Fukui Indices Research Articles

Spectroscopic and reactive properties of a newly synthesized quinazoline derivative: Combined experimental, DFT, molecular dynamics and docking study

The molecular geometry, the normal mode wavenumbers and corresponding vibrational assignments, natural bond orbital analysis and the HOMO-LUMO analysis of 3-(4-oxo-phenethyl-3,4-dihydroquinazolin-2-ylthio)-N-(3,4,5-trimethoxyphenyl)propanamide were performed by B3LYP level of theory using the 6-311++G(d,p)(5D,7F) basis set. The experimentally obtained wavenumbers are in agreement with the theoretically predicted wavenumbrs. From the MEP plot it is evident that the negative charge covers carbonyl group, mono substituted phenyl ring, O59 atom and the positive region is over the nitrogen atoms and hydrogen atoms. NLO behavior of the title molecule was investigated by the determination of the first and second order hyperpolarizabilities. The molecular orbitals and molecular electrostatic potential map are also reported. The NMR spectra and Fukui indices are also analyzed. Molecule sites important from the aspect of reactivity have been determined by calculations of average local ionization energy (ALIE), Fukui functions and bond dissociation energies (BDE). BDE for hydrogen abstraction served us to investigate the possibility for autoxidation mechanism of the investigated molecule. Molecular dynamics (MD) simulations were used in order to investigate which atoms of the title molecule have the most pronounced interactions with water molecules. Molecular docking studies reveal that the inhibitor forms a stable complex with HNE as is evident from the binding affinity −10.9 kcal/mol and the results suggest that the compound exhibit inhibitory activity against HNE.

Effect of Constituent Units, Type of Interflavan Bond, and Conformation on the Antioxidant Properties of Procyanidin Dimers: A Computational Outlook

Procyanidin (PC) dimers are powerful antioxidants, abundant in plant tissues, and also bioavailable. However, the role of the molecular structure of PCs on their antioxidant properties is still a controversial and not fully understood issue that needs to be addressed in a more specific way. The objective of this study was to analyze the effect of the constituent units, type of interflavan bond, and conformation on the antioxidant properties of PC dimers including PB3, PB4, PB5, PB6, PB7, and PB8, using the density functional theory (DFT) computational method. The analysis was performed in function of parameters that allow determining the ability of the molecules to transfer or to capture electrons, among which the chemical potential, bond dissociation enthalpy (BDE), gap energy, Fukui indices, and charge distribution of HOMO-LUMO orbitals. The factors that showed the most notable effects on the antioxidant properties of the PC dimers were the type of interflavan bond and the conformation. The antioxidant ability of the dimers PB3 and PB4 containing the interflavan bond C4–C8, in their Compact conformation, was very similar to each other but greater than those of dimers PB5, PB6, PB7, and PB8 containing the C4–C6 interflavan bond. PB8 showed the lowest antioxidant ability.

Phenol oxidation through its adduct formation with chromium complex of 1,4,8,11-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane: A theoretical study

Structural and electronic properties of [cis-[Cr(tmpcH)X2]n+ (n = 2 or 4; X = OH−, Cl−, Br− and H2O; tmpcH = 1,4,8,11-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane were analyzed by DFT and TD-DFT methods. The local reactivity active site of the ligand was determined by the condensed-to atom Fukui indexes (CAFI) f(r). In the study, the axial bond distance with metal ion undergoes a considerable change from shorter to longer as OH < Cl− < Br− < H2O, agreeing with the molecular orbital analysis where the dz2 energy is lowered for OH− compared to H2O at the axial position. After analyzing the geometrical data collected from literature for the complexes of Cr(II), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn (II) with tmpcH, it was found that the bond distance decreases with increasing number of d-electrons in the 3d orbital, suggesting that the over-lapping of oribital (π) from Npy with the metal d-orbital is more effective than those from Ncyclam with metal d-orbital. Therefore, the change of different oxidation states for [cis-[Cr(tmpcH)X2]n+ influences significantly the geometrical and electronic parameters. For cis-[Cr(tmpcH)Cl2]2+ the calculated bands are red shifted except for the lower energy band (595 nm) which agrees qualitatively with the experimental one; in addition, the effect of solvent on the electronic transition was analyzed. Furthermore, we collected the electronic data for several chromium complexes from the literature, and compared with our results by plotting the data against number of chromium compounds. Finally, the phenol oxidation properties of the chromium complexes were studied, and phenol forms an adduct with [Cr(tmpcH)Cl]3+ to yield [Cr(tmpcH)Cl-OPh]2+ which could produce the phenol radical, which is enhanced by the presence of -OCH3 group at para- position in the phenolic ring.

