Application of the allylboration reaction of terminal acetylenes with allyldihaloboranes for the preparation of capping agents for the synthesis of precursors of polymeric iron(II) clathrochelates

Template condensation on the iron(II) ion matrix of three cyclohexanedione-1,2-dioxime molecules with esters of 1,4-pentadienylboronic acids afforded apically functionalized bis(diolefin)-containing clathrochelates, which are new potential monomers for the preparation of functionalized carbochain polymers. The complexes were characterized by the data of elemental analysis, UV-Vis spectroscopy, ¹H, ¹¹B, and ¹³C NMR spectroscopy, ⁵⁷Fe Mössbauer spectroscopy, IR spectroscopy, and MALDI-TOF mass spectrometry. The molecular and crystal structures of the clathrochelates synthesized and the electron density distribution on a molecule of one of them were determined by X-ray diffraction analysis.     

Advanced solvent signal suppression for the acquisition of 1D and 2D NMR spectra of Scotch Whisky

A simple and robust solvent suppression technique that enables acquisition of high‐quality 1D ¹H nuclear magnetic resonance (NMR) spectra of alcoholic beverages on cryoprobe instruments was developed and applied to acquire NMR spectra of Scotch Whisky. The method uses 3 channels to suppress signals of water and ethanol, including those of ¹³C satellites of ethanol. It is executed in automation allowing high throughput investigations of alcoholic beverages. On the basis of the well‐established 1D nuclear Overhauser spectroscopy (NOESY) solvent suppression technique, this method suppresses the solvent at the beginning of the pulse sequence, producing pure phase signals minimally affected by the relaxation. The developed solvent suppression procedure was integrated into several homocorrelated and heterocorrelated 2D NMR experiments, including 2D correlation spectroscopy (COSY), 2D total correlation spectroscopy (TOCSY), 2D band‐selective TOCSY, 2D J‐resolved spectroscopy, 2D ¹H, ¹³C heteronuclear single‐quantum correlation spectroscopy (HSQC), 2D ¹H, ¹³C HSQC‐TOCSY, and 2D ¹H, ¹³C heteronuclear multiple‐bond correlation spectroscopy (HMBC). A 1D chemical‐shift‐selective TOCSY experiments was also modified. The wealth of information obtained by these experiments will assist in NMR structure elucidation of Scotch Whisky congeners and generally the composition of alcoholic beverages at the molecular level.     

Recent developments in the <Superscript>13</Superscript>C NMR spectroscopic analysis of paramagnetic hemes and heme proteins

Despite the wealth of information that has been obtained from the study of paramagnetic hemes and heme proteins by ¹H NMR spectroscopy, there are certain limitations imposed by the nature of paramagnetically affected resonances that are difficult to overcome. Although it has long been recognized that ¹³C NMR spectroscopy is likely to be a powerful complementary technique to overcome some of these limitations, the low sensitivity and low natural abundance of ¹³C nuclei has resulted in a lag in the application of ¹³C NMR spectroscopy to the study of paramagnetic hemes and heme proteins. The tremendous advances in methodology and instrumentation witnessed in the NMR field, coupled to the advent of recombinant DNA methods that have made possible the preparation and purification of significant quantities of proteins, and the biosynthesis of ¹³C-labeled heme, have contributed to an increased interest in the study of paramagnetic heme active sites by ¹³C NMR spectroscopy. As a consequence, ¹³C NMR spectroscopy is emerging as a powerful tool to study heme electronic structure and structure–function relationships in heme-containing proteins. In this report we strive to summarize some of the recent developments in the analysis of paramagnetic hemes and heme-containing proteins by ¹³C NMR spectroscopy.     

Assignment of the 1H- and 13C-NMR spectra of phenanthro[1,2-b]thiophene through the concerted application of two-dimensional NMR spectroscopic techniques

Two-dimensional nmr spectroscopy, by virtue of its second frequency domain which permits the segregation of spectral information along two frequency axes, considerably simplifies many assignment problems and facilitates others which may be impossible using conventional nmr methodology. A compound which falls into the latter category of assignment problem is phenanthro[1,2-b]thiophene. The assignment of the ¹H- and ¹³C-nmr spectra of phenanthro[1,2-b]thiophene are, however, reported through the concerted application of two-dimensional nmr techniques. Experiments utilized in making the assignments included: auto-correlated homonuclear (COSY) two-dimensional spectroscopy; heteronuclear two-dimensional J-resolved spectroscopy; proton-carbon chemical shift correlation two-dimensional spectroscopy; and two-dimensional ¹³C-¹³C double quantum coherence spectroscopy.     

