scholarly journals Chemoselective 18F-incorporation into pyridyl acyltrifluoroborates for rapid radiolabelling of peptides and proteins at room temperature

2020 ◽  
Vol 56 (5) ◽  
pp. 723-726 ◽  
Author(s):  
Aristeidis Chiotellis ◽  
Hazem Ahmed ◽  
Thomas Betzel ◽  
Matthias Tanriver ◽  
Christopher J. White ◽  
...  
Keyword(s):  
Isotope Exchange ◽  
Room Temperature ◽  
Prosthetic Group ◽  
Chemoselective Ligation

A new prosthetic group is reported for quantitative 18F-labelling of peptides and proteins based on the chemoselective ligation of potassium acyltrifluoroborates (KATs) and hydroxylamines without any detectable 18F/19F isotope exchange at the KAT moiety.

scholarly journals H/D Exchange Under Mild Conditions in Arenes and Unactivated Alkanes with C6D6 and D2O Using Rigid, Electron-rich Iridium PCP Pincer Complexes

2020 ◽  
Author(s):  
Joel D. Smith ◽  
George Durrant ◽  
Daniel Ess ◽  
Warren Piers
Keyword(s):  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Room Temperature ◽  
Pincer Complexes ◽  
Synthesis And Characterization ◽  
Hydrogen Isotope Exchange ◽  
Mild Conditions ◽  
Highly Active ◽  
Pcp Pincer

<div>The synthesis and characterization of an iridium polyhydride complex (Ir-H4)</div><div>supported by an electron-rich PCP framework is described. This complex readily loses molecular</div><div>hydrogen allowing for rapid room temperature hydrogen isotope exchange (HIE) at the hydridic</div><div>positions and the α-C-H site of the ligand with deuterated solvents such as benzene-d6, toluene-d8</div><div>and THF-d8. The removal of 1-2 equivalents of molecular H2 forms unsaturated iridium carbene</div><div>trihydride (Ir-H3) or monohydride (Ir-H) compounds that are able to create further unsaturation</div><div>by reversibly transferring a hydride to the ligand carbene carbon. These species are highly active</div><div>hydrogen isotope exchange (HIE) catalysts using C6D6 or D2O as deuterium sources for the</div><div>deuteration of a variety of substrates. By modifying conditions to influence the Ir-Hn speciation,</div><div>deuteration levels can range from near exhaustive to selective only for sterically accessible sites.</div><div>Preparative level deuterations of select substrates were performed allowing for procurement of</div><div>>95% deuterated compounds in excellent isolated yields; the catalyst can be regenerated by</div><div>treatment of residues with H2 and is still active for further reactions.</div>

Nitrogen Isotope Exchange between Liquid N2O3 and NO at Low Temperature and Elevated Pressure

1963 ◽  
Vol 18 (2) ◽  
pp. 235-241 ◽  
Author(s):  
E. U. Monse ◽  
Lois Nash Kauder ◽  
W. Spindel
Keyword(s):  
Low Temperature ◽  
Separation Factor ◽  
Isotope Exchange ◽  
Spectroscopic Data ◽  
Room Temperature ◽  
Nitrogen Isotopes ◽  
Nitrogen Isotope ◽  
Elevated Pressure ◽  
Single Stage ◽  
Stage Separation

The single stage separation factor, a, for nitrogen isotope exchange between liquid N2O3—N2O4-mixtures and their vapor has been measured at temperatures ranging from — 76°C to room temperature and pressures between 1 atm. and 7.4 atm.At —76°C and 1 atm., α = 1.061 ± 0.003;at —23°C and 1 atm., α=1.034 ± 0.002;at +23°C and 2.1 atm., α=1.017 ± 0.002;at +23°C and 7.4 atm., α=1.030 ± 0.002.The results are compared with values, calculated from spectroscopic data for N2O3, N2O4, NO and NO2. The value of α = 1.030 found at room temperature and 7.4 atm. pressure enhances the usefulness of the N2O3—NO-system for separating the nitrogen isotopes, since it eliminates the need of refrigeration.

scholarly journals Fast Carbon Isotope Exchange of Carboxylic Acids Enabled by Organic Photoredox Catalysis

2020 ◽  
Author(s):  
Duanyang Kong ◽  
Maxime Munch ◽  
Qiqige Qiqige ◽  
Christopher Cooze ◽  
Benjamin Rotstein ◽  
...  
Keyword(s):  
Transition Metal ◽  
Carbon Isotope ◽  
Carboxylic Acids ◽  
Isotope Exchange ◽  
Room Temperature ◽  
Reaction Times ◽  
Thermally Induced ◽  
Drug Molecules ◽  
Metal Catalyzed ◽  
Isotopic Incorporation

Carbazole/cyanobenzene photocatalysts promote the direct isotopic carboxylate exchange of C(sp3 )-acids with labelled CO2. Substrates that are not compatible with transition metal catalyzed degradation-reconstruction approaches or prone to thermally induced reversible decarboxylation undergo isotopic incorporation at room temperature in short reaction times. The radiolabelling of drug molecules and precursors with [11C]CO2 is demonstrated.

