NMR studies on 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one

An unsymmetrical heterocyclic diamine, 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one, was synthesized. Its ¹H and ¹³C NMR spectra were completely assigned by utilizing the two‐dimensional heteronuclear ¹³C–¹H multiple‐bond coherence (HMBC) spectroscopy, and heteronuclear ¹³C–¹H one‐bond correlation spectroscopy, homonuclear shift correlation spectroscopy (H,H‐COSY) and rotating frame Overhauser enhancement spectroscopy (ROESY). The structure of the compound was shown to be the phthalazinone rather than the phthalazine ether from cross peaks and chemical shifts of the protons. Copyright © 2002 John Wiley & Sons, Ltd.     

Solid‐State NMR and DFT Studies on the Formation of Well‐Defined Silica‐Supported Tantallaaziridines: From Synthesis to Catalytic Application

Single‐site, well‐defined, silica‐supported tantallaaziridine intermediates [≡Si‐O‐Ta(η²‐NRCH₂)(NMe₂)₂] [R=Me ( 2 ), Ph ( 3 )] were prepared from silica‐supported tetrakis(dimethylamido)tantalum [≡Si‐O‐Ta(NMe₂)₄] ( 1 ) and fully characterized by FTIR spectroscopy, elemental analysis, and ¹H,¹³C HETCOR and DQ TQ solid‐state (SS) NMR spectroscopy. The formation mechanism, by β‐H abstraction, was investigated by SS NMR spectroscopy and supported by DFT calculations. The C?H activation of the dimethylamide ligand is favored for R=Ph. The results from catalytic testing in the hydroaminoalkylation of alkenes were consistent with the N‐alkyl aryl amine substrates being more efficient than N‐dialkyl amines.     

脯氨酸类N-酰胺衍生物的核磁共振研究

脯氨酸类衍生物结构独特,鲜有报道利用核磁共振（nuclear magnetic resonance,NMR）技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱（1H-1H COSY）、1H-1H质子全相关谱（1H-1H TOCSY）、1H-1H核Overhauser效应谱（1H-1H NOESY）、13C NMR、无畸变的极化转移增强法（DEPT135°）、1H-13C检出1H的异核单量子相干（1H-13C HSQC）和1H-13C检出1H的异核多键相关（1H-13C HMBC）,对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜（DMSO）中L型和D型的顺反异构体以相同的比例同时存在.     

Complete assignment of the 1H and 13C NMR spectra of some N‐benzyl‐(piperidin or pyrrolidin)‐purines

The ¹H and ¹³C shifts of six N‐benzyl‐(piperidin or pyrrolidin)‐purines were fully assigned by a combination of HSQC and HMBC experiments. The ¹H,¹H coupling constants were also determined. Copyright © 2002 John Wiley & Sons, Ltd.     

Practical application of 1H benchtop NMR spectroscopy for the characterization of a nonaqueous phase liquid from a contaminated environment

Nonaqueous phase liquids (NAPLs) located at the surface of the water table and/or below the water table are often a significant source for groundwater contamination near current or former commercial/industrial facilities. Due to the complex and long history of many industrial sites, these NAPLs often contain a complex mixture of contaminants and as such can be difficult to fully characterize using conventional analytical methods. Remediation and risk assessment activities at sites containing NAPLs may, subsequently, be hindered as the contamination profile may not be fully understood. This paper demonstrates the application of bench-scale ¹H nuclear magnetic resonance (NMR) spectroscopy as a practical tool to assist with the characterization of complex NAPLs. Here, a NAPL collected from a contaminated site situated near a former chemical manufacturing facility was analyzed using a combination of one-dimensional (1D) ¹H NMR spectroscopy and two-dimensional (2D) ¹H J-resolved spectroscopy (JRES). It is shown that 1D NMR experiments are useful in the rapid identification of the classes of compounds present, whereas 2D JRES NMR experiments are useful in identifying specific compounds. The use of benchtop NMR spectroscopy as a simple and cost effective tool to assist in the analysis of contaminated sites may help improve the practical characterization of many heavily contaminated sites and facilitate improved risk assessments and remedial strategies.     

Indirect detection of 31P,X connectivities with proton sensitivity: application of two‐dimensional 31P‐relayed 1H,X correlation spectroscopy

Experiments for ¹H‐detected heteronuclear ¹H,X correlation spectroscopy with ³¹P‐relayed coherence transfer are described which allow the indirect detection of δX and ⁿJ(X,P) even in the absence of a direct J(X,H) coupling. The use of these techniques for the assignments of ¹³C, ¹⁵N, and ¹⁸³W NMR data of organophosphorus compounds is demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.     