The reactive activities of natural amino acids: key principles of peptide-templated Au cluster synthesis

Coating of gold nanoclusters with peptides is an important targeting method in biomedical applications. However, their synthetic method highly influences their targeting ability. Current methods often use harsh reagents and organic solvents to control morphology, which are not preferred for biomedical applications. Recently, several peptides with specific amino acid sequences have successfully been used to reduce Au ions and synthesize biocompatible peptide-covered gold particles in situ. However, the molecular mechanism of peptide-assisted nanocluster formation is yet unclear. Thus, reactive abilities of different amino acids should be studied to improve design of peptides with predetermined amino acid content and consequently, synthesize gold nanoclusters with improved performance. In this theoretical study, we have approximated the reactive abilities of 20 natural amino acids in their neutral state using density functional theory calculations, such as Fukui indices and HOMO/LUMO composition analysis. We have found that the top reducing agents are tryptophan, histidine, and tyrosine, and the strongest binding can be expected from methionine and cysteine. Further study of the exact reactive sites in these high reactive amino acids provided the deep insight for the peptide design route for the targeted gold nanocluster formation.

Understanding field variation, quantum chemical modeling and molecular orbital analyses of trans-3-(trans-4-imidazolyl) acrylic acid

In this work, a joint experimental (FTIR and FT-Raman) and theoretical (DFT and ab-initio) study on the structure and the vibrations of Trans-3-(trans-4-imidazolyl) acrylic acid (TTIAA) are compared and analyzed. The assignment of each normal mode has been made using the observed and calculated frequencies. The optimized geometries, harmonic vibrational wavenumbers and intensities of vibrational bands of trans-3-(trans-4-imidazolyl) acrylic acid (TTIAA) have been carried out using the HF/B3LYP method using the standard 6311++G(d,p) basis set calculations in this investigation. The result describes the variation in electrostatic and transport properties for zero and various external applied field. The variation in MPA charges are small due to the application of EFs: however, in most cases it is found to be systematic and almost uniform. When the field increases from 0.00 to 0.02 VÅ−1, the hybridization of molecular levels broadens the DOS and decreases the HLG from 3.6609 to 1.2325 eV; the decrease of band gap at the high field indicates that this molecule exhibit considerable electrical conductivity. Fukui indices to determine the local reactive site for the molecular systems during electrophilic, nucleophilic, radical and dual descriptor attacks. The results clearly show the superiority of MPA scheme. This study may be useful to design new molecules with more electrical conductivity.

Synthesis, Characterisation, and in Vitro Antibacterial Evaluation of a New Class of 2-substituted-4-methyl-7,8-dihydro-5H-pyrimido[4,5-d]thiazolo[3,2-a] Pyrimidines

The reaction of 2,4-dichloro-5-(chloromethyl)-6-methylpyrimidine with 4,5-dihydrothiazol-2-amine in chloroform led to the formation of 2-chloro-4-methyl-7,8-dihydro-5H-pyrimido[4,5-d]thiazolo[3,2-a]pyrimidine (3). The true structure of the target compound was confirmed by density functional theory calculations of condensed Fukui indices. The substitution of the 2-Cl function in compound 3 with different secondary amines yielded 2-substituted-4-methyl-7,8-dihydro-5H-pyrimido[4,5-d]thiazolo[3,2-a]pyrimidines in good yields. The assigned products were tested for their potential antibacterial activity and the results indicated that a few derivatives are valuable compounds with great potential to be used as antibacterial agents.

