Solvation of the proton and the trifluoromethanesulfonate ion in eight solvents

1991 ◽  
Vol 69 (12) ◽  
pp. 1985-1988 ◽  
Author(s):  
Robert L. Benoit ◽  
Daniel Figeys
Keyword(s):  
Complex Formation ◽  
Boron Trifluoride ◽  
Trifluoromethanesulfonic Acid ◽  
The Other ◽  
Aromatic Diamine ◽  
Enthalpies Of Solution ◽  
Proton Sponge ◽  
Enthalpies Of Transfer ◽  
Ion Proton ◽  
Solvent Basicity

The enthalpies of solution of a sterically hindered aromatic diamine, 1,8-bis(dimethylamino)naphthalene (proton sponge, PS) and of its trifluoromethanesulfonate salt, and of trifluoromethanesulfonic acid have been determined in water, methanol (MeOH), ethanol (EtOH), pyridine (Py), dimethyl sulfoxide (Me2SO), dimethylformamide (DMF), acetonitrile (MeCN), and sulfolane (Sul). Single ion enthalpies of transfer for CF3SO3− and H+, from Me2SO to the other solvents, have been calculated using two extrathermodynamic assumptions, namely the tetraphenylarsonium–tetraphenylborate one and the recently proposed assumption based on the equality of transfers of uncharged PS and its conjugated cation PSH+. While both sets of transfer enthalpies using each assumption, for CF3SO3− and H+, differ by some 12 kJ mol−1 for water and MeOH, the values are in satisfactory agreement for Py, DMF, Me2SO, and Sul. These results support the validity of both extrathermodynamic assumptions for the nonprotogenic solvents, thus putting on firm ground the solvent basicity scale based on the enthalpy of transfer of H+ (in kJ mol−1): Py(−63) > DMF(−32) > Me2SO(−27) > EtOH(−1) ~ H2O(0) ~ MeOH(+2) > PC(+44) > MeCN(+55) > Sul(+68). These values correlate well with the enthalpies of complex formation with boron trifluoride. Key words: solvation, proton, trifluoromethanesulfonate ion, proton sponge, extrathermodynamic assumption.

scholarly journals Simulation of the electron-paramagnetic-resonance spectrum of the iron-protein of nitrogenase. A prediction of the existence of a second paramagnetic centre

1978 ◽  
Vol 175 (3) ◽  
pp. 955-957 ◽  
Author(s):  
D J Lowe
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Paramagnetic Resonance Spectrum ◽  
Complex Formation ◽  
Resonance Spectrum ◽  
The Other ◽  
Paramagnetic Centre ◽  
Paramagnetic Resonance ◽  
Iron Protein ◽  
Integrated Intensities ◽  
Electron Paramagnetic

The e.p.r. spectra of the Fe-proteins of nitrogenase from all sources studied have unusual features in that they have very anisotropic linewidths and low integrated intensities. These characteristics can be explained by assuming that one of the two electrons accepted by these proteins is located at a rapidly relaxing paramagnetic centre that is unobservable by e.p.r., but causes anisotropic broadening of the e.p.r. signal of the other electron. Complex-formation between Fe-proteins and MgATP is described in terms of a 50-60 degrees rotation of the e.p.r.-observable centre.

Polarization and apparent dipole moments of some symmetrical molecules

1991 ◽  
Vol 56 (2) ◽  
pp. 406-410 ◽  
Author(s):  
Otto Exner ◽  
Ivan Mach
Keyword(s):  
Complex Formation ◽  
Standard Method ◽  
Dipole Moments ◽  
The Other ◽  
Atomic Polarization ◽  
Other Hand ◽  
Unknown Structure ◽  
Apparent Orientation

Polarization and apparent dipole moments of a series of symmetrical molecules were determined by the standard method in three solvents: benzene, p-xylene, and mesitylene. Their explanation by complex formation with solvent applies only in the case of 1,4-dicyanobenzene and 4,4’-dicyanobiphenyl since the apparent orientation polarizations (PO.app) are large and depend strongly on solvent. On the other hand, 1,4-dihalogenbenzenes do not form any complexes and PO.appis virtually zero. 1,4-Dihalogenbicyclo[2,2,2]octanes reveal also considerable PO.app which is attributed mainly to enhanced atomic polarization but – in the case of heavier halogens – also partly to complexes of unknown structure.