Phosphate Derivatives of Natural Lactones. II. Synthesis of Novel Dialkylphosphonates of Arteannuin B

Novel dialkylphosphonates of arteannuin B were synthesized in 45-47% yields by reaction of this cadinanolide with dialkylphosphites. Their structures were established using IR, PMR, ¹³C and ³¹P NMR spectroscopy, and two-dimensional ¹H-¹H NMR (COSY) spectroscopy. The reaction of arteannuin B and dialkylphosphites is highly stereoselective.     

Recent progress in investigations of surface structure and properties of solid oxide materials with nuclear magnetic resonance spectroscopy

In this review, some of the latest research developments on the characterization of the structure and properties of oxide materials by applying solid-state nuclear magnetic resonance spectroscopy (NMR), including the use of dynamic nuclear polarization (DNP) NMR, ¹⁷O NMR combined with surface selective labeling and ³¹P NMR coupled with phosphorous-containing probe molecules, are discussed.     

Detection of Radiocarbon Dioxide with Double-Resonance Absorption Spectroscopy

Fast and accurate quantitative detection of ¹⁴CO₂ has important applications in many fields. The optical detection method based on the sensitive cavity ring-down spectroscopy technology has great potential. But currently it has difficulties of insufficient sensitivity and susceptibility to absorption of other isotopes/impurity molecules. We propose a stepped double-resonance spectroscopy method to excite ¹⁴CO₂ molecules to an intermediate vibrationally excited state, and use cavity ring-down spectroscopy to probe them. The two-photon process significantly improves the selectivity of detection. We derive the quantitative measurement capability of double-resonance absorption spectroscopy. The simulation results show that the double-resonance spectroscopy measurement is Doppler-free, thereby reducing the effect of other molecular absorption. It is expected that this method can achieve high-selectivity detection of ¹⁴CO₂ at the sub-ppt level.     

Purity Determination of Phosphorus Compounds by Internat- Standard31 P Nmr Spectroscopy. an Experimental Study and Validation

Abstract

Due to the proportionality between the area of the NMR signal and the number of nuclei, internal standard³¹P NMR spectroscopy is in principle a rapid and simple method for determination of the purity of phosphorus compounds.nuclei, internal standard³¹P NMR spectroscopy is in principle a rapid and simple method for determination of the purity of phosphorus compounds.nuclei, internal standard³¹P NMR spectroscopy is in principle a rapid and simple method for determination of the purity of phosphorus compounds.nuclei, internal standard³¹P NMR spectroscopy is in principle a rapid and simple method for determination of the purity of phosphorus compounds.     

Investigation of microstructure of glycidyl methacrylate/α-methyl styrene copolymers by 1D- and 2D-NMR spectroscopy

The copolymers of glycidyl methacrylate/α-methyl styrene were synthesized. The quantitative ¹³C{¹H}-NMR spectroscopy was used to determine the copolymer compositions. The distortionless enhancement by polarization transfer, ¹³C-¹H heteronuclear single quantum coherence and total correlation spectroscopy were used for the complete spectral assignment of ¹³C{¹H}- and ¹H-NMR spectra.     

Synthesis and solid state 13C-NMR studies of some cellulose derivatives

Several cellulose derivatives were synthesized and characterized by IR and ¹H-NMR spectroscopy. The positions of substitution in these derivatives were confirmed using solid state ¹³C-NMR spectroscopy techniques.     

