Ring Protons Research Articles

Spin of Protons in NICA and PTR Storage Rings as an Axion Antenna

A new approach to search for axions in the storage ring experiments, applicable at a short coherence time of the in-plane polarization as is the case for protons is discussed. The technique can readily be applied at any storage ring equipped with internal polarimeter for the radial polarization of the beam (COSY, NICA, PTR). A possibility of substantial broadening of the range of attainable axion masses in storage rings with the hybrid electric and magnetic bending is pointed out, the PTR proton storage ring being an example.

Comprehensive symmetric-hybrid ring design for a proton EDM experiment at below 10−29e·cm

A concise demonstrative summary of the Symmetric Hybrid ring design for the storage ring proton electric dipole moment experiment is presented. Critical issues such as lattice design, background electrical fields,geometrical phase, general relativity, spin coherence time and polarimeter systematics are presented. Overall, we find that with the currently proposed design iteration, systematic error sources are reduced by orders of magnitude and that the ring alignment requirements are within the currently available technology.

Effects of polarization-reversed EMIC waves on the ring current dynamics

It is widely believed that the electromagnetic ion cyclotron (EMIC) waves play an important role in influencing the radiation belt and ring current dynamics. Most studies investigated the effects or characteristics of EMIC waves assuming their left-handed polarization. However, recent studies found that the polarization reversal, which occurs at higher latitudes along the wave propagation path, can change the wave-induced pitch angle diffusion coefficients. Whether such a polarization reversal can influence the global ring current dynamics remains unknown. In this study, we investigate the ring current dynamics and proton precipitation loss in association with the polarization reversed EMIC waves using the Ring current - Atmosphere interactions Model (RAM). The results indicate that the polarization reversal of H-Band EMIC waves truly can decrease the scattering rates of protons of 10 to 50 keV or > 100 keV by comparing with the scenario where the EMIC waves are considered as purely left-handed polarized. Additionally, it is found that the global ring current intensity and proton precipitation can be slightly affected by the polarization reversal, especially during the prestorm and recovery phase, but the effects are not that large during the main phase. This is probably because the H-Band EMIC waves contribute to the proton scattering loss primarily at E < 10 keV, an energy range that is not strongly affected by the polarization reversal.

1H NMR spectra, structure, and conformational exchange of S-n-alkyl-tetrahydrothiophenium cations of some ionic liquids

S-n-alkyl-tetrahydrothiophenium cations [R-THT]+ in some iodide or tetraphenylborate ion-pairs [R-THT][X] (R = methyl to n-decyl, X−= I−, [BPh4]−, [NTf2]−) are characterized in the solid state by puckered THT rings in twist forms. In contrast, solution 1H NMR spectra of compounds [R-THT][X] indicate a rapid conformational exchange leading to dynamic [ABCD]2 spin systems due to eight protons of the THT ring. These strongly coupled spectra obtained at high magnetic fields were analyzed by iterative methods and simulated successfully. In addition, molecular modeling and gauge-including atomic orbitals (GIAOs) based calculations of proton NMR chemical shifts for two such ion-pair compounds in solution were performed at the density functional theory (DFT) level . As a result, conformational equilibrium between two different pairs of isoenergetic twist forms of the THT ring in [Me-THT][I] (global and local energy minima) was found to exist. These theoretical results are discussed in view of experimental 1H NMR spectral data.

Study of the composition and structure of ion-conducting membranes based on polyvinyl alcohol by 1H NMR spectroscopy

