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Artículos de revistas sobre el tema "NMR spectroscopic techniques"

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Autor: Grafiati

Publicado: 6 de septiembre de 2023

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1

Chang, C. T. Philip, Jinli Qiao, Songhua Chen y A. Ted Watson. "Fracture Characterization with NMR Spectroscopic Techniques". Journal of Magnetic Resonance 126, n.º 2 (junio de 1997): 213–20. http://dx.doi.org/10.1006/jmre.1997.1175.

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2

Lu, Yao, Yong-Chao Lu, Hong-Qin Hu, Feng-Jin Xie, Xian-Yong Wei y Xing Fan. "Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods". Journal of Spectroscopy 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/8951658.

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Lignin is highly branched phenolic polymer and accounts 15–30% by weight of lignocellulosic biomass (LCBM). The acceptable molecular structure of lignin is composed with three main constituents linked by different linkages. However, the structure of lignin varies significantly according to the type of LCBM, and the composition of lignin strongly depends on the degradation process. Thus, the elucidation of structural features of lignin is important for the utilization of lignin in high efficient ways. Up to date, degradation of lignin with destructive methods is the main path for the analysis of molecular structure of lignin. Spectroscopic techniques can provide qualitative and quantitative information on functional groups and linkages of constituents in lignin as well as the degradation products. In this review, recent progresses on lignin degradation were presented and compared. Various spectroscopic methods, such as ultraviolet spectroscopy, Fourier-transformed infrared spectroscopy, Raman spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, for the characterization of structural and compositional features of lignin were summarized. Various NMR techniques, such as 1H, 13C, 19F, and 31P, as well as 2D NMR, were highlighted for the comprehensive investigation of lignin structure. Quantitative 13C NMR and various 2D NMR techniques provide both qualitative and quantitative results on the detailed lignin structure and composition produced from various processes which proved to be ideal methods in practice.

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3

Shah, A. M. y A. J. Rojivadiya. "Synthesis and Characterization of Imidazo[1,2-a]Pyrimidine". International Letters of Chemistry, Physics and Astronomy 52 (junio de 2015): 1–4. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.52.1.

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An efficient protocol for the synthesis of imidazo [1,2-a] pyrimidine was developed by using three component one-pot Biginelli synthesis. The synthesized compounds were characterized by spectroscopic techniques like FT-IR, 1H NMR, 13C NMR, and mass spectroscopy.

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4

Shah, A. M. y A. J. Rojivadiya. "Synthesis and Characterization of Imidazo[1,2-a]Pyrimidine". International Letters of Chemistry, Physics and Astronomy 52 (2 de junio de 2015): 1–4. http://dx.doi.org/10.56431/p-hnz44l.

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An efficient protocol for the synthesis of imidazo [1,2-a] pyrimidine was developed by using three component one-pot Biginelli synthesis. The synthesized compounds were characterized by spectroscopic techniques like FT-IR, 1H NMR, 13C NMR, and mass spectroscopy.

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5

Shah, A. M. y A. J. Rojivadiya. "An Expeditious Synthesis of 1,2,4-Triazolo[1,5-a]Pyrimidine". International Letters of Chemistry, Physics and Astronomy 51 (mayo de 2015): 1–4. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.51.1.

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A simple, efficient, and diversity oriented synthesis of library of 1,2,4-triazolo [1,5-a] pyrimidine was undertaken using 5-amino,1,2,4-triazole as a building block. The synthesized analogues were fully characterized by known spectroscopic techniques like FT-IR, 1H NMR, 13C NMR, and mass spectroscopy.

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6

Shah, A. M. y A. J. Rojivadiya. "An Expeditious Synthesis of 1,2,4-Triazolo[1,5-<i>a</i>]Pyrimidine". International Letters of Chemistry, Physics and Astronomy 51 (15 de mayo de 2015): 1–4. http://dx.doi.org/10.56431/p-p4100a.

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A simple, efficient, and diversity oriented synthesis of library of 1,2,4-triazolo [1,5-a] pyrimidine was undertaken using 5-amino,1,2,4-triazole as a building block. The synthesized analogues were fully characterized by known spectroscopic techniques like FT-IR, 1H NMR, 13C NMR, and mass spectroscopy.

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7

Pandiselvam, Ravi, Rathnakumar Kaavya, Sergio I. Martinez Monteagudo, V. Divya, Surangna Jain, Anandu Chandra Khanashyam, Anjineyulu Kothakota et al. "Contemporary Developments and Emerging Trends in the Application of Spectroscopy Techniques: A Particular Reference to Coconut (Cocos nucifera L.)". Molecules 27, n.º 10 (19 de mayo de 2022): 3250. http://dx.doi.org/10.3390/molecules27103250.

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The number of food frauds in coconut-based products is increasing due to higher consumer demands for these products. Rising health consciousness, public awareness and increased concerns about food safety and quality have made authorities and various other certifying agencies focus more on the authentication of coconut products. As the conventional techniques for determining the quality attributes of coconut are destructive and time-consuming, non-destructive testing methods which are accurate, rapid, and easy to perform with no detrimental sampling methods are currently gaining importance. Spectroscopic methods such as nuclear magnetic resonance (NMR), infrared (IR)spectroscopy, mid-infrared (MIR)spectroscopy, near-infrared (NIR) spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, fluorescence spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy (RS) are gaining in importance for determining the oxidative stability of coconut oil, the adulteration of oils, and the detection of harmful additives, pathogens, and toxins in coconut products and are also employed in deducing the interactions in food constituents, and microbial contaminations. The objective of this review is to provide a comprehensive analysis on the various spectroscopic techniques along with different chemometric approaches for the successful authentication and quality determination of coconut products. The manuscript was prepared by analyzing and compiling the articles that were collected from various databases such as PubMed, Google Scholar, Scopus and ScienceDirect. The spectroscopic techniques in combination with chemometrics were shown to be successful in the authentication of coconut products. RS and NMR spectroscopy techniques proved their utility and accuracy in assessing the changes in coconut oil’s chemical and viscosity profile. FTIR spectroscopy was successfully utilized to analyze the oxidation levels and determine the authenticity of coconut oils. An FT-NIR-based analysis of various coconut samples confirmed the acceptable levels of accuracy in prediction. These non-destructive methods of spectroscopy offer a broad spectrum of applications in food processing industries to detect adulterants. Moreover, the combined chemometrics and spectroscopy detection method is a versatile and accurate measurement for adulterant identification.