Conformational Alterations of α2-Antiplasmin Induced by Complex Formation with Plasmin

1979 ◽  
Author(s):  
E.F. Plow ◽  
B. Wiman ◽  
D. Collen
Keyword(s):  
Complex Formation ◽  
Structural Changes ◽  
Limited Proteolysis ◽  
Terminal Region ◽  
The Other ◽  
Antigenic Determinants ◽  
Chemical Analyses ◽  
Large Fragment ◽  
Reactive Site ◽  
Immunodiffusion Analysis

The conformational and structural changes induced in the α2-antiplasmin (AP) molecule by complex formation with plasmin have been analyzed utilizing quantitative radioimmuno-chemical analyses. Complexes prepared in plasmin excess -(PAP-P) and therefore subjected to limited proteolysis and complexes prepared in AP excess (PAP-A) have been compared with free AP. With AP antiserum, PAP-A, PAP-P and AP yielded reactions of complete identity by immunodiffusion analysis. In radioimmunoassay, however, these were clearly distinguished, and four distinct sets of antigenic determinants were delineated. Set I determinants were expressed equivalently by PAP-P, PAP-A and AP and were, therefore, not altered by complex formation. This set was recognized by 90% of the antibodies, and the determinants were all included within a large fragment of Mr 60,000 derived from the NH2-terminal region of AP. The other three sets of determinants were modulated by complex formation. Set II was expressed by PAP-A and AP but not by PAP-P, and these were sensitive to proteolysis by plasmin. Set III determinants were expressed only by AP and were localized to a peptide of Mr 8,000 derived from the COOH-terminal region of AP. Set IV determinants were also present only on AP but were not present in the peptide and required an intact reactive site in AP for expression. Thus, there is evidence for multiple conformational modulations in AP induced by complex formation, and these modulations can be pinpointed to specific loci within the AP molecule.

Interactions between cations and sugars. III. Free energies, enthalpies, and entropies of association of Ca2+, Sr2+, Ba2+, La3+, Gd3+ with D-ribose in water at 25 °C

1987 ◽  
Vol 65 (11) ◽  
pp. 2656-2660 ◽  
Author(s):  
Alfredo Maestre Alvarez ◽  
Nicole Morel-Desrosiers ◽  
Jean-Pierre Morel
Keyword(s):  
Thermodynamic Properties ◽  
Aqueous Solutions ◽  
Equilibrium Constant ◽  
The Other ◽  
Free Energies ◽  
Mean Values ◽  
Enthalpies Of Transfer ◽  
Other Hand ◽  
Solutions Of Electrolytes

The standard enthalpies of transfer of ribose and arabinose from water to aqueous solutions of electrolytes (CaCl2, SrCl2, BaCl2, LaCl3, and GdCl3) have been measured at 25 °C. A method is described to calculate from these data the equilibrium constant and the enthalpy for the association between the cations and the complexing isomers of ribose. Mean values relative to these isomers are given: the constants vary from 2.0 to 4.3 and the enthalpies from −5.9 to −17.9 kJ mol−1 for the different cations studied. The thermodynamic properties of association are not related to the size nor to the charge of the complexed cation in a simple way. On the other hand, the enthalpies of reaction are linearly correlated to the entropies of reaction.

Conclusion

2017 ◽  
Author(s):  
Dia Da Costa
Keyword(s):  
Complex Formation ◽  
The Other ◽  
Production Rule ◽  
Creative Economy ◽  
Embodied Knowledge ◽  
Transformative Potential

The conclusion draws out main findings and contributions of a book that provides historical, spatial and ethnographic specificity to creative economy discourses and their critiques. It calls for provincializing creative economy discourses everywhere that they circulate; charting out and seeing the relational constitution of what counts as creativity in hegemonic and unrecognized creative practices; and attending to a visceral materialism that traces the complex formation of embodied knowledge produced in structures of production, rule and feeling. Ultimately, the praxis of the two troupes and the creative, transformative potential embedded in their suffering, despair and pessimism not only indicates and explains their hunger called theater, it also reminds us to reimagine creative economy in the image of creativity rather than the other way around.

