demonstrates strong interactions between the hydrophobic tails of the surfactants and the alkyl chains of DDOA molecules.The interactions significantly reduce the diffusion of DDOA molecules. The different effects of the two surfactants could be attributable to their different alkyl hydrophobic tails. The hydrophobic tail of Span 20 is similar to the alkyl chain of DDOA, which could promote the adsorption of Span 20 on the fiber side surface rich in alkyl chains of DDOA.While the benzene ring in the hydrophobic tail of Triton X-100 could facilitate the primary nucleation of DDOA and the adsorpion of Triton X-100 on the fiber tip surface rich in aromatic structure of DDOA. The observations of this work will help the development of a convenient approach to tune the fiber network structure of molecular gels.

63Cu NMR investigation of effect of small additions of Sn to Al-1.7 at.%Cu in promoting accelerated phase transformations on aging

Very recently 63Cu NMR has been shown to be extremely sensitive in detecting and differentiating between the precipitate phases that form in Al-Cu alloys during heat treatment. This technique is now used to quantify the effectiveness of small additions of Sn to the alloy Al-1.7 at.% Cu in promoting the rapid nucleation and growth of the θ'-phase precipitate. Two parallel series of 63Cu NMR spectra were recorded for Al-1.7 at.% Cu and Al-1.7 at.% Cu-0.01 at.% Sn: (i) aged at 130° C to observe the comparative rate of phase evolution and (ii) aged at 200° C to observe the rate of growth of θ'-phase and to compare with the Vickers hardness of the alloys aged at 200° C for similar periods. Evidence is presented that a metastable precursor phase to θ' (labelled TPHM2757math001) is formed in Al-Cu-Sn which transforms to θ' on further aging.

NMR studies of modified nasicon-like, lithium conducting solid electrolytes*1

²⁷Al, ³¹P and ⁷Li NMR measurements have been performed on lithium conducting ceramics based on the LiTi₂(PO₄)₃ structure with Al, V and Nb metal ions substituted for either Ti or P within the framework NASICON structure. The ²⁷Al magic angle spinning NMR measurements have revealed that, although Al is intended to substitute for octahedral Ti sites, additional substitution into tetrahedral environments (presumably phosphorous sites) occurs with increasing amount of Al addition. This tetrahedral substitution appears to occur more readily in the presence of vanadium, in Li_1+xAl_xTi_2−x(PO₄)_2.9(VO₄)_0.1, whereas similar niobium additions (in place of vanadium) appear to stifle tetrahedral substitution. ⁷Li static NMR spectra reveal quadrupolar structure with C_q approximately 42 kHz, largely independent of substitution. Measurement of the ⁷Li central transition linewidth at room temperature reveals a relatively mobile lithium species (300–900 Hz) with linewidth tending to decrease with Al substitution and increase with increasing V or Nb. This new structural information is discussed in the context of ionic conduction in these ceramics.

Synthesis and structure of tris(triphenyltin)benzene-1,3,5-tricarboxylate and its tri-DMSO adduct

The molecular structure of (Ph₃SnO₂C)₃C₆H₃ reveals distorted tetrahedral C₃O geometries for each tin atom. No intermolecular Sn...O associations occur between the molecules so that the trinuclear molecule may be considered monomeric. An increase in coordination number at tin is indicated by ¹¹⁹Sn NMR measurements conducted in d₆-DMSO solution and this has been confirmed by a structure analysis of (DMSO·Ph₃SnO₂C)₃C₆H₃·2 DMSO. In this structure, the tin atom geometries are distorted trigonal bipyramidal, existing within trans-C₃O₂ donor sets. Thus, while is it possible for the tin atoms to increase their coordination numbers in (Ph₃SnO₂C)₃C₆H₃, molecular aggregation to form polymeric arrays is precluded, most likely due to steric constraints.

