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Journal articles on the topic 'NMR spectra of liquids'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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1

Ushakov, I. A., V. K. Voronov, D. S. Grishmanovskii, S. N. Adamovich, R. G. Mirskov, and A. N. Mirskova. "NMR spectra of metallated alkanolammonium ionic liquids." Russian Chemical Bulletin 64, no. 1 (January 2015): 58–61. http://dx.doi.org/10.1007/s11172-015-0821-x.

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2

Khudozhitkov, Alexander E., Peter Stange, Anne-Marie Bonsa, Viviane Overbeck, Andreas Appelhagen, Alexander G. Stepanov, Daniil I. Kolokolov, Dietmar Paschek, and Ralf Ludwig. "Dynamical heterogeneities in ionic liquids as revealed from deuteron NMR." Chemical Communications 54, no. 25 (2018): 3098–101. http://dx.doi.org/10.1039/c7cc09440j.

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Deuteron NMR spectroscopy is a suitable method to study dynamical heterogeneities in protic ionic liquids. In the ²H spectra of the protic ionic liquid [TEA][OTf] we observe anisotropic and isotropic signals at the same time.

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3

Messali, Mouslim. "Conventional versus ultrasound and microwave assisted synthesis: Some new environmentally friendly functionalized picolinium-based ionic liquids with potential antibacterial activity." Acta Pharmaceutica 65, no. 3 (September 1, 2015): 253–70. http://dx.doi.org/10.1515/acph-2015-0028.

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Abstract A green chemistry approach has been adopted for the synthesis of thirty-four new picolinium-based ionic liquids using microwave (MW) and ultrasound (US) irradiation as well as conventional thermal heating. Their structures were confirmed by FT-IR, 1H NMR, 13C NMR, 11B NMR, 19F NMR, 31P NMR, mass spectra and elemental analyses. The antimicrobial profile of the novel ionic liquids was evaluated and the minimum inhibitory concentration (MIC) showed their moderate to low antimicrobial activity against eight types of human pathogens.

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4

Wei, Chenyang, Zhengping Liu, Hongwei Tan, Liyan Huang, and Jun Li. "A non-metal route to realize the bio-based polyester of poly(hexylene succinate): preparation conditions, side-reactions and mechanism in sulfonic acid-functionalized Brønsted acidic ionic liquids." RSC Advances 10, no. 58 (2020): 35381–88. http://dx.doi.org/10.1039/d0ra07157a.

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5

Şaka, İrfan, Sedat Gümüş, and Azmi Gençten. "A Complete Product Operator Theory for IS (I=1, S = 1) Spin System and Application to 3D HMQC-COSY NMR Experiment." Zeitschrift für Naturforschung A 64, no. 5-6 (June 1, 2009): 377–86. http://dx.doi.org/10.1515/zna-2009-5-612.

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There exist a variety of multi-pulse NMR experiments for spectral assignment of complex molecules in solution. The conventional heteronuclear multiple-quantum coherence (HMQC) NMR experiment provides correlation between weakly coupled hetero-nuclei. The COSY is one of the most popular two-dimensional NMR experiment which is used to correlate J-coupled homo-nuclei of spectral assignment. The combination of the conventional HMQC and COSY NMR experiments yields a new experiment called 3D HMQC-COSY NMR experiment. The product operator theory is widely used for the analytical descriptions of multi-pulse NMR experiments for weakly coupled spin systems in liquids. In this study, complete product operator theory for weakly coupled IS (I = 1, S = 1) spin system is presented by obtaining the evolutions of the product operators under the spin-spin coupling Hamiltonian. As an application and a verification, analytical descriptions of 3D HMQC-COSY NMR experiment are obtained for weakly coupled ISnI’_S’m (I = I’ = 1/2; S = S’ = 1; n = 1,2, 3; m = 1, 2) multi-spin systems. Then the estimated spectra of this experiment for various multi-spin systems are explained in detail.

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6

Strate, Anne, Jan Neumann, Thomas Niemann, Peter Stange, Alexander E. Khudozhitkov, Alexander G. Stepanov, Dietmar Paschek, Daniil I. Kolokolov, and Ralf Ludwig. "Counting cations involved in cationic clusters of hydroxy-functionalized ionic liquids by means of infrared and solid-state NMR spectroscopy." Physical Chemistry Chemical Physics 22, no. 13 (2020): 6861–67. http://dx.doi.org/10.1039/d0cp00303d.

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Sensitive probe of like-charge attraction: analyzing infrared spectra allows counting the number of cations involved in clusters of opposite (c–a) and like-charged (c–c) ions in ionic liquids. This approach is also applicable to molecular liquids.

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7

Ylihautala, Mika, Petri Ingman, Jukka Jokisaari, and Peter Diehl. "129Xe and 131Xe NMR of Xenon in Mesophases of Cetyltrimethylammonium Bromide in Formamide." Applied Spectroscopy 50, no. 11 (November 1996): 1435–38. http://dx.doi.org/10.1366/0003702963904791.

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For the first time, noble gas NMR has been applied to a study of a lyotropic liquid crystal. 129Xe and 131Xe NMR spectra of natural xenon gas dissolved in pure formamide and three cetyltrimethylammonium bromide (CTAB)/formamide (FA) mixtures were recorded over wide temperature ranges. The CTAB/FA system forms micelles at low concentrations of CTAB and mesophases at higher concentrations and elevated temperatures. The phase transitions are observed in the series of xenon spectra. In addition, the free xenon gas signal is seen in the spectra at low temperature, when the CTAB/FA system has a coexisting solid/liquid phase. The gas signal indicates that Xe is not soluble in the solid but accumulates in macroscopic bubbles. The intensity variation of the central peak of the 131Xe NMR spectra shows the presence of a static external electric field gradient (EFG). However, the spectral satellites are not observed and, therefore, the magnitude of the EFG cannot be determined. The obvious reason for the missing 131Xe satellites is the orientation distribution of the EFG tensor leading to broadening of the satellites.

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8

Augustijn, Dieuwertje, Huub J. M. de Groot, and A. Alia. "HR-MAS NMR Applications in Plant Metabolomics." Molecules 26, no. 4 (February 10, 2021): 931. http://dx.doi.org/10.3390/molecules26040931.