One of the alternative types of proton-conducting membranes for a hydrogen-air solid polymer fuel cell is the type of hybrid membranes based on polyvinyl alcohol (PVA) crosslinked with aldehyde, modified by sulfonic acid. Earlier, for the first time, we obtained new ion – conducting membranes based on furfural-crosslinked PVA modified aminosulfonic acid (ASA) and tetraethoxysilane (TEOS), as well as membranes not crosslinked with furfural (FUR) or unmodified ASA and TEOS, by a liquid-phase synthesis method, in an organic medium-dimethyl sulfoxide. The values of their ionic conductivity and the degree of swelling in water are presented. In this work, the composition and structure of the obtained ion-conducting membranes are studied using liquid-phase nuclear magnetic resonance (NMR) spectroscopy on 1H nuclei. In the 1H NMR spectrum of an ion – conducting membrane not cross-linked with the «PVA/ASA», the signal of free OH groups of PVA is observed to disappear, but at the same time a characteristic triplet at 7.1 ppm. is preserved, having a constant of ∼51 Hz and components of the same intensity (1:1:1), which corresponds to protons of 14NH4+ hydrolyzed ASA. The disappearance of the expanded signal at 9.6 m. d. of protons of the free sulfo group of ASA and a narrow singlet signal at 5.8 m. d. of free protons of the NH2 group of ASA indicates the interaction of ASA with OH groups of PVA. In the 1H NMR spectrum of an ion – conducting membrane crosslinked with FUR – «PVA/ASA/FUR», signals of protons of the furan ring of FUR and a signal of its aldehyde group are observed, which is shifted to a strong field, which is determined by the formation of a chemical bond between FUR and the polymer chain of PVA. In the 1H NMR spectra of all membranes modified by ASA, the appearance of a second weaker-field 14NH4+ triplet is observed, and in the spectra of a number of ion – conducting hybrid membranes modified by TEOS – «PVA/ASA/FUR/TEOS», signals of the third type of 14NH4+ triplets shifted in a strong field relative to the other two 14NH4+ triplets were detected. The appearance of additional 14NH4+ triplets indicates the formation of several bound forms of the ammonium ion.

All are aromatic: A 3D globally aromatic cage containing five types of 2D aromatic macrocycles

All are aromatic: A 3D globally aromatic cage containing five types of 2D aromatic macrocycles

Исследование состава и структуры ионопроводящих мембран на основе поливинилового спирта методом спектроскопии ЯМР 1 Н

One of the alternative types of proton-conducting membranes for a hydrogen-air solid polymer fuel cell is the type of hybrid membranes based on polyvinyl alcohol (PVA) crosslinked with aldehyde, modified with sulfonic acid. Earlier, for the first time, we obtained new ion – conducting membranes based on furfural-crosslinked PVA modified with amino sulfonic acid (ASA) and tetraethoxysilane (TEOS), as well as membranes not crosslinked with furfural (FUR) or unmodified ASA and TEOS, by a liquid-phase synthesis method, in an organic medium-dimethyl sulfoxide. The values of their ionic conductivity and the degree of swelling in water are presented. In this work, the composition and structure of the obtained ion-conducting membranes are studied using liquid-phase nuclear magnetic resonance (NMR) spectroscopy on 1 H nuclei. In the 1 H NMR spectrum of an ion – conducting membrane not cross-linked with the «PVA/ASA», the signal of free OH groups of PVA is observed to disappear, but at the same time a characteristic triplet at 7.1 m.d. is preserved, having a constant of ~51 Hz and components of the same intensity (1:1:1), which corresponds to protons of 14 NH 4 + hydrolyzed ASA. The disappearance of the expanded signal at 9.6 m. d. of protons of the free sulfo group of ASA and a narrow singlet signal at 5.8 m. d. of free protons of the NH 2 group of ASA indicates the interaction of ASA with OH groups of PVA. In the 1 H NMR spectrum of an ion – conducting membrane crosslinked with FUR – «PVA/ASA/FUR», signals of protons of the furan ring of FUR and a signal of its aldehyde group are observed, which is shifted to a strong field, which is determined by the formation of a chemical bond between FUR and the polymer chain of PVA. In the 1 H NMR spectra of all membranes modified by ASA, the appearance of a second weaker-field 14 NH 4 triplet is observed, and in the spectra of a number of ion – conducting hybrid membranes modified by TEOS – «PVA/ASA/FUR/TEOS», signals of the third type of 14 NH 4 + triplets shifted in a strong field relative to the other two 14 NH 4 + triplets were detected. The appearance of additional 14 NH 4 + triplets indicates the formation of several bound forms of the ammonium ion.

