1H mas NMR study of OH groups in the AlPO4/SiO2 system

Three solids of composition SiO₂, AlPO₄ and 20∶80 mol/mol AlPO₄/SiO₂, respectively, were synthesized. Their textural properties were examined and¹H MAS NMR spectroscopy was used to characterize their surface OH groups. The results reveal that the solids are amorphous and texturally suitable for use as catalysts.     

顺磁性镧系金属有机配合物的1H核磁共振研究

顺磁类的核磁共振研究大多是简单化合物,偏重理论方面的研究,对镧系配合物曾有报道。由于这类样品对空气和湿气极为敏感,在国内外研究顺磁性¹H谱甚少。本文研究了含氯桥的醚基取代环戊二烯镧系配合物二聚体的¹H化学位移,线宽,弛豫时间T₁和磁化率,从中找出了顺磁类有机镧系配合物¹H NMR的规律。     

Synthesis and 1H, 13C and 15N NMR characterisation of substituted Pyrazolo[4,3-c]quinolines and related compounds

A wide range of novel and known alkyl substituted pyrazolo[4,3-c]quinolines and related compounds were synthesized. Some of these compounds can undergo tautomerism and differences have been noted in the structural assignments already published. For each of these compounds, a complete assignment was made using ¹H, ¹³C and ¹⁵N one- and two-dimensional NMR measurements, including NOESY, COSY, ¹H-¹³C HSQC and ¹H-¹³C HMBC. ¹H-¹⁵N HMBC NMR has proved crucial in determining the relevant tautomeric and protonated state of the compounds.     

1H MAS NMR characterization of hydrogen over silica-supported rhodium catalyst

Hydrogen species in both SiO₂ and Rh/SiO₂catalysts pretreated in different atmospheres (H₂, O₂, helium or air) at different temperatures (773 or 973 K) were investigated by means of¹H MAS NMR. In SiO₂ and O₂-pretreated catalysts, a series of downfield signals at ∼7.0, 3.8–4.0, 2.0 and 1.5–1.0 were detected. The first two signals can be attributed to strongly adsorbed and physisorbed water and the others to terminal silanol (SiOH) and SiOH under the screening of oxygen vacancies in SiO₂lattice, respectively. Besides the above signals, both upfield signal at ∼−110 and downfield signals at 3.0 and 0.0 were also detected in H₂-pretreated catalyst, respectively. The upfield signal at ∼−110 originated from the dissociative adsorption of H₂ over rhodium and was found to consist of both the contributions of reversible and irreversible hydrogen. There also probably existed another dissociatively adsorbed hydrogen over rhodium, which was known to be β hydrogen and in a unique form of “delocalized hydrogen”. It was presumed that the β hydrogen had an upfield shift of ca. −20–−50, though its¹H NMR signals, which, having been masked by the spinning sidebands of Si-OH, failed to be directly detected out. The downfield signal at 3.0 was assigned to spillover hydrogen weakly bound by the bridge oxygen of SiO₂. Another downfield signal at 0.0 was assigned to hydrogen held in the oxygen vacancies of SiO₂ (Si-H species), suffering from the screening of trapped electrons. Both the spillover hydrogen and the Si-H resulted from the migration of the reversible hydrogen and the β hydrogen from rhodium to SiO₂ in the close vicinity. It was proved that the above migration of hydrogen was preferred to occur at higher temperature than at lower temperature.     

