Equilibrium studies of triphenyltin(IV) complexes with glycine, glycyl-glycine, and glycyl-glycyl-glycine in different aqueous solutions of ethanol

2010 ◽  
Vol 88 (9) ◽  
pp. 877-885 ◽  
Author(s):  
Morteza Jabbari ◽  
Farrokh Gharib
Keyword(s):  
Hydrogen Bond ◽  
Stability Constant ◽  
Formation Constants ◽  
Least Squares Regression ◽  
Hydrogen Bond Donor ◽  
Equilibrium Studies ◽  
Hydrogen Bond Acceptor ◽  
Complex Species ◽  
The Stability ◽  
Glycyl Glycine

The protonation equilibria of glycine (gly), glycyl-glycine (gly-gly), and glycyl-glycyl-glycine (gly-gly-gly) and their formation constants with triphenyltin(IV) chloride were studied over a wide pH range (pH 1–11), using a combination of spectrophotometric and potentiometric methods at constant temperature (25 °C), different ethanol–water mixtures (50%–80%, v/v), and constant ionic strength (0.1 mol dm–3 NaClO4). Least-squares regression calculations are consistent with the formation of ph3SnHL+, ph3SnL, and ph3SnH–1L– complex species, where L– represents the fully dissociated form of each ligand. The stability constant of the formed complexes in different media were analyzed in terms of Kamlet, Abboud, and Taft (KAT) parameters. Single-parameter correlations of the stability constants versus α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity), and for π* (dipolarity/polarizability) are relatively poor in all solutions, but multi-parameter correlations represent significant improvements with regard to the single- and dual-parameter models. Linear correlation is observed when the experimental logβxyz values are plotted versus the calculated ones, while all the KAT parameters are considered. Also, the stability constant values of the formed complexes are determined in zero percent of organic solvent using the Yasuda–Shedlovsky extrapolation approach. Finally, the results are discussed in terms of the effect of solvent on complexation.

Hydrolysis of dimethylphenyltin(IV) and triphenyltin(IV) chlorides in different aqueous ethanol solutions

2008 ◽  
Vol 86 (8) ◽  
pp. 751-756 ◽  
Author(s):  
Morteza Jabbari ◽  
Farrokh Gharib ◽  
Mostafa Mohammadpour Amini ◽  
Amirreza Azadmehr
Keyword(s):  
Hydrogen Bond ◽  
Aqueous Ethanol ◽  
Formation Constants ◽  
Single Parameter ◽  
Hydrogen Bond Donor ◽  
Hydrogen Bond Acceptor ◽  
Polarity Parameter ◽  
Wide Ph Range ◽  
Hydrogen Bond Acceptor Basicity ◽  
Hydrolysis Of

The hydrolysis of [(Me)2(Ph)Sn(IV)]+ and [(Ph)3Sn(IV)]+ has been investigated at 25 °C and different aqueous solutions of ethanol, using a combination of spectrophotometric and potentiometric techniques. The species formed together with their formation constants have been determined using the computer program Squad over a wide pH range of 1 to 11. The hydrolysis constants in different media were analyzed in terms of Kamlet and Taft parameters. Single-parameter correlation of the formation constants, K11 and K12, versus α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity), and π* (dipolarity/polarizability) for both cases are relatively poor in all solutions, but multiparameter correlation represents significant improvement with regard to the single-parameter models. In this work, we have also used the normalized polarity parameter, ETN, alone and in combination with the Kamlet–Taft parameter to find a better correlation of the formation constants in different aqueous ethanol solutions.Key words: dimethylphenyltin(IV) chloride, triphenyltin(IV) chloride, hydrolysis constant, aqueous ethanol solutions, solvent effect.