Triterpenoids fromAbies species 18. NMR spectra of abieslactone and its dehydro derivative

The contradictions in the interpretations of the¹³C NMR spectrum of a natural lanostanoid, abieslactone, and of the 1H NMR spectrum a its 9,11-dehydro derivative reported in the literature were resolved by two-dimensional¹H-¹H and¹³C-¹H (COSY) NMR spectroscopy.Translated fromIzvestiya Akademi Nauk. Seriya Khimicheskaya, No. 11, pp.2780–2784, November,1996     

Deciphering the Conformational Choreography of Zinc Coordination Complexes with Standard and Novel Proton NMR Techniques Combined with DFT Methods

The presence of water has been shown to deeply impact the stability and geometry of Zn complexes in solution. Evidence for tetra‐ and penta‐coordinated species in a pyridylmethylamine–Zn^II model complex is presented. Novel ¹H NMR tools such as T₁‐filtered selective exchange spectroscopy and pure shifted gradient‐encoded selective refocusing as well as classical 2D (¹H–¹H) exchange spectroscopy, diffusion‐ordered spectroscopy and T₁(¹H) measurements, in combination with density functional theory methods allow the full conformational dynamics of a pyridylmethylamine–Zn^II complex to be revealed. Four conformers and two families of complexes depending on the hydration states are elucidated.     

Synthesis and enantioselective fluorescent sensors for amino acid derivatives based on BINOL

Four novel derivatives of 1,1′-bi-2-naphthol have been prepared and the structures of these compounds characterised by IR, MS, ¹H and ¹³C NMR spectroscopy and elemental analysis. The enantioselective recognition of these sensors has been studied by fluorescence titration and ¹H NMR spectroscopy. The sensors exhibited different chiral recognition abilities towards N-Boc-protected amino acid anions and formed 1:1 complexes between the host and the guest. Sensors exhibit excellent enantioselective fluorescent recognition ability towards the amino acid derivatives.     

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.     

Synthesis and Characterization of trans‐PdII Trimethylsilylchalcogenolates

The trans‐bis(trimethylsilyl)chalcogenolate palladium complexes, trans‐[Pd(ESiMe₃)₂(PnBu₃)₂] [E = S ( 1 ) and Se ( 2 )] were synthesized in good yields and high purity by reacting trans‐[PdCl₂(PBu₃)₂] with LiESiMe₃ (E = S, Se), respectively. These complexes were characterized by ¹H, ¹³C{¹H}, ³¹P{¹H} (and ⁷⁷Se{¹H}) NMR spectroscopy and single‐crystal X‐ray analysis. The reaction of 2 with propionyl chloride led to the formation of trans‐[Pd(SeC(O)CH₂CH₃)₂(PnBu₃)₂] ( 3 ), a trans‐bis(selenocarboxylato) palladium complex and thus established a new method for the formation of this type of complex. Complex 3 was characterized by ¹H, ¹³C{¹H}, ³¹P{¹H} and ⁷⁷Se{¹H} NMR spectroscopy and a single‐crystal X‐ray structure analysis.     

Correlation NMR spectroscopy of 1,1-dichloro-2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-diene

Assignment of all of the signals in the¹H and¹³C NMR spectra of 1,1-dichloro-2,3,4,5-tetraphenyl-l-germacyclopenta-2,4-diene has been carried out using two-dimensional NMR spectroscopy. Translated fromIzvestiya Akademii Nauk Seriya Khimicheskaya, No. 3, pp. 623–625, March, 1997.     

Synthesis,structural and conformational study of selected <Emphasis Type="Italic">N</Emphasis>-substituted phthalimides

This paper synthesizes N-substituted phthalimides derived from nitrogen heterocycles as potential 5-HT₄ ligands by using the Mitsunobu reaction. Conformational studies of some of the new compounds have been conducted using ¹H and ¹³C-NMR spectroscopy. Proton and carbon resonances were achieved through the application of one-dimensional selective NOE, two-dimensional NMR techniques-homonuclear COSY-45, NOESY and heteronuclear ¹H-¹³C HMQC correlated spectroscopy- and double resonance experiments. The crystal structure of compound 1 was determined by X-ray diffraction.     

Complete assignments of 1H and 13C NMR data for two new sesquiterpenes from Cyperus rotundus L.

Two new sesquiterpenes, epi‐guaidiol A (1) and sugebiol (3), together with four known sesquiterpenes, guaidiol A(2), sugetriol triacetate (4), cyperenoic acid (5), and cyperotundone (6) were isolated from the rhizomes of Cyperus rotundus L. Their structures were identified by MS and NMR experiments, and the complete assignments of ¹H and ¹³C NMR data for two new sesquiterpenes were obtained by the aid of two‐dimensional (2D) NMR techniques, including HSQC, HMBC, ¹H‐¹HCOSY and nuclear overhauser enhancement spectroscopy(NOESY). Copyright © 2009 John Wiley & Sons, Ltd.     

