Condensed Fukui Function Research Articles

Reactivity and a Charge-Transfer Model Analysis in Aminopolycarboxylic-Metal Complexes.

In the present work, we have calculated several density functional theory (DFT) reactivity descriptors for the aminopolycarboxylate (APC) acids at the B3LYP/6311++G (d,p) levels of theory, aiming to analyze their reactivity. Reactivity descriptors such as ionization energy, molecular hardness, electrophilicity, and condensed Fukui function local indices have been determined to predict the reactivity of APCs. The influence of the solvent was taken into account by employing the CPCM model. The results indicate that the solvation slightly modifies the tendency of the reactivity of the APCs studied. On the other hand, we applied a global and local charge-transfer partitioning model, which introduces two charge-transfer channels [one for accepting electrons (electrophilic) and another for donating one (nucleophilic)] to the complexation reaction of a set of APC acids with transition metals (Mn, Co, and Ni targets enlarged by Fe, Cu, and Zn). The correlation between the charges obtained for the interaction between APC acids and transition metal stability constants provides support for their interpretation as measures of the electrophilicity and nucleophilicity of a chemical species and, at the same time, allows one to describe the donation and back-donation processes in terms of the DFT of chemical reactivity. Also, the application of dual descriptors for these acids provides valuable information concerning the atoms in the reactants playing the most important roles in the reaction, thus helping to improve our understanding of the reaction under study.

Synthesis, Crystallographic, Quantum Chemical, Antitumor, and Molecular Docking/Dynamic Studies of 4-Hydroxycoumarin-Neurotransmitter Derivatives.

In this contribution, four new compounds synthesized from 4-hydroxycoumarin and tyramine/octopamine/norepinephrine/3-methoxytyramine are characterized spectroscopically (IR and NMR), chromatographically (UHPLC-DAD), and structurally at the B3LYP/6-311++G*(d,p) level of theory. The crystal structure of the 4-hydroxycoumarin-octopamine derivative was solved and used as a starting geometry for structural optimization. Along with the previously obtained 4-hydroxycoumarin-dopamine derivative, the intramolecular interactions governing the stability of these compounds were quantified by NBO and QTAIM analyses. Condensed Fukui functions and the HOMO-LUMO gap were calculated and correlated with the number and position of OH groups in the structures. In vitro cytotoxicity experiments were performed to elucidate the possible antitumor activity of the tested substances. For this purpose, four cell lines were selected, namely human colon cancer (HCT-116), human adenocarcinoma (HeLa), human breast cancer (MDA-MB-231), and healthy human lung fibroblast (MRC-5) lines. A significant selectivity towards colorectal carcinoma cells was observed. Molecular docking and molecular dynamics studies with carbonic anhydrase, a prognostic factor in several cancers, complemented the experimental results. The calculated MD binding energies coincided well with the experimental activity, and indicated 4-hydroxycoumarin-dopamine and 4-hydroxycoumarin-3-methoxytyramine as the most active compounds. The ecotoxicology assessment proved that the obtained compounds have a low impact on the daphnia, fish, and green algae population.

Crystal structure, surface analysis, and computational investigations of 1-(4‑chloro-3-nitrophenyl)-6,7-dihydro-1H-benzo[d][1,2,3]triazol-4(5H)-one as potential acceptor molecule for photovoltaics applications

Crystal structure of 1-(4‑chloro-3-nitrophenyl)-6,7-dihydro-1H-benzo[d][1,2,3]triazol-4(5H)-one has been investigated. Different basis sets were screened with functional B3LYP using DFT method to predict accurate geometry and properties. Non-covalent interactions were studied using Hirshfeld surface while intra-molecular interactions are investigated using NBO analysis. Frontier molecular orbital analysis was performed in gas phase and in aqueous medium. Vibrational assignments to various bond vibrations were made theoretically and compared with experimental values. UV-visible spectra was calculated using TD-DFT calculations and compared with experimentally recorded spectrum. Exciton binding energy, open circuit voltage, and electron reorganization energy were calculated. Chemical reactivity descriptors were calculated in different medium and results are compared. Condensed Fukui function analysis predicts strong electron accepting ability of compound. Dipole moment, polarizability and molecular refractivity was also calculated theoretically in different mediums.

