Electronic Chemical Potential Research Articles

Density functional theory study of the interplay between cation–π and intramolecular hydrogen bonding interactions in complexes involving methyl salicylate with Li+, Na+, K+, Be2+, Mg2+, Ca2+ cations

In the present study, the DFT (density functional theory) calculations are performed to gauge the effect of cation-π and intramolecular hydrogen bond (IMHB) interactions on each other in the formed complexes between methyl salicylate and Li+, Na+, K+, Be2+, Mg2+ and Ca2+ cations. The energetic, geometrical, topological parameters and the results of population analysis are applied to investigate these interactions. The calculations are carried out by using the atoms in molecules (AIM) and natural bond orbital (NBO) analyses. The computational results indicate that the presence of IMHB decreases/increases the binding energies in the mono/divalent complexes. On the other hand, the mutual influences of the IMHB and cation–π interactions decrease the IMHB strength of the studied systems. Finally, the frontier molecular orbital (FMO) analysis is employed to calculate the DFT-based global reactivity indices such as energy gap, chemical hardness and electronic chemical potential.

A key role of inner-cation-π interaction in adsorption of Pb(II) on carbon nanotubes: Experimental and DFT studies

Herein the adsorption and desorption of Pb2+ on oxidized (O-CNTs) and graphitized multi-walled carbon nanotubes (G-CNTs) were studied, and detailed adsorption mechanisms were discussed by experimental characterization and density functional theory (DFT) calculation. The adsorption of Pb2+ on CNTs was co-guided by complexation, ion exchange, electrostatic and cation-π interactions. According to the abnormally low release ratio of Pb2+ on both O-CNTs and G-CNTs (<9.03%), the O-containing groups on CNTs surface are not the only key factor affecting the adsorption behavior. The pore filling and complexation are the main mechanisms leading to irreversible adsorption, especially the important role of the inner-cation-π interaction in Pb2+ adsorption into the inner channel of CNTs at the high initial Pb2+ concentration, and DFT calculations further confirmed this result. The adsorption energy of the inner-cation-π interaction between Pb2+ and CNTs can be as high as − 77.851 kJ/mol, which is much higher than other interactions (≤−41.488 kJ/mol). Moreover, the stability of various adsorption mechanisms by HOMO-LUMO energy gap (Egap), electronic chemical potential (µ) and global hardness (η) were quantitatively measured and further revealed the inner-cation-π interaction is more stable. This study provides a deeper understanding of the removal of heavy metals by porous carbon-based nanomaterials.

1,3-Dipolar Cycloadditions by a Unified Perspective Based on Conceptual and Thermodynamics Models of Chemical Reactivity.

The main aim in the present report is to gain a deeper understanding of typical 1,3-dipolar cycloadditions by means of three chemical reactivity models in a unified perspective: conceptual density functional theory, distortion/interaction, and reaction force analysis. The focus is to explore the information provided by each reactivity model and how they complement or reinforce each other. Our results showed that the Bell-Evans-Polanyi (BEP) relationship is fulfilled, which is consistent with the Hammond-Leffler postulate. The electronic chemical potential based analysis classifies the reactions as HOMO-, HOMO/LUMO-, and LUMO-controlled reactions as the activation energy increases. It seems likely that HOMO-controlled reaction shifts into LUMO-controlled one as the transition state (TS) position does from early into late. Therefore, the transition from HOMO- (and early TS) into LUMO-controlled (and late TS) is paid by shifting the overall energy change into an endothermic direction, thus supporting the fulfillment of the BEP principle. While thermodynamic models unveil that the distortion or structural rearrangements mainly drive the activation barriers rather than interaction or electronic rearrangements in accord with the distortion/interaction and reaction force analysis, respectively. It is also found that both models are consistent when energy associated with structural and electronic reordering from reaction force analysis is respectively confronted with destabilizing (distortion and Pauli repulsion) and stabilizing (electrostatic and orbital interactions) contributions from the distortion/interaction model, which, on the other hand, increases as low activation barrier and high exothermicity are converted into the high barrier and low exothermicity along with the BEP relation. Finally, the reaction force constant reveals that all 1,3-dipolar cycloaddition reactions proceed by a synchronous single-step mechanism, unveiling that the degree of synchronicity is quite the same in all reactions, confirming the statement that BEP is fulfilled for similar reactions proceeding by a quite alike degree of synchronicity.