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Metabolomics is used to reduce the complexity of plants and to understand the underlying pathways of the plant phenotype. The metabolic profile of plants can be obtained by mass spectrometry or liquid-state NMR. The extraction of metabolites from the sample is necessary for both techniques to obtain the metabolic profile. This extraction step can be eliminated by making use of high-resolution magic angle spinning (HR-MAS) NMR. In this review, an HR-MAS NMR-based workflow is described in more detail, including used pulse sequences in metabolomics. The pre-processing steps of one-dimensional HR-MAS NMR spectra are presented, including spectral alignment, baseline correction, bucketing, normalisation and scaling procedures. We also highlight some of the models which can be used to perform multivariate analysis on the HR-MAS NMR spectra. Finally, applications of HR-MAS NMR in plant metabolomics are described and show that HR-MAS NMR is a powerful tool for plant metabolomics studies.

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9

Lyčka, Antonín, Roman Doleček, Petr Šimûnek, and Vladimír Macháček. "15N NMR spectra of some ionic liquids based on 1,3-disubstituted imidazolium cations." Magnetic Resonance in Chemistry 44, no. 5 (2006): 521–23. http://dx.doi.org/10.1002/mrc.1785.

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10

Aoki, Dan, Kenta Nomura, Masashi Hashiura, Yoshinori Imamura, Sonoka Miyata, Noritsugu Terashima, Yasuyuki Matsushita, et al. "Evaluation of ring-5 structures of guaiacyl lignin in Ginkgo biloba L. using solid- and liquid-state 13C NMR difference spectroscopy." Holzforschung 73, no. 12 (November 26, 2019): 1083–92. http://dx.doi.org/10.1515/hf-2019-0011.

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Abstract To discuss the macromolecular structure and properties of lignin, the complementary use of solid- and liquid-state nuclear magnetic resonance (NMR) combined with a specific 13C-enrichment technique may provide useful information. The 13C-enriched lignin was prepared by administering [guaiacyl ring-5(G5)-13C]-coniferin to a growing Ginkgo biloba L. shoot. The 13C-enriched cellulolytic enzyme lignin (EL) and its acetate prepared from the ginkgo shoot were examined by solid- and liquid-state 13C NMR spectroscopy. The 13C NMR spectrum derived only from the G5 carbon was obtained as a difference spectrum based on the spectra of the G5-13C enriched and un-enriched (UE) samples. The condensed structures, including the enriched G5-carbon, were evaluated using difference spectra. The chemical shifts of the enriched G5 carbon in both the solid- and liquid-state 13C NMR spectra agreed with each other in principle. The quantitative ratio of the condensed and uncondensed structures at G5 was found to be larger by solid-state cross polarization/magic angle spinning (CP/MAS) NMR than by liquid-state NMR.

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11

Yonker, C. R., T. S. Zemanian, S. L. Wallen, J. C. Linehan, and J. A. Franz. "A New Apparatus for the Convenient Measurement of NMR Spectra in High-Pressure Liquids." Journal of Magnetic Resonance, Series A 113, no. 1 (March 1995): 102–7. http://dx.doi.org/10.1006/jmra.1995.1061.

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12

Nesbitt, H. W., and K. N. Dalby. "High resolution O 1s XPS spectral, NMR, and thermodynamic evidence bearing on anionic silicate moieties (units) in PbO-SiO2 and Na2O-SiO2 glasses." Canadian Journal of Chemistry 85, no. 10 (October 1, 2007): 782–92. http://dx.doi.org/10.1139/v07-085.

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Recent technical advances in X-ray photoelectron spectroscopy (XPS) have largely overcome differential charging of insulator surfaces, with the result that O 1s linewidths for silicates can be routinely collected that are 50% to 100% narrower than had been previously obtainable. The bridging and nonbridging oxygen signals of glasses are well resolved and now can be accurately measured by XPS without resorting to ad hoc fitting procedures. All O 1s spectra of silicates collected so far are somewhat asymmetric to the high binding energy side of the peak, a characteristic due primarily to vibrational contributions in the ion state produced by photoemission (electronic excited state). This asymmetry must be considered if the proportion of bridging to nonbridging oxygen ratios are to be accurately determined from the XPS O 1s spectra of silicates. X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) experiments yield similar silicon-bridging oxygen (Si-O-Si) concentrations for PbO-SiO2 glasses. The data are proof that the reaction, 2PbO + SiO2 [Formula: see text] Pb2SiO4, does not go to completion (i.e., one or other reactant is not completely consumed). Instead, the data indicate that an equilibrium exists among these constituents, with the equilibrium constant for the reaction being near 15; ergo, some metal bridging oxygen (MBO or Pb-O-Pb), silicon bridging oxygen (BO or Si-O-Si), and nonbridging oxygen (NBO or M-O-Si) are present over the entire range of binary melt compositions. NMR and XPS spectroscopic techniques yield substantially different Si-O-Si concentrations in Na2O-SiO2 glasses of intermediate to high Na2O content. XPS experiments indicate higher proportions of Si-O-Si in Na2O-rich glasses than do the NMR studies. In spite of the different results, three independently collected sets of NMR experiments are similar and yield similar Si-O-Si concentrations. Five XPS experimental studies are likewise self-consistent (but different from the NMR studies). Comparison of data from the two spectroscopic techniques indicates that all experimental spectra are of good or reasonable quality, so that systematic experimental problems or the interpretation (i.e., fitting) of these spectra may be incorrect for one or both types of spectral data. Viscosity, conductivity, and the XPS data are consistent with (but not proof for) formation of an Na2Si2O5 species in the Na2O-SiO2 glasses. The most comprehensive NMR study is, by contrast, consistent with the formation of an orthosilicate species (Na4SiO4). The NMR and XPS results cannot yet be reconciled and additional experimental studies are required to resolve and to understand better Na2O-SiO2 liquids and glasses.Key words: XPS, high resolution, silicate glass, NMR.

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13

Djajaputra, D., and J. Ruvalds. "NMR spectra for a nested Fermi-liquid model." Physical Review B 55, no. 21 (June 1, 1997): 14148–51. http://dx.doi.org/10.1103/physrevb.55.14148.

