Computational 1H NMR: Part 3. Biochemical studies

This is the third and the last part of three closely interrelated reviews dealing with computation of ¹H nuclear magnetic resonance chemical shifts and ¹H–¹H spin–spin coupling constants. Present review deals with the computation of these parameters in biologically active natural products, carbohydrates, and other molecules of biological origin focusing on stereochemical applications of computational ¹H nuclear magnetic resonance to these objects.     

Monitoring of the insecticide trichlorfon by phosphorus-31 nuclear magnetic resonance (31P NMR) spectroscopy

Trichlorfon is an organophosphorus insecticide, which is extensively being used for protection of fruit crops. Trichlorfon is a thermal labile compound, which cannot be easily determined by gas chromatography (GC) and has no suitable group for sensitive detection by high performance liquid chromatography (HPLC). In this study, a ³¹P nuclear magnetic resonance (³¹P NMR) has been described for monitoring of trichlorfon without any separation step. The quantitative works of ³¹P NMR spectroscopy has been performed in the presence of an internal standard (hexamethylphosphoramide). Limit of detection (LOD) for this method has been found to be 55 mg L⁻¹, without any sample preparation, and the linear working range was 150-5500 mg L⁻¹. Relative standard deviation (R.S.D.%) of the method for three replicates within and between days was obtained ≤9%. The average recovery efficiency was approximately 99-112%. This method was applied for monitoring trichlorfon in a commercial insecticide sample and tomato sample.     

Bufadienolides and a new lignan from the bulbs of Urginea maritima

Thirty three compounds were obtained from the bulbs of Urginea maritima (Liliaceae). The compounds were identified by means of fast atom bombardment mass spectrometry (FAB-MS), nuclear magnetic resonance (1H-NMR), (13C-NMR), nuclear overhauser effects (NOE) and two dimensional (2D) NMR. Ten of them were new natural compounds. Nine were bufadienolides and only one was lignan in these compounds.     

Phosphoesterase activity and phosphate release from tributyl phosphate by aCitrobacter sp.

Tributyl phosphate (TBP) and other alkyl phosphates represent a class of persistent organophosphorus compounds of widespread use. Biodegradation of the phosphotriesters is postulated to occur through sequential hydrolytic cleavages via the phosphodiester and monoester intermediates to alcohol and inorganic phosphate (P_i). Immobilized cells of aCitrobacter sp. liberated P_i upon challenge with TBP but the reaction was short-lived. In vitro studies with purified phosphomonoesterase (phosphatase) used³¹P nuclear magnetic resonance to demonstrate P_i transfer onto ethanol (phosphotransferase activity). This suggested that in vivo the onset of a futile phosphohydrolytic and transphosphorylation cycle would limit the extent of phosphate production. A mutant deficient in the transphosphorylating phosphomonoesterase showed an extended release of P_i under challenge with TBP that was not subject to the complete and premature reaction termination that precluded application of the parent strain to possible industrial processes for alkyl phosphate biodegradation.     

Identification of an octyl methylphosphonofluoridate mixture in chemical industry samples

Summary As part of an international round robin verification exercise, samples were analysed from a simulated inspection, which may take place under a future Chemical Weapons Convention, of a facility producing the organophosphorus insecticide 2,2-dichloroethenyl dimethyl phosphate (Dichlorvos). The identification of an unknown potential chemical warfare agent, an octyl methylphosphonofluoridate mixture, by the combination of gas chromatography-mass spectrometry (both electron impact and chemical ionization) and nuclear magnetic resonance spectrometry (¹⁹F and ³¹P) is described in detail. This compound mixture was added in relatively small quantities to some of the complicated chemical industry samples.     

Simultaneous determination of phenolic compounds and triterpenic acids in oregano growing wild in Greece by 31P NMR spectroscopy

³¹P nuclear magnetic resonance (NMR) spectroscopy was used to detect and quantify simultaneously a large number of phenolic compounds and the two triterpenic acids, ursolic acid and oleanolic acid, extracted from two oregano species Origanum onites and Origanum vulgare ssp. Hirtum using two different organic solvents ethanol and ethyl acetate. This analytical method is based on the derivatization of the hydroxyl and carboxyl groups of these compounds with the phosphorous reagent 2‐chloro‐4,4,5,5‐tetramethyl‐1,3,2‐dioxa phospholane and the identification of the phosphitylated compounds on the basis of the ³¹P chemical shifts. Unambiguous assignment of the ³¹P NMR chemical shifts of the dihydroxy‐ and polyhydroxy‐phenols in oregano species as well as those of the triterpenic acids was achieved upon comparison with the chemical shifts of model compounds assigned by using two‐dimensional NMR techniques. Furthermore, the integration of the appropriate signals of the hydroxyl derivatives in the corresponding ³¹P NMR spectra and the use of the phosphitylated cyclohexanol as an internal standard allowed the quantification of these compounds. The validity of this technique for quantitative measurements was thoroughly examined. Copyright © 2012 John Wiley & Sons, Ltd.     