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8

Laurent, W., J. M. Bonny y J. P. Renou. "Muscle characterisation by NMR imaging and spectroscopic techniques". Food Chemistry 69, n.º 4 (junio de 2000): 419–26. http://dx.doi.org/10.1016/s0308-8146(00)00051-0.

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9

Gjuroski, Ilche, Julien Furrer y Martina Vermathen. "Probing the Interactions of Porphyrins with Macromolecules Using NMR Spectroscopy Techniques". Molecules 26, n.º 7 (30 de marzo de 2021): 1942. http://dx.doi.org/10.3390/molecules26071942.

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Porphyrinic compounds are widespread in nature and play key roles in biological processes such as oxygen transport in blood, enzymatic redox reactions or photosynthesis. In addition, both naturally derived as well as synthetic porphyrinic compounds are extensively explored for biomedical and technical applications such as photodynamic therapy (PDT) or photovoltaic systems, respectively. Their unique electronic structures and photophysical properties make this class of compounds so interesting for the multiple functions encountered. It is therefore not surprising that optical methods are typically the prevalent analytical tool applied in characterization and processes involving porphyrinic compounds. However, a wealth of complementary information can be obtained from NMR spectroscopic techniques. Based on the advantage of providing structural and dynamic information with atomic resolution simultaneously, NMR spectroscopy is a powerful method for studying molecular interactions between porphyrinic compounds and macromolecules. Such interactions are of special interest in medical applications of porphyrinic photosensitizers that are mostly combined with macromolecular carrier systems. The macromolecular surrounding typically stabilizes the encapsulated drug and may also modify its physical properties. Moreover, the interaction with macromolecular physiological components needs to be explored to understand and control mechanisms of action and therapeutic efficacy. This review focuses on such non-covalent interactions of porphyrinic drugs with synthetic polymers as well as with biomolecules such as phospholipids or proteins. A brief introduction into various NMR spectroscopic techniques is given including chemical shift perturbation methods, NOE enhancement spectroscopy, relaxation time measurements and diffusion-ordered spectroscopy. How these NMR tools are used to address porphyrin–macromolecule interactions with respect to their function in biomedical applications is the central point of the current review.

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10

Maity, Sanhita, Ravi Kumar Gundampati y Thallapuranam Krishnaswamy Suresh Kumar. "NMR Methods to Characterize Protein-Ligand Interactions". Natural Product Communications 14, n.º 5 (1 de mayo de 2019): 1934578X1984929. http://dx.doi.org/10.1177/1934578x19849296.

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Structural information pertaining to the interactions between biological macromolecules and ligands is of potential significance for understanding of molecular mechanisms in key biological processes. Recently, nuclear magnetic resonance (NMR) spectroscopic techniques has come of age and has widened its scope to characterize binding interactions of small molecules with biological macromolecules especially, proteins. NMR spectroscopy-based techniques are versatile due to their ability to examine weak binding interactions and for rapid screening the binding affinities of ligands with proteins at atomic resolution. In this review, we provide a broad overview of some of the important NMR approaches to investigate interactions of small organic molecules with proteins.

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11

Li, Yong-chao, Jing Yang, Xiu-ren Zhou, Xin-hong Liang y Qing-yun Fu. "Fusiformines A and B: new indole alkaloids from Melodinus fusiformis". Zeitschrift für Naturforschung B 71, n.º 3 (1 de marzo de 2016): 193–95. http://dx.doi.org/10.1515/znb-2015-0052.

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AbstractFusiformines A (1) and B (2), two new monoterpenoid indole alkaloids, were isolated from the twigs and leaves of Melodinus fusiformis. Their structures were established by extensive spectroscopic techniques, including 2D NMR spectroscopy and mass spectrometry.

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12

Muresan-Pop, Marieta, Irina Kacsó, Xenia Filip, Emilia Vanea, G. Borodi, N. Leopold, I. Bratu y S. Simon. "Spectroscopic and physical–chemical characterization of ambazone–glutamate salt". Spectroscopy 26, n.º 2 (2011): 115–28. http://dx.doi.org/10.1155/2011/414103.

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Ambazone monohydrate C8H11N7S · H2O (AMB), a well-known antimicrobial compound, was used together with Glutamic Acid C5H9NO4(Glu) to obtain a new solid form using the solvent-drop grinding procedure. The screening of the new solid form was best achieved by the combined use of X-ray Powder Diffraction (XRPD) and several spectroscopic techniques (Fourier Transformed Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Raman and13C-NMR spectroscopy) together with Differential Scanning Calorimetry (DSC), Differential thermal analysis and thermogravimetry (DTA–TGA). The combination of the mentioned analytical techniques allows the compound to be assigned to an ambazone–glutamate salt which crystallizes in monoclinic system having the following lattice parameters:a=9.8352,b=4.7014,c=40.0987 Å and β=94.505°. DSC, TGA data and the before mentioned spectroscopic techniques support the ambazone–glutamate salt formation.

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13

Abdelhamid, Abdalla S., Reem H. Alzard, Lamia A. Siddig, Aya Elbahnasy, Duha Aljazmati, Zaina Kadoura, Hind Zeidane, Rufaida Elshikh y Ahmed Alzamly. "Facile Synthesis, Characterization, and Photocatalytic Performance of BiOF/BiFeO3 Hybrid Heterojunction for Benzylamine Coupling under Simulated Light Irradiation". Photochem 3, n.º 1 (21 de marzo de 2023): 187–96. http://dx.doi.org/10.3390/photochem3010012.

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Under simulated light irradiation, the aerobic oxidation of benzylamine to N,N-benzylidenebenzylamine was carried out as a model reaction to investigate the photocatalytic activity of a hydrothermally prepared composite based on BiOF and BiFeO3 materials. The prepared photocatalysts were characterized using several spectroscopic techniques, such as powder X-ray diffraction (PXRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). Band gap analysis showed that the composite exhibits a band gap that lies in the UV region (3.5 eV). Nonetheless, pristine BiOF and BiFeO3 exhibited band gaps of 3.8 eV and 2.15 eV, respectively. N,N-benzylidenebenzylamine was selectively achieved with a high conversion yield of ~80% under atmospheric conditions in which the product was confirmed using 1H-NMR, 13C-NMR, and FTIR spectroscopic techniques. Various control experiments were conducted to further confirm the enhanced photocatalytic performance of the reported composite.