MCl2 (M=Hg, Cd, Zn, Mn) catalysed hydrochlorination of acetylene – a Density Functional Theory study

A Density Functional Theory method has been employed in this research to conduct an in-depth study of the correlation between the conversion of acetylene to vinyl chloride catalysed by MCl2 (M=Hg, Cd, Zn, Mn) and the electron affinity. From the analysis of the adsorption energy and energy profile of acetylene hydrochlorination reaction, combined with Fukui indices and outer-shell Mulliken population change alongside reaction pathway, it can be concluded that, the outermost electron migration is the main factor affecting the catalytic property of MCl2 (M=Hg, Cd, Zn, Mn) catalyst. The Mulliken population change of the central atom M2+ (M=Hg, Cd, Zn) share similar tendency along the reaction pathway, the only difference is Hg2+ gained more electrons than the other two when acetylene got absorbed, and that proved that Hg(II) got better electron withdrawing, which is a main motivator of better catalytic properties in acetylene hydrochlorination reaction.

Multiscale Computational Study of Electronic Structure and Properties of Electrochemical Nano-Systems

Over the past few decades the electrochemistry of nano-sized systems has shown a strong growth worldwide in many areas of research and proved its significance in today’s competitive environment. However, there still remains an enormous potential for further development which could revolutionize many areas of human life. Unfortunately, in some cases, that potential is screened out by complexity and multilevel character of systems and processes at a nanometer scale. The success of future applications in a high-tech industry requires deep understanding of fundamental mechanisms on different levels of description and their communication. That could be provided only by appropriate combination of experimental study with predictive theoretical modeling. Nowadays, more and more scientists in different fields of chemistry are using computational modeling methods in their research, either as a technique per se, or as a complement to experimental work. However, despite the increasing attention to computational nanoscience and biology the specificity of application of standard theoretical and computational modeling in nanotechnology is complicated due to complexity of the systems of interest and needs to be discussed separately, especially in the view of multilevel representation of systems and processes on nanoscale. Modern methods of computational chemistry comprise a variety of approximations allowing to model relatively simple properties as well as complex processes such as catalytic reactions or electronic transport. One of the major tasks of computational chemistry in electrochemistry is to explore a large number of potential systems in order to select the most appropriate candidates for further detailed study. Sometimes this leads to many difficulties because the computational cost increases exponentially with complexity of process of interest. For example, the modeling of chemical reactions on electrode requires to explore the multidimensional potential energy surface (PES) in reaction coordinates (distances, orientations …) which could be very complex. From other side for the task of preliminary selection one does not need a high accuracy and simple estimation is often enough. In that case the computationally expensive modeling could be efficiently replaced by study of appropriate precursors. It is well known that chemical reactions are mainly defined by wave function/electronic density of active regions, so the study of electronic structure of the atoms directly involved in the reaction of interest could provide valuable information for the preliminary analysis. Moreover, recently a number of efficient methods to study of electronic structure was developed which allows in combination with multiscale approximations quickly and efficiently model a large systems. Unfortunately many of that approximations are not frequently used in practical applications and researchers are still operate with simplified models (like HOMO/LUMO model) which are easy understandable and intuitive but does not count many things (methodological and physical/chemical), like dependence from DFT-functional, density redistribution and orbitals correlation, etc. The work reviews the latest achievements in the development of electronic structure analysis methods [1] (Fukui indexes, fragment analysis, transition orbitals, transmission spectra, etc.) and their application to study electronic structure of complex systems. The presentation is supplemented by a number of practical examples that shows how the new tools could improve the quality of analysis. E. Baerends, T. Ziegler, J. Autschbach, D. Bashford, A. Bérces, F. Bickelhaupt, C. Bo, P. Boerrigter, L. Cavallo, D. Chong, L. Deng, R. Dickson, D. Ellis, M. van Faassen, L. Fan, T. Fischer, C. Guerra, M. Franchini, A. Ghysels, A. Giammona, S. van Gisbergen, A. Götz, J. Groeneveld, O. Gritsenko, M. Grüning, S. Gusarov, F. Harris, P. van den Hoek, C. Jacob, H. Jacobsen, L. Jensen, J. Kaminski, G. van Kessel, F. Kootstra, A. Kovalenko, M. Krykunov, E. van Lenthe, D. McCormack, A. Michalak, M. Mitoraj,S. Morton, J. Neugebauer, V. Nicu, L. Noodleman, V. Osinga, S. Patchkovskii, M. Pavanello, P. Philipsen, D. Post, C. Pye, W. Ravenek, J. Rodríguez, P. Ros, P. Schipper, G. Schreckenbach, J. Seldenthuis, M. Seth, J. Snijders, M. Solà, M. Swart, D. Swerhone, G. Velde, P. Vernooijs, L. Versluis, L. Visscher, O. Visser, F. Wang, T. Wesolowski, E. van Wezenbeek, G. Wiesenekker, S. Wolff, T. Woo and A. Yakovlev, Amsterdam Density Functional 2013, SCM, Theoretical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands, 2013 Figure 1

