Synthesis,Spectroscopic Characterization and Redox Reactivity of Some New N-(2,6-Di-Tert-Butyl-L-Hydroxyphenyl) Salicylaldimines

New substituted N- (2,6-Di-tert-butyl-l-hydroxyphenyl) Salicylaldimines (L_xH) were prepared by the condensation of various hydroxy and methoxy salicylaldehyde derivatives and 2,6-Di-tert-butyl-4-aminophenol and characterized by elemental analysis, IR, UV-Vis, ¹H NMR spectroscopy, as well as ESR studies of the oxidation products of L_xH. It was found that L_xH, unlike analogous electron-withdrawing C1, Br, NO₂ bearing derivatives, in the solid state exist both in associated and non-associated forms. UV-Vis and ¹H, NMR studies show that L_xH in solutions exists both in phenolimine and ketoamine tautomer forms. In addition, alcohol solutions of L_xH exhibited a new band in the region of 630-675 run. The ESR studies of one -electron oxidation of L_xH, in the condition of THF, CHC1₃ and toluene solutions at 300 K, indicate the formation of corresponding primary or secondary phenoxyl radicals. It was found that the stability and conversion pathway of the primary phenoxyl radicals are dependent upon both kind and position of the substituents in salicylaldehyde moiety of L_xH. For some L_xH without observation of primary phenoxyl radicals, the secondary Coppinger's type radical was detected. The ESR parameters of all radical intermediates have been determined.     

A Spectroscopic Study of Polynuclear Complex of Iron(III) with Inuline Oligomers

The infrared spectra of the hydrates of inuline oligomers and the complex of iron(III) with inuline oligomers and their partial deuterated analogs were studied. From the appearance and frequencies of the bands in the range of OH and OD vibrations it was concluded that these crystalohydrates have one type of H₂O molecule, and relatively weak hydrogen bond (estimated O_w…O distances are 280 and 283 pm for inuline and its complex, respectively). From the FTIR spectra of the complex the β₂-form for iron(III) oxihydroxide (FeOOH) was determined. On the basis of the electron spin resonance spectra it was concluded that Fe⁺³ ions of octahedral configuration (g-value 2.03 ± 0.01) were present in the complex. From the measured ESR line width (ΔH = 100 ± 5 mT) the approximate Fe inter atomic distance of 0.21 nm was calculated, indicating a dense packing of Fe atoms in the cluster.     

A 1H NMR Study of Palladium(II) Coordination Compounds with 2-Aminooxypropanoic Acid and Its Methyl Ester

The ¹H NMR spectra of 2-aminooxypropanoic acid, its methyl ester and their hydrochlorides have been inspected. The interaction of these ligands with palladium(II) has been investigated in deuterium oxide and in dimethyl sulfoxide. The metal has been found to form a chelate with the acid, whereas its esters coordinated to the metal through the nitrogen atom of the aminooxy group only. In dimethyl sulfoxide, also the methyl esters and hydrochlorides of 2-aminooxybutanoic, 2-aminooxy-3-methylpentanoic,as well as the ester of 2-aminooxyhexanoic and the hydrochoride of the ester of 2-aminooxy-3-phenylpropanoic acid have been studied.     

Noninvasive (1)H and (23)Na nuclear magnetic resonance imaging of ancient Egyptian human mummified tissue

Historic mummies are a unique example of the human desire for immortality. Therefore, it is not surprising that modern diagnostic imaging has been widely applied to study them. Yet, magnetic resonance imaging (MRI) of such old remains has never been successfully achieved in a noninvasive way without rehydration. Furthermore, the impact of artificial mummification as done in ancient Egypt by natron (a blend of NaCl, Na(2)CO(3), NaHCO(3) and NaP(2)SO(4)) on human tissue with a particular focus on the sodium spatial distribution has never been addressed. Here, we show for the very first time completely noninvasive (1)H and (23)Na imaging of an ancient Egyptian mummified finger by nuclear magnetic resonance (NMR). Protons could be visualized by NMR only in the tissue close to surface and sodium primarily in the bone, while computer tomography images both, soft tissue and bone but does not distinguish between different chemical elements. The selective enrichment of sodium in the bone may by due to postmortem incorporation of (23)Na into the tissue by natron-based mummification because our reference measurement of a historical finger not subjected to artificial mummification showed no sodium signal at all. Our results demonstrate not only the general feasibility of nonclinical MRI to visualize historic dry human tissues but also shows the specific (1)H and (23)Na spatial distributions in such mummy tissue, which is particularly interesting for archeology and may open up a new application for MRI.     