Secondary bonding in para-substituted diphenyltellurium dichlorides (p-XC6H4)2TeCl2 (X = H, Me, MeO) probed by 125Te MAS NMR spectroscopy. Crystal and molecular structure of (p-MeC6H4)2TeCl2

The solid-state structures of the previously known para-substituted diphenyltellurium dichlorides, (p-XC₆H₄)₂TeCl₂ (X=H (1), Me (2), MeO (3)) were investigated by ¹²⁵Te MAS NMR spectroscopy and in case of 2 by single crystal X-ray diffraction. The ¹²⁵Te-NMR shielding anisotropy (SA) was studied by tensor analyses based on relative intensities of the observed spinning sidebands. Solid-state NMR parameters, namely the isotropic chemical shift (δ_iso), anisotropy (ζ) and asymmetry (η), were discussed in relation to the molecular structures established by X-ray crystallography. The asymmetry (η) was found to be particularly sensitive to structural differences stemming mostly from the diverse secondary Te...Cl interactions, but no correlation with geometric parameters could be established.

Studies on the mechanism of the peroxyoxalate chemiluminescence reaction Part 1. Confirmation of 1,2-dioxetanedione as an intermediate using 13C nuclear magnetic resonance spectroscopy

A simple model peroxyoxalate chemiluminescence system was monitored directly across a range of temperatures (from −80 to +20 °C) using ¹³C nuclear magnetic resonance spectroscopy. These experiments were made possible by the utilisation of ¹³C doubly labelled oxalyl chloride, which was reacted with anhydrous hydrogen peroxide in dry tetrahydrofuran. Ab initio quantum calculations were also performed to estimate the ¹³C nuclear magnetic resonance (NMR) shift of the most commonly postulated key intermediate 1,2-dioxetanedione and this data, in concert with the spectroscopic evidence, confirmed its presence during the reaction.

Oligomethylene-bridged dinuclear triorganotin triflates and diphenylphosphinates. Ion pairing in the solid state and electrolytic dissociation in solution of [Ph2Sn(CH2)nSnPh2X](O3SCF3) (X = OH, O2PPh2; n = 1-3)

The condensation of [Ph₂(OH)Sn(CH₂)_nSn(OH)Ph₂] (1-3; n = 1-3) with HO₃SCF₃ and HO₂PPh₂ provided [Ph₂Sn(CH₂)_nSnPh₂(OH)](O₃SCF₃) (4-6; n = 1-3) and [Ph₂(O₂PPh₂)Sn(CH₂)_nSn(O₂PPh₂)Ph₂] (10-12; n = 1-3), respectively. The reaction of [Ph₂Sn(CH₂)_nSnPh₂(OH)](O₃SCF₃) (4-6; n = 1-3) with HO₂PPh₂ and NaO₂PPh₂ gave rise to the formation of [Ph₂Sn(CH₂)_nSnPh₂(O₂PPh₂)](O₃SCF₃) (7-9; n = 1-3) and [Ph₂(OH)Sn(CH₂)_nSn(O₂PPh₂)Ph₂] (13-15; _n = 1-3), respectively. In the solid state, compounds 4-9 comprise ion pairs of cationic cyclo-[Ph₂SnCH₂SnPh₂(OH)]₂²⁺, cyclo-[Ph₂Sn(CH₂)_nSnPh₂(OH)]⁺ (n = 2, 3), and cyclo-[Ph₂Sn(CH₂)_nSnPh₂(O₂PPh₂)]⁺ (n = 1-3) and triflate anions. In MeCN, the eight-membered-ring system cyclo-[Ph₂SnCH₂SnPh₂(OH)]₂²⁺ appears to be in equilibrium with the four-membered-ring system cyclo-[Ph₂SnCH₂SnPh₂(OH)]⁺. In contrast, compounds 10-15 show no ionic character. Compounds 1-15 were characterized by multinuclear NMR spectroscopy in solution and in the solid state, IR spectroscopy, conductivity measurements, electrospray mass spectrometry, osmometric molecular weight determinations, and X-ray crystallography (4, 5, 7, and 12).

