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
Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2995
Author(s):  
Artur Jamrozik ◽  
Mateusz Barczewski ◽  
Grzegorz Framski ◽  
Daniel Baranowski ◽  
Paulina Jakubowska ◽  
...  

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.


2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Rizwana Sarwar ◽  
Umar Farooq ◽  
Sadia Naz ◽  
Nadia Riaz ◽  
Syed Majid Bukhari ◽  
...  

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.


2010 ◽  
Vol 75 (10) ◽  
pp. 3214-3223 ◽  
Author(s):  
Ananya Majumdar ◽  
Yan Sun ◽  
Meha Shah ◽  
Caren L. Freel Meyers

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 478-482 ◽  
Author(s):  
Sara A. Lisboa ◽  
Dmitry V. Evtuguin ◽  
Carlos Pascoal Neto

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.


1993 ◽  
Vol 34 (4) ◽  
pp. 1159-1163 ◽  
Author(s):  
Maribel G. Nonato ◽  
Mary J. Garson ◽  
Roger J.W. Truscott ◽  
John.A. Carver

2008 ◽  
Vol 8 (4) ◽  
pp. 2096-2101 ◽  
Author(s):  
Claudio Evangelisti ◽  
Patrizio Raffa ◽  
Federica Balzano ◽  
Gloria Uccello Barretta ◽  
Giovanni Vitulli ◽  
...  

Pt nanoclusters have been generated by reaction of Pt vapour and mesitylene vapour and the role of the mesitylene/platinum ratio and the Pt particle size has been evaluated, quenching the resulting mesitylene solvated Pt atoms with 1,3-divinyltetramethyldisiloxane (DVS) as additional ligand. The Pt particle sizes have been estimated on the basis of DOSY (Diffusion-Ordered SpectroscopY) analysis and information on their structure features have been obtained by combined use of 2D NMR techniques.


2015 ◽  
Vol 71 (12) ◽  
pp. 1074-1079 ◽  
Author(s):  
Marianne E. Burnett ◽  
Hannah M. Johnston ◽  
Kayla N. Green

Nicotinamides are a class of compounds with a wide variety of applications, from use as antimicrobial agents to inhibitors of biological processes. These compounds are also cofactors, which are necessary components of metabolic processes. Structural modification gives rise to the activities observed. Similarly, 1,3,4-thiadiazoles have been shown to possess antioxidant, antimicrobial, or anti-inflammatory biological activity. To take advantage of each of the inherent characteristics of the two aforementioned functional groups, 2-nicotinamido-1,3,4-thiadiazole, C8H6N4OS, was synthesized. Since defining chemical connectivity is paramount in understanding biological activity, in this report, the structural characterization of 2-nicotinamido-1,3,4-thiadiazole has been carried out using X-ray crystallographic methods. The NMR-derived assignments were made possible by utilizing one- (1D) and two-dimensional (2D) NMR techniques. In addition, UV–Visible and IR spectroscopies, and elemental analysis were used to fully characterize the product synthesized by the one-step reaction between nicotinoyl chloride hydrochloride and 2-amino-1,3,4-thiadiazole. Computational parameters related to blood–brain barrier permeability are also presented.


2015 ◽  
Vol 17 (8) ◽  
pp. 4383-4392 ◽  
Author(s):  
Ilona van Zandvoort ◽  
Eline J. Koers ◽  
Markus Weingarth ◽  
Pieter C. A. Bruijnincx ◽  
Marc Baldus ◽  
...  

Complementary (2D) NMR techniques provide new insights into the molecular structure of humin by-products.


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