Structure, Vibrational Analysis and Chemical Reactivity Descriptors of 4-Bromo-3-(Methoxymethoxy) Benzoic Acid: A DFT Study

In this study, the structure and various molecular parameters of 4-bromo-3-(methoxymethoxy) benzoic acid are determined at the B3LYP/6-311++G(d,p) level of theory. Present study provides comparision and discussion of calculated and experimental optimized parameters. The values of descriptors such as ionization energy, hardness, electrophilicity, condensed Fukui function and energy were determined to predict the reactivity of 4-bromo-3-(methoxymethoxy) benzoic acid. The influence of the solvent on reactivity parameters has been studied adopting the PCM model. The analysis shows that solvation alters the values of reactivity descriptors. A vibrational assessment of the molecule has also been performed. To gain a better understanding of the properties of the title molecule, parameters such as the molecular electrostatic potential surface and the HOMO-LUMO band gap have been computed. The dipole moment, polarizability and hyperpolarizability were also estimated to probe into non-linear optical properties of the chemical.

Experimental and theoretical spectroscopic properties of 2,3-Dimethoxybenzaldehyde using quantum chemical method

The interpretation of active functional groups have been characterized by FT-IR and FT-Raman spectroscopies with the help of potential energy distributions. Hartree-Fock (HF) calculations of the 2,3-Dimethoxybenzaldehyde (DMBA) carried out by 6-311++G(d,p) basis set. Hyperconjugative associations present in the particle were likewise evaluated utilizing normal bond orbital (NBO) examination. The condensed Fukui functions explored the sites available for nucleophilic and electrophilic attack in the form of local based descriptors.

Spectroscopic, quantum mechanical, electronic excitation properties (Ethanol solvent), DFT investigations and molecular docking analysis of an anti-cancer drug Bendamustine

In this investigation, optimization geometry of the molecule, FT-IR, FT-Raman, and UV-Vis spectra, vibrational frequencies, assigning of suitable vibrational modes of Bendamustine (an anti-cancer drug) were summarised on the grounds of distribution of potential energy. Spectroscopic investigations are attempted by employing DFT/B3LYP with 6-311++G (d, p) level. The output of the computations was implemented to model the spectra of the Bendamustine, which agrees well with the recorded spectra. The TDFT had been utilized to compute the strengths of oscillators. To ascertain the transfer of charge inside the molecule HOMO and LUMO analytics have been utilized. The NBO investigation has been employed to verify the stability of the molecule by observing internal charge transfer, hyperconjugation, and energy of stabilization. Molecular electrostatic potential and Mulliken's charges were thoroughly studied by using DFT methods. The NLO characteristics of the title drug molecule were investigated with B3LYP and HF basis functionals. The reactive sites and reactivity of the title drug molecule have been extensively studied with help of condensed Fukui functions and global descriptors. The molecular docking investigations of the title drug molecule were executed with the DNA binding protein of Cellular Tumour Antigen P53.

Synthesis, in vitro and in silico antitumor evaluation of 3-(2,6-dichlorophenyl)-1,5-diphenylpentane-1,5‑dione: Structure, spectroscopic, RDG, Hirshfeld and DFT based analyses

New bischalcone derivative 3-(2,6-dichlorophenyl)-1,5-diphenylpentane-1,5‑dione (C23H18Cl2O2) has been efficiently synthesized and the solid state formation of the grown crystals was characterized by X-ray crystallographic diffraction (XRD)analysis at 296 K. The single crystal XRD results show that the title compound belongs to triclinic system with unit cell dimensions, a = 9.4104 (12) (Å), b = 10.2951(13) (Å), c = 10.9411(15) (Å) and V = 980.9(Å3). The key contributor intermolecular interactions C‒O···H/H···O‒C were explored by Hirshfeld surface analysis. The active functional group interpretations have been carried using FT-IR and FT-Raman spectroscopies with the assistance of energy distributions. Density functional theory (DFT) calculations of the synthesized compound carried out for better understanding of molecular futures. Hyperconjugative interactions present in the molecule were also quantified using natural bond orbitals (NBO). Reactivity and stability of the title molecule assessed utilizing global reactivity descriptors. The condensed Fukui functions explored the available electrophile and nucleophile regions in the form of local based descriptors. The reduced density gradient (RDG) isosurfaces reveals the dominance of non-bonded interactions of the title compound. MTT assay revealed that the title compound had potentiate antitumor activity against human lung cancer A549 cells with 40.71 µg/mL IC50 value. Moreover the capability of the compound to be interconnected within the key amino acids of lung cancer receptor binding sites was detected by molecular docking. Antibacterial and antifungal efficacy of the title compound studied using Kirby-Bauer disc diffusion technique.

Molecular structure, interactions, and antimicrobial properties of curcumin-PLGA Complexes-a DFT study.