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14

Štokr, Jan, Bohdan Schneider, Danica Doskočilová, Stanislav Ševčík, and Martin Přádný. "Conformation of dimethylaminoethanol, its methyl ether and of the corresponding trimethylammonium iodides. NMR and vibrational spectra." Collection of Czechoslovak Chemical Communications 52, no. 5 (1987): 1256–71. http://dx.doi.org/10.1135/cccc19871256.

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By analysis of fully coupled 13C NMR spectra and of 1H NMR spectra of dimethylaminoethanol, its methyl ether, and of the corresponding trimethylammonium iodides, populations of isomers generated by rotation about the bonds N-CH2, CH2-CH2, and CH2-O in these compounds in solution were determined. By analysis of Raman and infrared spectra of these compounds in the solid and liquid states it was found that in the crystalline state these compounds form structures with parallel N-CH3 and O-CH2 bonds, which are also preferred in the liquid state.

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15

Szerb, Elisabeta I., Réka-Anita Domokos, Carmen Creţu, Massimo La Deda, and Vasile Chiş. "Vibrational and Nuclear Magnetic Resonance Properties of 2,2′-Biquinolines: Experimental and Computational Spectroscopy Study." Journal of Nanoscience and Nanotechnology 21, no. 4 (April 1, 2021): 2404–12. http://dx.doi.org/10.1166/jnn.2021.18969.

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Experimental (IR, Raman and NMR) techniques and quantum chemical (DFT) methods have been applied to investigate the vibrational and NMR properties of a new ligand based on 2,2′-biquinoline (bq) functionalized with polar hydrophilic tetraethylene glycol monomethylether (TEG) chains (bq_TEG). Vibrational and NMR spectra of the ligand have been explained based on DFT computational data obtained at B3LYP/6-311+G(d,p) level of theory. For the spectroscopic analysis we started from the parent molecule 2,2′-biquinoline and explained the changes in the spectra of bq_TEG in close relation to the corresponding spectra of bq. Our data point to a trans conformation of bq_TEG in solid state, as wells as in liquid phase. The excellent agreement between the experimental and computed data allowed for a reliable assignment of the vibrational and NMR spectra, both for bq and bq_TEG.

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16

Xie, Tao, Zong Guan, Niels-Patrick Pook, and Mimoza Gjikaj. "Ionic Liquids Based on Hexachloridometalate(V) Anions (Sb, Nb and Ta) and Nitrile-functionalized Pyridinium Cations." Zeitschrift für Naturforschung B 68, no. 10 (October 1, 2013): 1095–102. http://dx.doi.org/10.5560/znb.2013-3138.

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Single crystals of 1-(cyanoethyl)-3-methyl-pyridin-1-ium hexachloridoantimonate(V) (1), 1- (cyanomethyl)-3-methyl-pyridin-1-ium hexachloridoniobate(V) (2), 1-(cyanomethyl)-3-methylpyridin- 1-ium hexachloridotantalate(V) (3), 1-(cyanopropyl)-3-methyl-pyridin-1-ium hexachloridoniobate( V) (4), and 1-(cyanopropyl)-3-methyl-pyridin-1-ium hexachloridotantalate(V) (5) have been synthesized and characterized by X-ray diffraction. Compounds 1-3 crystallize in the triclinic space group P1̄ with Z = 2, and compounds 4 and 5 in the monoclinic space group C2/c with Z = 8. FTRaman spectra have been recorded and interpreted, especially with respect to the anions [MCl6]-. In addition, NMR spectra, a study of the melting behavior and elemental analyses complete the characterization.

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17

Yang, Juan, Daqi Zhang, and Yan Li. "How to remove the influence of trace water from the absorption spectra of SWNTs dispersed in ionic liquids." Beilstein Journal of Nanotechnology 2 (September 30, 2011): 653–58. http://dx.doi.org/10.3762/bjnano.2.69.

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Single-walled carbon nanotubes (SWNTs) can be efficiently dispersed in the imidazolium-based ionic liquids (ILs), at relatively high concentration, with their intrinsic structure and properties retained. Due to the hygroscopicity of the ILs, water bands may be introduced in the absorption spectra of IL-dispersed SWNTs and cause problems in spectral deconvolution and further analysis. In order to remove this influence, a quantitative characterization of the trace water in [BMIM]+[PF6]− and [BMIM]+[BF4]− was carried out by means of UV–vis-NIR absorption spectroscopy. A simple yet effective method involving spectral subtraction of the water bands was utilized, and almost no difference was found between the spectra of the dry IL-dispersed SWNT samples treated under vacuum for 10 hours and the spectra of the untreated samples with subtraction of the pure water spectrum. This result makes it more convenient to characterize SWNTs with absorption spectra in the IL-dispersion system, even in the presence of trace amount of water.

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18

Bowley, R. M., O. Buu, and R. A. Nyman. "The Effect of the Demagnetizing Field on the NMR Spectra for Liquids Enclosed in a Cylinder." Journal of Low Temperature Physics 137, no. 1/2 (October 2004): 1–26. http://dx.doi.org/10.1023/b:jolt.0000044232.64825.98.

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19

Makulski, Włodzimierz, and Agata J. Wikieł. "Liquid and gas phase NMR spectra of 13CH313CHO acetaldehyde." Journal of Molecular Structure 1152 (January 2018): 145–53. http://dx.doi.org/10.1016/j.molstruc.2017.09.066.

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20

Rutar, V., M. Kovač, and G. Lahajnar. "Improved NMR spectra of liquid components in heterogeneous samples." Journal of Magnetic Resonance (1969) 80, no. 1 (October 1988): 133–38. http://dx.doi.org/10.1016/0022-2364(88)90065-0.

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21

Abbasi, Mohsen. "Design, preparation and characterization of a new ionic liquid, 1,3-disulfonic acid benzimidazolium chloride, as an efficient and recyclable catalyst for the synthesis of tetrahydropyridine under solvent-free conditions." RSC Advances 5, no. 83 (2015): 67405–11. http://dx.doi.org/10.1039/c5ra10699k.

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In the present work, 1,3-disulfonic acid benzimidazolium chloride as a new ionic liquid, is synthesized, and characterized by studying its FT-IR, ¹H NMR, ¹³C NMR as well as mass spectra.