Proton Dynamics in Letovicite, (NH4)3H(SO4)2: A H and N NMR Spectroscopic Study

The improper ferroelastic phase letovicite (NH₄)₃H(SO₄)₂ has been studied by ¹H MAS NMR as well as by static ¹⁴N NMR experiments in the temperature range of 296–425 K. The ¹H MAS NMR resonance from ammonium protons can be well distinguished from that of acidic protons. A third resonance appears just below the phase transition temperature which is due to the acidic protons in the paraelastic phase. The lowering of the second moment M₂ for the ammonium protons takes place in the same temperature range as the formation of domain boundaries, while the signals of the acidic protons suffer a line narrowing in the area of T_c. The static ¹⁴N NMR spectra confirm the temperature of the motional changes of the ammonium tetrahedra. Two-dimensional ¹H NOESY spectra indicate a chemical exchange between ammonium protons and the acidic protons of the paraphase.     

Structural Elucidation of Novel Derivatives of Pyranobisquinolines 1H-NMR, 13C-NMR and Mass Spectroscopic Study of (7H)-6,8-Dichloro-7-methyl-pyrano(3,2-c:5,6-c′)bisquinoline and (7H)-6,8-dichloro-7-methyl-pyrano (3,2-c:5,6-b′)bisquinoline

Elucidation of the structure of hitherto unknown novel pyranobisquinoline derivatives, (7H)-6,8-Dichloro-7-methyl -pyrano(3,2-c;5,6-c′)bisquinoline 5 and (7H)-6,8-Dichloro-7-methyl-pyrano(3,2-c:5,6-b′)bisquinoline 4 obtained as unexpected products¹ in the Michael type reaction of vinylacetate on 4-hydroxyquinoline-2(lH)-one 1 by NMR methods is reported.     

1H and 13C NMR Spectra of Alditolyl Derivatives of 3-Hydrazino-5-Methyl[1,2,4]triazino[5,6-b]indole and Their Cyclized Products.

The ¹H and ¹³C NMR spectra of sugar (5-methyl [1, 2, 4]-triazino [5, 6-b] indol-3-yl) hydrazones (1), per-0-acetyl aldehydo sugar 1-acetyl-1-(5-methyl [1, 2, 4] triazino [5, 6-b]-indol-3-yl) hydrazones (2), l- (penta-0-acetyl-pentitol-1-yl)-10-methyl [l, 2, 4] triazolo [3′, 4′:3, 4] [l, 2, 4] triazino [5, 6-b]-indoles (3) have been investigated. The 2 D NMR (H, C COSY) spectrum of 2a has been studied.     

Quantitative Evaluation of the Lactate Signal Loss and Its Spatial Dependence in PRESS Localized H NMR Spectroscopy

Localized ¹H NMR spectroscopy using the 90°−t₁−180°−t₁+t₂−180°−t₂−Acq. PRESS sequence can lead to a signal loss for the lactate doublet compared with signals from uncoupled nuclei which is dependent on the choice of t₁ and t₂. The most striking signal loss of up to 78% of the total signal occurs with the symmetrical PRESS sequence (t₁=t₂) at an echo time of 2/J (290 ms). Calculations have shown that this signal loss is related to the pulse angle distributions produced by the two refocusing pulses which leads to the creation of single quantum polarization transfer (PT) as well as to not directly observable states (NDOS) of the lactate AX₃ spin system: zero- and multiple-quantum coherences, and longitudinal spin orders. In addition, the chemical shift dependent voxel displacement (VOD) leads to further signal loss. By calculating the density operator for various of the echo times TE=n/J, n=1, 2, 3, …, we calculated quantitatively the contributions of these effects to the signal loss as well as their spatial distribution. A maximum signal loss of 75% can be expected from theory for the symmetrical PRESS sequence and TE=2/J for Hamming filtered sinc pulses, whereby 47% are due to the creation of NDOS and up to 28% arise from PT. Taking also the VOD effect into account (2 mT/m slice selection gradients, 20-mm slices) leads to 54% signal loss from NDOS and up to 24% from PT, leading to a maximum signal loss of 78%. Using RE-BURP pulses with their more rectangular pulse angle distributions reduces the maximum signal loss to 44%. Experiments at 1.5 T using a lactate solution demonstrated a maximum lactate signal loss for sinc pulses of 82% (52% NDOS, 30% PT) at TE=290 ms using the symmetrical PRESS sequence. The great signal loss and its spatial distribution is of importance for investigations using a symmetrical PRESS sequence at TE=2/J.     

Assignment of the 1H and 13C Spectra of 5-Methylthio-4H-1-(p-R1-phenyl)-3a-(p-R2-phenyl)-3a,4-dihydro (1,2,4) oxadiazolo(4,5-a), 1,5-benzodiazepines using 2D NMR Spectroscopy.