Density functional calculations are performed to study the molecular structure, interactions, and antimicrobial activity of curcumin-poly lacto glycolic acid (Cur-PLGA) complexes. The calculations are performed on curcumin (Cur), glycolic acid (SSC and AAT conformers), lactic acid (LA), Cur-SSC, Cur-AAT, Cur-LA, and Cur-PLGA complexes using dispersion corrected M06-2X functional with 6-31 + G* basis set. The condensed Fukui functions of Cur are calculated to identify the favorable reactive sites. Inter- and intramolecular H-bond interactions are analyzed in detail through natural bond orbital, Atoms in Molecule, and Reduced density gradient analyses. The interaction energy values indicate that the interaction between Cur and AAT is stronger than the other studied complexes. Further, our calculations show that the PLGA interacted with Cur is having lower LUMO energy and density values. This indicates that the antimicrobial activity is high in this complex.

Inhibition Effect of Atenolol on Copper Corrosion in 1M HNO3: Experimental Study and DFT

Atenolol was examined as a copper corrosion inhibitor in 1M nitric acid solution using the mass loss technique and quantum chemical studies, based on density functional theory (DFT) at the B3LYP level with the base 6-311G (d,p). The inhibitory efficiency of the molecule increases with increasing concentration and temperature. The adsorption of the molecule on the copper surface follows the modified Langmuir model. The thermodynamic quantities of adsorption and activation were determined and discussed. The calculated quantum chemical parameters related to the inhibition efficiency are the energy of the highest occupied molecular orbital E(HOMO), the energy of the lowest unoccupied molecular orbital E(LUMO), the HOMO-LUMO energy gap, the hardness (η), softness (S), dipole moment (μ), electron affinity (A), ionization energy (I), absolute electronegativity (χ),absolute electronegativity (χ), fraction (ΔN) of electrons transferred from Atenolol to copper and electrophilicity index(ω). The local reactivity was analyzed through the condensed Fukui function and condensed softness indices to determine the nucleophilic and electrophilic attack sites. There is good agreement between the experimental and theoretical results.

Modeling Vitexin and Isovitexin Flavones as Corrosion Inhibitors for Aluminium Metal

Theoretically, the aluminium corrosion inhibitive performance of vitexin (VTX) and isovitexin (SVT) were evaluated with a view of establishing the mechanism of the inhibition process. Calculations which include the consideration of several global descriptors were studied to describe and correlate the reactivity of the molecules with the computed descriptors. First and second-order condensed Fukui functions were employed to analyze local reactivity parameters, while simulations involving the adsorbed molecules on Al (1 1 0) surface were conducted through quench dynamic simulations and the mechanism of physical adsorption was established with SVT relatively been a better inhibitor on Al surface than VTX.

Mechanism of urea decomposition catalyzed by Sporosarcina pasteurii urease based on quantum chemical calculations

ABSTRACT To provide theoretical guidance for better healing ability of microbial self-healing concrete, the mechanism of urea decomposition catalyzed by Sporosarcina pasteurii urease in Microbial Induced Carbonate Precipitation was investigated by quantum chemical calculations. The active site model considering bonded residues, non-bonded residues, and flap region residues was established. The formation of initial coordination, the state change of bound water, and the role of residues in the catalytic process were investigated by analysing electrostatic potential, condensed Fukui function, cavity volume, and reaction path using Gaussian, Multiwfn, and POCASA. The results showed that the O atom in urea tended to form initial coordination with Ni1 when urea entered the active site, after which W1 and W3 would be expelled. As the flap region changed from open to closed, W2 would be expelled. Carbamate anion was generated and ammonia was released by the nucleophilic attack of bridging hydroxide (WB) and the proton transfer of Asp363 residue. Carbamic acid was generated and Ni1-WB-Ni2 was regenerated by the proton transfer of Ala366 and Asp363 residues when W4 re-entered the active site. The proton transfer process involving the non-bonded residue Ala366 was the rate-determining step with an energy barrier of 10.39 kcal/mol.

Teaching a neural network to attach and detach electrons from molecules

Interatomic potentials derived with Machine Learning algorithms such as Deep-Neural Networks (DNNs), achieve the accuracy of high-fidelity quantum mechanical (QM) methods in areas traditionally dominated by empirical force fields and allow performing massive simulations. Most DNN potentials were parametrized for neutral molecules or closed-shell ions due to architectural limitations. In this work, we propose an improved machine learning framework for simulating open-shell anions and cations. We introduce the AIMNet-NSE (Neural Spin Equilibration) architecture, which can predict molecular energies for an arbitrary combination of molecular charge and spin multiplicity with errors of about 2–3 kcal/mol and spin-charges with error errors ~0.01e for small and medium-sized organic molecules, compared to the reference QM simulations. The AIMNet-NSE model allows to fully bypass QM calculations and derive the ionization potential, electron affinity, and conceptual Density Functional Theory quantities like electronegativity, hardness, and condensed Fukui functions. We show that these descriptors, along with learned atomic representations, could be used to model chemical reactivity through an example of regioselectivity in electrophilic aromatic substitution reactions.