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22

Cui, Yingna, Jingmei Yin, Changping Li, Shenmin Li, Ailing Wang, Guang Yang, and Yingping Jia. "Experimental and theoretical studies on compositions, structures, and IR and NMR spectra of functionalized protic ionic liquids." Physical Chemistry Chemical Physics 18, no. 29 (2016): 19731–37. http://dx.doi.org/10.1039/c6cp03293a.

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23

Syvitski, Raymond T., and E. Elliott Burnell. "NMR and molecular structure of partially oriented mono and para methyl- and chlorobenzenes dissolved in nematic liquid crystals." Canadian Journal of Chemistry 77, no. 11 (November 1, 1999): 1761–74. http://dx.doi.org/10.1139/v99-144.

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Spectral parameters, order parameters, and structural parameters, including the vibrationally corrected ralpha structure of the partially oriented solutes p-xylene, p-chlorotoluene, p-dichlorobenzene, toluene, and chlorobenzene dissolved in three liquid crystal mixtures, are reported. For samples containing the three solutes p-xylene, p-dichlorobenzene, and 1,3,5-trichlorobenzene, multiple quantum (MQ) nuclear magnetic resonance was used to aid in the analysis of the complex high-resolution spectra of the p-xylene. The high-resolution spectra of 1,3,5-trichlorobenzene and p-dichlorobenzene were easily identified and analyzed once the calculated p-xylene spectrum was subtracted from the experimental one. The methyl groups of p-xylene, p-chlorotoluene, and toluene have similar geometries when the structure is determined from dipolar couplings corrected for harmonic vibrations.Key words: nematic liquid crystal, NMR, molecular structure, order parameter.

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24

Nardelli, Francesca, Silvia Borsacchi, Lucia Calucci, Elisa Carignani, Francesca Martini, and Marco Geppi. "Anisotropy and NMR spectroscopy." Rendiconti Lincei. Scienze Fisiche e Naturali 31, no. 4 (August 16, 2020): 999–1010. http://dx.doi.org/10.1007/s12210-020-00945-3.

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Abstract In this paper, different aspects concerning anisotropy in Nuclear Magnetic Resonance (NMR) spectroscopy have been reviewed. In particular, the relevant theory has been presented, showing how anisotropy stems from the dependence of internal nuclear spin interactions on the molecular orientation with respect to the external magnetic field direction. The consequences of anisotropy in the use of NMR spectroscopy have been critically discussed: on one side, the availability of very detailed structural and dynamic information, and on the other side, the loss of spectral resolution. The experiments used to measure the anisotropic properties in solid and soft materials, where, in contrast to liquids, such properties are not averaged out by the molecular tumbling, have been described. Such experiments can be based either on static low-resolution techniques or on one- and two-dimensional pulse sequences exploiting Magic Angle Spinning (MAS). Examples of applications of NMR spectroscopy have been shown, which exploit anisotropy to obtain important physico-chemical information on several categories of systems, including pharmaceuticals, inorganic materials, polymers, liquid crystals, and self-assembling amphiphiles in water. Solid-state NMR spectroscopy can be considered, nowadays, one of the most powerful characterization techniques for all kinds of solid, either amorphous or crystalline, and semi-solid systems for the obtainment of both structural and dynamic properties on a molecular and supra-molecular scale. Graphic abstract

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25

Qu, Chen, Takao Kishimoto, Masahiro Hamada, and Noriyuki Nakajima. "Dissolution and acetylation of ball-milled lignocellulosic biomass in ionic liquids at room temperature: application to nuclear magnetic resonance analysis of cell-wall components." Holzforschung 67, no. 1 (January 1, 2013): 25–32. http://dx.doi.org/10.1515/hf-2012-0037.

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Abstract Nuclear magnetic resonance (NMR) analysis of entire plant cell walls without isolating their components gained importance over the last decade. Recently, a dissolution method and an NMR analysis of entire plant cell walls were reported, in which finely ball-milled lignocellulosic biomass was dissolved at 100°C in the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride. In the present study, several ILs were examined with or without co-solvent to find milder dissolution conditions to mitigate possible degradation processes. Co-solvents, including N,N-dimethylacetamide, pyridine, and dimethyl sulfoxide, increased the solubilization efficiency of ILs. For example, ball-milled fir wood was completely dissolved in 1-allyl-3-methylimidazolium chloride ([Amim]Cl) at 30°C in the presence of these co-solvents. The heteronuclear single-quantum coherence NMR spectra of acetylated fir, birch, and bamboo cell walls, which were recovered from [Amim]Cl/pyridine (1:1, w/w) solution, had a high analytical power.

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26

Li, Wensi, and Shengyu Feng. "New Functionalized Ionic Liquids Based on POSS for the Detection of Fe3+ Ion." Polymers 13, no. 2 (January 7, 2021): 196. http://dx.doi.org/10.3390/polym13020196.

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This study reports a novel series of imidazolium ionic liquids (ILs) based on polyhedral oligomeric silsesquioxanes (POSS) towards effective detection of metal ions, especially Fe3+ ion. 1H, 13C, 29Si NMR, high resolution mass spectra (HRMS) and Fourier transform infrared spectra (FTIR) were applied to confirm the structures of the ILs based on POSS (ILs-POSS). The three ILs-POSS were synthesized via a green chemistry approach—a thiol-ene “click” reaction without metal ions as catalysts. Furthermore, the spherical vesicle structures of the ILs-POSS were observed and caused by self-assembly behaviors. Through comprehensive characterizations, these ILs-POSS have performed excellent thermal stabilities and low glass transition temperatures. In addition, we found it very meaningful that the limits of detection (LODs) of the three ILs-POSS for the detection of the Fe3+ ion were 7.91 × 10−8 M, 1.2 × 10−7 M, and 1.2 × 10−7 M, respectively. These data illustrate that these ILs-POSS have great potential for the detection of the Fe3+ ion. In conclusion, this study not only prepared novel ILs-POSS, but also provided new materials as fluorescent sensors in the detection of Fe3+.

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Li, Wensi, and Shengyu Feng. "New Functionalized Ionic Liquids Based on POSS for the Detection of Fe3+ Ion." Polymers 13, no. 2 (January 7, 2021): 196. http://dx.doi.org/10.3390/polym13020196.

