The First Observation and Full Characterization of All Atropisomers and Their Allowed Interconversions in an Octahedral Bis(bipyridine)ruthenium(II) Complex with Two Lopsided Bicyclic Ligands, as Studied by 2D NMR Techniques at Variable Temperature

1999 ◽  
Vol 38 (12) ◽  
pp. 2762-2763 ◽  
Author(s):  
Aldrik H. Velders ◽  
Anna C. G. Hotze ◽  
Jaap G. Haasnoot ◽  
Jan Reedijk
Keyword(s):  
Variable Temperature ◽  
2D Nmr ◽  
Full Characterization ◽  
Nmr Techniques

scholarly journals Phytochemical Investigation of the Australian Lichens Ramalina glaucescens and Xanthoria parietina

2009 ◽  
Vol 4 (7) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
Daniel A. Dias ◽  
Sylvia Urban
Keyword(s):  
Antibacterial Properties ◽  
Usnic Acid ◽  
2D Nmr ◽  
Antibacterial Activities ◽  
2D Nmr Spectroscopy ◽  
Full Characterization ◽  
Phytochemical Investigation ◽  
Xanthoria Parietina ◽  
Shift Assignment

Phytochemical investigation of the Australian lichen, Ramalina glaucescens resulted in the isolation of a new halogenated depside, 5-chlorosekikaic acid 5, together with (+)-usnic acid 1, sekikaic acid 2, atranorin 6 and parietin 7, the latter of which was isolated from the associated (co-occurring) lichen, X. parietina. Compound 5 is suspected to be an artifact of the isolation procedure. All structures were assigned using spectroscopic methods and mass spectrometry. In addition to the full characterization of 5, this report represents the first application of 2D NMR spectroscopy to complete the unequivocal chemical shift assignment for compounds 2 and 7. Compounds 1-2 and 5-7 all displayed varying degrees of antitumor activity (ranging from an IC50 of 15 μM to >44 μM) with compounds 1, 2 and 5 also displaying antibacterial properties. Of these, (+)-usnic acid 1 displayed the most significant antitumor and antibacterial activities.

scholarly journals Synthesis and Characterization of Low-Cost Cresol-Based Benzoxazine Resins as Potential Binders in Abrasive Composites

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2995
Author(s):  
Artur Jamrozik ◽  
Mateusz Barczewski ◽  
Grzegorz Framski ◽  
Daniel Baranowski ◽  
Paulina Jakubowska ◽  
...  
Keyword(s):  
Low Cost ◽  
2D Nmr ◽  
Additional Analysis ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Voc Emission ◽  
Chemical Structures ◽  
Oxazine Ring ◽  
Nmr Techniques

A series of cresol-based benzoxazines were synthesized for potential application as a polymer matrix in abrasive composites. The chemical structures of the obtained benzoxazine resins were investigated in detail using Fourier transform infrared spectroscopy (FTIR) and hydrogen-1 as well as carbon-13 nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR) with an additional analysis using two-dimensional NMR techniques (2D NMR 1H-1H COSY, 1H-13C gHSQC and gHMBC). Structural analysis confirmed the presence of vibrations of -O-C-N- at ~950 cm−1 wavenumber, characteristic for an oxazine ring. The thermal properties of benzoxazine monomers were examined using differential scanning calorimetry (DSC) analysis. The polymerization enthalpy varied from 143.2 J/g to 287.8 J/g. Thermal stability of cresol-based benzoxazines was determined using thermogravimetry (TGA) analysis with additional analysis of the amount of volatile organic compounds (VOC) emitted from the synthesized benzoxazines during their crosslinking by static headspace coupled with gas chromatography technique (HS-GC). The amount of residual mass significantly differed between all synthesized polybenzoxazines in the range from 8.4% to 21.2%. The total VOC emission for benzoxazines decreased by 46–77% in reference to a conventional phenolic binder. The efficiency of abrasive composites with the benzoxazine matrix was evaluated based on abrasion tests. Performed analyses confirmed successful synthesis and proper chemical structure of cresol-based benzoxazines. All the experiments indicated that benzoxazines based on different cresol isomers significantly differ from each other. Good thermal performance and stability of the abrasive composites with the polybenzoxazine matrix and significantly lower VOC emission allow us to state that benzoxazines can be a promising and valuable alternative to the phenolics and a new path for the development of modern, eco-friendly abrasives.