Spectral and Structural Characterization of Metformin with Different Counter Anions: Comparative Analysis and DFT Calculations

The metformin perchlorate (MetH+·ClO4 −) with a new crystal structure was synthesized, characterized and comparatively studied with other metformin salts of Cl− and NO3 − by different spectroscopic techniques such as TGA-DSC and FT-IR as well as UV-visible spectroscopic studies. DFT calculations were performed by rwb97xd and 6-31G+(d,p) basis set for structure optimization and frequency calculations. Similar to MetH+·Cl−, the crystal packing of MetH+·ClO4 −andMetH+·NO3 − were stabilized by hexagonal hydrogen bond elongated network. The relative stability and reactivity of these salts were determined by exploring the DFT chemical descriptors such as chemical hardness, electronegativity, electronic chemical potential, electrophilicity and hardness. These calculations were employed to get the subset of variables that could categorize the metformin salts according to their reactivity.

Experimental and computational investigations of some new cabamothioate compounds

The new derivatives of S-aryl (trichloroacetyl) carbamothioate were prepared from a two-component reaction of 2-naphthalenethiol or thiophenol derivatives and trichloroacetyl isocyanate in CH2Cl2 at room temperature at high yields. The reaction was a simple and efficient procedure with high yield and available stating materials in a short time for the synthesis of these compounds that no side reactions were observed. The structures of the products were confirmed by IR, 1H NMR, 13C NMR spectroscopy, and elemental analysis. Quantum theoretical calculations for the three structures of compounds (3a, 3b and 3c) were performed using the G3MP2, LC-ωPBE, MP2, and B3LYP methods with the 6-311+G(d,p) basis set. Geometric parameters of optimized the structures were compared with the experimental measurements. The structures of the products were confirmed by IR, 1H NMR, 13C NMR, and elemental analysis. IR spectra data and 1H NMR and 13C NMR chemical shifts computations of the compounds were calculated. Frontier molecular orbitals (FMOs), total density of states (DOS), thermodynamic parameters and molecular electrostatic potentials (MEP) of the title compounds were investigated by theoretical calculations. Molecular properties such as the ionization potential (I), electron affinity (A), chemical hardness (η), electronic chemical potential (μ) and electrophilicity (ω) were investigated for the structures. Consequently, there was an excellent agreement between experimental and theoretical results.

Study of the properties of sulfonic cation exchanger

In this research work, we have firstly synthesized the sulfonated polyvinyl chloride cation exchanger based on local raw materials. It was firstly created syntheses methodology of the sulfonated polyvinyl chloride cation exchanger and determined syntheses reaction parameters. It was first investigated that thermodynamics of synthesized the sulfonated polyvinyl chloride cation exchanger: kinetics, sorption isotherms, change of thermodynamics function (Gibbs energy, Entropy, and Entalpy). DFT calculation of synthesized the sulfonated polyvinyl chloride cation exchanger: energy difference between LUMO and HOMO molecular orbitals, Chemical Hardness (η), Electronegativity (χ), Electronic chemical potential (μ), Global electrophilicity Index (ω) and Chemical Softness (s) were firstly computed. We have used thermodynamic methods in doing thermodynamics research. The Frontier molecular orbital method was used on doing DFT calculation by 6-311G (d,p) basis set. These firstly synthesized the sulfonated polyvinyl chloride cation exchanger based on local raw materials is very cheap and effective; it will be used in the chemical industry for softening or cleaning waste water from Ca2+ or Mg2+ ions and different heavy ions. Electrochemical impedance measurements show that the quasi-substitution process has become between Mg+2 and Ca+2 ions and Na+ on the sulfonated polyvinyl chloride cation exchanger in the result of which growth of charge transfer and dielectric constant of mediums. Investigating thermodynamic parameters of this compound will be used for some purposes: a deep understanding of the thermodynamics of sorption processes and using determined thermodynamics in real production processes of water softened materials. DFT calculation investigating gives a deep understanding of how thermodynamics properties can depend on the molecular structure of water softened polymer materials.