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This study reports a novel series of imidazolium ionic liquids (ILs) based on polyhedral oligomeric silsesquioxanes (POSS) towards effective detection of metal ions, especially Fe3+ ion. 1H, 13C, 29Si NMR, high resolution mass spectra (HRMS) and Fourier transform infrared spectra (FTIR) were applied to confirm the structures of the ILs based on POSS (ILs-POSS). The three ILs-POSS were synthesized via a green chemistry approach—a thiol-ene “click” reaction without metal ions as catalysts. Furthermore, the spherical vesicle structures of the ILs-POSS were observed and caused by self-assembly behaviors. Through comprehensive characterizations, these ILs-POSS have performed excellent thermal stabilities and low glass transition temperatures. In addition, we found it very meaningful that the limits of detection (LODs) of the three ILs-POSS for the detection of the Fe3+ ion were 7.91 × 10−8 M, 1.2 × 10−7 M, and 1.2 × 10−7 M, respectively. These data illustrate that these ILs-POSS have great potential for the detection of the Fe3+ ion. In conclusion, this study not only prepared novel ILs-POSS, but also provided new materials as fluorescent sensors in the detection of Fe3+.

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28

Mitronin, A. V., E. A. Srebnaya, V. I. Privalov, and A. A. Prokopov. "High resolution-¹Н NMR spectroscopy of oral liquid in young patients with wedge-shaped lesions." Endodontics Today 18, no. 4 (January 3, 2021): 20–25. http://dx.doi.org/10.36377/1683-2981-2020-18-4-20-25.

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Aim. The comparison of saliva 1Н NMR spectra in patients with wedge-shaped lesions before and after treatment.Materials and methods. Saliva as a study material was taken from patients with wedge-shaped lesions before and after treatment. The treatment method was remineralizing therapy that included the use of the oral rinse containing zinchydroxyapatite. 1Н NMR spectroscopy was chosen as an investigation method.Results. In most cases it is noted that after treatment the content of propionic and butyric acids was on the rise in relation of acetic acid. Overall concentration of 1Н protons didn't change significantly.Conclusions. 1Н NMR spectra analysis shows organic acid distribution in oral liquid before and after treatment, which helps to evaluate its response.

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29

Lapina, Anastasiya S., and Vladimir A. Kurkin. "The study of the flavonoid composition of the herb of monarda fistulosa leaves." Aspirantskiy Vestnik Povolzhiya 19, no. 5-6 (May 28, 2020): 135–42. http://dx.doi.org/10.17816/2072-2354.2019.19.3.135-142.

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Actuality. The herb of Monarda fistulosa L. contains the essential oil and flavonoids, which are of the greatest interest in terms of pharmacological properties. The herb of Monarda fistulosa L. contains a number of flavonoids (rutin, hesperidin, diosmin, quercetin, luteolin, luteolin-7-O-glucoside, naringenin, catechin), however, the literature on the flavonoid composition of this plant is contradictory. In turn, this gives rise to a variety of approaches to standartization of the herb Monarda fistulosa L. The aim is to study the flavonoid composition of Monarda fistulosa L. by means of column chromatography and high performance liquid chromatography (HPLC). Materials and methods. The herb Monarda fistulosa L. was collected during the flowering period at the Botanical Garden of Samara University in 2018. Individual substances were isolated by means of column chromatography. Bruker DRX 500 instrument (126.76 MHz) was used to determine 13C NMR spectra, and Bruker AM 300 instrument (300 MHz) was used to determine 1H NMR spectra. Mass spectra were recorded by mass-spectrometer Kratos MS-30, UV spectra were recorded by means of the spectrophotometer Specord 40 (Analytik Jena). HPLC analysis was carried out with the use of chromatograph Milichrom-6 (NPO Nauchpribor). Results. For the first time column chromatography by means of 1H-NMR, 13C-NMR, UV spectroscopy, mass spectrometry allowed to isolate from Monarda fistulosa L. and characterize the following flavonoids: isorhoifolin (7-O-rutinoside of apigenin), linarin (7-O-rutinoside of acacetin), didymin (7-O-rutinoside of isosakuranetin), monardoside (5-O-rutinoside of apigenin), apigenin, acacetin. The composition of flavonoids was studied by means of HPLC method and isolated individual substances. Conclusion. The results can be used to develop a pharmacopoeial monograph for a new type of raw material Monarda fistulosa herb.

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30

Busson, Roger, Paul J. Claes, and Hubert Vanderhaeghe. "Determination of the Composition of Gentamicin Sulfates by 1H and 13C Nuclear Magnetic Spectroscopy." Journal of AOAC INTERNATIONAL 69, no. 4 (July 1, 1986): 601–8. http://dx.doi.org/10.1093/jaoac/69.4.601.

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Abstract The British Pharmacopoeia test controlling the composition of gentamicin sulfate is based on CW 60 MHz magnetic resonance spectroscopy. Application of this method to FT 90 MHz spectra was evaluated. Results clearly show the limitations of this technique and point out the need for more reliable assay methods. Thus a 13C nuclear magnetic resonance (NMR) procedure for quantitative analysis of gentamicin sulfate was developed. Ratios of 4 gentamicin components (C1, C2, C1., and C2.) were obtained from peak height measurements of selected resonance signals in spectra recorded under steady-state conditions. Relative response factors were determined from spectra of a reference mixture or, alternatively, from spectra of the individual pure components. Results obtained by the 13C NMR method were in agreement with those obtained by liquid chromatography using pre-column derivatization.

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31

Khetrapal, C. L., K. V. Ramanathan, N. Suryaprakash, and S. Vivekanandan. "Natural Abundance2H NMR Spectra of Molecules Oriented in Liquid Crystals." Journal of Magnetic Resonance 135, no. 1 (November 1998): 265–66. http://dx.doi.org/10.1006/jmre.1998.1557.

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32

Carravetta, M., F. Castiglione, G. De Luca, M. Edgar, J. W. Emsley, R. D. Farrant, E. K. Foord, et al. "Symmetry and Phase-Selected NMR Spectra of Liquid Crystalline Samples." Journal of Magnetic Resonance 135, no. 2 (December 1998): 298–309. http://dx.doi.org/10.1006/jmre.1998.1574.

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33

Pang, Jin-Hui, Xin Liu, Miao Wu, Yu-Ying Wu, Xue-Ming Zhang, and Run-Cang Sun. "Fabrication and Characterization of Regenerated Cellulose Films Using Different Ionic Liquids." Journal of Spectroscopy 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/214057.