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14

Gunawan, Ramdhan y Asep Bayu Dani Nandiyanto. "How to Read and Interpret 1H-NMR and 13C-NMR Spectrums". Indonesian Journal of Science and Technology 6, n.º 2 (15 de mayo de 2021): 267–98. http://dx.doi.org/10.17509/ijost.v6i2.34189.

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Nuclear magnetic resonance spectroscopy or NMR is a chemical instrument that can be used to evaluate the structure of a chemical compound other than FTIR, GC-MS, and HPLC. NMR spectroscopy commonly used for compound analysis is 1H-NMR and 13C-NMR. Techniques can be used to determine the structure conformation, the number of protons, and the number of carbons in the structure of a chemical compound. So far, there have been many publications related to the use of this spectroscopic technique. However, the steps in reading and interpreting the spectra of both 1H-NMR and 13C-NMR are not described in detail. Thus, in this paper, we described the steps in reading and interpreting the 1H-NMR and 13C-NMR spectra based on the level of difficulties: (1) simple compounds, (2) fairly complex compounds, (3) more complex compounds, and (4) very complex compounds.

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15

Ali, Muhammad Shaiq, Waqar Ahmed y Syed Amir Ibrahim. "Guaianolide and seco-Guaianolide from Salvia nubicola (Lamiaceae)". Zeitschrift für Naturforschung B 60, n.º 9 (1 de septiembre de 2005): 1012–15. http://dx.doi.org/10.1515/znb-2005-0917.

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A sesquiterpene-lactone of the guaianolide class (nubenone) and a seco-guaianolide (nubenoic acid) have been isolated from Salvia nubicola collected in Quetta, Pakistan. Structures of both sesquiterpenes were elucidated with the aid of spectroscopic techniques including two dimensional NMR spectroscopy.

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16

Szmatoła, Michał, Justyna Chrobak, Rafał Grabowski, Jolanta Iłowska, Julia Woch, Iwona Szwach, Izabela Semeniuk et al. "Spectroscopic Methods in the Evaluation of Modified Vegetable Base Oils from Crambe abyssinica". Molecules 23, n.º 12 (7 de diciembre de 2018): 3243. http://dx.doi.org/10.3390/molecules23123243.

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Raw vegetable oil from Crambe abyssinica was subjected to oxidative treatment to enhance its viscosity. The oxidation processes were carried out in the presence of N-hydroxyphthalimide with or without supercritical CO2 as a solvent. Four spectroscopic techniques (Raman, UV-VIS, FT-IR, NMR) were applied to assess the chemical changes taking place during the oxidation. Raman and NMR spectroscopy proved best in the assessment of the chemical transformations leading to increased viscosity of the modified vegetable oil.

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17

Knüttel, A., R. Kimmich y K. H. Spohn. "Indirect 13C tomography and volume-selective spectroscopy via proton NMR. I. Spectroscopic techniques". Journal of Magnetic Resonance (1969) 86, n.º 3 (febrero de 1990): 526–41. http://dx.doi.org/10.1016/0022-2364(90)90030-d.

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18

Gotts, H. "Characterization of Process Induced Contamination and Residues on Semiconductor Components Via FTIR and Raman Microanalysis". Microscopy and Microanalysis 7, S2 (agosto de 2001): 152–53. http://dx.doi.org/10.1017/s1431927600026830.

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FTIR and Raman microanalysis may be used as a powerful combination to determine the identity, and hence infer the source, of contaminant particles which diminish yields of semiconductor components and devices. The complimentarity of these techniques arises from the underlying spectroscopic selection rules.Vibrational spectroscopic techniques are commonly used to characterize the molecular structure of bulk organic materials. These bulk materials typically represent purified fractions of components which may be further investigated with various classical instrumental techniques such as Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR) spectroscopy, UV-Vis spectroscopy. However, these classical technique may have limited value for the interrogation of small impure particles or materials of limited quantity(ng.).Elemental techniques such as Scanning Electron Microscopy coupled to Energy Dispersive Spectroscopy are enhanced by the specificity of FTIR Microprobe Spectroscopy and Raman Microprobe Spectroscopy which are now used in process laboratories to characterize and identify particulate and thin film residues with the intent of device yield enhancement.

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19

Chen, Kuizhi. "A Practical Review of NMR Lineshapes for Spin-1/2 and Quadrupolar Nuclei in Disordered Materials". International Journal of Molecular Sciences 21, n.º 16 (7 de agosto de 2020): 5666. http://dx.doi.org/10.3390/ijms21165666.

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NMR is a powerful spectroscopic method that can provide information on the structural disorder in solids, complementing scattering and diffraction techniques. The structural disorder in solids can generate a dispersion of local magnetic and electric fields, resulting in a distribution of isotropic chemical shift δiso and quadrupolar coupling CQ. For spin-1/2 nuclei, the NMR linewidth and shape under high-resolution magic-angle spinning (MAS) reflects the distributions of isotropic chemical shift, providing a rich source of disorder information. For quadrupolar nuclei, the second-order quadrupolar broadening remains present even under MAS. In addition to isotropic chemical shift, structural disorder can impact the electric field gradient (EFG) and consequently the quadrupolar NMR parameters. The distributions of quadrupolar coupling and isotropic chemical shift are superimposed with the second-order quadrupolar broadening, but can be potentially characterized by MQMAS (multiple-quantum magic-angle spinning) spectroscopy. We review analyses of NMR lineshapes in 2D DQ–SQ (double-quantum single-quantum) and MQMAS spectroscopies, to provide a guide for more general lineshape analysis. In addition, methods to enhance the spectral resolution and sensitivity for quadrupolar nuclei are discussed, including NMR pulse techniques and the application of high magnetic fields. The role of magnetic field strength and its impact on the strategy of determining optimum NMR methods for disorder characterization are also discussed.