6,9-Dibromo-2a,10b-diphenyl-2a,5,10,10b-tetrahydro-2H,3H-2,3,4a,10a-tetraazabenzo[g]cyclopenta[cd]azulene-1,4-dione monohydrate

2006 ◽  
Vol 62 (5) ◽  
pp. o1754-o1755
Author(s):  
Neng-Fang She ◽  
Sheng-Li Hu ◽  
Hui-Zhen Guo ◽  
An-Xin Wu
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Title Compound ◽  
Supramolecular Structure ◽  
Hydrogen Bond Donor ◽  
Hydrogen Bond Acceptor ◽  
Compound C ◽  
Bifurcated Hydrogen Bond

The title compound, C24H18Br2N4O2·H2O, forms a supramolecular structure via N—H...O, O—H...O and C—H...O hydrogen bonds. In the crystal structure, the water molecule serves as a bifurcated hydrogen-bond acceptor and as a hydrogen-bond donor.

scholarly journals Machine learning models for hydrogen bond donor and acceptor strengths using large and diverse training data generated by first-principles interaction free energies

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Christoph A. Bauer ◽  
Gisbert Schneider ◽  
Andreas H. Göller
Keyword(s):  
Machine Learning ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Training Data ◽  
Free Energies ◽  
Hydrogen Bond Donor ◽  
Chemical Application ◽  
Hydrogen Bond Acceptor ◽  
Donor And Acceptor ◽  
Target Values

Abstract We present machine learning (ML) models for hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD) strengths. Quantum chemical (QC) free energies in solution for 1:1 hydrogen-bonded complex formation to the reference molecules 4-fluorophenol and acetone serve as our target values. Our acceptor and donor databases are the largest on record with 4426 and 1036 data points, respectively. After scanning over radial atomic descriptors and ML methods, our final trained HBA and HBD ML models achieve RMSEs of 3.8 kJ mol−1 (acceptors), and 2.3 kJ mol−1 (donors) on experimental test sets, respectively. This performance is comparable with previous models that are trained on experimental hydrogen bonding free energies, indicating that molecular QC data can serve as substitute for experiment. The potential ramifications thereof could lead to a full replacement of wetlab chemistry for HBA/HBD strength determination by QC. As a possible chemical application of our ML models, we highlight our predicted HBA and HBD strengths as possible descriptors in two case studies on trends in intramolecular hydrogen bonding.

scholarly journals The Characteristics of PD-L1 Inhibitors, from Peptides to Small Molecules

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1940 ◽  
Author(s):  
Yanwen Zhong ◽  
Xuanyi Li ◽  
Hequan Yao ◽  
Kejiang Lin
Keyword(s):  
Hydrogen Bond ◽  
Small Molecules ◽  
Pharmacophore Model ◽  
Amino Acid Residues ◽  
Tumor Treatment ◽  
Hydrogen Bond Donor ◽  
Treatment Results ◽  
Hydrogen Bond Acceptor ◽  
Checkpoint Pathway ◽  
Pharmacophore Models

The programmed cell death ligand protein 1 (PD-L1) is a member of the B7 protein family and consists of 290 amino acid residues. The blockade of the PD-1/PD-L1 immune checkpoint pathway is effective in tumor treatment. Results: Two pharmacophore models were generated based on peptides and small molecules. Hypo 1A consists of one hydrogen bond donor, one hydrogen bond acceptor, two hydrophobic points and one aromatic ring point. Hypo 1B consists of one hydrogen bond donor, three hydrophobic points and one positive ionizable point. Conclusions: The pharmacophore model consisting of a hydrogen bond donor, hydrophobic points and a positive ionizable point may be helpful for designing small-molecule inhibitors targeting PD-L1.

The determination of the stoichiometry and stability constant of weak complexes in solution: a restatement of the "straight-line" method

1983 ◽  
Vol 61 (6) ◽  
pp. 1100-1102 ◽  
Author(s):  
Aurelio Beltrán-Porter ◽  
José A. Ramírez
Keyword(s):  
Stability Constant ◽  
Stoichiometric Ratio ◽  
Complex Species ◽  
Line Method ◽  
Straight Line ◽  
Weak Complexes ◽  
The Stability ◽  
Degree Of Condensation ◽  
Straight Line Method

Usually, to establish the degree of condensation of a complex species in solution, primarily when it is a weak complex, is more cumbersome than to determine the stoichiometric ratio itself. The present work describes a modification of the Asmus method in order to render it suitable for the determination of the actual stoichiometric coefficients and the stability constant of weak complexes whatever the degree of condensation may be.