Density Functional Theory Reactivity Studies on X3N@C80 (X = Sc, Gd, Lu) Fullerenes

Density functional theory studies have been performed to reveal the reactivity of the sites in Sc3N@C80, Gd3N@C80 and Lu3N@C80 endohedral fullerenes. The condensed Fukui functions have been calculated using Mulliken atomic charges. The calculations show that the carbon atom sites are in direct contact with the endohedral cluster favourable nucleophilic attack. Similarly, the carbon atoms which are away from the direct bonding with the cluster are favourable for the electrophilic attack. This is also confirmed from the charge transfer analysis. It is noted that the spin multiplicity decides the reactivity sites and stability of the Gd3N@C80 system. The HOMO-LUMO gap value indicates that Gd3N@C80 with S = 7 is stable than the S = 21 system. Finally, present studies indicate that the charge transfer between the C80 cage and X3N plays a major role to determine the reactivity of the sites in the C80 cage.

Role of the nucleophilicity of the amino group of benzidines in the synthesis of hemiaminal ethers

This paper presents a study of the reaction between some aromatic amines and formaldehyde in ethanol. Anisidines reacting with formaldehyde produced cyclic or linear aminals (hexahydrotriazines or methanediamines) whilst benzidines produced hemiaminal ethers (N,N′-bis(alkoxymethyl)benzidines) by reacting with formaldehyde, using alcohol as solvent. Condensed Fukui functions were calculated for the amines studied here, thereby enabling it to be established that the course of the reaction depends on the nucleophilicity of the amino functionality.

Aromaticity indices, electronic structural properties, and fuzzy atomic space investigations of naphthalene and its aza-derivatives

The aromaticity and CDFT properties of naphthalene and its aza-derivatives were theoretically investigated using density functional theory (DFT) electronic structure method. The reactivity and chemistry of Azanaphthalene (1-AN), 1, 2-diazanaphthalene (1, 2-DAN), 1, 3-diazanaphthalene (1, 3-DAN), 1, 4-diazanaphthalene (1,4-DAN), 1, 5-diazanaphthalene (1, 5-DAN), 1, 6-diazanaphthalene (1, 6-DAN), 1, 7-diazanaphthalene (1,7-DAN) and 1, 8-diazanaphthalene (1, 8-DAN) were thoroughly explored and predicted focusing more on the fuzzy atomic space analysis, quantum chemical descriptors (CDFT), natural bond orbital (NBO), and structural electronic properties. The CDFT is focused on predicting the condensed Fukui function and dual descriptors along with condensed local electrophilicity and nucleophilicity investigation. From the aromaticity computational study, 1,7-DAN gave PDI, FLU, FLU-π, PLR, HOMA, BIRD and LOLIPOP values of approximately one (1) was found to be the most aromatic in the group, and strongest π-stacking ability. The aromaticity follows the trend: 1, 7-DAN > 1, 8-DAN > 1, 5-DAN > 1, 6-DAN > 1, 4-DAN > 1, 2-DAN > 1-AN > naphthalene. The second order perturbation energy NBO analysis revealed that the 3 highest stabilization energies in the molecules are C6–Na to C3–C4(π∗−π∗ 236.90 kcal/mol) of 1, 6-DAN, C3–C4 to C1–C2 (π∗−π∗236.37 kcal/mol) of 1-AN and C7–N10 to C2–C4 (π∗−π∗235 kcal/mol) of 1, 3-DAN.

Dispersion-corrected density functional theory studies on glycolic acid-metal complexes

The structure and metal complexation studies using dispersion-corrected density functional theory methods are performed for four stable glycolic acid conformers named SSC, GAC, SAC, and AAT. The condensed Fukui functions are calculated to study the favourable reactive site for metal binding on the glycolic acid conformers. The interaction of alkali metal ions (Na+, K+) with different binding sites (carboxyl, hydroxyl oxygen) of the glycolic acid conformers in the gas phase is investigated at the same level of theory. Our calculations show that the order of stability changes into SSC > AAT > GAC = SAC due to the binding of the metal ion. The relative energy values indicate that the AAT conformer is more stable than the GAC and SAC conformers. This occurs when a metal ion (Na+, K+) is bound with the carboxyl oxygen atom of glycolic acid. The QTAIM, RDG, NCI, ELF, LOL, and NBO analysis are employed in this work to understand the strength of intra- and intermolecular interactions in the glycolic acid metal complexes.