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20

Ji, Zhurun, Rucheng Dai y Zengming Zhang. "Characterization of fine particulate matter in ambient air by combining TEM and multiple spectroscopic techniques – NMR, FTIR and Raman spectroscopy". Environmental Science: Processes & Impacts 17, n.º 3 (2015): 552–60. http://dx.doi.org/10.1039/c4em00678j.

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We report a study of the microstructures and spectroscopic characteristics of PM_2.5and its potential sources in Beijing by combining transmission electron microscopy and multiple spectroscopic techniques: nuclear magnetic resonance, Fourier transform infrared and Raman spectroscopy.

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21

Zangger, Klaus y lan M. Armitage. "Silver and Gold NMR". Metal-Based Drugs 6, n.º 4-5 (1 de enero de 1999): 239–45. http://dx.doi.org/10.1155/mbd.1999.239.

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Silver and gold, together with copper, form the transition metal group IB elements in the periodic table and possess very different nuclear magnetic resonance (NMR) spectroscopic properties. While there is only one gold isotope (A197u) , which has a spin of 3/2 and therefore a quadrupole moment, silver occurs in two isotopic forms (A107g and A109g ), both of which have a spin 12 and similar NMR spectroscopic properties. The unfavorable properties of gold have prevented its NMR spectroscopic investigation thus far. On the other hand, there are several reports of silver NMR. However, the low sensitivity of silver, combined with its long relaxation times have rendered the direct detection of silver possible only with concentrations greater than a few tenth molar. Reviewed here are the general limitations of silver NMR and some techniques to partially overcome these limitations, as well as a summary of currently available chemical shift and scalar coupling data on A109g .

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22

Rahman, S. M. Mizanur, Swati Shabnom, M. Abdul Quader y M. Amzad Hossain. "PHYTOCHEMICAL STUDY ON THE ETHYLACETATE EXTRACT OF THE LEAVES OF Mesua ferrea LINN". Indonesian Journal of Chemistry 8, n.º 2 (17 de junio de 2010): 242–44. http://dx.doi.org/10.22146/ijc.21637.

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Furano-napthyl-hydroxy cyclohexyl type of compound was isolated first times in plant from the ethyl extracts of the leaves of Mesua ferrea. The structure of the compound has been established by the modern spectroscopic techniques such as UV, IR, 1H-NMR, 13C-NMR and mass spectroscopy and identified as 12, 13-furano-8-hydroxy napthyl-6-0-b-2',3',4',6' tetrahydroxy-5',5' dimethyl cyclohexyl ether. Keywords: Mesua ferrea Linn; Euphorbiaceae; Medicinal plant; new compound; spectral analysis

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23

Zaukuu, John-Lewis Zinia, Eszter Benes, György Bázár, Zoltán Kovács y Marietta Fodor. "Agricultural Potentials of Molecular Spectroscopy and Advances for Food Authentication: An Overview". Processes 10, n.º 2 (24 de enero de 2022): 214. http://dx.doi.org/10.3390/pr10020214.

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Meat, fish, coffee, tea, mushroom, and spices are foods that have been acknowledged for their nutritional benefits but are also reportedly targets of fraud and tampering due to their economic value. Conventional methods often take precedence for monitoring these foods, but rapid advanced instruments employing molecular spectroscopic techniques are gradually claiming dominance due to their numerous advantages such as low cost, little to no sample preparation, and, above all, their ability to fingerprint and detect a deviation from quality. This review aims to provide a detailed overview of common molecular spectroscopic techniques and their use for agricultural and food quality management. Using multiple databases including ScienceDirect, Scopus, Web of Science, and Google Scholar, 171 research publications including research articles, review papers, and book chapters were thoroughly reviewed and discussed to highlight new trends, accomplishments, challenges, and benefits of using molecular spectroscopic methods for studying food matrices. It was observed that Near infrared spectroscopy (NIRS), Infrared spectroscopy (IR), Hyperspectral imaging (his), and Nuclear magnetic resonance spectroscopy (NMR) stand out in particular for the identification of geographical origin, compositional analysis, authentication, and the detection of adulteration of meat, fish, coffee, tea, mushroom, and spices; however, the potential of UV/Vis, 1H-NMR, and Raman spectroscopy (RS) for similar purposes is not negligible. The methods rely heavily on preprocessing and chemometric methods, but their reliance on conventional reference data which can sometimes be unreliable, for quantitative analysis, is perhaps one of their dominant challenges. Nonetheless, the emergence of handheld versions of these techniques is an area that is continuously being explored for digitalized remote analysis.

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24

Sarpal, A. S., Paulo R. M. Silva, Juliana L. Martins, Julio J. Amaral, Marianne M. Monnerat, Valnei S. Cunha, Romeu J. Daroda y Wanderley de Souza. "Biodiesel Potential of Oleaginous Yeast Biomass by NMR Spectroscopic Techniques". Energy & Fuels 28, n.º 6 (30 de mayo de 2014): 3766–77. http://dx.doi.org/10.1021/ef402516x.

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25

Brunner, Eike y Harry Pfeifer. "ChemInform Abstract: NMR Spectroscopic Techniques for Determining Acidity and Basicity". ChemInform 41, n.º 47 (28 de octubre de 2010): no. http://dx.doi.org/10.1002/chin.201047221.

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26

KARABACAK ATAY, Çiğdem y Mehmet ULUTÜRK. "Synthesis and Theoretical Calculations of Benzoic Acid-Based New Mono Azo Dye". Süleyman Demirel Üniversitesi Fen Edebiyat Fakültesi Fen Dergisi 17, n.º 2 (25 de noviembre de 2022): 559–67. http://dx.doi.org/10.29233/sdufeffd.1181119.

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This study describes the synthesis, characterization and theoretical calculation of 3,5-dihydroxy-2-(naphthalen-2-yldiazenyl) benzoic acid. The synthesized compound was obtained through efficient synthetic route using 2-Naphthylamine and 3,5-dihydroxybenzoic acid as starting materials and characterized by various spectroscopic techniques such as Fouirer Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), Carbon Nuclear Magnetic Resonance Spectroscopy (13C-NMR), Ultraviolet–visible spectroscopy (UV-Vis). All theoretical calculation was performed with Density Functional Theory (DFT). Optimized molecular structure, vibrational spectra, NMR chemical shift values, frontier molecular orbitals, bond lengths (Å), bond angles (°) and Molecular Electrostatic Potential (MEP) diagram of molecule were calculated using the 6-311G(d,p) basis set. It has been observed that the results obtained from the experimental and theoretical calculations support each other and were in harmony.