A gamma monitoring technique for estimating plutonium contamination around nuclear weapons facilities

The objectives of this study were to establish a ratio for²⁴¹Am to²³⁹Pu in soil at the Rocky Flats Plant and to compare²⁴¹Am concentrations obtained using in-situ and laboratory gamma spectroscopy measurements to concentrations determined with radiochemical analysis and alpha spectroscopy. Soil samples were collected for radiochemical and laboratory gamma spectroscopy analysis from vertical profiles in 3 cm layers to a depth of 21 cm at predetermined locations along transects oriented in the direction of prevailing winds. The origin for the transects was the center of the 903 Pad at the Rocky Flats Plant, which is believed to be the source for most of the²⁴¹Am and²³⁹Pu contamination. A 100 minute in-situ gamma spectroscopy measurement was made at each soil sample location with a portable HPGe detector. Soil samples were dried, passed through a 2 mm sieve, mixed, and split in two fractions. One fraction was analyzed radiochemically for²⁴¹Am and²³⁹Pu and the second was analyzed using laboratory gamma spectroscopy. The median ratio of²⁴¹Am to²³⁹Pu activities, which appears to be independent of soil depth and distance from suspected sources, was 0.17. There is a strong correlation between²⁴¹Am and²³⁹Pu concentrations determined using radiochemical analysis with alpha spectroscopy and concentrations determined with laboratory gamma spectroscopy. Results from in-situ gamma spectroscopy measurements were also correlated with the radiochemical analyses but exhibited greater variability than laboratory measurements. This on-going investigation has demonstrated that it is possible to indirectly measure²³⁹Pu concentrations in soil if the ratio of²⁴¹Am to²³⁹Pu can be established. The results indicate that judicious use of a combination of radiochemical analyses with laboratory and in-situ gamma spectroscopy measurements may provide a cost-effective approach for characterization of large sites where²⁴¹Am and²³⁹Pu contamination occur.     

Recent studies of unstable nuclei far from stability with the on-line isotope separators of JAERI

Studies on the decay of unstable nuclei using the two on-line isotope separators of JAERI are reviewed for the past five years. With the previously established ion-source technique using mono-oxide ion formation in a thermal ion source, the new nuclides¹²⁵Pr and¹²⁷Pr have been identified in heavy-ion fusion residues. Further, with a newly developed gas-jet coupled thermal ion source, the new nuclides¹⁶⁶Tb,¹⁶⁵Gd,¹⁶¹Sm and²³⁶Am have been identified by bombarding²³⁸U and²³⁵U targets with a proton or⁶Li beam. Other studies, including off-line experiments, by decay spectroscopy, laser spectroscopy and Mössbauer spectroscopy are described.     

NMR study of the spatial structure of synthetic pyrethroids

The spatial isomers of the new synthetic analogs of ethyl permithrinic ether and permethrin were investigated by NMR (¹H, ¹³C, DEPT (distortionless enhancement by polarization transfer), COSY (correlation spectroscopy), CHCORR (heteronuclear (C, H) shift correlation spectroscopy), ROESY (rotating-frame Overhauser effect spectroscopy)). Several tendencies were revealed in the ¹H and ¹³C chemical shifts of the α atoms of the substituents in the 2nd and 3rd positions of the cyclopropane ring. For substituents cis-orientated relative to the ester group, the spectra show a paramagnetic shift of the ¹H signals and the diamagnetic shift of the ¹³C signals relative to the trans-orientated substituents. The ¹H and ¹³C chemical shifts of the α atoms of the substituents in the 2nd and 3rd positions of the cyclopropane ring permit an unambiguous determination of the stereochemistry of ethyl permethrinic ether and permethrin analogs.     

Synthesis and structure of nitroethylpyrrolidone carboxylates

3-Methoxycarbonyl-4-phenyl- and 4-(3-pyridyl)-2-pyrrolidones react with 2-aryl(heteryl)-1-nitroethenes to form C³-adducts as one or two diastereomers. Their structure was characterized by the IR, ¹H, and ¹³C NMR spectroscopy, using the two-dimensional correlation spectroscopy.     

Real‐Time Interrogation of Aspirin Reactivity,Biochemistry, and Biodistribution by Hyperpolarized Magnetic Resonance Spectroscopy

Hyperpolarized magnetic resonance spectroscopy enables quantitative, non‐radioactive, real‐time measurement of imaging probe biodistribution and metabolism in vivo. Here, we investigate and report on the development and characterization of hyperpolarized acetylsalicylic acid (aspirin) and its use as a nuclear magnetic resonance (NMR) probe. Aspirin derivatives were synthesized with single‐ and double‐¹³C labels and hyperpolarized by dynamic nuclear polarization with 4.7 % and 3 % polarization, respectively. The longitudinal relaxation constants (T₁) for the labeled acetyl and carboxyl carbonyls were approximately 30 seconds, supporting in vivo imaging and spectroscopy applications. In vitro hydrolysis, transacetylation, and albumin binding of hyperpolarized aspirin were readily monitored in real time by ¹³C‐NMR spectroscopy. Hyperpolarized, double‐labeled aspirin was well tolerated in mice and could be observed by both ¹³C‐MR imaging and ¹³C‐NMR spectroscopy in vivo.     