Separation and atropisomer isolation of ortho-halogenated tetraarylporphyrins by HPLC: Full characterization using 1D and 2D NMR

2012 ◽  
Vol 16 (03) ◽  
pp. 316-323 ◽  
Author(s):  
Carlos J.P. Monteiro ◽  
Mariette M. Pereira ◽  
Nuno P. F. Gonçalves ◽  
Carla G. Carvalho ◽  
Ângela C.B. Neves ◽  
...  
Keyword(s):  
2D Nmr ◽  
Preparative Hplc ◽  
Full Characterization ◽  
Nmr Techniques

The separation and isolation of the four atropisomers of ortho-halogenated tetraarylporphyrins by semi-preparative HPLC is described. Full characterization and assignment of all 1 H and 13 C resonances of 5,10,15,20-tetrakis(2-fluoro or 2-chlorophenyl)porphyrins and 5,10,15,20-tetrakis(2-fluoro or chloro-5-N-ethylsulfamoylphenyl)porphyrins by 1D and 2D NMR techniques is reported. The outcome is an unequivocal evidence of the chlorosulfonation of meso-tetra(2-haloaryl)porphyrins on the 5′-position.

scholarly journals Isolation and Characterization of Two New Antimicrobial Acids from Quercus incana (Bluejack Oak)

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Rizwana Sarwar ◽  
Umar Farooq ◽  
Sadia Naz ◽  
Nadia Riaz ◽  
Syed Majid Bukhari ◽  
...  
Keyword(s):  
Ethyl Acetate Fraction ◽  
Structural Formula ◽  
2D Nmr ◽  
Spectroscopic Technique ◽  
Pentanoic Acid ◽  
One Dimensional ◽  
Isolation And Characterization ◽  
Nmr Techniques ◽  
New Compounds

Two new compounds [1-2] were purified from ethyl acetate fraction of Quercus incana. The structure of these compounds is mainly established by using advanced spectroscopic technique such as UV, IR, one-dimensional (ID) and two-dimensional (2D) NMR techniques, and EI mass. The structural formula was deduced to be 4-hydroxydecanoic acid [1] and 4-hydroxy-3-(hydroxymethyl) pentanoic acid [2]. Both isolated compounds were tested for their antimicrobial potential and showed promising antifungal activity against Aspergillus niger and Aspergillus flavus.

scholarly journals Versatile1H−31P−31P COSY 2D NMR Techniques for the Characterization of Polyphosphorylated Small Molecules

2010 ◽  
Vol 75 (10) ◽  
pp. 3214-3223 ◽  
Author(s):  
Ananya Majumdar ◽  
Yan Sun ◽  
Meha Shah ◽  
Caren L. Freel Meyers
Keyword(s):  
Small Molecules ◽  
2D Nmr ◽  
Nmr Techniques

Characterization of non-cellulosic glucans in Eucalyptus globulus Labill. wood and kraft pulp

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 478-482 ◽  
Author(s):  
Sara A. Lisboa ◽  
Dmitry V. Evtuguin ◽  
Carlos Pascoal Neto
Keyword(s):  
Eucalyptus Globulus ◽  
Fiber Surface ◽  
2D Nmr ◽  
Structural Features ◽  
Kraft Pulping ◽  
Hot Water ◽  
Pulp Yield ◽  
Naoh Solution ◽  
Nmr Techniques

Abstract The amount of non-cellulosic glucans in Eucalyptus globulus wood (approx. 4.5%) was assessed by extraction of sawdust with a 0.5 M NaOH solution at 90–120°C and the structural features were elucidated in a glucan-enriched polysaccharide fraction isolated by hot water extraction (120°C, 2 h). Isolated soluble glucans were characterized by wet chemistry methods and a set of 1D and 2D NMR techniques. The major proportion of glucans consisted of amylose (20%) and amylopectin (80%), although a small proportion of β-(1→3)-glucan (<0.2% on wood weight) was also detected. Although glucans are easily removed in the initial phase of kraft pulping, notable amounts were found in unbleached pulp and it was supposed that in the final stage of kraft pulping a fraction of α-glucan is precipitated onto the fiber surface and contributes to the pulp yield.