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27

Catchen, Gary L. "Perturbed-Angular-Correlation Spectroscopy: Renaissance of a Nuclear Technique". MRS Bulletin 20, n.º 7 (julio de 1995): 37–46. http://dx.doi.org/10.1557/s0883769400037167.

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During the past decade, perturbed-angular-correlation (PAC) spectroscopy has emerged as an important technique in several areas of materials science. PAC spectroscopy is used to measure the effects of local fields at well-defined lattice sites in a crystal. These measurements can provide unique information about the structures, kinetics, and energetics associated with point defects, the mechanisms of phase transitions, and the strengths and symmetries of chemical bonds of atoms on surfaces and at interfaces. In what follows, I describe the PAC technique in the context of several examples of these applications and I comment on the historical evolution of this spectroscopy.Hyperfine InteractionsThe field of hyperfine interactions encompasses spectroscopic techniques that use the electric and magnetic nuclear moments to measure the specific extranuclear environment of the nuclear moments. Examples of these techniques are nuclear-magnetic-resonance (NMR), nuclear-quadrupole-resonance (NQR), electron-paramagnetic-resonance (EPA), muon-spin-rotation (MSR), Mössbauer-effect (ME), and perturbed-angular-correlation (PAC) spectroscopies. Each of these techniques is well-suited to certain types of measurements but useless for others. For example, NMR spectroscopy can be particularly useful for measuring chemical shifts associated with nuclei of atoms that are major constituents of crystalline solids. However, nuclear electricquadrupole interactions associated with some NMR-active nuclei are not only difficult to measure but they often obscure much of the chemical-shift information by producing spectral-line broadening. PAC spectroscopy can be used to accurately measure the nuclear electric-quadrupole interactions at the sites of nuclei of atoms that are trace dopants in crystals. But the PAC technique is insensitive to the effects of local charge distributions that produce the NMR chemical shifts. ME spectroscopy can be used to measure both of these effects as well as nuclear magnetic-dipole interactions. However, ME measurements are often only practical on crystals that have one of several elements as a major constituent, that is, either Fe or Sn. In addition, the ME sensitivity depends on temperature, and the NMR and EPR sensitivities also depend on temperature. However, the PAC measurement is independent of temperature, which can be a great advantage for studying phenomena such as phase transitions.

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28

Weber, Carina, Stefan Pusch, Dieter Schollmeyer, Sascha Münster-Müller, Michael Pütz y Till Opatz. "Characterization of the synthetic cannabinoid MDMB-CHMCZCA". Beilstein Journal of Organic Chemistry 12 (21 de diciembre de 2016): 2808–15. http://dx.doi.org/10.3762/bjoc.12.279.

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The synthetic cannabinoid MDMB-CHMCZCA was characterized by various spectroscopic techniques including NMR spectroscopy and tandem mass spectrometry. The synthetic sample was found to be of S-configuration by VCD spectroscopy and comparison of the data with DFT calculations, while ECD spectroscopy was found to be inconclusive in this case. The enantiomeric purity of samples from test purchases and police seizures was assessed by a self-developed chiral HPLC method.

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29

Eerdekens, Maarten, Ismael López-Duarte, Gunther Hennrich y Thierry Verbiest. "Thin Films of Tolane Aggregates for Faraday Rotation: Materials and Measurement". Coatings 9, n.º 10 (16 de octubre de 2019): 669. http://dx.doi.org/10.3390/coatings9100669.

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We present organic, diamagnetic materials based on structurally simple (hetero-)tolane derivatives. They form crystalline thin-film aggregates that are suitable for Faraday rotation (FR) spectroscopy. The resulting new materials are characterized appropriately by common spectroscopic (NMR, UV-Vis), microscopy (POM), and XRD techniques. The spectroscopic studies give extremely high FR activities, thus making these materials promising candidates for future practical applications. Other than a proper explanation, we insist on the complexity of designing efficient FR materials starting from single molecules.

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Jagriti Chatterjee,, Subhojyoti Chatterjee. "Reviewing Spectroscopic Techniques: A New Weapon for Monitoring Corona Virus". International Journal for Modern Trends in Science and Technology, n.º 8 (5 de agosto de 2020): 44–50. http://dx.doi.org/10.46501/ijmtst060809.

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Chemical, structural, and physical properties are parameterized and comprehended in the molecular properties of a molecule. They are therefore calculable and can be categorized as molecular energetics, spectral quantities, and properties that are not physical observables (for example, aromaticity, isoelectronic and bond order), i.e., measurable and non-measurable properties. Different aspects of theory and experiments give more insightful information of biologically living complex macromolecules. For example, the structure of nucleic acids and proteins (like the CoV envelope (E) protein)are measured by X-ray crystallography and NMR techniques, etc., in order to understand their properties and functionalities. More detailed structural information of these biomolecules can further be captured through techniques such as molecular spectroscopy. For example, X-ray photoemission spectroscopy captures insight into the molecular interactions and bonding nature of the biomolecules (such as envoloped RNA coronaviruses). These biologically important spectroscopic techniques have been discussed in this mini review report.

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Kleebe, Hans-Joachim, Giuliano Gregori, Florence Babonneau, Yigal D. Blum, D. Brent MacQueen y Sylvie Masse. "Evolution of C-rich SiOC ceramics". International Journal of Materials Research 97, n.º 6 (1 de junio de 2006): 699–709. http://dx.doi.org/10.1515/ijmr-2006-0115.

