Cobalt-Mediated Decarboxylative Homocoupling of Alkynyl Carboxylic Acids

2014 ◽  
Vol 67 (5) ◽  
pp. 701 ◽  
Author(s):  
Michael G. Leeming ◽  
George N. Khairallah ◽  
Sandra Osburn ◽  
Krista Vikse ◽  
Richard A. J. O'Hair
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Final Stage ◽  
Mononuclear Complex ◽  
Collision Induced Dissociation ◽  
Reductive Coupling ◽  
Second Stage ◽  
Mononuclear Complexes ◽  
Relative Activation ◽  
Bond Homolysis

Cobalt-mediated decarboxylative Glaser-like C–C bond coupling of carboxylates has been studied in the gas phase using collision-induced dissociation (CID) multistage mass spectrometry (MSn) experiments. Both the identity of the carboxylate RCO2– (R = Me, HC≡C, MeC≡C, and PhC≡C) and the nuclearity of the complex ([CoCl(O2CR)2]– versus [Co2Cl3(O2CR)2]–) play a role in the types of reactions observed and their relative activation energies. In the first stage of CID, the mononuclear complex [CoCl(O2CMe)2]– undergoes decarboxylation, while the dinuclear [Co2Cl3(O2CMe)2]– undergoes cluster fission to yield [CoCl3]–; all acetylenic carboxylate complexes [CoCl(O2CR)2]– and [Co2Cl3(O2CR)2]– undergo decarboxylation. Isolation of the decarboxylated products followed by a second stage of CID results in a second decarboxylation event for all systems except for [CoCl(Me)(O2CMe)]–, which undergoes bond homolysis. In the final stage of CID, all acetylenic complexes undergo Glaser coupling, forming reduced Co anions. Overall dinuclear cobalt clusters are superior to mononuclear complexes at promoting decarboxylation and reductive coupling. The order of reactivity among the acetylide ligands is PhC≡C > MeC≡C > HC≡C.

Rapid Evaluation of Suitable Substrates with High Affinity to Artificial Caffeine Receptors by MS Based Techniques

2005 ◽  
Vol 60 (10) ◽  
pp. 1077-1082 ◽  
Author(s):  
Daniela Mirk ◽  
Heinrich Luftmann ◽  
Siegfried R. Waldvogel
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Collision Induced Dissociation ◽  
Rapid Evaluation ◽  
Tandem Mass ◽  
Binding Affinities ◽  
Electrospray Tandem Mass Spectrometry ◽  
Relative Stabilities ◽  
Receptor Complexes ◽  
High Affinity

A modification of our triphenylene ketal based receptor facilitates electrospray tandem mass spectrometry investigations. Binding affinities of eleven potential substrates, e.g. caffeine and other xanthine alkaloids, are probed in the gas phase with collision induced dissociation. The relative stabilities of the substrate-receptor complexes are rapidly determined and the findings are correlated with the corresponding results in solution.

scholarly journals Photoproducts of the Photodynamic Therapy Agent Verteporfin Identified via Laser Interfaced Mass Spectrometry

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5280
Author(s):  
Chris Furlan ◽  
Jacob A. Berenbeim ◽  
Caroline E. H. Dessent
Keyword(s):  
Mass Spectrometry ◽  
Photodynamic Therapy ◽  
Macular Degeneration ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Red Light ◽  
Solution Phase ◽  
Collision Induced Dissociation ◽  
Free Base ◽  
New Information

Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250 to 790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.

The Chemistry and Characteristics of Nitric Acid-Graphite Intercalation

1982 ◽  
Vol 20 ◽  
Author(s):  
Sophia R. Su ◽  
Daniel W. Oblas
Keyword(s):  
Mass Spectrometry ◽  
Nitric Acid ◽  
Gas Phase ◽  
Contributory Factor ◽  
Fourth Stage ◽  
Acid Vapor ◽  
Step Process ◽  
Second Stage ◽  
Graphite Intercalation ◽  
One Step

ABSTRACTGas-phase intercalation of graphite by nitric acid is a one-step process. The weight uptake of the sample is a function of nitric acid vapor pressure. A pure second stage compound was formed when the HNO3 reservoir was maintained at 17°C. Only a fourth stage compound was formed when the acid was kept at 0°C. The product gases due to intercalation and gas species evolved during deintercalation were analyzed by mass spectrometry. NO2 and H2O were the major components detected from the intercalation product gases. A small amount of oxygen was also present. The existence of O2 is probably due to the photo-chemical decomposition of nitric acid. As such, the photodecomposition of nitric acid is not a contributory factor in the intercalation chemistry.

scholarly journals Synthesis and structural investigation of a series of mannose-containing oligosaccharides using mass spectrometry

2018 ◽  
Vol 16 (2) ◽  
pp. 228-238
Author(s):  
S. Daikoku ◽  
R. Pendrill ◽  
Y. Kanie ◽  
Y. Ito ◽  
G. Widmalm ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Acid Hydrolysis ◽  
Gas Phase ◽  
Structural Investigation ◽  
Collision Induced Dissociation ◽  
Linkage Isomers ◽  
Hydrolysis Of ◽  
Reactivity Order

Gas-phase collision-induced dissociation and acid hydrolysis of mannose-containing oligosaccharides were performed, which revealed the reactivity order of linkage isomers.

Mass Spectrometry of Gangliosides from Human Sensory and Motor Cortex

2013 ◽  
Vol 66 (7) ◽  
pp. 781 ◽  
Author(s):  
Corina Flangea ◽  
Dragana Fabris ◽  
Željka Vukelić ◽  
Alina D. Zamfir
Keyword(s):  
Mass Spectrometry ◽  
Motor Cortex ◽  
Brain Regions ◽  
Collision Induced Dissociation ◽  
Tandem Ms ◽  
Acetylneuraminic Acid ◽  
Second Stage ◽  
Specific Composition ◽  
The Central Nervous System ◽  
Human Motor

Sialylated glycosphingolipids, known as gangliosides, are highly expressed in the central nervous system exhibiting region-specific composition in correlation to the specialised functions of particular brain regions. In the present study high resolution tandem mass spectrometry on a quadrupole time-of-flight instrument with nanoelectrospray was optimised and applied for the first comparative assessment of the ganglioside profile in single specimens of adult human motor and somatosensory cortex. In the second stage, the structural analysis performed by collision induced dissociation tandem MS disclosed the presence in motor cortex of a fucose-ganglioside Fuc-GM1 (d18 : 1/20 : 0) isomer exhibiting both N-acetylneuraminic acid and fucose residues linked to the inner galactose.

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