scholarly journals Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2689
Author(s):  
Franjo Frešer ◽  
Gregor Hostnik ◽  
Jelena Tošović ◽  
Urban Bren
Keyword(s):  
Dft Calculations ◽  
Gallic Acid ◽  
Coordination Compound ◽  
Density Functional ◽  
Ph Dependence ◽  
Building Blocks ◽  
Formation Constants ◽  
Molar Ratio ◽  
Compound Formation ◽  
Vis Spectroscopy

One important property of tannins involves their ability to form coordination compounds with metal ions, which is vital for the bioavailability of these ions, as well as for the antibacterial and antioxidative activities of tannins. In this study, the pH dependence of interactions between gallic acid, one of the basic building blocks of tannins, and Fe(II) ions, was investigated using UV/Vis spectroscopy, in conjunction with density functional theory (DFT) calculations. Moreover, two models were developed to explain the processes taking place in the solution. The first model treated the reaction as a simple bimolecular process while the second also considered the protolytic equilibrium, which was proven very successful in discerning the pH dependence of formation constants, and whose assumptions were well supported by DFT calculations. We showed that the two-time deprotonated gallic acid species forms the coordination compound with Fe(II) ions in a 1:1 molar ratio. To gain better insight into the process, the coordination compound formation was also studied using various DFT functionals, which further supported the model results. Furthermore, due to the relatively low sample amounts needed, the methodology developed here will be useful to study compounds that are more difficult to isolate.

The Affinity of Indium(III) for Nitrogen-donor Ligands in Aqueous Solution. A Study of the Complexing of Indium(III) with Polyamines by Differential Pulse Voltammetry, Density Functional Theory, and Crystallography

2007 ◽  
Vol 62 (3) ◽  
pp. 386-396 ◽  
Author(s):  
James M Harrington ◽  
Karen A. Oscarson ◽  
S. Bart Jones ◽  
Joseph H. Reibenspies ◽  
Libero J. Bartolotti ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Differential Pulse Voltammetry ◽  
Density Functional ◽  
Differential Pulse ◽  
Formation Constants ◽  
Donor Ligands ◽  
Nitrogen Donor Ligands ◽  
Diglycolic Acid ◽  
Nitrogen Donor ◽  
Pulse Voltammetry

The affinity of In(III) for N-donor ligands was investigated by differential pulse voltammetry, DFT calculations, and crystallography. The structure of [In(tpen)(CH3COO)](ClO4)2 ・ 0.5H2O (1) is reported (tpen = N,N,N´ ,N´-tetrakis(2-pyridylmethyl)ethylenediamine): Monoclinic, P21/n, a = 8.687(4), b = 7.767(8), c = 20.432(10) Å , β = 93.372(8)°, Z = 4, R = 0.0518. The In(III) center is 7-coordinate, with six In-N bonds to the tpen ligand in the range 2.306 - 2.410 Å, and a unidentate acetate group with In-O = 2.247 Å. The formation constants of In3+ in 0.1 M NaNO3+ at 25 °C are (M = In(III), L = ligand, H = proton): L = triethylenetetramine, logβ (MLH2) = 25.3±}0.3, logK1 = 14.43±}0.09, and logβ (ML(OH)2) = 27.7±}0.1; tetraethylenepentamine, logβ (MLH) = 20.8±}0.2, and ML (logβ (ML) = 20.1±}0.3); diglycolic acid, (logβ (MLH) = 8.06±}0.06), logK1 = 6.02±} 0.06, logβ2 = 9.40±}0.08; tpen, logK1 = 17.71±}0.07; N,N´-bis(2-pyridylmethyl)ethylenediamine, logK1 = 14.69±}0.05; 1,10-phenanthroline, logK1 = 6.81±}0.07, logK2 = 6.44±}0.07, logK3 = 6.20±}0.08. Correlations are shown between the determined formation constants for the polyamines and logK1(NH3) values for a wide variety of metal ions. For M(II) ions, the log K1(NH3) values are experimental data, but for M(III) ions the data are predicted by an empirical dual-basicity equation, including logK1(NH3) = 4.0 for In(III). DFT calculations are used to obtain ΔE for the reaction [M(H2O)6]n+ + NH3 ⇆[M(H2O)5NH3]n+ + H2O for M(II) through M(IV) ions in water, represented as a structureless medium with the dielectric constant of water. Correlations are found that support the predicted value of logK1(NH3) for In(III) of 4.0. The nature of the intercepts on such correlations are discussed.

scholarly journals Novel Insights into the Configurations of Lead(II)-Benzohydroxamic Acid Coordination Compounds in Aqueous: A Combined Experimental and Computational Study