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Abstract Carbon-rich Si –O–C polymer-derived ceramics (PDCs) were investigated by various spectroscopic techniques, in order to characterize the evolution of their predominantly amorphous microstructure upon thermal treatment up to 1450 °C. Particular attention was addressed to modifications of the excess free carbon phase present in these materials. Surprisingly, the carbon clusters exhibited high stability above the pyrolysis temperature. Despite the high volume fraction of carbon, only a very limited carbothermal reduction process was detected. This study is divided into two parts: Part I deals with characterization tools that reveal a rather low lateral resolution and are hence termed here as integral spectroscopic techniques, i. e., solid-state NMR and Raman spectroscopy. In contrast, Part II illustrates the experimental results obtained from the very same materials characterized by spectroscopic and imaging techniques with high lateral resolution, i. e., electron energy-loss spectroscopy (EELS), high-resolution transmission electron microscopy (HRTEM), and energy-filtered TEM. In addition to materials characterization, emphasize of both papers is also to compare the information gained by either integral or local spectroscopy techniques and to highlight the strengths and weaknesses of either approach.

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Muniyappan, Srinivasan, Yuxi Lin, Young-Ho Lee y Jin Hae Kim. "17O NMR Spectroscopy: A Novel Probe for Characterizing Protein Structure and Folding". Biology 10, n.º 6 (21 de mayo de 2021): 453. http://dx.doi.org/10.3390/biology10060453.

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Oxygen is a key atom that maintains biomolecular structures, regulates various physiological processes, and mediates various biomolecular interactions. Oxygen-17 (17O), therefore, has been proposed as a useful probe that can provide detailed information about various physicochemical features of proteins. This is attributed to the facts that (1) 17O is an active isotope for nuclear magnetic resonance (NMR) spectroscopic approaches; (2) NMR spectroscopy is one of the most suitable tools for characterizing the structural and dynamical features of biomolecules under native-like conditions; and (3) oxygen atoms are frequently involved in essential hydrogen bonds for the structural and functional integrity of proteins or related biomolecules. Although 17O NMR spectroscopic investigations of biomolecules have been considerably hampered due to low natural abundance and the quadruple characteristics of the 17O nucleus, recent theoretical and technical developments have revolutionized this methodology to be optimally poised as a unique and widely applicable tool for determining protein structure and dynamics. In this review, we recapitulate recent developments in 17O NMR spectroscopy to characterize protein structure and folding. In addition, we discuss the highly promising advantages of this methodology over other techniques and explain why further technical and experimental advancements are highly desired.

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Silwood, C. J. L., E. Lynch, A. W. D. Claxson y M. C. Grootveld. "1H and 13C NMR Spectroscopic Analysis of Human Saliva". Journal of Dental Research 81, n.º 6 (junio de 2002): 422–27. http://dx.doi.org/10.1177/154405910208100613.

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We have explored the ability of high-resolution NMR techniques to (1) index salivary biomolecules and (2) provide valuable data regarding intra- and inter-subject variability in the concentrations of a series of components readily determinable by this technique (organic acids and malodorous amines). Experiments were conducted on ‘whole’ saliva samples collected from 20 patients, either randomly during their daily activities, or, for investigations involving the quantification of salivary biomolecules, immediately after they woke in the morning throughout a three-day period. These NMR techniques permitted us to detect greater than 60 metabolites, together with agents arising from dietary, oral health care product, and pharmaceutical sources. Highly significant “between-subject” differences in the a.m. waking salivary metabolite concentrations were found for 9 out of 11 components monitored. It is concluded that NMR spectroscopy serves as a powerful technique for the multicomponent analysis of human saliva.

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Ali, Muhammad Shaiq, Zeeshan Ahmed, Joseph Ngoupayo y Muhammad Imran Ali. "Terpenoids from Clerodendrum formicarum Gürke (Lamiaceae) of Cameroon". Zeitschrift für Naturforschung B 65, n.º 4 (1 de abril de 2010): 521–24. http://dx.doi.org/10.1515/znb-2010-0414.

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The ethanolic extract of the leaves of Clerodendrum formicarum, a Lameacious plant of Cameroon, afforded a new abeo-abietane diterpenoid named formidiol (1) together with some known diand triterpenoids. They include 12,16-epoxy-11,14-dihydroxy-6-methoxy-17(15→16)-abeo-abieta- 5,8,11,13,15-pentanene-3,7-dione (2), trans-phytol, friedelin and friedlan-3β -ol. Structures of all the isolated constituents have been characterized with the aid of 1D NMR spectroscopy while the structure of a new metabolite was elucidated via 2D NMR spectroscopic techniques.

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Senthilkumar, Gopal, Chinnusamy Umarani y Dhurairaj Satheesh. "Synthesis, Spectral Characterization, Antibacterial, Antifungal and Anticancer Evaluation of N-[4-(1,3-Benzothiazol-2-ylcarbamoyl)phenyl]pyrazine-2-carboxamide". Asian Journal of Organic & Medicinal Chemistry 6, n.º 2 (2021): 102–6. http://dx.doi.org/10.14233/ajomc.2021.ajomc-p320.

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A new organic compound, N-[4-(1,3-benzothiazol-2-ylcarbamoyl)-phenyl]pyrazine-2-carboxamide was synthesized through the reaction between 4-amino-N-(benzo[d]thiazol-2-yl)benzamide and pyrazine-2-carboxylic acid. The synthesized compound has been characterized by spectroscopic techniques such as 1H NMR, 13C NMR, FT-IR and mass spectroscopy. The synthesized compound was screened to antibacterial (Staphylococcus aureus, Klebsiella pneumonia and Escherichia coli), antifungal (Candida albicans and Aspergillus niger) activities. The anticancer activity of the title compound was also evaluated against MDA-MB-231 breast cancer cells.

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36

Abd El-Lateef, Hany M. y Ahmed H. Tantawy. "Synthesis and evaluation of novel series of Schiff base cationic surfactants as corrosion inhibitors for carbon steel in acidic/chloride media: experimental and theoretical investigations". RSC Advances 6, n.º 11 (2016): 8681–700. http://dx.doi.org/10.1039/c5ra21626e.

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A new family of Schiff base cationic surfactants (CSSB) having various alkyl chain lengths were prepared and their chemical structure was elucidated by using different spectroscopic techniques (FTIR, ¹³C-NMR and ¹H-NMR).