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The demand for substitution of fossil-based materials by renewable bio-based materials is increasing with the fossil resources reduction and its negative impacts on the environment. In this study, environmentally friendly regenerated cellulose films were successfully prepared using 1-allyl-3-methylimidazolium chloride (AmimCl), 1-butyl-3-methylimidazolium chloride (BmimCl), 1-ethyl-3-methylimidazolium chloride (EmimCl), and 1-ethyl-3-methylimidazolium acetate (EmimAc) as solvents, respectively. The results of morphology from scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that all the cellulose films possessed smooth, highly uniform, and dense surface. The solid-state cross-polarization/magic angle spinning (CP/MAS)13C NMR spectra and X-ray diffraction (XRD) corroborated that the transition from cellulose I to II had occurred after preparation. Moreover, it was shown that the ionic liquid EmimAc possessed much stronger dissolubility for cellulose as compared with other ionic liquids and the cellulose film regenerated from EmimCl exhibited the most excellent tensile strength (119 Mpa). The notable properties of regenerated cellulose films are promising for applications in transparent biodegradable packaging and agricultural purpose as a substitute for PP and PE.

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34

Astuti, Maria Dewi, Tuti Sriwinarti, and Kamilia Mustikasari. "ISOLATION AND IDENTIFICATION OF TERPENOID COMPOUNDS FROM n-HEXANA EXTRACT OF PERMOT PLANT BRACTS (Passiflora foetida L)." Jurnal Sains dan Terapan Kimia 11, no. 2 (October 3, 2017): 80. http://dx.doi.org/10.20527/jstk.v11i2.4041.

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Isolation and identification of terpenoids compounds from n-hexane extract of permot bracts plants (Passiflora foetida L.) has been done. Crude powder of the bracts permot plants were macerated with n-hexane. Fractionated of n-hexane extract on a vacuum liquid chromatography to afford three fractions (A, B and C). Purification of fraction B with TLC preparative to afford isolate B1 and B2.. A compound of spectra UV-Vis B1 indicating the presence of conjugation of double bond (C=C), furthermore the IR spectra showed vibration for - OH group, C=O of the ester group, C-O group, and methyl group (-CH3) in position gem dimethyl. 1H-NMR spectra showed the signal from methoxy group (OCH3), olefin protons (-CH=CH-), protons in carbon to the oxygenation (C-OH), two units gem dimethyl, and three methyl group (-CH3). 13C-NMR spectra showed thesignal from carbon aliphatic group, carbon carbonil (C=O) of the ester group, double bond carbon (C=C), and carbon to the oxygenation (C-OCH3 and C-OH)). Based on the analysis of UV-Vis, IR, 1H-NMR, and 1H-NMR spectrocopies data, isolate B1 is suggested from terpenoids type triterpenoids pentacyclic that conjugation of double bond and ester group.Keywords: Terpenoids, triterpenoids pentacyclic, permot (Passiflora foetida L.), and n-hexane extract.

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35

Morgado, Pedro, João Barras, and Eduardo J. M. Filipe. "From nano-seggregation to mesophases: probing the liquid structure of perfluoroalkylalkanes with 129Xe NMR spectroscopy." Physical Chemistry Chemical Physics 22, no. 26 (2020): 14736–47. http://dx.doi.org/10.1039/d0cp02123g.

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36

Thern, Holger F., and Songhua Chen. "DDTW-A Method for Gas Reservoir Evaluation Using Dual Wait-Time NMR and Density Log Data." SPE Reservoir Evaluation & Engineering 4, no. 04 (August 1, 2001): 289–96. http://dx.doi.org/10.2118/72501-pa.

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Summary Accurate estimates of porosity, fluid saturations, and in-situ gas properties are critical for the evaluation of a gas reservoir. By combining data from a dual wait-time (DTW) nuclear magnetic resonance (NMR) log and a density log, these properties can be determined more reliably than by either of the data alone. The density and NMR dual wait-time (DDTW) technique, introduced in this paper, is applicable to reservoirs where the pore-filling fluid consists of a liquid phase and a gas phase. The low proton density of the gas phase causes a reduction in the NMR signal strength resulting in underestimation of the apparent porosity. The polarization for different wait-times depends on the spin-lattice relaxation time of each fluid and may cause additional NMR porosity underestimation. The density log, on the other hand, delivers a porosity that is overestimated because of the presence of a gas phase. These data, together with known correlations for gas properties, yield a robust approach for the gas-zone porosity, f, and the flushed zone gas saturation, Sg, xo. DDTW also derives gas properties including the in-situ gas density, ?g, as well as the two NMR-related properties, hydrogen index, IH, g, and spin-lattice relaxation time, T1g. Two field examples illustrate the method, and an error propagation study shows the reliability of the technique. Introduction NMR well logging yields information about fluid and rock properties. Depending on the goal of the investigation, various NMR measurement procedures are employed. Differences in the acquisition pulse sequence - including the wait-time (tw) between the echo-train measurements - characterize these procedures. Common evaluation techniques estimate different petrophysical properties, such as incremental and total porosities or movable (fm, NMR) and irreducible (fir, NMR) fluid fractions. More sophisticated methods separate the response of multiple fluids for hydrocarbon typing and saturation estimation. DTW NMR Log. Water as the wetting phase is dominated by surface relaxation and usually has a shorter T1 than hydrocarbons. DTW NMR uses the T1 contrast between aqueous fluid and hydrocarbon phases to achieve partial or full polarization for different fluid phases. The DTW log acquires two echo trains with a long (tw, L) and a short (tw, S) wait-time in a single pass; tw, L is chosen to fully polarize both water and hydrocarbon, and tw, S is sufficiently long to fully polarize the water fraction, while the hydrocarbon fraction is only partially polarized, causing porosity underestimation. An interpretation technique for DTW NMR data - used mainly qualitatively - is the differential spectrum method (DSM).1 A successful quantitative evaluation technique is the time domain analysis (TDA).2 Both techniques require the calculation of either differential echo signals or differential T2 spectra, where the spectra are derived from echo-train data by inversion. The differential signals are significantly weaker than the original signal, and the noise level increases because the incoherent noise of the echo trains is added. Differential data, therefore, are unfavorable in terms of their signal-to-noise ratio (SNR). SNR often limits the applicability of evaluation techniques that are based solely on NMR data. Particularly when coupled with low hydrocarbon saturation and the low proton density of a gas phase, poor SNR is the limiting factor in estimating accurate reservoir properties. Density Log. The density log provides a bulk density, ?b, of the investigated formation. Additional information about the density of the rock matrix and formation fluids determines the density porosity fr. An established method to evaluate gas-bearing formations combines the apparent porosities provided by the density and the neutron logging tools. For many data sets, however, this method yields only semiquantitative results because of the strong influence of rock mineralogy on the neutron measurement. Theory The porosity of clean formations bearing only liquid-phase components can be accurately quantified by either the NMR or the density logging tool. However, the tool's responses are significantly altered by the presence of a gas phase, causing the estimated porosities to deviate from the formation porosity. Three main effects cause the deviation.Low IH, g decreases the NMR porosity.Partial polarization Pg<1 decreases the NMR-derived porosity, if the wait-time between the NMR measurements is insufficiently long.Low ?g increases the density porosity. The characterization of a hydrocarbon gas by three key properties, ?g, IH, g, and T1g, effectively quantifies these effects. DTW NMR Log. In a two-phase system with one gas and one liquid phase, the total NMR porosity ft, NMR is expressed byEquation 1 where the first term on the right side describes the contribution of the gas phase and the second term describes the contribution of the liquid phase. The polarization P (with P?[0,1]) quantifies the reduction of the NMR signal caused by underpolarization. The termsEquation 2Equation 3 describe the polarization of the liquid and gas phases, respectively. Some approximations can be made for common reservoir conditions.IH, l is close to 1 for an aqueous-phase liquid and most oleic-phase liquids. In the presence of a light liquid hydrocarbon, its value can be slightly smaller (IH, l =0.8-1).If tw 3T1, the polarization is nearly unity. Typical tw values range from 1 to several seconds, whereas typical T1 values for formation water range from a few milliseconds to a few seconds. However, in a porous medium saturated with two fluid phases, the wetting phase (i.e., water) saturates smaller pores, and the maximum T1 of the aqueous-phase liquid usually reduces to values less than several hundreds of milliseconds.3 Thus, Pl is unity for aqueous-phase liquids in a two-phase system, when data are acquired with typical wait-time parameters in an MRIL®* DTW acquisition (i.e., tw, S,˜1–2 seconds and tw, L,˜6–10 seconds).