2018 ◽  
Author(s):  
Jianyong He ◽  
Haisheng Han ◽  
Chenyang Zhang ◽  
Dandan Yuan ◽  
Mengjie Tian ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Computational Study ◽  
First Principle ◽  
X Ray Diffraction ◽  
Esi Ms ◽  
Benzohydroxamic Acid ◽  
Vis Spectroscopy ◽  
Experimental Approaches ◽  
Principle Density Functional Theory

Novel collector lead(II)-benzohydroxamic acid (Pb [II]-BHA) complexes in aqueous solution were characterized by using experimental approaches, including Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction spectroscopy (PXRD), Ultraviolet-visible (UV-Vis) spectroscopy, and electrospray ionization–mass spectrometry (ESI-MS), and first-principle density functional theory (DFT) calculations with consideration of solvation effects. The Job plot delineated that a single coordinated Pb(BHA)+ should be formed first, and the binary structures of Pb(BHA)2 can be formed subsequently. Moreover, the Pb(II)-BHA species aggregated with each other to form highly complicated structures. ESI-MS results validated the existence of Pb-(BHA)n=1,2. The well-consistent infrared spectra from the DFT calculations and FTIR measurements indicated that the cis-amide (Za)-type BHA conformer may be dominant in the solid-state crystals of BHA. The first-principle calculations suggested that Pb(BHA)2 should be the most stable structure, and the Pb atom in Pb(BHA)+ will play as an active site to attack nucleophiles. These findings are meaningful to further illustrate the adsorption mechanism of Pb(II)-BHA complexes in mineral processing.

scholarly journals Determination of optimal feed profile in semi-batch reactor: DFT and experimental studies on a Case Study of parallel and serial reactions take place

2021 ◽  
Author(s):  
Bugra AKMAN ◽  
Omur ARAS ◽  
Yunus KAYA
Keyword(s):  
Bisphenol A ◽  
Dft Calculations ◽  
Density Functional ◽  
Batch Reactor ◽  
Experimental Studies ◽  
Basis Set ◽  
Molar Ratio ◽  
Stoichiometric Ratio ◽  
Acetone Concentration ◽  
By Products

Semi-batch reactor systems can be used at different areas due to its advantages of the feed manipulation. Common practices are temperature control of the exothermic reactions or selectivity adjustment of the production process include serial and parallel reactions. Bisphenol A (BPA) is theoretically synthesized with 2 moles of phenol and 1 mol of acetone. During the reaction, a stoichiometric ratio or high acetone concentration causes the formation of by-products. This situation has been confirmed by density functional theory (DFT) calculations. In these calcula-tions, the B3LYP method and the 6-311++G(d, p) basis set were used. DFT calculations show that by-products can be formed in the synthesis of bisphenol a. The common method used to solve the by-product problem is to work with high molar phenol/acetone ratios. But this brings additional operating and investment costs. In this study, semi-batch reaction experiments were performed which stoichiometric acetone was fed in reactor with various pulsed modes in the presence of homogenous and heterogonous catalysts. Time versus conversion and selectivity data were collected at various catalyst concentrations. All runs were compared with the results of batch and semi-batch runs performed in over molar ratio of phenol/acetone. As a result, it has been shown that high conversion and selectivity can be achieved by providing energy efficiency with pulsed mode semi batch reactor.

scholarly journals Synthesis of HZSM-5 Rich in Paired Al and Its Catalytic Performance for Propane Aromatization

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 622
Author(s):  
Dezhi Shi ◽  
Sen Wang ◽  
Hao Wang ◽  
Pengfei Wang ◽  
Li Zhang ◽  
...  
Keyword(s):  
Density Functional ◽  
Catalytic Performance ◽  
Molar Ratio ◽  
Propane Conversion ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Molar Ratios ◽  
Propane Aromatization ◽  
Vis Spectroscopy ◽  
Stabilization Effect

A series of HZSM-5 catalysts with similar Si/AlF mole ratio, textual properties and morphology, but different contents of AlF pairs, were synthesized by controlling the Na/Al molar ratios in the precursor gel and used for propane aromatization. It is shown that the catalyst with a Na/Al molar ratio of 0.8 in the synthetic gel possesses the highest paired AlF concentration (64.4%) and shows higher propane conversion (38.2%) and aromatics selectivity (19.7 wt.%). Propane pulse experiments, micro reactor activity estimation, Operando diffuse reflectance ultraviolet-visible (DR UV-vis) spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) analysis of coke species deposited on the catalysts provide evidence that AlF pairs in the ZSM-5 framework promote oligomerization and cyclization reactions of olefins, and then produce more aromatics. Density Functional Theory (DFT) calculations demonstrate that the cyclization of olefins and hydride transfer reaction occurring on AlF pairs in HZSM-5 zeolite show a lower free energy barrier and a higher rate constant than those on single AlF, indicating that the structure of AlF pairs in the HZSM-5 zeolite has a stronger electrostatic stabilization effect on the transition states than that of single AlF.