Intermolecular C-H Quaternary Alkylation of Aniline Derivatives Induced by Visible-Light Photoredox Catalysis.

The intermolecular direct C-H alkylation of aniline derivatives with α-bromo ketones to build a quaternary carbon center was reported with a visible-light catalysis procedure. The reaction covers a variety of functional groups with good to excellent yields. A regioselectivity favoring the ortho position for the amine group was observed and investigated with Fukui indices and spectral methods.

Computational model for the acylation step of the β-lactam ring: Potential application for l,d-transpeptidase 2 in mycobacterium tuberculosis

Tuberculosis (TB) remains a major global health quandary. The peptidoglycan layer of mycobacterium tuberculosis (M.tb) consists of glycoproteins that are crosslinked by transpeptidases. Carbapenems are a subfamily of β-lactam antibiotics that inactivate the L,D-transpeptidase enzyme effectively (3 → 3 crosslinks). The mechanism of ring opening and thioester bond formation between the β-lactam core and the Cys354 active residue (for L,D-transpeptidase) during the acylation step is still the subject of considerable discussion. Herein, an acylation mechanism is proposed through four possible model transition states (TS), namely four membered-ring (TS-4, TS-4-His and TS-4-water) and six membered-ring (TS-6-water) transition states. The quantum chemical calculations for these TS models were performed with Density Functional Theory (DFT) using the B3LYP functional and the 6-31 + G(d) basis set. The calculated thermodynamic properties such as relative reaction energies (ΔEreaction), Gibbs free energies (ΔG), enthalpy energies (ΔH) and entropy contributions (ΔS) were reported at 298.15 K for the four considered pathways. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were calculated to evaluate and compare the chemical reactivities of the considered TS models. Natural bond orbital (NBO) analysis was performed to determine the effective intermolecular orbital interactions E(2) derived by the second perturbation theory. The chemical hardness (η) and softness (S) and Fukui indices (fk+, fk−) of these TS models were compared to confirm the feasibility and preference of the considered pathways. The outcome of this study will pave the way for an improved understanding of the LDT/carbapenem acylation reaction at a molecular level.

Spectral investigations, DFT based global reactivity descriptors, Inhibition efficiency and analysis of 5-chloro-2-nitroanisole as π-spacer with donor-acceptor variations effect for DSSCs performance

FTIR, FT-Raman, UV, NMR and quantum chemical calculation studies are performed on 5-chloro-2-nitroanisole, in order to gain the insights of its structural, spectroscopic and electronic properties (Fukui indices, HOMO and LUMO energy gap, MESP and Global reactivity descriptors). A complete vibrational analysis of 5-chloro-2-nitroanisole is performed by HF/B3LYP methods using 6-31G(d,p) basis set. To estimate the electronic transitions, the UV spectra of title compound are predicted in gas phase and ethanol. The obtained absorption maxima at 389.94 nm (in ethanol) is predicted possibly due to HOMO→LUMO transition with 85% contribution and assigned as π-π*. The MESP map shows that the negative potential sites are localized on oxygen atom (O10) as well as the positive potential sites are identified around the hydrogen and ring carbon atoms. The analysis of Fukui indices is also carried out to distinguish the nucleophilic and electrophiic centers. The prediction of reactive sites by MESP is well supported by this Fukui indices analysis. The correlations between the statistical thermodynamics and temperature are also obtained. It is seen that the heat capacities, entropies and enthalpies increase with increasing the intensities of the molecular vibrations. Furthermore, the first hyperpolarizability of 5-chloro-2-nitroanisole is calculated and the results are discussed. This result indicates that 5-chloro-2-nitroanisole is a good candidate of nonlinear optical materials.