4-Amino-1,8-naphthalimide-based anion receptors: employing the naphthalimide N-H moiety in the cooperative binding of dihydrogenphosphate

The 4-amino-1,8-naphthalimide-based anion receptor 3 binds dihydrogenphosphate with 1:1 stoichiometry through cooperative hydrogen bonding to a naphthalimide N–H and thiourea N–H groups. This was clearly established from ¹H NMR titration experiments in DMSO-d₆ where a substantial shift in the resonance for the naphthalimide N–H was observed concomitant with the expected thiourea N–H chemical shift migration upon successive additions of H₂PO₄⁻. However, whilst ¹H NMR titration experiments indicate that 3 was capable of binding other anions such as acetate, the naphthalimide N–H does not participate and the N–H resonance was essentially invariant during the titration. The lack of cooperative binding in this instance was justifiable on steric grounds.

Fluorescent anion sensors based on 4-amino-1,8-naphthalimide that employ the 4-amino N-H

The new charge neutral 4-amino-1,8-naphthalimide based anion sensors 2 and 3 bind to both acetate and dihydrogenphosphate with 1:1 stoichiometry through hydrogen bonding to both thiourea N–H atoms and in the case of dihydrogenphosphate, the naphthalimide 4 amino N–H group as well. This was clearly established from ¹H NMR titration experiments with H₂PO₄^- in DMSO-d₆ where a substantial shift in the resonance for the naphthalimide N–H was observed concomitant with the expected migration of the thiourea N–H chemical shifts. The binding constants determined from the titration studies indicate that the new sensors bind H₂PO₄^- more strongly than AcO⁻. Fluorescence titrations with sensor 3 indicate quenching of 59% and 36% upon addition of acetate and dihydrogenphosphate, respectively.

New insights in asymmetric tetraorganodistannoxane ladder formation. A NMR-spectroscopic and crystallographic study

The syntheses of the asymmetrically substituted tetraorganodistannoxanes [t-Bu₂(X)SnOSn(Y)(CH₂SiMe₃)₂1₂ (1, X = Y = OH; 2, X = Cl, Y = OH; 3, X = Y = Cl) are reported and their structures in solution and in the solid state are characterized by multinuclear NMR spectroscopy and single crystal X-ray analyses. In toluene, the tetrahydroxy-substituted derivative 1 is in equilibrium with the organotin oxides cyclo-[t-Bu₂Sn{OSn(CH₂SiMe₃)₂}₂O] (4), cyclo[(Me₃SiCH₂)₂Sn(OSnt-Bu₂)₂O] (5), and cyclo-(t-Bu₂SnO)₃, and some additional, undefined species containing pentacoordinated tin atoms. In contrast, the dihydroxydichloro-substituted derivative 2 is inert in solution.

Prevalence of the thioamide {···H-N-C=S}2 synthon-solid-state (X-ray crystallography), solution (NMR) and gas-phase (theoretical) structures of O-methyl-N-aryl-thiocarbamides

Structural investigations, i.e. solid-state (X-ray), solution (¹H NMR) and gas-phase (theoretical), on molecules with the general formula MeOC(S)N(H)C₆H₄-4-Y: Y = H (1), NO₂ (2), C(O)Me (3), Cl (4) have shown a general preference for the adoption of an E-conformation about the central C–N bond. Such a conformation allows for the formation of a dimeric hydrogen-bonded {H–N–C=S}₂ synthon as the building block. In the cases of 1–3, additional C–H^...O interactions give rise to the formation of tapes of varying topology. A theoretical analysis shows that the preference for the E-conformation is about the same as the crystal packing stabilisation energy and consistent with this, the compound with Y = C(O)OMe, (5), adopts a Z-conformation in the solid-state that facilitates the formation of N–H^...O, C–H^...O and C–H^...S interactions, leading to a layer structure. Global crystal packing considerations are shown to be imperative in dictating the conformational form of molecules 1–5.