Computationally Assisted Design of High Signal-to-Noise Photoinduced Electron Transfer-Based Voltage-Sensitive Dyes

2020 ◽  
Author(s):  
Rishikesh Kulkarni ◽  
Anneliese Gest ◽  
Chun Kei Lam ◽  
Benjamin Raliski ◽  
Feroz James ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dft Calculations ◽  
Photoinduced Electron Transfer ◽  
Density Functional ◽  
Embryonic Stem ◽  
High Sensitivity ◽  
Md Simulations ◽  
High Signal ◽  
Signal To Noise ◽  
Green Fluorescent

<p>High signal-to-noise optical voltage indicators will enable simultaneous interrogation of membrane potential in large ensembles of neurons. However, design principles for voltage sensors with high sensitivity and brightness remain elusive, limiting the applicability of voltage imaging. In this paper, we use molecular dynamics (MD) simulations and density functional theory (DFT) calculations to guide the design of a bright and sensitive green-fluorescent voltage-sensitive fluorophore, or VoltageFluor (VF dye), that uses photoinduced electron transfer (PeT) as a voltage-sensing mechanism. MD simulations predict an 11% increase in sensitivity due to membrane orientation, while DFT calculations predict an increase in fluorescence quantum yield, but a decrease in sensitivity due to a decrease in rate of PeT. We confirm these predictions by synthesizing a new VF dye and demonstrating that it displays the expected improvements by doubling the brightness and retaining similar sensitivity to prior VF dyes. Combining theoretical predictions and experimental validation has resulted in the synthesis of the highest signal-to-noise green VF dye to date. We use this new voltage indicator to monitor the electrophysiological maturation of human embryonic stem cell-derived medium spiny neurons. </p>

Efficient Prediction of Structural and Electronic Properties of Hybrid 2D Materials Using DFT and Machine Learning

2018 ◽  
Author(s):  
Sherif Tawfik ◽  
Olexandr Isayev ◽  
Catherine Stampfl ◽  
Joseph Shapter ◽  
David Winkler ◽  
...  
Keyword(s):  
Machine Learning ◽  
Band Gap ◽  
Density Functional ◽  
2D Materials ◽  
Van Der Waals ◽  
Building Blocks ◽  
Machine Learning Techniques ◽  
Interlayer Distance ◽  
Computational Screening ◽  
Wide Range

Materials constructed from different van der Waals two-dimensional (2D) heterostructures offer a wide range of benefits, but these systems have been little studied because of their experimental and computational complextiy, and because of the very large number of possible combinations of 2D building blocks. The simulation of the interface between two different 2D materials is computationally challenging due to the lattice mismatch problem, which sometimes necessitates the creation of very large simulation cells for performing density-functional theory (DFT) calculations. Here we use a combination of DFT, linear regression and machine learning techniques in order to rapidly determine the interlayer distance between two different 2D heterostructures that are stacked in a bilayer heterostructure, as well as the band gap of the bilayer. Our work provides an excellent proof of concept by quickly and accurately predicting a structural property (the interlayer distance) and an electronic property (the band gap) for a large number of hybrid 2D materials. This work paves the way for rapid computational screening of the vast parameter space of van der Waals heterostructures to identify new hybrid materials with useful and interesting properties.

Spectroscopic investigations and DFT studies of synthesized 4-acetamidophenyl 3,4,5-trimethoxybenzoate and 4-acetyl phenyl 3,4,5-trimethoxybenzoate a novel conjugate of gallic acid

2020 ◽  
Vol 17 ◽  
Author(s):  
Sangeeta Srivastava ◽  
Nadeem Ahmad Ansari ◽  
Sadaf Aleem
Keyword(s):  
Gallic Acid ◽  
Density Functional ◽  
Energy Gap ◽  
Basis Set ◽  
Major Constituent ◽  
Orbital Energy ◽  
Reactivity Descriptors ◽  
Homo And Lumo ◽  
Electrophilic Reactivity ◽  
Global And Local