N-Heterocyclic Carbenes–Cu

The electronic structures of N-heterocyclic carbenes (NHC) imidazolinylidene, thiazolinylidene, imidazolylidene, thiazolylidene, and 1,2,4-triazolylidene and their complexes with cuprous halides (CuX, X = Cl, Br, I) were investigated theoretically at the B3LYP/def2-SVP level. In contrast to other NHCs, imidazolylidene and 1,2,4-triazolylidene do not dimerize owing to the negligible coefficient of the vacant p-orbital at the carbene centre in their respective LUMOs. This is further supported by their greater thermodynamic and kinetic stabilities revealed by greater activation free energies and smaller standard free energies for their dimerization. Second-order perturbation interactions in the natural bond orbital (NBO) analysis of the NHCs indicate that six π electrons are delocalized in imidazolylidene, thiazolylidene, and 1,2,4-triazolylidene, conferring aromatic character and thereby enhancing their thermodynamic stability. NBO analysis reveals the existence of effective back bonding from a d orbital of Cu to the NHC, increasing the Wiberg bond index of the C–Cu bond to ~1.5. Owing to the large electronic chemical potential (μ) and high nucleophilicity indices, NHCs are able to transfer their electron density effectively to the cuprous halides having low μ values and high electrophilicity indices to yield stable NHC–CuI complexes. Large values of the Fukui function f(r) at the carbene centre of the NHCs and Cu atom of the NHC–CuI complexes indicate their softness. Imidazolylidene was found to be the softest, rationalizing wide use of this class of NHCs as ligands. The coordination of the NHCs to cuprous halides is either barrierless or has a very low activation free energy barrier. In the A3 reaction wherein NHC–Cu(I) complexes are used as catalyst, the reaction of NHC–CuI with phenylacetylene changes the latter into acetylide accompanied by raising the energy level of its HOMO considerably compared with the level of the uncomplexed alkyne, making its reaction with benzaldehyde barrierless.

Adsorption and Photocatalytic Reduction of Carbon Dioxide on TiO2

The photocatalytic activity of TiO2 depends on numerous factors, such as the chemical potential of electrons, charge transport properties, band-gap energy, and concentration of surface-active sites. A lot of research has been dedicated to determining the properties that have the most significant influence on the photocatalytic activity of semiconductors. Here, we demonstrated that the activity of TiO2 in the gas-phase reduction of CO2 is governed mainly by the desorption rate of the reaction intermediates and final products. This indicates that the specific surface area of TiO2 and binding strength of reaction intermediates and products are the main factors affecting the photocatalytic activity of TiO2 in the investigated process. Additionally, it was shown that rutile exhibits higher photocatalytic activity than anatase/rutile mixtures mainly due to its high efficiency in the visible portion of the electromagnetic spectrum.

Synthesis, X-ray structure, and DFT analysis of a binary complex of 3,3'-[(3-benzimidazolyl)methylene]bis(4-hydroxy-2H-1-benzopyran-2-one): 5-Methyl-1,3-thiazol-2(3H)-imine

A combined theoretical and experimental investigation on a pharmaceutically important binary complex 3,3'-[(3-benzimidazolyl)methylene]bis(4-hydroxy-2H-1-benzopyran-2-one): 5-methyl-1,3-thiazol-2(3H)-imine is presented in this manuscript. The compound crystallizes in the monoclinic crystal system with space group Cc with unit cell parameters: a = 19.8151(8) Å, b = 15.2804(6) Å, c = 8.3950(4) Å, β = 94.0990(10)°, V = 2535.36(19) Å3, Z = 4, T = 296(2) K, μ(MoKα) = 0.184 mm-1, Dcalc = 1.490 g/cm3, 35833 reflections measured (5.332° ≤ 2Θ ≤ 56.678°), 6168 unique (Rint = 0.0467, Rsigma = 0.0388) which were used in all calculations. The final R1 was 0.0435 (I &gt; 2σ(I)) and wR2 was 0.1073 (all data). The crystal structure has been determined by the conventional X-ray diffraction method, solved by direct methods and refined by the full matrix least squares procedure. Intramolecular hydrogen bonding of the type C–H⋅⋅⋅O and O–H⋅⋅⋅O is present and the crystal structure stabilizes via N–H…O, C–H…N and O–H…N intermolecular interactions. The optimized structural parameters have been compared and the parameters like ionization potential, electron affinity, global hardness, electron chemical potential, electronegativity, and global electrophilicity based on HOMO and LUMO energy values were calculated at B3LYP/6-311G(d,p) level of theory for a better understanding of the structural properties of the binary complex.