One-pot green synthesis,study of fluorescence properties,and biological activity of pyrano[3,2-c]chromenes derivatives via mesoporous materials MgO/SBA-15

This current work describes the preparation of MgO-SBA-15 catalysts by ultrasonic method, and it is characterized by the different analysis techniques of XRD, BET, SEM, and IRTF. In order to find out an application for this mesoporous material, MgO/SBA-15 was used as a heterogeneous catalyst in the one-pot synthesis of pyrano[3,2-c]chromenes derivatives isolated at room temperature reaction according to green chemistry criteria. To enhance these derivatives, a spectroscopic study of molecular fluorescence properties was carried out as well as an identification analysis by nuclear magnetic resonance and FTIR was used. Furthermore, biological activity experiment is also carried out, from where the obtained test results were satisfactory for AC09 , AC05 , and AC10 compounds and they are checked after computation by molecular modeling.     

Application of Phosphorus-31 Nuclear Magnetic Resonance Spectrosocopy for the Study of Human Diabetic Cataractogenesis

Intact human Senses incubated at 5.5 mM (normal) and 35.5 mM glucose were examined by phosphorus-31 nuclear magnetic resonance (31P NMR) spectroscopy. Lense in 35.5 mM glucose showed an altered metabolic steady-state characterized by a lowered adenosine triphosphate/inorganic orthophosphate ratio. ³¹P NMR spectroscopy can be used to measure metabolic changes in the lens. This model offers an important means to study dynamic metabolism in the human lens in the setting of diabetic cataractogenesis.     

Carbon-13 nuclear magnetic resonance spectra of some 2-substituted tetrahydropyrans

Fourier transform carbon-13 nuclear magnetic resonance spectra have been obtained and interpreted for some 2-substituted tetrahydropyrans. The effects of the substituents on α, β, γ and δ-carbon atoms are discussed. Using suitable reference compounds the γ-parameter can be used for quantitative conformational analysis.     

活泼氢的核磁共振氢谱

核磁共振氢谱是有机化合物结构表征中最常使用的波谱方法之一,提供了有机化合物质子的化学位移、积分面积和耦合裂分等信息。常见的活泼氢是与氧、氮和硫共价相连的氢原子,存在着快速交换机制,与碳上的氢有显著的差异。在不同条件下活泼氢化学位移不固定、峰形多变并且耦合裂分情况复杂。本文探讨了如何通过核磁共振氢谱解析活泼氢,培养学生对谱图进行观察、分析以及结构推导的能力。     

钯催化苄基氯衍生物、三丁基烯丙基锡和一氧化碳三组分偶联反应:α,β-不饱和酮的有效合成

研究了苄基氯衍生物、CO和三丁基烯丙基锡在零价钯催化剂(Pd(PPh3)4)存在下的反应,结果表明,可有效发生三组分偶联反应,生成不饱和酮化合物.再经碱性氧化铝柱提纯后,转化为α,β-不饱和酮化合物6a～6n,其中,6b,6d～6h,6j,5l和6l～6n等未见文献报道,其结构经红外光谱、1H和13C核磁共振以及高分辨质谱表征确定.     

Restricted diffusion in NMR in arbitrary inhomogeneous magnetic fields and an application to circular layers

The multiple correlation function technique is a versatile approach for the computation of the nuclear magnetic resonance (NMR) magnetization of spins diffusing in inhomogeneous fields. The difficulties in deriving the required interaction matrices are one of the main limitations of this technique. In this work, methods to compute the interaction matrices of general magnetic field profiles from those of linear fields by basic matrix manipulations are presented. As an example, susceptibility induced magnetic field profiles that are generated by cylindrical capillaries residing in homogeneous magnetic fields are considered.     

Fluorine nuclear magnetic resonance parameters for hydrochlorofluoropropanes with one terminal hydrogen atom and all possible combinations of fluorine and chlorine atoms in the other positions

This paper presents the ¹⁹F nuclear magnetic resonance chemical shifts and couplingconstants for all saturated compounds with three carbon atoms at least one fluorineatom, one terminal hydrogen atom and all possible combinations of fluorine and chlorineatoms in the remaining six positions.     