: Gallic acid is abundantly found in amla (Phyllanthus emblica), a deciduous of the family phyllanthaceae. Gallic acid, the major constituent of the plant was methylated to 3,4,5 trimethoxy gallic acid, which then underwent steglich esterification first with paracetamol and then with 4-hydroxy acetophenone to yield 4-acetamidophenyl 3,4,5-trimethoxybenzoate and 4-acetyl phenyl 3,4,5-trimethoxybenzoate “respectively”. 1H NMR, 13C NMR, UV, FT-IR and mass spectroscopy were used to characterize the synthesized compounds. Density functional theory (B3YLP) using 6-31G (d,p) basis set have been used for quantum chemical calculations. AIM (Atom in molecule) approach depicted weak molecular interactions within the molecules whereas the reactive site and reactivity within the molecule were examined by global and local reactivity descriptors. The HOMO and LUMO energies and frontier orbital energy gap were calculated by time dependant DFT approach using IEFPCM model. Small value for HOMO–LUMO energy gap indicated that easier charge transfer occurs within compound 4. The nucleophilic and electrophilic reactivity were determined by MEP (molecular electrostatic potential) experiment. Polarizability, dipole moment, and first hyperpolarizability values were calculated to depict the NLO (nonlinear optical) property of both the synthesized compounds. The antimicrobial activity was also carried out and broad spectrum antibacterial activity against several strains of bacteria and certain unicellular fungi were exhibited by synthesized compound 3.

Photoreaction of 3,4-dimethoxy-1-nitrobenzene with butylamine. A pH dependence of regioselectivity

1986 ◽  
Vol 51 (8) ◽  
pp. 1665-1670 ◽  
Author(s):  
Petr Kuzmič ◽  
Libuše Pavlíčková ◽  
Jiří Velek ◽  
Milan Souček
Keyword(s):  
Ph Dependence ◽  
Molar Ratio

Irradiation of 3,4-dimethoxy-1-nitrobenzene in the presence of butylamine leads to the formation of both possible photosubstitution products, i.e., 2-methoxy-4-nitro-N-butylaniline and 2-methoxy-5-nitro-N-butylaniline with the predominance of the latter. Regioselectivity of the reaction as measured by molar ratio of the two isomeric products varies with pH of the solution, ranging from 3 : 1 at pH 10 to 12. The results are discussed in view of possible use of 3,4-dimethoxy-1-nitrobenzene moiety as a lysine-directed photoaffinity probe.

scholarly journals One-step synthesis of nitrogen-grafted copper-gallic acid for enhanced methylene blue removal

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shella Permatasari Santoso ◽  
Vania Bundjaja ◽  
Artik Elisa Angkawijaya ◽  
Chintya Gunarto ◽  
Alchris Woo Go ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Adsorption Capacity ◽  
Gallic Acid ◽  
Synthesis Method ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
One Step ◽  
Detailed Assessment ◽  
Higher Temperature

AbstractNitrogen-grafting through the addition of glycine (Gly) was performed on a metal- phenolic network (MPN) of copper (Cu2+) and gallic acid (GA) to increase its adsorption capacity. Herein, we reported a one-step synthesis method of MPN, which was developed according to the metal–ligand complexation principle. The nitrogen grafted CuGA (Ng-CuGA) MPN was obtained by reacting Cu2+, GA, and Gly in an aqueous solution at a molar ratio of 1:1:1 and a pH of 8. Several physicochemical measurements, such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), N2 sorption, X-ray diffraction (XRD), and thermal gravimetry analysis (TGA), were done on Ng-CuGA to elucidate its characteristics. The analysis revealed that the Ng-CuGA has non-uniform spherical shaped morphology with a pore volume of 0.56 cc/g, a pore size of 23.25 nm, and thermal stability up to 205 °C. The applicational potential of the Ng-CuGA was determined based on its adsorption capacity against methylene blue (MB). The Ng-CuGA was able to adsorb 190.81 mg MB per g adsorbent at a pH of 6 and temperature of 30 °C, which is 1.53 times higher than the non-grafted CuGA. Detailed assessment of Ng-CuGA adsorption properties revealed their pH- and temperature-dependent nature. The adsorption capacity and affinity were found to decrease at a higher temperature, demonstrating the exothermic adsorption behavior.

γ-Valerolactone-Introduced Controlled-Isomerization of Glucose for Lactic Acid Production over Sn-Beta Catalyst

2021 ◽  
Author(s):  
Xinpeng Zhao ◽  
Zhimin Zhou ◽  
hu luo ◽  
Yanfei Zhang ◽  
Wang Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Lactic Acid ◽  
Dft Calculations ◽  
Acid Production ◽  
Density Functional ◽  
Lactic Acid Production ◽  
Hydrothermal Conversion ◽  
Functional Theory ◽  
Environment Friendly

Combined experiments and density functional theory (DFT) calculations provided insights into the role of the environment-friendly γ-valerolactone (GVL) as a solvent in the hydrothermal conversion of glucose into lactic acid...

Sign in / Sign up

Export Citation Format

Share Document