Ce3+掺杂La2O3的17O固体核磁共振研究

本文用水热共沉淀法制备Ce³⁺掺杂La₂O₃的前驱体,随后在H₂/N₂气氛下用高温煅烧法合成了不同Ce³⁺浓度的掺杂La₂O₃。由于Ce³⁺的掺杂,¹⁷O固体核磁共振谱图中在698、650和558处出现了新的共振峰;随着Ce³⁺掺杂浓度的增加,这些峰的强度也随之增强。根据谱峰位置和强度,对谱图进行了归属:698、650处的共振峰应源自与Ce³⁺相连的四配位O(OCeLa₃),558处的信号则来自于与Ce³⁺相连的六配位O(OCeLa₅)。通过¹⁷O固体核磁共振能够直接观测与Ce³⁺直接相连的O显示该方法将可能用于研究稀土掺杂氧化物功能材料。     

Structure of deacetylazadirachtinol application of 2D1H-1H and 1H-13C shift correlation spectroscopy

A new insect antifeedant, and ecdysis inhibitor deacetylazadirachtinol, was isolated from $\text{Azadirachta}$$\text{indica}$ (Meliaceae) collected in Haiti and its structure (1) was elucidated by the spectral comparison with azadirachtin using two-dimensional ¹H-¹H and ¹H-¹³C shift correlation spectroscopies.     

Interpretation dü spectre RMN-3H du PK-11195 (3H)

(1D-³H NMR) of PK 11195 ³H gives a complex spectrum. Homonuclear 2D-³H NMR (COSY and J. Resolved) gives useful information such as tritium chemical shifts, ³H-³H and ³H-¹H coupling constant, percentage of isotopomers and specific activity.     

Stereochemicai study of 7-aryl-1,7,8,8a-tetrahydro-3(2H)indolizinones by1H and13C NMR

Stereochemistry of 7-aryl-1,7,8,8a-tetrahydro-3(2H)-indolizinones was studied by¹H and¹³C NMR. Complete assignment of¹H NMR signals and analysis of¹H-¹H coupling constants were performed using the iterative PANIC program. Values of³ J _6,7,³ J _7,8endo, and⁴ J _5,7 allow one to unambiguously identify the correspondingexo- andendo-stereoisomers. For stereoisomers with exo-orientation of H(7), complete assignment of¹³C NMR signals was performed on the basis of analysis of the¹³C-¹H coupling constants using two dimensional heteronuclear shift-correlating spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 591–593, March, 1996.     

Ce3+掺杂La2O3的17O固体核磁共振研究

本文用水热共沉淀法制备Ce³⁺掺杂La₂O₃的前驱体,随后在H₂/N₂气氛下用高温煅烧法合成了不同Ce³⁺浓度的掺杂La₂O₃。由于Ce³⁺的掺杂,¹⁷O固体核磁共振谱图中在698、650和558处出现了新的共振峰;随着Ce³⁺掺杂浓度的增加,这些峰的强度也随之增强。根据谱峰位置和强度,对谱图进行了归属：698、650处的共振峰应源自与Ce³⁺相连的四配位O(OCeLa₃),558处的信号则来自于与Ce³⁺相连的六配位O(OCeLa₅)。通过¹⁷O固体核磁共振能够直接观测与Ce³⁺直接相连的O显示该方法将可能用于研究稀土掺杂氧化物功能材料。     

Ambidentate Properties of Asymmetric Substituted Imidazoles. Direction of Benzylation of 2-[N-(4-Chlorophenyl)carbamoyl]methylthio-4-phenyl-1H-imidazole

On the basis of ¹H-¹H two dimensional NMR spectroscopy (NOESY) it has been unambiguously shown that the benzylation of 2-[N-(4-chlorophenyl)carbamoyl]methylthio-4-phenyl-1H-imidazole occurs at the N₍₁₎ atom. This data was confirmed by comparison of the properties of the alkylation product obtained with the corresponding N₍₃₎-benzylimidazole isomer synthesized independently. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 882–886, June, 2005.     

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.     

129Xe NMR study of the localization of PdCl2 supported on carbon nanotubes

Localization of PdCl₂ clusters supported on multi-wall carbon nanotubes (MWCNT) has been investigated using ¹²⁹Xe NMR of adsorbed xenon. As-made MWCNTs with channels initially inaccessible for adsorption and ball-milled MWCNTs with the totally accessible internal surface were used as supports. The observed ¹²⁹Xe NMR spectra were determined by the dynamics of xenon exchange between the aggregate pores and nanotube channels. No considerable changes of the ¹²⁹Xe NMR spectrum with the concentration of supported PdCl₂ were observed for the as-made MWCNT, while an additional resonance appeared for the ball-milled nanotubes. The ¹²⁹Xe NMR experiments evidenced the supported species to be localized on the internal surface of the ball-milled MWCNT.     