对位取代四苯基卟啉及其铁(Ⅲ)配合物的~1H NMR研究

本文用BRUKER MSL-400型超导核磁共振仪,对于对位取代四苯基卟啉[H_2(p-X)TPP,X=Cl,H,CH_3,OCH_3],对位取代四苯基卟啉铁(Fe(Ⅲ)(p-X)TPPCl)及其轴向配合物([Fe(Ⅲ)(p-X)TPP(HIm)_2]~+Cl~-,([Fe(Ⅲ)(p-CH_3)TPPYm]~+Cl~-,Y=2-CH_3Im,2-C_2H_5-4-CH_3Im,n-C_3H_7NH_2,N(C_2H_5)_3)的质子核磁共振谱进行了较系统的研究,探讨了分子对称性、电子结构、顺磁效应等对~1H NMR谱的影响以及铁卟啉配合物的电子自旋离域机理。     

Some aspects of fundamental chemistry of the Universal Extraction (UNEX) process for the simultaneous separation of major radionuclides (cesium, strontium, actinides, and lanthanides) from radioactive wastes

Summary Scientists at the Idaho National Laboratory (INL) and Khlopin Radium Institute (KRI) collaboratively developed and validated the concept of a Universal Extraction (UNEX) process for simultaneously removing the major radionuclides (Cs, Sr, actinides, and lanthanides) from acidic radioactive waste in a single solvent extraction process. The process chemistry is unique and complicated, since the extractants, chlorinated cobalt dicarbollide (CCD), polyethylene glycol (PEG), and diphenyl-N,N-di-n-butylcarbamoylmethylphosphine oxide (Ph₂CMPO), operatesynergistically to extract the major radionuclides.A combination of classical chemistry techniques, infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy were utilized to identify and explain the structures formed in the organic phase with protons or metal ions. Model systems, CCD-PEG and CCD-bidentate organophosphorus compounds were studied and possible structures of complexes, existing in the organic phase, are proposed and properties of the UNEX extractant are discussed.     

Some spectroscopic properties of cyclic organolead compounds I

The nuclear magnetic resonance and infrared properties of two new cyclic organolead compounds are discussed.     

On the heavy atom on light atom relativistic effect in the NMR shielding constants of phosphine tellurides

The relativistic HALA effect has been shown to depend on the spatial deformation of the lone electron pairs of a heavy atom, as demonstrated for alkyl and alkene phosphine tellurides. It was found that HALA effect on phosphorous nuclear magnetic resonance shielding constant is strongly dependent on the spatial arrangements of light substituents on phosphorus, resulting in the deformation of the lone electron pairs of tellurium.     

汉防己甲素衍生物的合成及其生物活性

为寻找更为有效的抗肿瘤药物,改善汉防己甲素的抗肿瘤活性,本文以汉防己甲素为原料,经过Suzuki反应设计并合成了6个新的双苄基异喹啉类衍生物。新化合物经过质谱(MS)、核磁共振氢谱(~1H NMR)、核磁共振碳谱(~(13)C NMR)等技术手段进行了结构确证。采用细胞计数试剂盒(CCK-8)法初步评价了6个新化合物对人肺癌细胞(A549)和小鼠白血病细胞(P388)的抗肿瘤活性。结果表明,化合物均有不同程度的抗肿瘤活性,其中化合物H1、H4、H6对A549细胞的抗肿瘤活性(IC5010μmol/L)明显优于阳性对照汉防己甲素。     

Application of high-field proton nuclear magnetic resonance (1H-NMR) spectroscopy for the analysis of explosives and related compounds in groundwater samples – a comparison with the high-performance liquid chromatography (HPLC) method

High-field proton nuclear magnetic resonance (¹H-NMR) spectroscopy was applied to the analysis of nitroaromatics and nitramines in ammunition waste water. The ¹H-chemical shifts data of a variety of reference compounds are presented. Three groundwater samples, taken near the former ammunition plant Elsnig (Saxony), were analysed by high-performance liquid chromatography (HPLC) and by proton nuclear magnetic resonance spectroscopy. The results of HPLC and NMR analyses are compared and discussed.     

Density functional calculations of NMR chemical shifts and ESR g-tensors

An overview is given on recent advances of density functional theory (DFT) as applied to the calculation of nuclear magnetic resonance (NMR) chemical shifts and electron spin resonance (ESR) g-tensors. This is a new research area that has seen tremendous progress and success recently; we try to present some of these developments. DFT accounts for correlation effects efficiently. Therefore, it is the only first-principle method that can handle NMR calculations on large systems like transition-metal complexes. Relativistic effects become important for heavier element compounds; here we show how they can be accounted for. The ESR g-tensor is related conceptually to the NMR shielding, and results of g-tensor calculations are presented. DFT has been very successful in its application to magnetic properties, for metal complexes in particular. However, there are still certain shortcomings and limitations, e.g., in the exchange-correlation functional, that are discussed as well. Received: 24 October 1997 / Accepted: 19 December 1997