Theoretical investigation of methoxide ion reaction on the 7-methyl-4,6-dinitrobenzofuroxan

Reaction of the methoxide ion on the 7-methyl-4,6-dinitrobenzofuroxan (DNBF) 1 has been studied theoretically by means of DFT/B3LYP technique to interpret the kinetic–thermodynamic competition between the three possible compounds that are carbanion DNBF− 4 and the two complexed forms (2, 3) of the methoxide group in positions 5 and 7, respectively. Optimized geometry, nbo atomic charge distribution, thermodynamic/kinetic parameters (ΔrH°T, ΔrS°T, ΔrG°T, ΔH*, ΔS*, and ΔG*) and IRC path have been calculated for possible products and their transitional states using water as solvent. All obtained ΔrG°T are negative, ranging from −19.16 to −42.87 kcal mol−1 (1 cal = 4.184 J), indicating the possible observation of all products, but the experimenters only detected the anionic form DNBF−. Fukui indices, which were calculated by means of NBO atomic charge distribution, confirm the electrophilicity of the sites C5 and C7. Transition states barriers, ΔG*, are 14.97, 15.16, and 21.94 kcal mol−1 for the three possible products 2, 3, and 4, respectively, in water. As expected, the most stable compound is carbanion, but it also exhibits the highest activation barrier. If this situation formally engenders a double kinetic–thermodynamic competition, the very weak activation energy of the two complexes in C5 and C7 makes improbable the simultaneous detection of the three expected compounds.

Theoretical Studies of the Vibrational Spectra and Molecular Structures of Dosulepin and Doxepin

Dosulepin and doxepin are tricyclic antidepressants. The molecular geometries, harmonic vibrational frequencies, quantum chemical parameters and thermodynamic properties of dosulepin and doxepin were calculated by Generalized Gradient Approximation methods developed by Perdew and Wang (GGA-PW91) and Becke-Lee-Yang-Parr (GGA-BLYP) in the gas phase and solution media. The local reactivity of these drugs was studied by the Fukui indices in order to predict both the reactive centers and the possible sites of nucleophilic and electrophilic attacks. Computational and chemical simulations were carried out for these drugs. Quantum chemical parameters of dosulepin and doxepin were calculated and compared. The simulation results show that dosulepin is quite a reactive drug. The fundamental modes of the vibrational frequencies were determined for dosulepin and doxepin. The BLYP/PW91 analyses of the wavenumbers show that the frequencies assigned to doxepin are higher than those assigned to dosulepin in the gas phase and solution media.

Theoretical and experimental reinvestigation of methoxide ion reaction with 7-methyl 4-nitro benzofuroxan

DFT/B3LYP theoretical study has been performed in order to interpret the kinetic-thermodynamic competition between compounds obtained by reaction of the methoxide ion on the 7-methyl 4-nitro benzofuroxan. Geometry, atomic charge distribution, transition states, IRC path, thermodynamic, and kinetic parameters ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]*, [Formula: see text]*, and [Formula: see text]*) have been calculated for all possible products. In gaseous state or in the presence of water as solvent, all [Formula: see text] values were found to be negative, ranging from [Formula: see text]12.54[Formula: see text]kcal mol[Formula: see text] to [Formula: see text]29.85[Formula: see text]kcal mol[Formula: see text] in water, indicating that all possible products should form spontaneously. Those values indicated the possible observation of all products but experimenters only detect simultaneously two [Formula: see text]-complexes in C5 and C7 among three possibilities. The Fukui indices obtained by NBO atomic charge distribution confirm the super electrophilicity of those two sites. For transition states barriers, [Formula: see text]* ranged from 18.98[Formula: see text]kcal mol[Formula: see text] to 42.12[Formula: see text]kcal mol[Formula: see text] in gaseous state and from 18.59[Formula: see text]kcal mol[Formula: see text] to 24.22[Formula: see text]kcal mol[Formula: see text] in water. The unexpected result of our calculations is that the most stable compound is the unobserved carbanion but it also exhibits the highest activation barrier. Our results indicated the existence of two consecutive kinetic/thermodynamic competitions that occur in separate periods. The simultaneous observation of the three compounds is impossible because compound 4 occurs as a trace at the time compound 2 disappears completely. Experimental reinvestigation of the studied reaction leads by a very slow process to the earlier unobserved carbanion. Reaction mechanisms were also discussed on the basis of IRC calculations.