Study on the interactions between anti-tumor metal complexes and mononucleotides using trans -[en2Os(η2-H2)(CF3SO3)](CF3SO3) as a 1H NMR probe in a competitive mode

The interaction of several anti-tumor metal complexes with dGMP have been investigated using trans-[en₂Os(η²-H₂)]²⁺ as a ¹H NMR probe in a competitive mode. Me₂SnCl₂, Bu₂SnCl₂, Et₂Sn(phen)Cl₂ and Et₂SnCl₂can bind to dGMP mainly via phosphate; Cp₂TiCl₂ binds to dGMP mainly via phosphate and N₇. The binding constant for (CH₃)₂SnCl₂ binding to phosphate of dGMP exceeds 2.71×10⁴. The binding constant for Cp₂TiCl₂ to phosphate is even greater than that of Sn(IV). Cis-platin has high affinity for both N₇ and phosphate, but mainly for N₇. Binding of the probe to N₇ of dGMP reduces the binding affinity for phosphate of the same dGMP molecule by a factor of 5 to 6. Much the same factor is expected to apply to other metals containing agents interacting with dGMP.     

Phosphorus Derivatives of Natural Lactones. Synthesis of New Grosshemin Dialkylphosphonates

New phosphorus-containing derivatives of grosshemin were synthesized in 68-70% yield by reacting this guaianolide with dialkylphosphites. Their structures were established by IR, PMR, ¹³C NMR, and ³¹P NMR spectroscopies and two-dimensional ¹H-¹H NMR spectroscopy (COSY). The reaction of grosshemin with dialkylphosphites was found to be highly stereoselective.     

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.     

Ionic mobility and structure of fluorozirconates Rb2? x (NH4) x ZrF6 ( x > 1.5) by NMR, x-ray structure analysis, and impedance spectroscopy

The ionic mobility in the temperature interval 180 to 480 K, structure, and electrophysical properties of rubidium-ammonium hexafluorozirconates Rb_2−x (NH₄) _x ZrF₆ (1.5 ≤ x ≤ 2.0) are studied by methods of the ¹⁹F, ¹H NMR spectroscopy, x-ray structure analysis, differential thermal analysis, and impedance spectroscopy. Correlations between the composition of the cationic sublattice, the character of ionic motions, and the phase transition temperature (of the type order-disorder) are established in these compounds. The salient feature of the high-temperature modifications of these fluorozirconates with x ≥ 1.5 is the translation diffusion of ions inside the fluoride and ammonium sublattices and the ¹⁹F NMR spectra are characterized by monoaxial anisotropy of the magnetic shielding tensor of the fluorine nuclei. Fluorozirconates with x > 1.5 are shown to belong with the structural type (NH₄)₂ZrF₆. The rubidium cations isomorphically replace the ammonium cations. The electrophysical characteristics of the compounds are examined in the temperature interval 300 to 480 K. It is established that the electroconductivity of these compounds increases with x. Original Russian Text ? V.Ya. Kavun, A.V. Gerasimenko, A.B. Slobodyuk, N.A. Didenko, N.F. Uvarov, V.I. Sergienko, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 5, pp. 563–570. Based on the paper delivered at the 8th Meeting “Fundamental Problems of Solid-State Ionics”, Chernogolovka (Russia), 2006.     