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37

Duan, Zhen Hua, Chang Yu Cheng, Yang Hai, and Ju Lan Wang. "Determination and Identification of Chondroitin Sulfate from Tilapia Byproducts." Advanced Materials Research 690-693 (May 2013): 1318–21. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.1318.

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In order to probe the structure of chondroitin sulfate (CS) from tilapia fish, the CS was extracted from tilapia (Oreochromis niloticus) byproducts with the combination of ultrasonic and microwave, some means including high performance liquid chromatography (HPLC), infrared spectra (IR) and nuclear magnetic resonance (NMR) were used in this paper. The data of HPLC exhibited that the obtained chondroitin sulfate is of highly purity (98.78%). IR and NMR spectra indicated that the sample consisted of both chondroitin-4-sulfate and chondroitin-6-sulfate, and the proportion of chondroitin-6-sulfate was higher than chondroitin-4-sulfate.

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38

Lesot, Philippe, Christie Aroulanda, Herbert Zimmermann, and Zeev Luz. "Enantiotopic discrimination in the NMR spectrum of prochiral solutes in chiral liquid crystals." Chemical Society Reviews 44, no. 8 (2015): 2330–75. http://dx.doi.org/10.1039/c4cs00260a.

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Theory and applications to stereo- and bio-chemistry of the discrimination of enantiotopic elements observed in the NMR spectra of prochiral solutes dissolved in chiral liquid crystals are comprehensively discussed.

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39

Ostras’, Alexei S., Daniil M. Ivanov, Alexander S. Novikov, and Peter M. Tolstoy. "Phosphine Oxides as Spectroscopic Halogen Bond Descriptors: IR and NMR Correlations with Interatomic Distances and Complexation Energy." Molecules 25, no. 6 (March 19, 2020): 1406. http://dx.doi.org/10.3390/molecules25061406.

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An extensive series of 128 halogen-bonded complexes formed by trimethylphosphine oxide and various F-, Cl-, Br-, I- and At-containing molecules, ranging in energy from 0 to 124 kJ/mol, is studied by DFT calculations in vacuum. The results reveal correlations between R–X⋅⋅⋅O=PMe3 halogen bond energy ΔE, X⋅⋅⋅O distance r, halogen’s σ-hole size, QTAIM parameters at halogen bond critical point and changes of spectroscopic parameters of phosphine oxide upon complexation, such as 31P NMR chemical shift, ΔδP, and P=O stretching frequency, Δν. Some of the correlations are halogen-specific, i.e., different for F, Cl, Br, I and At, such as ΔE(r), while others are general, i.e., fulfilled for the whole set of complexes at once, such as ΔE(ΔδP). The proposed correlations could be used to estimate the halogen bond properties in disordered media (liquids, solutions, polymers, glasses) from the corresponding NMR and IR spectra.

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40

Rajendran, A., D. Ragupathy, M. Priyadarshini, A. Magesh, P. Jaishankar, N. S. Madhavan, K. Sajitha, and S. Balaji. "Effective Extraction of Heavy Metals from their Effluents Using Some Potential Ionic Liquids as Green Chemicals." E-Journal of Chemistry 8, no. 2 (2011): 697–702. http://dx.doi.org/10.1155/2011/202380.

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Synthesis of nine Task Specific Ionic liquids (TSILs), their characterization using1H NMR spectral studies and other physical properties and potential applications in the removal of certain heavy metals such as Nickel, Iron, Zinc, Copper and Lead has been studied. The removal of these heavy metals from the industrial effluents / contaminated water bodies using these ionic liquids has been proved to be more successful than conventional methods such as precipitation, cementation, reverse osmosis, ion exchange and adsorption.

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41

González Guerra, Guillermo M., Alejandro Alatorre-Ordaz, Gerardo González Garcia, and Jesus S. Jaime-Ferrer. "Synthesis and characterization of novel functionalized perarylated polysiloxane for proton exchange membrane fuel cells." MRS Advances 4, no. 64 (2019): 3579–85. http://dx.doi.org/10.1557/adv.2019.419.