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Almeida, Celso, Somaia Elsaedi, Stefan Kehraus y Gabriele M. König. "Novel Bisabolane Sesquiterpenes from the Marine-derived Fungus Verticillium tenerum". Natural Product Communications 5, n.º 4 (abril de 2010): 1934578X1000500. http://dx.doi.org/10.1177/1934578x1000500401.

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Chemical investigations of the marine-derived fungus Verticillium tenerum yielded two new hydroxylated bisabolane-type sesquiterpenes verticinol A (1) and B (2). The planar structures of the new compounds were elucidated by employing spectroscopic (NMR, UV, and IR) and mass spectrometric techniques. The absolute configuration of the cyclohexenyl moiety was deduced by a combination of CD spectroscopy and NOESY measurements.

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38

Medina, Jessica, Diana Caro Rodríguez, Victoria A. Arana, Andrés Bernal, Pierre Esseiva y Julien Wist. "Comparison of Attenuated Total Reflectance Mid-Infrared, Near Infrared, and 1H-Nuclear Magnetic Resonance Spectroscopies for the Determination of Coffee’s Geographical Origin". International Journal of Analytical Chemistry 2017 (1 de noviembre de 2017): 1–8. http://dx.doi.org/10.1155/2017/7210463.

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The sensorial properties of Colombian coffee are renowned worldwide, which is reflected in its market value. This raises the threat of fraud by adulteration using coffee grains from other countries, thus creating a demand for robust and cost-effective methods for the determination of geographical origin of coffee samples. Spectroscopic techniques such as Nuclear Magnetic Resonance (NMR), near infrared (NIR), and mid-infrared (mIR) have arisen as strong candidates for the task. Although a body of work exists that reports on their individual performances, a faithful comparison has not been established yet. We evaluated the performance of 1H-NMR, Attenuated Total Reflectance mIR (ATR-mIR), and NIR applied to fraud detection in Colombian coffee. For each technique, we built classification models for discrimination by species (C. arabica versus C. canephora (or robusta)) and by origin (Colombia versus other C. arabica) using a common set of coffee samples. All techniques successfully discriminated samples by species, as expected. Regarding origin determination, ATR-mIR and 1H-NMR showed comparable capacity to discriminate Colombian coffee samples, while NIR fell short by comparison. In conclusion, ATR-mIR, a less common technique in the field of coffee adulteration and fraud detection, emerges as a strong candidate, faster and with lower cost compared to 1H-NMR and more discriminating compared to NIR.

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39

Hassoun, Abdo, María Guðjónsdóttir, Miguel A. Prieto, Paula Garcia-Oliveira, Jesus Simal-Gandara, Federico Marini, Francesca Di Donato, Angelo Antonio D’Archivio y Alessandra Biancolillo. "Application of Novel Techniques for Monitoring Quality Changes in Meat and Fish Products during Traditional Processing Processes: Reconciling Novelty and Tradition". Processes 8, n.º 8 (14 de agosto de 2020): 988. http://dx.doi.org/10.3390/pr8080988.

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In this review, we summarize the most recent advances in monitoring changes induced in fish and other seafood, and meat and meat products, following the application of traditional processing processes by means of conventional and emerging advanced techniques. Selected examples from the literature covering relevant applications of spectroscopic methods (i.e., visible and near infrared (VIS/NIR), mid-infrared (MIR), Raman, nuclear magnetic resonance (NMR), and fluorescence) will be used to illustrate the topics covered in this review. Although a general reluctance toward using and adopting new technologies in traditional production sectors causes a relatively low interest in spectroscopic techniques, the recently published studies have pointed out that these techniques could be a powerful tool for the non-destructive monitoring and process optimization during the production of muscle food products.

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40

Desai, S. S., P. A. Tatke y S. Y. Gabhe. "ISOLATION AND CHARACTERIZATION OF BETAINE FROM DRIED SEEDS OF ACHYRANTHES ASPERA". INDIAN DRUGS 50, n.º 04 (25 de abril de 2013): 56–59. http://dx.doi.org/10.53879/id.50.04.p0056.

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Marker compounds play an important role in standardization of herbal extracts and herbal formulations. The isolation of marker/s from crude extract or fractions of an extract is often a lengthy and expensive process and it many times requires numerous separation steps involving use of different separation techniques. The present work describes new method of isolation of betaine, a chemical marker from the plant Achyranthes aspera by preparative TLC and its characterization by chemical and spectroscopic techniques like IR, NMR and mass spectroscopy.

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41

Desai, S. S., P. A. Tatke y S. Y. Gabhe. "ISOLATION AND CHARACTERIZATION OF BETAINE FROM DRIED SEEDS OF ACHYRANTHES ASPERA". INDIAN DRUGS 50, n.º 04 (25 de abril de 2013): 56–59. http://dx.doi.org/10.53879/id.50.04.p0056.

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Marker compounds play an important role in standardization of herbal extracts and herbal formulations. The isolation of marker/s from crude extract or fractions of an extract is often a lengthy and expensive process and it many times requires numerous separation steps involving use of different separation techniques. The present work describes new method of isolation of betaine, a chemical marker from the plant Achyranthes aspera by preparative TLC and its characterization by chemical and spectroscopic techniques like IR, NMR and mass spectroscopy.

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42

Casa, Stefanie, Guliz Ersoy Ozmen y Maged Henary. "(Z)-3-(Dicyanomethylene)-4-((5-fluoro-3,3-dimethyl-1-(3-phenylpropyl)-3H-indol-1-ium-2-yl) methylene)-2-(((E)-5-fluoro-3,3-dimethyl-1-(3-phenylpropyl)indolin-2-ylidene)methyl) cyclobut-1-en-1-olate". Molbank 2023, n.º 1 (3 de febrero de 2023): M1576. http://dx.doi.org/10.3390/m1576.

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Recent literature on this topic highlights the significance of adding malononitrile moiety and halogen substituents to the squaraine scaffold to create redshifted fluorophores into the near-infrared optical region. Herein, a redshifted hydrophobic squaraine dye is synthesized via a three-step pathway. The reported dye is characterized by spectroscopic techniques, such as 1H NMR, 19F NMR, 13C NMR, and high-resolution mass spectroscopy. Optical properties are also reported using absorbance and fluorescence studies. The hydrophobicity of the dye was studied with absorbance and fluorescence spectroscopy in water–methanol mixtures and showed J-aggregates as the water concentration increased. Density functional theory calculations were conducted to assess its electron delocalization as well as observe the three-dimensional geometry of the dye as a result of the dicyanomethylene modification and the two bulky phenyl groups.