ЭЛЕКТРОННЫЙ МЕХАНИЗМ ВОССТАНОВИТЕЛЬНЫХ ПРОЦЕССОВ В ДОМЕННЫХ И ФЕРРОСПЛАВНЫХ ПЕЧАХ

The existing versions of the iron solid-phase reduction theory are based on atomic-molecular idea and consider reduction as an exchange between the oxide's molecules and a reducing agent (oxygen atoms). But them there are no atoms and molecules in solid oxides and metals. There are only ions and the electrons that bind them. Redox reactions are a process of exchange not by atoms, but by electrons. Therefore, it is impossible to create a consistent theory of processes taking place on another - electronic level from the standpoint of atomic-molecular representations. The electronic theory of reduction developed by the authors describes the electric and mass transfer in the gas and condensed phases, the exchange of electrons between the reducing agent and the oxide, the redistribution of electrons between cations and anions in the oxide lattice, and the transformation of the oxide crystal lattice into a metal lattice, as well as the effect of pressure and temperature on these processes. According to the theory, the direct result of the extraction of one oxygen anion from the crystal lattice on the oxide surface is the formation of an anionic vacancy and two free electrons connected with it. In complex and poor ores, vacancies and electrons are diffuse in the oxide volume, accumulate and merge at cations whose Fermi level is lower than the chemical potential of electrons in vacancies. The results known from experiments and the practice of producing cast iron and ferroalloys are explained by the participation in the oxidation-reduction reaction in the layer of low-temperature plasma charged particles solid reactants. Plasma is formed due to thermionic emission from the reducing agent surface the and thermal ionization of gases. It was shown that carbothermal reduction of active metals, as well as iron from strong complex oxides, occurs only with solid carbon. In this case, a counter-transfer of carbon to the oxide surface and oxide to the carbon surface occurs through the plasma, as a result of which carbide shells are formed on each surface of them. The formation of carbides etches the surface, slows down and stops recovery. The shells material melting and draining transfers the restoration into a kinetic process and ensures its effective flow.

Computational study of noncovalent interactions within the various complexes of para aminosalicylic acid and Cr2+, Mn+, Fe2+, Co+, Ni2+, Cu+, Zn2+ cations: exploration of the enhancing effect of the cation–π interaction on the intramolecular hydrogen bond

The quantum chemical calculations are performed to investigate the effect of cation–π interactions on structural and electronic characterization of the various complexes of para aminosalicylic acid with mono- (Mn+, Co+, Cu+) and divalent (Cr2+, Fe2+, Ni2+, Zn2+) metal cations. Topological analysis of the atoms in molecules is applied to evaluate the nature of the considered interactions. Electron populations obtained from the natural bond orbital analysis also give insight into the electron nature of the studied systems. The achieved outcomes from calculations show that the strongest/weakest interactions belong to the divalent/monovalent complexes. Besides, one O–H···O intramolecular hydrogen bond (H-bond) is observed in the analyzed complexes. Our findings indicate that the H-bond of complexes is placed in the medium H-bonds category. In addition, it can be stated that the O–H···O H-bond is strengthened/weakened by cation–π interactions in the presence of divalent/monovalent complexes. The energy gap, electronic chemical potential, chemical hardness, softness, and electrophilicity index are also calculated by using frontier molecular orbitals.

Determination of the structural, electronic, optoelectronic and thermodynamic properties of the methylxanthine molecules theophylline and theobromine.