Synthesis, Characterization, and Biological Activity of Water-Soluble, Dual Anionic and Cationic Ruthenium–Arene Complexes Bearing Imidazol(in)ium-2-dithiocarboxylate Ligands

An efficient synthetic protocol was devised for the preparation of five cationic ruthenium-arene complexes bearing imidazol(in)ium-2-dithiocarboxylate ligands from the [RuCl2(p-cymene)]2 dimer and 2 equiv of an NHC·CS2 zwitterion. The reactions proceeded cleanly and swiftly in dichloromethane at room temperature to afford the expected [RuCl(p-cymene)(S2C·NHC)]Cl products in quantitative yields. When the [RuCl2(p-cymene)]2 dimer was reacted with only 1 equiv of a dithiolate betaine under the same experimental conditions, a set of five bimetallic compounds with the generic formula [RuCl(p-cymene)(S2C·NHC)][RuCl3(p-cymene)] was obtained in quantitative yields. These novel, dual anionic and cationic ruthenium-arene complexes were fully characterized by various analytical techniques. NMR titrations showed that the chelation of the dithiocarboxylate ligands to afford [RuCl(p-cymene)(S2C·NHC)]+ cations was quantitative and irreversible. Conversely, the formation of the [RuCl3(p-cymene)]- anion was limited by an equilibrium, and this species readily dissociated into Cl- anions and the [RuCl2(p-cymene)]2 dimer. The position of the equilibrium was strongly influenced by the nature of the solvent and was rather insensitive to the temperature. Two monometallic and two bimetallic complexes cocrystallized with water, and their molecular structures were solved by X-ray diffraction analysis. Crystallography revealed the existence of strong interactions between the azolium ring protons of the cationic complexes and neighboring donor groups from the anions or the solvent. The various compounds under investigation were highly soluble in water. They were all strongly cytotoxic against K562 cancer cells. Furthermore, with a selectivity index of 32.1, the [RuCl(p-cymene)(S2C·SIDip)]Cl complex remarkably targeted the erythroleukemic cells vs mouse splenocytes.

Chemical characterization and biochemical activity of polysaccharides isolated from Egyptian Ulva fasciata Delile

This study gives updated information on the isolation of ulvan from green alga Ulva fasciata Delile in Egypt through isolation and chemical characterization of sulfate polysaccharides by two sequential extraction steps using different solvents; distilled water, HCl and Na2EDTA forming fraction I (F-I). Fraction II (F-II) was obtained from remaining seaweeds using NaOH to give FDWNaOH, FHClNaOH, and FEDTANaOH. All products obtained were tested for their biological activities. The highest polysaccharides total extraction yield was 11.8% for water extract (F-I and F-II). The highest protein content was found in FEDTANaOH (2.44%). The highest sulfate content was recorded for F-I (HCl) (21.38%). Total carbohydrates range was 11.99–63.90% for F-I and 15.06–76.65% for F-II. Monosaccharides; galactose, rhamnose, and uronic acid were detected at all fractions, with concentrations varying from 0.11 to 1.34%, from 0.61 to 1.81% and from 11.06 to 19.30%, respectively. 1H NMR of F-II demonstrated the signals of ring and methyl protons of polysaccharide. The appearance of the stretching bands of the sulfate ester (C-O-S) and sulfate groups (S=O) in the FT-IR spectrum of FHClNaOH confirmed the presence of sulfated polysaccharides, typical of ulvan. The microbial species Vibrio damsela was the most susceptible to FDWNaOH, followed by Aeromonas hydrophila and Vibrio fluvialis with inhibition zones of 30, 22, 22 mm at 150 mg/ml, respectively. FDWNaOH was the most effective fraction having antifouling property. The highest antioxidant activity was observed for F-IHCl followed by FDWNaOH. At concentrations 25 and 50 mg/l, FEDTANaOH displayed the highest anti-inflammatory activity (94.0 and 91.40%, respectively).