Structural properties, magnetism and reactivity of [formula omitted] nanoalloys

Nickel-iron nanoparticles are magnetic and reactive. Both properties depend on the relative concentration of nickel and iron, which noticeably affects certain catalytic reactions among other applications. Density Functional Theory calculations, in the generalized gradient approximation to exchange and correlation, were conducted for neutral and charged Ni13-xFex nanoalloys with the aim of obtaining, from a first principles perspective, a better understanding of how the atomic structure, chemical order, magnetic properties, and reactivity depend on the composition and charge state. The atomic and electronic structures were determined without symmetry constraints for low-energy isomers with an exhaustive scan of the structural, homotopic, and spin degrees of freedom. The relative stability was analyzed in terms of the excess energy and the second difference in energy; the global reactivity was assessed by means of DFT indicators like the electronegativity and chemical hardness; local reactivity within each nanoalloy was characterized through the condensed Fukui functions. Finally, the first stage of oxidation is explored for the most and less reactive of the investigated nanoalloys.

Mechanistic insight into the degradation of ibuprofen in UV/H2O2 process via a combined experimental and DFT study

The study investigated the degradation kinetic and transformation mechanism of ibuprofen (IBP) in UV/H2O2 process from both experimental and theoretical aspects. Impacts of H2O2 dosage, solution pH, quenching agent, and concentration of nitrite (NO2−) on IBP degradation in UV/H2O2 process were evaluated. Both experimental results and theoretical calculations indicated that •OH played an important role in the degradation of IBP and its transformation products. The second-order rate constants of •OH and •NO2 with IBP were calculated as 3.93 × 109 M−1 s−1 and 5.59 × 10−3 M−1 s−1, based on the transition state theory, which explained the phenomenon that addition of NO2− inhibited IBP degradation. Further, according to the results of ultra-high-resolution mass and density functional theory calculations, mechanisms of a detailed degradation pathway for IBP were clarified. Namely, the detailed mechanistic formation pathways for hydroxylated and keto-based products were proposed. Then, possible active sites of the keto-based products, as well as the corresponding subsequent products were predicted by Condensed Fukui Function. Our study can broaden the knowledge of the reactions of emerging contaminants with •OH, and provide theoretical foundation for the optimization of UV/H2O2 process.

DFT investigations on arylsulphonyl pyrazole derivatives as potential ligands of selected kinases

AbstractUsing the density functional theory (DFT) formalism, we have investigated the properties of some arylsulphonyl indazole derivatives that we studied previously for their biological activity and susceptibility to interactions of azoles. This study includes the following physicochemical properties of these derivatives: electronegativity and polarisability (Mulliken charges, adjusted charge partitioning, and iterative-adjusted charge partitioning approaches); free energy of solvation (solvation model based on density model and M062X functional); highest occupied molecular orbital (HOMO)–lowest occupied molecular orbital (LUMO) gap together with the corresponding condensed Fukui functions, time-dependent DFT along with the UV spectra simulations using B3LYP, CAM-B3LYP, MPW1PW91, and WB97XD functionals, as well as linear response polarisable continuum model; and estimation of global chemical reactivity descriptors, particularly the chemical hardness factor. The charges on pyrrolic and pyridinic nitrogen (the latter one in the quinolone ring of compound 8, as well as condensed Fukui functions) reveal a significant role of these atoms in potential interactions of azole ligand–protein binding pocket. The lowest negative value of free energy of solvation can be attributed to carbazole 6, whereas pyrazole 7 has the least negative value of this energy. Moreover, the HOMO–LUMO gap and chemical hardness show that carbazole 6 and indole 5 exist as soft molecules, while fused pyrazole 7 has hard character.

Mechanism study on the oxidation of ethylbenzene: A theoretical and computational approach

The oxidation mechanism of ethylbenzene to acetophenone by tert-butyl hydrogen peroxide has been studied at the (U)M06-2X-D3/def2-SVP level of theory. Results showed that a series of hydrogen abstraction processes and radical combination lead to the formation of the 1,1-dimethylethyl-1-phenylethyl peroxide, which is a key intermediate. Then the decomposition of this peroxide generates acetophenone and other by-products. Condensed Fukui Function and Natural Bond Orbital theory were applied to reveal the reaction position and explain chemical stereoselectivity. Two notable hyperconjugation effects were also reported in the transition state structure.