Real‐Time Interrogation of Aspirin Reactivity,Biochemistry, and Biodistribution by Hyperpolarized Magnetic Resonance Spectroscopy

Hyperpolarized magnetic resonance spectroscopy enables quantitative, non‐radioactive, real‐time measurement of imaging probe biodistribution and metabolism in vivo. Here, we investigate and report on the development and characterization of hyperpolarized acetylsalicylic acid (aspirin) and its use as a nuclear magnetic resonance (NMR) probe. Aspirin derivatives were synthesized with single‐ and double‐¹³C labels and hyperpolarized by dynamic nuclear polarization with 4.7 % and 3 % polarization, respectively. The longitudinal relaxation constants (T₁) for the labeled acetyl and carboxyl carbonyls were approximately 30 seconds, supporting in vivo imaging and spectroscopy applications. In vitro hydrolysis, transacetylation, and albumin binding of hyperpolarized aspirin were readily monitored in real time by ¹³C‐NMR spectroscopy. Hyperpolarized, double‐labeled aspirin was well tolerated in mice and could be observed by both ¹³C‐MR imaging and ¹³C‐NMR spectroscopy in vivo.     

Electrochemistry of Klason Lignin

The possibility of the use of Klason lignin extracted from sunflower husks as a cathode-active material for primary lithium battery has been demonstrated for the first time. The chemical composition, morphological and physical features were characterized by X-ray energy dispersive spectroscopy, impedance spectroscopy, scanning electron microscopy, and infrared spectroscopy. Electrochemical behavior of Klason lignin vs. Li/Li⁺ was studied by galvanostatic discharge and cyclic voltammetry. The reaction mechanism in electrochemical system was discussed. The maximum specific capacity of Klason lignin amounted to 380 mAh g^–1 at a current density of 25 mA g^–1.     

Synthesis of alkyl-substituted phosphorus phthalocyanines and triazatetrabenzocorroles

New alkyl-substituted phosphorus phthalocyanines and triazatetrabenzocorroles were synthesized. The structures of these complexes were confirmed by ¹H, ¹³C, and ³¹P NMR spectroscopy, mass spectrometry, and electronic absorption spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1403–1407, July, 2007.     

Synthesis,Characterization, and Activity of Cyclotriphosphazene-Cyclene Conjugates

Abstract

Two novel cyclotriphosphazene derivatives were synthesized from hexachloro cyclotriphosphzene. Their structures were characterized by ¹H, ³¹P, and ¹³C NMR spectroscopy as well as by IR spectroscopy and electrospray ionization-mass spectrometry (ESI-MS). The Zn complex of 4d was effective in hydrolytic DNA cleavage reactions.     

Modern NMR Spectroscopy of Organolithium Compounds

Modern methods of NMR spectroscopy, in particular the two-dimensional techniques, offer new chances for structure determinations in the field of organolithium compounds, where the combination of ¹H-, ¹³C-, and ⁶⁽⁷⁾Li-NMR spectroscopy is an especially useful feature. Chemical shift correlations which also include the lithium nuclei allow a complete assignment of the ¹H-, ¹³C-, and ⁶Li-NMR spectra and thereby a better characterization of the various aggregates and complexes present in solution. Spatial proximities of ⁶Li and ¹H can be detected by nuclear Overhauser experiments, and ⁶⁽⁷⁾Li-NMR exchange spectroscopy can provide new information with regard to the mechanisms and energetics of dynamic processes like aggregate interchange and complexation. After a short resumé of the experimental aspects of the NMR spectroscopy of organolithium compounds and a discussion of the NMR parameters of these systems, new experimental techniques are presented. Areas of application of these newly conceived one- and two-dimensional NMR experiments are illustrated with selected examples. The results show that even more detailed information about the structure and reactivity of organolithium compounds, which are so important for organic synthesis, can be expected in the future.