The ¹H NMR spectra of the title benzodiazepines derivatives is highly congested because all the protons are in aromatic enviroment so many proton signals remain overlap even 300 MHz or higher fields. With this in mind, the assignment of the ¹H and ¹³C spectra of these compounds obtained using COSY, NOESY, HMQC and HMBC experiments is reported.     

Assignment of the 1H and 13C NMR Chemical Shifts of (3,4-Dihydro-2H-pyran-5-yl)-oxo-acetic Acid Methyl Ester Using the Two Dimensional HMBC Technique

The identification of (3, 4-dihydro-2H-pyran-5-yl)-oxo-acetic acid methyl ester has been realized by combination of two dimensional HETCOR and HMBC techniques. ¹³C and ¹H chemical shifts asignements are described.     

Assignment of the 1H and 13C Spectra of 5-Methylthio-4H-1-(p-R1-phenyl)-3a-(p-R2-Phenyl)-3a, 4-dihydro (1,2,4) oxadiazolo(4,5-a), 1, 5-benzodiazepines Using 2D NMR Spectroscopy

The ¹H NMR spectra of the title benzodiazepines derivatives is highly congested because all the protons are in aromatic environment so many proton signals remain overlap even 300 MHz or higher fields. With this in mind, the assignment of the ¹H and ¹³C spectra of these compounds obtained using COSY, NOESY, HMQC and HMBC experiments is reported.     

1H NMR study of multiply charged anions of Ni-octaethylporphin

An analysis of¹H NMR spectra of reduced Ni-octaethylporphin (NiOEP)ⁿ⁻ n=2,3) complexes has allowed the conclusion that the first and third excess electrons are localized on orbitals of the porphyrin ligand, while the first excess electron is on the d_x ²-y²-orbital of Ni. This is a basis for thinking that in the course of NiOEP reduction the energy of the lowest unoccupied molecular orbital of the ligand becomes smaller than that of the d_x ²-y²-orbital of nickel. Institute of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 513–517, July–August, 1997.     

Assignments of 1H and 13C NMR Spectral Data for Benzoylecgonine,a Cocaine Metabolite

The complete assignment of the ¹H and ¹³C NMR spectra of benzoylecgonine, a cocaine metabolite, was performed, with the aid of some 2D experiments such as gCOSY and gHSQC.     

稀土配合物RE(TPTZ)Cl3的合成、表征及荧光性能研究

首次以2,4,6-三吡啶基三嗪（TPTZ）与Sm, Eu, Tb和Dy氯化物反应,合成四种单一稀土配合物以及Tb分别1∶1掺Gd, Y, La的三种异核配合物。经元素分析、稀土络合滴定、摩尔电导率、红外光谱、紫外光谱和差热-热重测定表明,配合物的组成分别为RE（TPTZ）Cl3·3H2O（RE=Sm, Eu, Tb, Dy）和Tb0.5Ln0.5（TPTZ）Cl3·3H2O（Ln=Gd, Y, La）;TPTZ作为三齿配体与稀土离子配位,即中心环提供一个N原子,两个吡啶环分别提供一个N原子;配合物中3个水分子与稀土离子配位,1个Cl-在外界,2个在内界,为1∶1型电解质;配合物内外界可能为[RE（TPTZ）（H2O）3Cl2] Cl,稀土离子的配位数为8。配合物的荧光光谱测试表明,四种单一稀土配合物中,Tb配合物发光最强;三种1∶1掺杂异核Tb配合物荧光强度大于纯Tb配合物,表明Y3＋, La3＋和Gd3＋都可以敏化Tb3＋的发光,其中Gd3＋的敏化作用最强,Y3＋次之,La3＋最差。     

13C NMR and 2D (H,H and H,C COSY) Spectra of Triazolo-triazino-indole Derivatives and the Conformational Analysis of the Respective C-Nucleoside Analogues

¹³C NMR and 2D (H,H and H,C COSY) spectra of selected examples of sugar (5H-1,2,4-triazino[5,6-b]-indol-3-yl) hydrazones, peracetylated sugar-1-acetyl -1- (5-acetyl-1,2,4-triazino[5,6-b]indol-3-yl)hydrazones, and 10-acetyl-3-(per-0-acetylalditol-1-yl)-1,2,4-triazolo[4′, 3′:2,3][1,2,4]triazino[5,6-b]indole have been reported. The conformation of the latter C-nucleoside analogues have been determined by analysis of their ¹H NMR spectra. The D-galacto, D-manno and L-arabino isomers are preponderantly existing in the planar zigzag arrangement of carbon atoms.     