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Bajju, Gauri D., Deepmala, Sunil Kumar Anand, Sujata Kundan y Narinder Singh. "Electrochemical and Spectroscopic Characterization of Aluminium(III)-para-methyl-meso-tetraphenylporphyrin Complexes Containing Substituted Salicylates as Axial Ligands". International Journal of Electrochemistry 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/409375.

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A series of aluminium(III)-p-methyl-meso-tetraphenylporphyrin (p-CH3TPP-Al(III)) containing axially coordinated salicylate anion [p-CH3TPP-Al-X)], where X = salicylate (SA), 4-chlorosalicylate (4-CSA), 5-chlorosalicylate (5-CSA), 5-flourosalicylate (5-FSA), 4-aminosalicylate (4-ASA), 5-aminosalicylate (5-ASA), 5-nitrosalicylate (5-NSA), and 5-sulfosalicylate (5-SSA), have been synthesized and characterized by various spectroscopic techniques including ultraviolet-visible (UV-vis), infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy,13C NMR, and elemental analysis. A detailed study of electrochemistry of all the synthesized compounds has been done to compare their oxidation and reduction mechanisms and to explain the effect of axial coordination on their redox properties.

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Bala, Muhammad, Ebrahim Kadwa y Holger Friedrich. "Structural Identification of Products from the Chloromethylation of Salicylaldehyde". Synlett 30, n.º 01 (26 de noviembre de 2018): 44–48. http://dx.doi.org/10.1055/s-0037-1610334.

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In the functionalization of salicylaldehyde to give 5-(chloromethyl)salicylaldehyde, two byproducts [5-(hydroxymethyl)salicylaldehyde and 5,5′-methylenebis(salicylaldehyde)] were also isolated. Detailed characterizations and structural analyses of all three products by single-crystal X-ray diffraction, multinuclear NMR spectroscopy, high-resolution mass spectrometry, and IR spectroscopic techniques are presented and discussed. A strategy is presented for the preferential isolation of the two byproducts through column chromatography.

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Jash, Shyamal K., Dilip Gorai, Lalan C. Mandal y Rajiv Roy. "Nuclear Magnetic Resonance Spectroscopic Behaviour of Some Selective Natural Flavonoids: A Look Through". Mini-Reviews in Organic Chemistry 17, n.º 2 (28 de febrero de 2020): 185–96. http://dx.doi.org/10.2174/1570193x16666181224110603.

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Flavonoids are considered as a significant class of compounds among the natural products, exhibiting a variety of structural skeletons as well as multidirectional biological potentials. In structural elucidations of natural products, Nuclear Magnetic Resonance (NMR) spectroscopy has been playing a vital role; the technique is one of the sharpest tools in the hands of natural products chemists. The present resume deals with hard-core applications of such spectral technique, particularly in structural elucidation of flavonoids; different NMR techniques including 1H-NMR, 13C-NMR, and 2D-NMR [viz. 1H-1H COSY, COLOC, HMBC, HMQC] are described in detail.

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Bansal, V., G. J. Krishna, A. Chopra y A. S. Sarpal. "Detailed Hydrocarbon Characterization of RFCC Feed Stocks by NMR Spectroscopic Techniques". Energy & Fuels 21, n.º 2 (marzo de 2007): 1024–29. http://dx.doi.org/10.1021/ef060268x.

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Sarpal, A. S., M. I. S. Sastry, G. S. Kapur, V. Bansal, A. K. Mehta y A. K. Bhatnagar. "Molecular dynamics studies of a lubricant system by NMR spectroscopic techniques". Lubrication Science 16, n.º 4 (agosto de 2004): 361–75. http://dx.doi.org/10.1002/ls.3010160405.

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Thathong, Yuranan, Kittiya Wongkhan y Rukkiat Jitchati. "Two Ruthenium Complexes with Phenanthroline Ligand for Dye-Sensitized Solar Cells". Advanced Materials Research 651 (enero de 2013): 115–19. http://dx.doi.org/10.4028/www.scientific.net/amr.651.115.

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We report the synthetic route of two ruthenium dye-sensitizers; namely, Ru(4,4-dicarboxylic-2,2-bipyridine)(1,10-phenanthroline)(NCS)2 (6) and Ru(4,4-dicarboxylic-2,2-bipyridine)(1,10-phenanthroline-5-carboxylic acid)(NCS)2 (7), which both complexes were characterized by 1H NMR, 13C NMR and UV-Vis spectroscopic techniques.

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Wolny, Juliusz A., Volker Schünemann, Zoltán Németh y György Vankó. "Spectroscopic techniques to characterize the spin state: Vibrational, optical, Mössbauer, NMR, and X-ray spectroscopy". Comptes Rendus Chimie 21, n.º 12 (diciembre de 2018): 1152–69. http://dx.doi.org/10.1016/j.crci.2018.10.001.

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Monakhova, Yulia B., Thomas Kuballa, Jenny Leitz y Dirk W. Lachenmeier. "Determination of Diethyl Phthalate and Polyhexamethylene Guanidine in Surrogate Alcohol from Russia". International Journal of Analytical Chemistry 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/704795.

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Analytical methods based on spectroscopic techniques were developed and validated for the determination of diethyl phthalate (DEP) and polyhexamethylene guanidine (PHMG), which may occur in unrecorded alcohol. Analysis for PHMG was based on UV-VIS spectrophotometry after derivatization with Eosin Y and1H NMR spectroscopy of the DMSO extract. Analysis of DEP was performed with direct UV-VIS and1H NMR methods. Multivariate curve resolution and spectra computation methods were used to confirm the presence of PHMG and DEP in the investigated beverages. Of 22 analysed alcohol samples, two contained DEP or PHMG.1H NMR analysis also revealed the presence of signals of hawthorn extract in three medicinal alcohols used as surrogate alcohol. The simple and cheap UV-VIS methods can be used for rapid screening of surrogate alcohol samples for impurities, while1H NMR is recommended for specific confirmatory analysis if required.

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