Infrared spectroscopic characterization of hydrogen-bonded propylene oxide − ethanol and propylene oxide − 2-fluoroethanol complexes isolated in solid neon matrices

2013 ◽  
Vol 91 (12) ◽  
pp. 1292-1302 ◽  
Author(s):  
Osama Y. Ali ◽  
Elyse Jewer ◽  
Travis D. Fridgen
Keyword(s):  
Hydrogen Bond ◽  
Propylene Oxide ◽  
Spectroscopic Characterization ◽  
Hydrogen Bond Donor ◽  
Hydrogen Bond Acceptor ◽  
Reduced Frequency ◽  
Enthalpy Of Proton Transfer ◽  
The Difference ◽  
Bonded Complexes ◽  
Hydrogen Bonded

The infrared absorption spectra of hydrogen-bonded complexes of propylene oxide with either ethanol or 2-fluoroethanol have been recorded in neon matrices. Mixtures of propylene oxide and ethanol or propylene oxide and 2-fluoroethanol vapors were mixed with an excess of neon gas and deposited onto a KBr substrate at 4.2 K. The results indicate that hydrogen-bonded complexes were formed with propylene oxide as the hydrogen bond acceptor and either ethanol or 2-fluoroethanol as the hydrogen bond donors. The features assigned to the O−H stretch were red-shifted by 175 and 193 cm−1 for the ethanol- and 2-fluoroethanol-containing complexes, respectively. The difference in red shifts can be accounted for due to the greater acidity of 2-fluroethanol. Deuterium isotope experiments were conducted to help confirm the assignment of the O–H stretch for the complexes. As well, structures and infrared spectra were calculated using B3LYP/6-311++G(2d,2p) calculations and were used to compare with the experimental spectra. A “scaling equation” rather than a scaling factor was used and is shown to greatly increase the utility of the calculations when comparing with experimental spectra. An examination of the O–H stretching red shifts for many hydrogen-bound complexes reveals a relationship between the shift and the difference between the acidity of the hydrogen bond donor and the basicity of the hydrogen bond acceptor (the enthalpy of proton transfer). Both hydrogen-bonded complexes and proton-bound complexes appear to have a maximum in the reduced frequency value that corresponds to complexes where the hydrogen/proton are equally shared between the two bases.

Enthalpies of interaction of nitrogen base solutes with organic solvents

1985 ◽  
Vol 63 (9) ◽  
pp. 2540-2544 ◽  
Author(s):  
W. Kirk Stephenson ◽  
Richard Fuchs
Keyword(s):  
Hydrogen Bond ◽  
Organic Solvents ◽  
Butyl Alcohol ◽  
Hydrogen Bond Donor ◽  
Butyl Ether ◽  
Hydrogen Bond Acceptor ◽  
Nitrogen Base ◽  
Benzene Toluene ◽  
Polar Interactions ◽  
S Model

Heats of solution of triethylamine, aniline, pyridine, and model compounds (3-ethylpentane, benzene) in 17 organic solvents (n-heptane, cyclohexane, carbon tetrachloride, 1,2-dichloroethane, α,α,α-trifluorotoluene, triethylamine, butyl ether, ethyl acetate, dimethylformamide, dimethyl sulfoxide, benzene, toluene, mesitylene, t-butyl alcohol, 1-octanol, methanol, 2,2,2-trifluoroethanol) have been combined with solute heats of vaporization to give enthalpies of transfer from vapor to solvent (ΔH(v → s)). Differences between solute and model values (ΔΔH(v → s) = ΔH(v → s) (solute) – ΔH(v → s) (model)) were used to evaluate nitrogen base solute–solvent polar interactions. Correlations of ΔΔH(v → s) with Taft–Kamlet solvatochromic parameters (π*, α, β) have been determined.Aniline was found to be a better hydrogen bond donor acid than hydrogen bond acceptor base. Nevertheless, alcohols donate H-bonds to aniline. Triethylamine and pyridine are stronger HBA bases than aniline. The π* (dipolarity–polarizability) parameter of aniline (as a solute) is calculated to be 1.10.