Conformation analysis of d‐glucaric acid in deuterium oxide by NMR based on its JHH and JCH coupling constants

d ‐Glucaric acid (GA) is an aldaric acid and consists of an asymmetric acyclic sugar backbone with a carboxyl group positioned at either end of its structure (i.e., the C1 and C6 positions). The purpose of this study was to conduct a conformation analysis of flexible GA as a solution in deuterium oxide by NMR spectroscopy, based on J‐resolved conformation analysis using proton–proton (³J_HH) and proton–carbon (²J_CH and ³J_CH) coupling constants, as well as nuclear overhauser effect spectroscopy (NOESY). The ²J_CH and ³J_CH coupling constants were measured using the J‐resolved heteronuclear multiple bond correlation (HMBC) NMR technique. NOESY correlation experiments indicated that H2 and H5 were in close proximity, despite the fact that these protons were separated by too large distance in the fully extended form of the chain structure to provide a NOESY correlation. The validities of the three possible conformers along the three different bonds (i.e., C2? C3, C3? C4, and C4? C5) were evaluated sequentially based on the J‐coupling values and the NOESY correlations. The results of these analyses suggested that there were three dominant conformers of GA, including conformer 1 , which was H2H3:gauche, H3H4:anti, and H4H5:gauche; conformer 2 , which was H2H3:gauche, H3H4:anti, and H4H5:anti; and conformer 3 , which was H2H3:gauche, H3H4: gauche, and H4H5:anti. These results also suggested that all three of these conformers exist in equilibrium with each other. Lastly, the results of the current study suggested that the conformational structures of GA in solution were ‘bent’ rather than being fully extended. Copyright © 2016 John Wiley & Sons, Ltd.     

Aryl‐Phosphonate Lanthanide Complexes and Their Fluorinated Derivatives: Investigation of Their Unusual Relaxometric Behavior and Potential Application as Dual Frequency 1H/19F MRI Probes

A series of low molecular weight lanthanide complexes were developed that have high ¹H longitudinal relaxivities (r₁) and the potential to be used as dual frequency ¹H and ¹⁹F MR probes. Their behavior was investigated in more detail through relaxometry, pH‐potentiometry, luminescence, and multinuclear NMR spectroscopy. Fitting of the ¹H NMRD and ¹⁷O NMR profiles demonstrated a very short water residence lifetime (<10 ns) and an appreciable second sphere effect. At lower field strengths (20 MHz), two of the complexes displayed a peak in r₁ (21.7 and 16.3 mM ^?1 s^?1) caused by an agglomeration, that can be disrupted through the addition of phosphate anions. NMR spectroscopy revealed that at least two species are present in solution interconverting through an intramolecular binding process. Two complexes provided a suitable signal in ¹⁹F NMR spectroscopy and through the selection of optimized imaging parameters, phantom images were obtained in a MRI scanner at concentrations as low as 1 mM . The developed probes could be visualized through both ¹H and ¹⁹F MRI, showing their capability to function as dual frequency MRI contrast agents.     

Study of alkaloids from the flora of the Siberian and Altai regions. 6. Crystal and molecular structure of songorine Z-oxime

Oximation of songorine afforded a mixture of its Z- and E-oximes. The crystal and molecular structure of the Z-isomer was established by X-ray diffraction analysis. Its structure was also confirmed by the spectral data (2D ¹H—¹H and ¹³C—¹H NMR spectroscopy and mass spectrometry). The structure of isomeric E-oxime was established by comparing its NMR spectroscopic data (¹H and ¹³C) with the data for the Z-isomer.     

Host-Guest Interaction in Ethylene and Ethane Separation on Zeolitic Imidazolate Frameworks as Revealed by Solid-State NMR Spectroscopy

The separation of ethane/ethylene mixture by using metal-organic frameworks (MOFs) as adsorbents is strongly associated with the pore size-sieving effect and the adsorbent-adsorbate interaction. Herein, solid-state NMR spectroscopy is utilized to explore the host-guest interaction and ethane/ethylene separation mechanism on zeolitic imidazolate frameworks (ZIFs). Preferential access to the ZIF-8 and ZIF-8-90 frameworks by ethane compared to ethylene is directly visualized from two-dimensional ¹H-¹H spin diffusion MAS NMR spectroscopy and further verified by computational density distributions. The ¹H MAS NMR spectroscopy provides an alternative for straightforwardly extracting the adsorption selectivity of ethane/ethylene mixture at 1.1∼9.6 bar in ZIFs, which is consistent with the IAST predictions.     

Rhaposerine and rhaserolide, new sesquiterpene lactones fromRhaponticum serratuloides

Two new crystalline guaianolides,viz., rhaposerine and rhaserolide, were isolated from an ethanolic extract of the above-ground part of the plantRhaponticum serratuloides by column chromatography along with sesquiterpene lactones,viz., centaurepensin and acroptilin, which have been found in other plants. The chemical structures of the title lactones were established by¹H and¹³C NMR spectroscopy and 2D¹H−¹H (COSY) and¹³C−¹H (COSY and COLOC) NMR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2010–2014, October, 1999.