RHF and DFT (wB97XD and B3LYP) methods with the 6-31++G** basis set have been used to study structural, optoelectronic and thermodynamic properties of Theophylline and Theobromine. Dipole moment, average polarizability, anisotropy, first-order molecular hyperpolarizability, second-order molecular polarizability, HOMO and LOMO energy gap, molar refractivity, chemical hardness, chemical softness, electronic chemical potential, electronegativity, electrophilicity index, dielectric constant, electric susceptibility, refractive index and their thermodynamic properties have equally been calculated. To understand the vibrational analysis of our system, IR and RAMAN frequencies were calculated and described. Results reveal that molecules can have applications in linear and nonlinear optical devices, photonic devices and in molecular electronics. Equally, from dipole moment, average polarizability, anisotropy, first-order molecular hyperpolarizability, second-order molecular polarizability, HOMO and LOMO energy gap, molar refractivity, chemical hardness, chemical softness, electronic chemical potential, electronegativity, electrophilicity index and literature we suggest that Theophylline and Theobromine be consider as candidates for the treatment of COVID-19 and other respiratory diseases.Electronic supplementary materialThe online version of this article (10.1007/s11082-020-02617-w) contains supplementary material, which is available to authorized users.

Effect of dynamic ions on band structure of plasmon excitations

In this paper, we develop a new method to study the plasmon energy band structure in multispecies plasmas. Using this method, we investigate a plasmon dispersion band structure of various quasineutral plasma systems with arbitrary degree of electron degeneracy. The linearized Schrödinger–Poisson model is used to derive an appropriate coupled pseudoforce system from which the energy dispersion structure is calculated. It is shown that the introduction of ion dynamics, as opposed to static ion assumption in the jellium model with a wide plasmon bandgap, can significantly modify the plasmon dispersion character leading to a new low-level energy band caused by the electron–ion interactions. The investigation on the effect of ion charge-state and chemical potential of electrons on the plasmonic band structure indicates some interesting features and reveals the fundamental role played by ions in the phonon assisted plasmon excitations in different kinds of plasma systems. Moreover, our study confirms that ion charge screening has a significant impact on plasmon excitations in multispecies plasmas. The plasmon band structure in pair-ion or electron–positron plasmas indicates the unique role of positive charges on collective excitations. Current research helps us to better understand the underlying mechanisms of collective interactions in charged environment and the important role played by heavy charged particles on elementary plasmon excitations, which have important applications in plasmonic devices. The method developed in this research may also be extended to study magnetized quantum plasmas as well as to investigate surface plasmon–polariton interactions in nanometallic structures.

Screening Effects on Electron Capture Rates and Type Ia Supernova Nucleosynthesis

Abstract Type Ia supernovae (SNe Ia) are believed to be a thermonuclear explosion of a white dwarf, but the mass of their progenitors is still an open problem. In near-Chandrasekhar-mass (near-M Ch) models of SNe Ia, the central density reaches ≳109 g cm−3. The electron chemical potential becomes higher than the Q-values of electron capture (EC) transitions between fp-shell nuclei, so a portion of the available electrons is captured by iron group elements and thus neutron-rich isotopes are formed. Since EC reaction rates are sensitive to the density, the degree of neutronization is a key to distinguish near- and sub-M Ch models. In order to compare observations and theoretical models, an accurate treatment of EC reactions is necessary. In previous theoretical works, however, effects of electron screening on ECs are ignored. Screening lowers EC rates and thus leads to a higher electron fraction. We implement electron screening on ECs to calculate explosive SN Ia nucleosynthesis in a near-M Ch single degenerate model. It is found that some of neutron-rich nuclear abundances, namely, those of 46,48Ca, 50Ti, 54Cr, 58Fe, 64Ni, and 67,70Zn, decrease when screening effects on ECs are considered. Of these, 50Ti, 54Cr, and 58Fe are particularly interesting because a significant portion of the solar abundance of these nuclei is presumed to originate from SNe Ia. We conclude that implementing the screening effect on ECs in modern SN Ia models is desirable to precisely calculate abundances of neutron-rich nuclides.