Probing the surface acidity of modified γ-alumina with1H and15N high-resolution solid state NMR spectroscopy

¹H MAS NMR and¹⁵N NMR studies of adsorbed N₂ and N₂O molecules were used to characterize Br?nsted and Lewis acidic sites of unmodified γ-Al₂O₃ and γ-Al₂O₃ modified with NaOH. Changes in the concentrations of surface hydroxyls with the increase in the number of more “basic” OH groups for NaOH/γ-Al₂O₃ have been found by¹H MAS NMR experiments. Two different types of Lewis acidic sites in γ-Al₂O₃ have been revealed using¹⁵N NMR studies. The strongest sites are poisoned even at small NaOH concentrations (ca. 0.05 wt.%). Not only the number of electron-accepting sites but also their strength are supposed to decrease for modified γ-alumina.     

Structure Solution of Nano-Crystalline Small Molecules Using MicroED and Solid-State NMR Dipolar-Based Experiments

Three-dimensional electron diffraction crystallography (microED) can solve structures of sub-micrometer crystals, which are too small for single crystal X-ray crystallography. However, R factors for the microED-based structures are generally high because of dynamic scattering. That means R factor may not be reliable provided that kinetic analysis is used. Consequently, there remains ambiguity to locate hydrogens and to assign nuclei with close atomic numbers, like carbon, nitrogen, and oxygen. Herein, we employed microED and ssNMR dipolar-based experiments together with spin dynamics numerical simulations. The NMR dipolar-based experiments were ¹H-¹⁴N phase-modulated rotational-echo saturation-pulse double-resonance (PM-S-RESPDOR) and ¹H-¹H selective recoupling of proton (SERP) experiments. The former examined the dephasing effect of a specific ¹H resonance under multiple ¹H-¹⁴N dipolar couplings. The latter examined the selective polarization transfer between a ¹H-¹H pair. The structure was solved by microED and then validated by evaluating the agreement between experimental and calculated dipolar-based NMR results. As the measurements were performed on ¹H and ¹⁴N, the method can be employed for natural abundance samples. Furthermore, the whole validation procedure was conducted at 293 K unlike widely used chemical shift calculation at 0 K using the GIPAW method. This combined method was demonstrated on monoclinic l-histidine.     

Characteristics and formation of [AlO4Al12(OH)24(H2O)12]7+ in electrolysis process

[AlO₄Al₁₂(OH)₂₄(H₂O)₁₂]⁷⁺ (Al₁₃) formation in electrolysis process is studied. The results detected by²⁷Al NMR spectroscopy show that high content of Al₁₃ polymer is formed in the partially hydrolyzed aluminum solution prepared by controlled electrolysis process. In the produced electrolyte of total Al concentration ([Al_T]) 2.0 mol · L⁻¹ with a basicity (B = OH/Al molar ratios) of 2.0, the content of Al₁₃ polymer is over 60% of total Al. Dynamic light scattering shows that the size distribution of the final electrolyte solutions ([Al_T] = 2.0 mol · L⁻¹) is trimodal with B = 2.0 and bimodal with B = 2.5. The aggregates of Al₁₃ complexes increase the particle size of partially hydrolyzed aluminum solution.     

2D-NMR: Part VI. 2D-INADEQUATE spectral analysis and crystal structure of tricyclo[7.3.1.02,7]tridecane

2-Hydroxy-13-oxo-tricyclo[7.3.1.0^2,7]tridecane derivatives can be obtained by reaction of cyclohexanone with alcohols under alkaline conditions. The unambiguous assignment of all signals of the¹H-NMR- and¹³C-NMR-spectrum is possible by 2D-¹H-¹³C-shift correlation and 2D-INADEQUATE. Compound1 crystallizes in space group P2₁/n witha=8.518 (1),b=14.789 (2),c=19.321 (2) Å, =94.91 (1)°,Z=8,D _c =1.22 Mg cm^–3. The structure refined toR=0.100 andR _w =0.097 for 1719 observed reflections. Two independent molecules form centrosymmetric hydrogen-bonded dimers.Part V:Haslinger E.,Kalchhau-ser H.,Robien W.,Steindl H., Monatsh. Chem.115, 597 (1984).