Simulation and Optimization of the Spin Coherence Time of Protons in a Prototype EDM Ring

Simulation and Optimization of the Spin Coherence Time of Protons in a Prototype EDM Ring

Proton Ring Evolution and Its Effect on Magnetosonic Wave Excitation: Particle‐In‐Cell Simulation and Linear Theory

AbstractIn this letter, we used one‐dimensional (1‐D) particle‐in‐cell (PIC) simulations as well as linear theory to investigate the relationship between proton ring evolution and fast magnetosonic (MS) wave excitation. Simulations demonstrate that most of the ring protons can be scattered toward lower energies via MS waves excited by the initial proton ring distribution, leading to the increase of the proton ring speed corresponding to the maximum phase space density. These protons with a higher ring speed can further excite MS waves at a lower frequency. As a result, a new “double ring” distribution is found to be formed through scattering of higher energy protons by the lower frequency MS waves. The letter demonstrates the detailed evolution process of proton ring distribution and its effect on the excitation of MS waves.

Hadron polarization control at integer spin resonances in synchrotrons using a spin navigator

We consider the capability of flexible spin-transparent polarization control and manipulation in conventional synchrotrons at integer spin resonances by means of spin navigators. The latter are designed as a couple of small solenoids separated by a constant beam bend. We formulate the requirements to the navigator design considering the criteria for stability of the spin motion in the presence of synchrotron energy oscillations. We propose the design of a novel spin-flipping system free of resonant beam depolarization based on such a spin navigator. We discuss the possibilities of testing spin-flipping systems at an integer spin resonance with protons in the Nuclotron ring at JINR in Dubna, Russia, and with deuterons in the RHIC rings at BNL in Upton, New York. The results are relevant to the existing and future facilities where the spin transparency mode can be applied for polarization control.

Structural and computational examination of hydrogen-bonding between the C-H bonds of phenylphosphates and nitrate ions

In an effort to understand the packing forces that control the ubiquitous interactions between nitrate (NO3−) anions and phosphate moieties, the C-H structural data concerning phenylphosphates and a NO3− were obtained from the Cambridge Structural Database (CSD) tabulated, averaged, and compared to elucidate these variables. In addition, molecular modeling was undertaken using density functional theory calculations to explore the characteristics of this interaction. In particular, the varying reactivity of the protons on the phenol ring and the resulting impact on NO3− bonding was explored. These electronic structure gas phase calculations identified the different atomic charges of the ortho-, meta-, and para-protons on the phenol ring, which were found to be in agreement with the observed crystallographic trends. Overall, it was determined that based on the strong agreement between the model and experimental data, the charge on the ring protons controls the hydrogen bonding to the NO3− ion and the ultimate construction of the molecule.

Pagoda[5]arene with Large and Rigid Cavity for the Formation of 1∶2 Host–Guest Complexes and Acid/Base-Responsive Crystalline Vapochromic Properties

Pagoda[5]arene (P5), which is composed of five 2,6-dimethoxylanthracene (2,6-DMA) subunits bridged by methylene groups at 1,5 positions, was conveniently synthesized in 43% by trifluoroacetic acid ...

Isolation, characterization and semi-synthesis of natural products dimeric amide alkaloids

Isolation, characterization and semi-synthesis of natural products dimeric amide alkaloids

A NMR study of binding the metabolite of SN38 derivatives to a model nicked DNA decamer mimicking target of Topo I inhibitors

