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

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.

Binding Properties of 2-Acetylnaphthalene with Hydroxypropyl Cyclodextrins from Fluorescence Quenching Experiments

2005 ◽  
Vol 59 (5) ◽  
pp. 691-695 ◽  
Author(s):  
Maximilian Seel ◽  
T. C. Werner
Keyword(s):  
Complex Formation ◽  
Fluorescence Quenching ◽  
Binding Site ◽  
Thermodynamic Parameters ◽  
Binding Constant ◽  
Binding Constants ◽  
Dispersion Forces ◽  
Binding Properties ◽  
Hydroxypropyl Cyclodextrins

The quenching of 2-acetylnaphthalene (2-AN) fluorescence by hydroxypropyl cyclodextrins (HP-CD) has been analyzed using modified Stern–Volmer plots to obtain binding constants as a function of temperature for 2-AN:HP-CD complexes. The HP-CDs were commercially available and contained 4–7 HP groups per CD molecule for α-CD, β-CD, and γ-CD. HP substitution causes a 12 to over 40% increase in binding constant ( Kave) for 2-AN compared to that for unsubstituted CDs, although the Kave value is not strongly dependent on the extent of HP substitution for β-CD. No evidence of formation of a 2:2 complex, such as that observed with 2-AN and γ-CD, is observed with 2-AN and HP-γ-CD. Thermodynamic parameters (ΔH°o and ΔS°o) suggest that the increase in Kave with HP substitution is due to an enlarged binding site for the HP-CDs that allows greater motional freedom for 2-AN. Comparison is made to the binding of 2-methylnaphthoate (2-MN) to CDs and HP-CDs, and the larger Kave values for 2-MN over 2-AN are attributed to greater dispersion forces for 2-MN complex formation.

scholarly journals Interactions of Aβ1-42 Peptide and Its Three Fragments (Aβ8-12, Aβ8-13, and Aβ5-16) with Selected Nonsteroidal Drugs and Compounds of Natural Origin

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1579
Author(s):  
Krzysztof Żamojć ◽  
Karolina Streńska ◽  
Dariusz Wyrzykowski ◽  
Lech Chmurzyński ◽  
Joanna Makowska
Keyword(s):  
Molecular Dynamics ◽  
Steady State ◽  
Amino Acid ◽  
Complex Formation ◽  
Amino Acid Residues ◽  
Binding Properties ◽  
Natural Origin ◽  
Steady State Fluorescence ◽  
The Stability ◽  
Steady State Fluorescence Spectroscopy

In the following paper, we present the results of our studies on the interactions of the Aβ1-42 peptide and its three short fragments, namely Aβ5-16 (RHDSGYEVHHQK; HZ1), Aβ8-13 (SGYEVH; HZ2), and Aβ8-12 (SGYEV; HZ3) with selected painkillers (ibuprofen and aspirin) and compounds of natural origin (anabasine and epinephrine). Steady-state fluorescence spectroscopy was used to study the binding properties of the selected systems. Additionally, based on molecular dynamics (MD) calculations supported by NMR-derived restrains, we have proposed the most likely area of the interactions of Aβ1-42 and Aβ5-16 peptides with the investigated compounds. The influence of symmetrically oriented side chains of amino acid residues present in the first part of the Aβ1-42 sequence on the stability of the resulting complexes has been discussed. Finally, the changes in the peptide structures on account of complex formation were analyzed.

scholarly journals Formation of Intermediate Transcription Initiation Complexes at pfliD and pflgM by ς28 RNA Polymerase

2001 ◽  
Vol 183 (21) ◽  
pp. 6244-6252 ◽  
Author(s):  
Jennifer R. Givens ◽  
Colleen L. McGovern ◽  
Alicia J. Dombroski
Keyword(s):  
Complex Formation ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
General Phenomenon ◽  
Temperature Dependent ◽  
Binding Properties ◽  
Serovar Typhimurium ◽  
Open Complex Formation ◽  
Flagellum Biosynthesis ◽  
Dna Strand

ABSTRACT The ς subunit of prokaryotic RNA polymerase is an important factor in the control of transcription initiation. Primary ς factors are essential for growth, while alternative ς factors are activated in response to various stimuli. Expression of class 3 genes during flagellum biosynthesis in Salmonella enterica serovar Typhimurium is dependent on the alternative ς factor ς28. Previously, a novel mechanism of transcription initiation at the fliC promoter by ς28holoenzyme was proposed. Here, we have characterized the mechanism of transcription initiation by a holoenzyme carrying ς28 at the fliD and flgM promoters to determine if the mechanism of initiation observed at pfliC is a general phenomenon for all ς28-dependent promoters. Temperature-dependent footprinting demonstrated that promoter binding properties and low-temperature open complex formation are similar for pfliC, pfliD, and pflgM. However, certain aspects of DNA strand separation and complex stability are promoter dependent. Open complexes form in a concerted manner at pflgM, while a sequential pattern of open complex formation occurs at pfliD. Open and initiated complexes formed by holoenzyme carrying ς28 are generally unstable to heparin challenge, with the exception of initiated complexes at pflgM, which are stable in the presence of nucleoside triphosphates.

Sign in / Sign up

Export Citation Format

Share Document