Topological and Electronic Properties of Chlorine-Substituents on the α-Diimine Ni-based Catalysts

The effect of substituent nature and position on a series of late transition metal catalysts based on nickel (A–D) was investigated practically and theoretically. Catalyst A bearing isopropyl groups on the ortho position showed the highest activity while for the ortho and para chlorine substituted catalysts B–D insignificant activities were observed. These experimental results were confirmed by theoretical study on the (pre)catalysts. Based on that, thermodynamics, atomic/molecular effective parameters such as bond distances, bond angles, band gap or chemical hardness, charge of Mulliken on Ni center, electronic chemical potential, global electrophilicity index and also activation energy of the pre-catalyst through the alkylation were calculated. To pursue the steric and electronic effects of substituent on the axial and equatorial sites of active center, electronic density, electron location function, localized orbital locator graphs as topological properties were studied. As a result, complex A with lower activation energy for alkylation, higher stability, greater Mulliken charge on Ni center and high electronic density around the active center was found as a highly active catalyst. In addition, polymerization conditions such as polymerization temperature and ethylene pressure showed significant effect on the catalysts productivity and branching density of the produced polyethylene.

Theoretical study of structural effects on reactivity and stability of isomeric pyrano-, thiopyrano-, and selenopyranopyrroles

In this study, global and local DFT reactivity descriptors for isomeric pyrano-, thiopyrano- and selenopyranopyrroles have been calculated. The geometric optimization of the obtained structures was realized with the density functional theory (DFT, B3LYP) at the level of 6-31G(d) and show these isomers have planar configurations. The structural properties such as dipole moments, bond lengths and bond angles of these isomers were calculated. The heats of formation have also been calculated based on the optimized geometry. The energies of HOMO and LUMO molecular orbitals are used to determine several global descriptors as a measure of their electronic properties, relative stabilities and chemical reactivities. These include total energy (E), ionization potential (I), electron affinity (A), chemical hardness (η), chemical softness (S), electronic chemical potentials (μ) and electrophilicity (ω). Selenopyrano[2,3-c]pyrrole possesses the highest electrophilicity and minimum chemical hardness among the calculated isomeric structures. The largest calculated dipole moment belongs to pyrano[3,2-b]pyrrole, while thiopyrano[3,4-b]pyrrole has the lowest.

Synthesis, spectroscopic characterization and antibacterial evaluation by chalcones derived of acetophenone isolated from Croton anisodontus Müll.Arg.

Chalcones and their derivatives have been widely studied at research institutions and industries, in order to verify their biological properties against various diseases. In this work, it was carry out the synthesis of chalcones (E)-3-(furan-2-yl) -1- (2‑hydroxy-3,4,6-trimethoxyphenyl) prop‑2-en-1-one (HYTFURFURAL) and (E) -1- (2‑hydroxy-3,4-dimethoxyphenyl) -3-(thiophen-2-yl) prop‑2-en-1-one (HYTTHIOPHENE) by Claisen-Schmidt aldolic condensation reaction. The molecular structures of these new heteroaryl chalcones have been elucidated and characterized by 1H and 13C Nuclear Magnetic Resonance, Fourier transform Raman (FT-Raman), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), and Ultraviolet-Visible (UV–Vis) spectroscopy. Calculations using the Functional Density Theory (DFT) were performed to predict the vibrational wavenumbers and to obtain the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) molecular orbitals, and starting from them, the quantum descriptors: vertical ionization energy (I), vertical electron affinity (A), chemical potential (μ), electronegativity (χ), global hardness (η), and electrophilicity index (ω). Antimicrobial and modulatory antibiotic activities of these chalones were also investigated. The mechanism of the NorA and MepA efflux pump inhibition was also studied by means of molecular docking. The HYTFURFURAL and HYTTHIOPHENE chalcones did not present intrinsic activity against the tested bacterial strains; however, they were able to potentiate the activity of norfloxacin against the SA1199B (NorA) strain, as well as the activity of ciprofloxacin against the K2068 (MepA) strain. These results indicate that the HYTFURFURAL and HYTTHIOPHENE chalcones are promising compounds as adjuvants to the norfloxacin and ciprofloxacin antibiotics in the treatment of infections caused by S. aureus.