In this account we present NMR based results of the interaction of 7-ethyl-9-hydroxymethyl-10-hydroxycamptothecin (1), a derivative of SN38, with a model nicked DNA decamer mimicking the wild type DNA target of Topoisomerase I inhibitors from the camptothecin family. The title compound 1 can be considered a main metabolite of phase I in the metabolic pathway of camptothecin derivatives bearing the alkylamino substituent. Therefore, its pharmacodynamic properties are of interest. It was established by DOSY (Diffusion Ordered Spectroscopy) that compound 1 forms a fairly stable molecular complex with a model nicked DNA decamer with affinity constant Ka 3.02 mM−1. The analysis of NOESY experiments revealed intermolecular cross peaks and mutual induced shifts on both interacting components allowing the conclusion that guest molecule 1 is stacking the nitrogen bases inside the nick. MD (Molecular Dynamics) analysis of four possible inclusions of 1 inside the nick allows establishing the detailed geometry of a complex. Two conformations are suggested as the ones best representing the results of molecular modeling reconciled with experimental NOESY results. The aromatic core of both structures is stacking the nitrogen bases in a nick facing the unbroken strand with ring A. The protons in ring E interact with ribose protons of edge bases of a nick. In conclusion, it can be asserted that SN38 derivative 1 can effectively bind the molecular target of Topo I enzyme and play a role as a Topo I inhibitor.

Synthetic, spectroscopic, structural, and electrochemical investigations of ferricenium derivatives with weakly coordinating anions: ion pairing, substituent, and solvent effects.

A facile and effective strategy for the preparation of a series of ferricenium complexes bearing either electron-donating or electron-withdrawing substituents with weakly coordinating anions such as [B(C6F5)4]- or SbF6- is reported. These systems were thoroughly investigated for their ground state electronic structures in both solution and solid states using infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies as well as single crystal X-ray crystallography and electrochemical measurements. The X-ray structures of the six electron-deficient ferricenium derivatives are of particular interest as only a handful (∼5) of such derivatives have been structurally characterized to date. Comparison of the structural data for both neutral and oxidized derivatives reveals that the nature of the substituents on the cyclopentadienyl (Cp) ligands displays a more significant impact on the metal-ligand separations (FeCt) in the oxidized species than in their neutral analogs. Our 1H-NMR measurements corroborate that in the neutral ferrocene derivatives, electron-donating ring substitutions lead to a greater shielding of the ring protons while electron-withdrawing groups via induction deshield the nearby ring protons. However, the data for the paramagnetic ferricenium derivatives reveals that this substitutional behavior is more complex and fundamentally reversed, which is further supported by our structural studies. We ascribe this reversal of behavior in the ferricenium derivatives to the δ back-donation from the iron atom into the Cp rings which can lead to the overall shielding of the ring protons. Interestingly, our NMR results for the electron-deficient ferricenium derivatives in solution also indicate a direct correlation between the solvent dielectric constant and the energy barrier for rotation around the metal-ligand bond in these systems, whereas such a correlation is absent or not significant in the case of the electron-rich ferricenium species or the corresponding neutral ferrocene analogs. In this work, we also present the electrochemical behavior of the corresponding ferricenium/ferrocene redox couples including potential values (E1/2), peak-to-peak separation (ΔE1/2), and diffusion coefficients (D) of the redox active species in order to provide a concise outline of these data in one place. Our electrochemical studies involved three different solvents and two supporting electrolytes. Notably, our findings point to the significant effect of ion-pairing in lowering the energy necessary for reduction of the ferricenium ion and E1/2 in lower-polarity media. This has significant implications in applications of the ferrocene or ferricenium derivatives as redox agents in low-polarity solvents where an accurate determination of redox potential is critical.

Синтез 5-фенил-(5,6-дифенил-)-2,3-дигидро-1,2,4-триазин-3-тионов и исследование их реакций с 1,2-дибромэтаном