Convenient Synthesis 1H, 13C NMR Study and X-Ray Crystal Structure Determination of Some New Disubstituted Thiophenes

2,5-, 3,4- and 2,3-Thienylenediacrylic (1, 4 and 7 respectively) were synthesized in one step reaction by catalytic vinylation of the corresponding dibromothiophenes in the presence of cyclohexylamine salt of acrylic acid. 2,4-Thienylenediacrylic acid 10 was prepared by catalytic vinylation of 3-(4-bromo-2-thienyl)acryilic acid.     

13C NMR Chemical Shifts Substituent Effects of (E)- and (Z)-N-ethyl-N-Methylamides

Carbon-13 NMR chemical shifts of a series of (E)- and (Z)-N-ethyl-N-methylamides [RC(O)NEtMe, R=H, Me, Et, i-Pr, t-Bu, CF₃, ClCH₂, Cl₂CH, Cl₃C, BrCH₂, Br₂CH, Br₃C and ICH₂] are reported. The α-carbon and carbonyl carbon chemical shifts are correlated with the empirical α-substituent effect and Charton's electrical parameter ([sgrave]_I), respectively. The N-alkyl carbon resonances were attributed mainly to the γ- and δ-effects of R.     

1H NMR Study of Hydrogen Bonding and Hydrogen to Deuterium Isotope Exchange in Ureido Sugars

Abstract

The acidic properties of ureido NH protons in two new derivatives of methyl 3,4,6-triacetyl-2-deoxy-β-D-glucopyranoside and i-butylamine (1) and L-leucine (2) were studied by ¹H NMR. Stronger influence of polar aprotic solvents, more effective interaction with nitroxyl radical and faster H/D exchange indicate that N1'-H proton which is proximate to the glucopyranose ring is more acidic than N3'-H one in both ureido sugars, this conclusion was supported by semi-empirical AM1 calculation. Hydrogen to deuterium exchange rates are 1.2 x 10^?2 to 5.5x 10^?3 M^?1 min^?l. Significantly slower exchange of N3'-H proton standing by Leu residue in 2 can be explained by the existence of internal H-bonds.     

Determination of water self-diffusion coefficient in complex food products by low field 1H PFG-NMR: comparison between the standard spin-echo sequence and the T1-weighted spin-echo sequence

In 1990, Van Den Enden et al. proposed a method for the determination of water droplet size distributions in emulsions using a pulsed-field-gradient nuclear magnetic resonance (PFG-NMR) T1-weighted stimulated-echo technique. This paper describes both the T1-weighted spin-echo sequence, an improved method based on this earlier work, and, the standard PFG spin-echo sequence. These two methods were compared for water self-diffusion coefficient measurement in the fatty protein concentrate sample used as a 'cheese model.' The transversal and longitudinal relaxation parameters T1 and T2 were determined according to the temperature and investigated for each sample; fat-free protein concentrate sample, pure anhydrous milk fat, and fatty protein concentrate sample. The water self-diffusion in fat-free protein concentrate samples followed a linear behavior. Consequently, the water self-diffusion coefficient could be easily characterized for fat-free protein concentrate samples. However, it seemed more complicated to obtain accurate water self-diffusion in fatty protein concentrate samples since the diffusion-attenuation data were fitted by a bi-exponential function. This paper demonstrates that the implementation of the T1-weighted spin-echo sequence, using the different T1 properties of water and fat phases, allows the accurate determination of water self-diffusion coefficient in a food product. To minimize the contribution of the 1H nuclei in the fat phase on the NMR echo signal, the fat protons were selectively eliminated by an additional 180 degrees pulse. This new method reduces the standard errors of diffusion data obtained with a basic spin-echo technique, by a factor of 10. The effectiveness of the use of the T1-weighted spin-echo sequence to perform accurate water self-diffusion coefficients measurement in fatty products is thus demonstrated.     

Correlations in 11B NMR spectra of dihalo derivatives of bis(1,2-dicarbollyl)cobalt(III)

In the ¹¹B NMR spectra of dihalo derivatives of bis(dicarbollyl)cobalt(III), we have identified a correlation between the ¹¹B NMR chemical shifts of substituted boron atoms and boron atoms found in other positions on the carborane skeleton. We have observed an increased shielding effect for fluorine atoms (compared with other halogens), manifested in an upfield shift of the ¹¹B NMR signals for antipodal and trans boron atoms. For the fluorine-containing compound Bu₄N⁺ [8,8′-F₂-3,3′-Co(1,2-C₂B₉H₁₀)₂]⁻, we propose the following sequence of electron density transfer: B(8) → {B(6) and B(10)} → B(4, 7). __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 547–549 (cont.), July–August, 2006.