Experimental and theoretical investigations of lignin-urea-formaldehyde wood adhesive: Density functional theory analysis

In view of its chemical structure, lignin has recently become an interesting candidate for various applications. This work serves to optimize the isolation process of lignin from sugar industry by-product (bagasse can, molasses beet) applying alkali treatment. For this purpose, the effect of alkali and sulfuric acid concentrations have been studied ranging from 10% (w/v) to 20% (w/v) and 1.5 M–3 M, respectively. Moreover, the isolated lignins were characterized by different complementary analysis such as FT-IR and TGA/DTG.The aim behind this work is to reduce formaldehyde emissions and improving mechanical as well as physical properties of wood adhesive. Lignin was added with different ratios, as partial substitution, in urea-formaldehyde (UF) (5:95; 10:90; 13:87 and 15:85, w: w) and compared to commercial control UF (0:100). Furthermore, a theoretical calculation, using the density functional theory (DFT)/B3LYP method validated that the coniferyl alcohol (G), sinapyl alcohol (S) and paracoumaryl alcohol (H) can suck up on the energy of the orbital borders, electronic affinity, electronic chemical potential and thermodynamic properties. The results obtained showed that the efficiency of these molecules is influenced with different degrees by several descriptors. It was also found that the compounds G and S out of H studied were more efficient within the density functional theory (DFT) at the B3LYP/6–31 (d,p) computational level.

Adsorption of acid Blue 25 dye by CPAA coated on SBA-15 in aqueous solution: A density functional theory study

In this research, the geometric and electronic structure of the Acid Blue 25 dye as adsorbate and SBA-15 mesoporous silica functionalized with cross-linked polyacrylic acid (CPAA) polymer (SBA-15/CPAA) as adsorbent are studied using density functional theory (DFT) in the aqueous phase. In order to determine the best site of the dye for interacting with adsorbent, the atomic Hirshfeld charges and frontier orbitals are investigated. The result of this investigation confirms that the sulfonate group of the dye is the best nucleophilic site. The adsorbent has two protonated sites (–NH2+ and = OH+) to attract dye anion. The evaluation of calculated adsorption energy, quantum descriptors such as electronic chemical potential (μ) and chemical hardness (η), dipole momentum and solvent effect are shown that the (–NH2+) group in comparison with (=OH+) group attracts the sulfonate group of the dye with more potent force and forms more stable complex. The adsorbent and adsorbate species have the full charge before adsorption. The results of computed transferred charge and the bond order determined that the interaction is mainly electrostatic. In this work, thermodynamic parameters such as enthalpy, entropy, and Gibbs free energy changes are calculated. The results of these parameters showed that the adsorption is an exothermic and spontaneous process. Besides, the obtained values of thermodynamic parameters are in the range of electrostatic interaction.

Reactivity and Stability of Metalloporphyrin Complex Formation: DFT and Experimental Study.

The interaction of three cationic porphyrins—meso-tetrakis (N-methylpyridinium-4-yl) porphyrin (TMPyP), meso-tetrakis (1,3-dimethylimidazolium-2-yl) porphyrin (TDMImP), and meso-tetrakis (1,2-dimethylpyrazolium-4-yl) porphyrin (TDMPzP)—with five heavy metals was studied computationally, and binding constants were calculated based on data obtained by an experimental method and compared. The reactivity and stability of their complexes formed with lead, cadmium, mercury, tin, and arsenic ions were observed in DFT global chemical reactivity descriptors: the electronic chemical potential (µ), chemical hardness (η), and electrophilicity (ω). The results show that M-TDMPzP has higher chemical hardness and lower electrophilicity compared to M-TMPyP and M-TDMImP, indicating the reaction of TDMPzP with metals will form a more stable complex. Specifically, Cd-TDMPzP complexes can stabilize the system, with a lower energy and electronic chemical potential, higher chemical hardness, smaller electrophilicity, and higher binding constant value compared to Pb-TDMPzP and Hg-TDMPzP. This result suggests that the interaction of the Cd2+ ion with TDMPzP will produce a stable complex.