THE PULSE HEIGHT DISTRIBUTION FROM BORON TRIFLUORIDE PROPORTIONAL COUNTERS IRRADIATED WITH 4.87-MEV. NEUTRONS

1955 ◽  
Vol 33 (5) ◽  
pp. 219-224 ◽  
Author(s):  
D. B. James ◽  
W. Kubelka ◽  
S. A. Heiberg ◽  
J. B. Warren
Keyword(s):  
Fast Neutron ◽  
Boron Trifluoride ◽  
Pulse Height ◽  
The Other ◽  
Height Distribution ◽  
Q Value ◽  
Pulse Height Distribution ◽  
Neutron Spectra ◽  
Proportional Counters ◽  
Q Values

Two boron trifluoride proportional counters, one containing normal isotopic boron and the other containing boron enriched to 96% B10, have been irradiated with 4.87-Mev. neutrons from the reaction D(d, n)He3. In addition to the reactions B10(n, α)Li7 and B10(n, α)Li7* with Q-values of 2.79 Mev. and 2.31 Mev. respectively, two other reactions have been observed. These are (i) F19(n, α)N16* with a Q-value of −1.77 ± 0.15 Mev. and (ii) either B10(n, p)Be10 or, much more probably, B10(n, t)Be8 with a Q-value of 0.35 ± 0.20 Mev. Owing to the presence of these two reactions, the analysis of complex fast-neutron spectra by the use of such counters is not feasible.

Complex Formation between Anisole and Boron Trifluoride: Structural and Binding Properties

2008 ◽  
Vol 112 (51) ◽  
pp. 13600-13608 ◽  
Author(s):  
Tao Lin ◽  
Weijiang Zhang ◽  
Lichang Wang
Keyword(s):  
Complex Formation ◽  
Boron Trifluoride ◽  
Binding Properties

scholarly journals Identification of Domains and Residues within the ɛ Subunit of Eukaryotic Translation Initiation Factor 2B (eIF2Bɛ) Required for Guanine Nucleotide Exchange Reveals a Novel Activation Function Promoted by eIF2B Complex Formation

2000 ◽  
Vol 20 (11) ◽  
pp. 3965-3976 ◽  
Author(s):  
Edith Gomez ◽  
Graham D. Pavitt
Keyword(s):  
Catalytic Activity ◽  
Complex Formation ◽  
Translation Initiation ◽  
Translation Initiation Factor ◽  
The Other ◽  
Initiation Factor ◽  
Missense Mutations ◽  
Nucleotide Exchange ◽  
Eukaryotic Translation ◽  
Eukaryotic Translation Initiation

ABSTRACT Eukaryotic translation initiation factor 2B (eIF2B) is the guanine nucleotide exchange factor for protein synthesis initiation factor 2 (eIF2). Composed of five subunits, it converts eIF2 from a GDP-bound form to the active eIF2-GTP complex. This is a regulatory step of translation initiation. In vitro, eIF2B catalytic function can be provided by the largest (epsilon) subunit alone (eIF2Bɛ). This activity is stimulated by complex formation with the other eIF2B subunits. We have analyzed the roles of different regions of eIF2Bɛ in catalysis, in eIF2B complex formation, and in binding to eIF2 by characterizing mutations in the Saccharomyces cerevisiaegene encoding eIF2Bɛ (GCD6) that impair the essential function of eIF2B. Our analysis of nonsense mutations indicates that the C terminus of eIF2Bɛ (residues 518 to 712) is required for both catalytic activity and interaction with eIF2. In addition, missense mutations within this region impair the catalytic activity of eIF2Bɛ without affecting its ability to bind eIF2. Internal, in-frame deletions within the N-terminal half of eIF2Bɛ disrupt eIF2B complex formation without affecting the nucleotide exchange activity of eIF2Bɛ alone. Finally, missense mutations identified within this region do not affect the catalytic activity of eIF2Bɛ alone or its interactions with the other eIF2B subunits or with eIF2. Instead, these missense mutations act indirectly by impairing the enhancement of the rate of nucleotide exchange that results from complex formation between eIF2Bɛ and the other eIF2B subunits. This suggests that the N-terminal region of eIF2Bɛ is an activation domain that responds to eIF2B complex formation.

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