Aqueous Reactions of Sparingly Soluble Tellurites I. Silver Tellurite

1972 ◽  
Vol 50 (11) ◽  
pp. 1788-1791 ◽  
Author(s):  
M. C. Mehra ◽  
S. M. Kahn
Keyword(s):  
Experimental Data ◽  
Stability Constant ◽  
Constant Temperature ◽  
Solubility Product ◽  
Complex Species ◽  
Ionic Medium ◽  
The Stability ◽  
Aqueous Reactions

The aqueous interactions of the sparingly soluble silver tellurite show that in a controlled ionic medium and at a constant temperature, an aqueous complex,[Formula: see text] is formed in presence of free tellurite ions. The solubility product of silver tellurite and the stability constant of the complex species have been evaluated from the experimental data.

SINGLE MOLECULE IMMOBILIZATION OF π-CONJUGATED MOLECULES ON Au USING DENDRIMER-BASED TEMPLATES

2005 ◽  
Vol 04 (04) ◽  
pp. 467-473 ◽  
Author(s):  
ABDELHAK BELAISSAOUI ◽  
HIDEO TOKUHISA ◽  
EMIKO KOYAMA ◽  
MASATOSHI KANESATO
Keyword(s):  
Hydrogen Bond ◽  
Ftir Spectroscopy ◽  
Single Molecule ◽  
Binding Constant ◽  
Hydrogen Bond Donor ◽  
Hydrogen Bond Interaction ◽  
Hydrogen Bond Acceptor ◽  
Conjugated Molecules ◽  
The Core ◽  
Conjugated Molecule

We demonstrate that immobilization of a π-conjugated molecule containing a bipyridine moiety as a hydrogen bond acceptor on Au using a dendrimer-based template with 3,4-dihydroxybenzene moiety at the core as a hydrogen bond donor. The hydrogen bond interaction was used for the linkage between the conjugated molecule and the template to improve the method to fabricate single-molecule arrays we reported before.1 Although the binding constant is small ( K = 120 ± 20 M -1) in CDCl 3, it was demonstrated that the dendrimer spacer serves as a template to isolate the π-conjugated molecule, and is removable simply with a CH 2 Cl 2 rinsing by surface FTIR spectroscopy.

scholarly journals Review on Carbon Dioxide Absorption by Choline Chloride/Urea Deep Eutectic Solvents

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Rima J. Isaifan ◽  
Abdukarem Amhamed
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Bond ◽  
Ionic Liquids ◽  
Choline Chloride ◽  
Deep Eutectic Solvents ◽  
Absorption Capacity ◽  
Carbon Dioxide Absorption ◽  
Hydrogen Bond Donor ◽  
Separation Processes ◽  
Hydrogen Bond Acceptor

In the recent past few years, deep eutectic solvents (DESs) were developed sharing similar characteristics to ionic liquids but with more advantageous features related to preparation cost, environmental impact, and efficiency for gas separation processes. Amongst many combinations of DES solvents that have been prepared, reline (choline chloride as the hydrogen bond acceptor mixed with urea as the hydrogen bond donor) was the first DES synthesized and is still the one with the lowest melting point. Choline chloride/urea DES has proven to be a promising solvent as an efficient medium for carbon dioxide capture when compared with amine alone or ionic liquids under the same conditions. This review sheds light on the preparation method, physical and chemical characteristics, and the CO2 absorption capacity of choline chloride/urea DES under different temperatures and pressures reported up to date.

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