Characterization of partially deuteriated transition metal polyhydrido complexes by heteronuclear 2D NMR techniques

1991 ◽  
Vol 29 (13) ◽  
pp. S38-S44 ◽  
Author(s):  
Daniel Nanz ◽  
Wolfgang Von Philipsborn ◽  
Urs E. Bucher ◽  
Luigi M. Venanzi
Keyword(s):  
Transition Metal ◽  
2D Nmr ◽  
Nmr Techniques

scholarly journals Protoflavanones from the Wood Stem of Salvertia convallariodora

2017 ◽  
Vol 12 (4) ◽  
pp. 1934578X1701200
Author(s):  
Mariana L. de Mesquita ◽  
José E. de Paula ◽  
Laila S. Espindola ◽  
Luiz A. L. Soares ◽  
Tania M. G. da Silva ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Ethyl Acetate Extract ◽  
2D Nmr ◽  
Phytochemical Analysis ◽  
Brazilian Cerrado ◽  
Stem Wood ◽  
Full Characterization ◽  
Glucosyl Ester ◽  
First Time

Phytochemical analysis of the ethyl acetate extract of stem wood of Salvertia convallariodora A. St.-Hil. (Vochysiaceae), a Brazilian Cerrado species, led to the isolation and full characterization of three new non-aromatic B-ring flavanones (1-3) as well as the terpene mixture of sericic acid (4), 24-hydroxytormentic acid (5), 24-hydroxytormentic acid glucosyl ester (6), and sericoside (7), all identified for the first time from S. convallariodora. The structures of the new flavanones (1-3) were established from IR, LC-PDA-qTOF-MS, and NMR spectral data, including 2D NMR experiments.

Introduction of Phosphine-Gold(I) Precursors into a Cys-modified Enkephalin Neuropeptide as Part of Solid Phase Peptide Synthesis

2007 ◽  
Vol 62 (3) ◽  
pp. 460-466 ◽  
Author(s):  
Judy Caddy ◽  
Ulrich Hoffmanns ◽  
Nils Metzler-Nolte
Keyword(s):  
Nmr Spectra ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
2D Nmr ◽  
Protecting Group ◽  
2D Nmr Spectroscopy ◽  
Full Characterization ◽  
Gold Thiolate ◽  
Optimized Conditions

The synthesis and full characterization of a series of (triphenylphosphine)gold complexes with thiol-containing amino acids and peptides is reported. Boc-Cys-Au(PPh3) was prepared in solution by reaction of Boc-Cys-OH with (Ph3P)AuCl. The related Ac-Cys-Au(PPh3) and an Au derivative of the cysteine-modified neuropeptide enkephalin (Enk), [Cys]5-Au(PPh3)-Enk, were prepared on the resin, using the orthogonal trityl-protecting group on Cys. For comparison, the metal-free [Cys]5-Enk and an S-tert-butyl-protected [Cys]5-Enk were also prepared. Most noteworthy, gold complexation works best when carried out on the resin, and the gold thiolate survives cleavage from the resin under optimized conditions. The new conjugates were comprehensively characterized, including 1D and 2D NMR spectroscopy, and mass spectrometry. Along with characteristic changes in the 1H and 13C NMR spectra, 31P NMR spectra reveal a characteristic downfield shift of ca. 5 ppm upon complexation of the Au(PPh3)-fragment to Cys, which is also pertinent in the Au-labelled [Cys]5-Enk.

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