5-Phenyl-(5,6-diphenyl-)-1,2,4-triazine-3(2H)-thions (1,2) were synthesized by condensation of phenylglyoxal monohydrate with thiosemicarbazide and benzyl with thiosemicarbazide hydrochloride, respectively. Phenylglyoxal monohydrate was obtained by oxidation of acetophenone with selenous acid by the Riley reaction, while benzyl (1,2-diphenylethane-1,2-dione) waw obtained by oxidation of (2-hydroxy-1,2-diphenylethanone) benzoin with nitric acid by the known procedure. The compounds 1 and 2 were studied in reactions with 1,2-dibromoethane in various ratios. The interaction of triazinethione 1 with 1,2-dibromoethane in molar ratios of 1:1 and 1:2 led to the formation of a previously unknown 3-[(2-bromoethyl)sulfanyl]-5-phenyl-1,2,4-triazine (3а). Using a double excess of 1,2-dibromoethane increased the yield of compound 3а by 11 %. The interaction of triazinethione 2 with 1,2-dibromoethane in molar ratios 1:1 and 2:1 led to the formation of 3-[(2-bromoethyl)sulfanyl]-5,6-diphenyl-1,2,4-triazine (3b). In the 1H NMR spectra of compounds 3a,b there are signals of aromatic ring protons in the region of 7.23-8.81 ppm, a triplet of protons of the SCH2 group at 3.22 and 4.06 ppm, and a triplet of protons of the CH2Br group at 4.39 and 5.28 ppm. It is of interest that1,2-bis-(5-phenyl-[1,2,4]triazinyl-3-sulfanyl)-ethane is formed in the case of the reaction of compound 1 with 1,2-dibromoethane in the 2:1 ratio of reagents. In the 1H NMR spectra of the latter, in contrast to the spectrum of compound 3a, there is a signal of the S-CH2 group protons, which are equivalent in this structure and form a singlet at 3.79 ppm. Compound 3a was also studied by chromatography-mass spectrometry (direct sample insertion). It should be noted that under the conditions of mass spectrum imaging, the bromine atom is split off and the mass spectrum shows a peak with m/z 216 with an intensity of 38% and no peak of the molecular ion. The peak with the maximum intensity (m/z 116, 100 %) seems to correspond to 4-thia-6,7-diaza-1-azoniumbicyclo[3.2.0]hept-1(5)-ene. Its high intensity is due to the fact that the structure of the 1,2-dihydrotriazetium cation is aromatic.

Fast and practical synthesis of carboxymethyl cellulose from office paper waste by ultrasonic-assisted technique at ambient temperature

This report demonstrates the fastest technique to successfully achieve carboxymethyl cellulose (CMC) from office paper waste, within 30 min at ambient temperature using ultrasonic-assisted method as a source of energy. The obtained CMC was characterized using FTIR, TGA, and NMR techniques to confirm its structure. The FTIR spectrum showed characteristic peaks of carboxymethyl groups and its salt at the wavenumbers of 1585 (C=O) and 1412 (C-O) cm−1. The TGA results of CMC exhibited the loss of carbon dioxide at ca. 260 – 300 °C. Moreover, a higher ash yield of the obtained CMC indicated the substitution of carboxymethyl in the structure. The CMC product structure was confirmed using 13C- and HMBC 2D-NMR. The HMBC 2D-NMR results indicated a correlation between carbonyl and methylene carbons of carboxymethyl groups and protons of pyranose ring, implying that pyranose ring was substituted successfully by monocholoroacetic acid (MCA). The optimal conditions were obtained by using 4.11 ml of 30%w/v NaOH and 1.4 g of MCA in 40 ml of isopropanol at ambient temperature. The resulting CMC showed 0.75 degree of substitution at 18.75 W/ml ultrasonic intensity.

Fluxional dynamics of terpyridine ligand in [Ru(bpy-d8)2(η2-tpy)]2+ complex

Herein, we report the fluxional dynamic behaviour of terpyridineligand in [Ru(bpy-d8)(η2-tpy)]2+ 1. Reaction of Ru(bpy-d8)2Cl2·2H2O with 2,2′:6′,2′′-terpyridine in refluxing methanol afforded 1. Complex 1 has been characterized by 1H NMR spectroscopic analysis. Variable temperature 1H NMR data reveals that the pendant pyridine ring of the tpy ligand in Ru(bpy-d8)2(tpy)]2+ rotates which effects the adjacent ring protons. Moreover, protonation of 1 with trifluoroacetic acid (TFA) confirms that peripheral N on the pendant pyridyl ring of the tpy ligand affects the chemical shifts of protons on the tpy pendant pyridyl ring.&#x0D; Bangladesh J. Sci. Ind. Res.55(4), 253-260, 2020