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ABSTRACTThis work presents the synthesis and characterization of a pearylated polysiloxane material (PAP) from a polycondensation reaction, followed by functionalization with HClSO3 by an electrophilic substitution reaction. According to the characterization techniques applied, a sulfonated pearylated polysiloxane was also obtained, (SPAP). The purpose of this sulfonated material is to obtain an ionomer able to be applied in hydrogen fuel cells of the proton exchange membrane kind (PEMFC). The reaction to produce the polysiloxane precursor was carried out with the commercial reagents: PhSiCl3, Ph2SiCl2 and Ph3SiCl in anhydrous THF at 75 °C and the SPAP material was obtained by sulfonation of the precursor with chlorosulfonic acid. PAP and SPAP were characterized by 1H, NMR for liquids, 29Si NMR for solids, IR-ATR, SEM, and cyclic voltammetry. The NMR 29Si spectra show that PAP and PAPS contain crosslinking regions due to PhSiCl3, growing chain zones due to Ph2SiCl2 and polymer termination zones due to Ph3SiCl, obtaining a mixture of siloxanes. The analysis by cyclic voltammetry indicates that by integrating the area under the curve of the adsorption peaks of H2, a value of 0.062 mC/cm2 is obtained, a value close to the commercial ionomer of Nafion®.

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42

Milata, Viktor. "Nitro and aminobenzimidazoles." Acta Chimica Slovaca 11, no. 2 (October 1, 2018): 182–88. http://dx.doi.org/10.2478/acs-2018-0026.

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AbstractA summary of the preparation methods of 2 tautomeric and 4N-methylated benzimidazoles with a nitro group on the benzene ring (1–6) and with an amino group in the same positions (7–12) were summarized. Annular tautomerism of the title compounds1–12has been studied using1H,13C and15N NMR spectra in liquid and solid state (CPMAS), UV spectra and quantum chemical calculations.

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43

Minkwitz, Rolf, and Jens Jakob. "Darstellung und spektroskopische Charakterisierung von Trifluormethylazosulfonylmethan CH3S(O) 2NNCF3 / Preparation and Spectroscopic Characterization of Trifluoromethylazosulfonylmethan CH3S(O)2NNCF3." Zeitschrift für Naturforschung B 52, no. 1 (January 1, 1997): 135–37. http://dx.doi.org/10.1515/znb-1997-0125.

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44

Barman, Siti, and Mahendra Nath Roy. "Hollow circular compound-based inclusion complexes of an ionic liquid." RSC Advances 6, no. 80 (2016): 76381–89. http://dx.doi.org/10.1039/c6ra14138b.

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Inclusion complex formation between hollow circular compounds, e.g. crown ethers, and an ionic liquid, 1-methyl-3-octylimidazolium tetrafluoroborate, in acetonitrile solvent is studied by means of conductivity measurements, IR and NMR spectra.

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45

Zhang, Yang, Xiao Hua Tu, Cheng Ping Miao, and Jian Yi Wu. "Synthesis and Characterization of N-butyl-N-methylimidazolium- D-(-)-tartrate Chiral Ionic Liquid." Advanced Materials Research 518-523 (May 2012): 3989–92. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3989.

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A novel CIL of N-butyl-N-methyl imidazolium-D-(-)-tartrate has been designed and synthesized by neutralization reaction. Its structure was characterized by 1H-NMR and 13C-NMR spectra, the optical rotation was characterized by polarimeter with the value of-15.0º, and the purity was characterized by ion chromatography with the value of 98.4%.

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46

Tykarska, Marzena, Anna Drzewicz, Mateusz Szala, and Magdalena Żurowska. "NMR spectra of chiral smectic liquid crystals differing in helical parameters." Liquid Crystals 45, no. 9 (February 21, 2018): 1385–95. http://dx.doi.org/10.1080/02678292.2018.1441455.

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47

Chiccoli, C., P. Pasini, G. Skačej, C. Zannoni, and S. Žumer. "NMR spectra from Monte Carlo simulations of polymer dispersed liquid crystals." Physical Review E 60, no. 4 (October 1, 1999): 4219–25. http://dx.doi.org/10.1103/physreve.60.4219.

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48

Panov, Mikhail, Pavlo Bielytskyi, Daniel Gräsing, Alexandra Yurkovskaya, and Jörg Matysik. "Same spectral signature in liquid-state and solid-state 1H photo-CIDNP NMR spectra of cyclohexanone." Molecular Physics 117, no. 19 (August 26, 2018): 2756–61. http://dx.doi.org/10.1080/00268976.2018.1512722.

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49

Kumar, B. S. Arun, N. Suryaprakash, K. V. Ramanathan, and C. L. Khetrapal. "Spectral assignments based on the 13C NMR spectra of mixed liquid crystals of opposite diamagnetic anisotropies." Journal of Magnetic Resonance (1969) 76, no. 2 (February 1988): 256–63. http://dx.doi.org/10.1016/0022-2364(88)90108-4.

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50

Chen, Min, Aixia Pan, Tong He, Lulu Xu, Yu Fang, Huaming Li, and Jimin Xie. "Efficient Synthesis of 1-Acetylpyrene Using [Bmim]Cl–FeCl3 Ionic Liquid as Dual Catalyst and Solvent." International Journal of Chemical Reactor Engineering 11, no. 1 (June 18, 2013): 1–7. http://dx.doi.org/10.1515/ijcre-2012-0021.

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Abstract Friedel–Crafts acylation of pyrene with acetic anhydride to 1-acetylpyrene catalyzed by three metal chloride and three Lewis acidic ionic liquids (ILs) containing 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and different metal chloride was investigated. ILs were prepared and tested for the acylation to explore the effects of Lewis acidity of ILs on the synthesis of 1-acetylpyrene. [Bmim]Cl–FeCl3 was found to be the most suitable catalyst, and the possible pathway for the acylation of pyrene with acetic anhydride catalyzed by [Bmim]Cl–FeCl3-IL was discussed. Pure 1-acetylpyrene was obtained and its structure was identified by gas chromatography–mass spectrometer, Fourier transform infrared and 1H NMR spectra.

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