The coordinating ability of the antibiotic cycloserine towards transition metal halides

1980 ◽  
Vol 33 (1) ◽  
pp. 57 ◽  
Author(s):  
C Preti ◽  
G Tosi
Keyword(s):  
Field Theory ◽  
Magnetic Properties ◽  
Ring Opening ◽  
Isotope Exchange ◽  
Room Temperature ◽  
Manganese Complexes ◽  
Chemical Analyses ◽  
Conductivity Measurements ◽  
Crystal Field Theory ◽  
Experimental Conditions

A series of cycloserine complexes of chromium(III), manganese(II), rhodium(III) and iridium(III) halides has been prepared and characterized by chemical analyses, conductivity measurements, room temperature magnetic moment studies, electronic, i.r. and far-i.r. spectra and isotope exchange (deuteration) experiments. From the magnetic properties it was concluded that the above ligand forms high- spin complexes with chromium(III) and manganese(II) and low-spin complexes with rhodium(III) and iridium(III). The position and multiplicity of the metal-halogen stretching modes in the far-i.r. region have been extensively investigated, the results being particularly useful in distinguishing between the mer and fac isomers in the ML3X3-type octahedral complexes. The ligand behaves as monodentate O-bonded. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of the crystal field theory and the various parameters have been calculated. The calculated Dq parameters are in accord with the presence of CrO6, CrN3X3, RhO3X3 and IrO3X3 chromophores according to the infrared results. The values of B and C obtained for the manganese complexes are significantly lower than the corresponding values for the free gaseous ion. Under our experimental conditions no metal-induced ring opening of the ligand was observed.

scholarly journals Efficient bulk mass accommodation of N<sub>2</sub>O<sub>5</sub> into neutral aqueous aerosol

2016 ◽  
Author(s):  
Goran Gržinić ◽  
Thorsten Bartels-Rausch ◽  
Andreas Türler ◽  
Markus Ammann
Keyword(s):  
Aqueous Solution ◽  
Isotope Exchange ◽  
Room Temperature ◽  
Direct Evidence ◽  
Aerosol Particles ◽  
Radioactive Tracer ◽  
Accommodation Coefficient ◽  
Bulk Mass

Abstract. An isotope exchange experiment with the short-lived radioactive tracer 13N is used to trace N2O5 uptake into nitrate containing aqueous aerosol particles. While uptake of 13N labelled N2O5 to deliquesced Na2SO4 aerosol is consistent with previous studies, in presence of aerosol phase nitrate efficient exchange of labeled nitrate with the non-labeled nitrate pool was observed. The experiments provide direct evidence for efficient bulk mass accommodation of N2O5 into aqueous solution with an accommodation coefficient >0.4 at room temperature, as well as for the fast disproportionation into nitronium and nitrate. While for experimental reasons this study is limited to non-acidic aerosol, it is likely that mass accommodation is not limiting N2O5 uptake also under wider ranges of conditions.

scholarly journals Fast Carbon Isotope Exchange of Carboxylic Acids Enabled by Organic Photoredox Catalysis

2020 ◽  
Author(s):  
Duanyang Kong ◽  
Maxime Munch ◽  
Qiqige Qiqige ◽  
Christopher Cooze ◽  
Benjamin Rotstein ◽  
...  
Keyword(s):  
Transition Metal ◽  
Carbon Isotope ◽  
Carboxylic Acids ◽  
Isotope Exchange ◽  
Room Temperature ◽  
Reaction Times ◽  
Thermally Induced ◽  
Drug Molecules ◽  
Metal Catalyzed ◽  
Isotopic Incorporation

Carbazole/cyanobenzene photocatalysts promote the direct isotopic carboxylate exchange of C(sp3 )-acids with labelled CO2. Substrates that are not compatible with transition metal catalyzed degradation-reconstruction approaches or prone to thermally induced reversible decarboxylation undergo isotopic incorporation at room temperature in short reaction times. The radiolabelling of drug molecules and precursors with [11C]CO2 is demonstrated.

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