Insight into the Mechanism of the Michael Reaction.

The mechanism for the nucleophilic addition step of the Michael reaction between methanethiol as a model Michael donor and several α-substituted methyl acrylates (X=F, Cl, Me, H, CN, NO2 ) as model Michael acceptors is described in detail. We suggest a novel way to condense electrophilic Fukui functions at specific atoms in terms of the contributions from the atomic orbitals to the LUMO or, more generally, to the orbital controlling the reaction. This procedure correctly associates activation energies to local electrophilic Fukui indices for the cases treated in this work. The calculated reaction barriers strongly depend on the nature of the substituent. As a general rule, activation energies are governed by structural changes, although electronic factors are significant for electron-withdrawing groups. Nucleophilic addition to Michael receptors is best described as a highly nonsynchronous process, in which the geometry of the transition state comprises a nonplanar six-membered ring. Formation of the S⋅⋅⋅C bond, which defines the interaction between the reactants, progresses ahead of all other primitive processes in the early stages of the transformation. In view of our results, we postulate that highly complex chemical reactions, as is the case for the nucleophilic addition step studied herein, that involve cleavage/formation of a total of six bonds, lower their activation energies by favoring nonsynchronicity, that is, for these types of systems, primitive changes should advance at different rates.

Theoretical study of the formation of α-bromoglycidic esters in aliphatic series using the DFT quantum mechanical method with B3LYP/6-311G (d, p)

In the present work we used density functional theory (DFT) with B3LYP/6-311G (d, p) to describe the reaction between isopropyl dibromoacetate and isobutyraldehyde. We calculated the optimized geometry of the two reactants, the transition states and the products obtained. We determined the energies corresponding to the reactants and the products as well as electron density, isodensity surfaces of the HOMO and LUMO and the localization of the transition states, and calculated the electrophilic and nucleophilic character of the reactants, the condensed local softness and some thermodynamic quantities (enthalpy, entropy and Gibbs free energy). We used natural population analysis (NPA) to determine Fukui indices, atomic electronic populations and reactivity indices. Finally, we analyzed the potential energy surface and studied the reaction mechanism.

Bistriazine-based streptocyanines. Preparation, structural determination and optoelectronic properties

A series of bistriazine-based streptocyanines has been selectively prepared. A variety of substituents has been introduced into the triazine ring with p-phenylenediamine as a conjugated spacer between the triazine and the streptocyanine moieties. Fukui indices have been used to explain the different sequential reactivity of the chlorine atoms in the triazine ring. 1D- and 2D-DNMR spectroscopy and computational calculations have been carried out to explain the dynamic behavior of these complex systems, which can be explained by the presence of a Cl … H bond. This method was used to build conjugated systems and to show the interaction between the triazine part, the spacer, and the streptocyanine moiety. A study of the optoelectronic properties has been performed by UV–vis and fluorescence spectroscopy. Streptocyanine-based bistriazines are violet-blue emitters and large Stokes shifts of more than 6000 cm−1 were observed. The title compounds showed interesting properties which have potential for use in optoelectronic devices.

Experimental and DFT Studies on the Behavior of Caffeine as Effective Corrosion Inhibitor of Copper in 1M HNO3

Caffeine was tested as copper corrosion inhibitor in 1M HNO 3 using mass loss technique at 308-328K and theoretical studies based on quantum chemistry. The inhibition efficiency is concentration and temperature dependent: Caffeine showed an inhibition efficiency of 78% at 5mM for T =328K. The thermodynamic adsorption parameters ( were determined and analyzed. They revealed a spontaneous adsorption process and a strong interaction between Caffeine and the metal surface. Adsorption isotherms including Langmuir, Temkin and El-Awady were tested. It was found that Caffeine adsorbs on copper according to the modified Langmuir adsorption isotherm. The Dubinin Raduskevitch model was used to distinguish between chemisorption and physisorption. Activation parameters ( were also determined and discussed. Furthermore, the quantum chemical properties/descriptors most relevant to the potential action of the molecule as corrosion inhibitor such as highest occupied molecular energy (E HOMO ), lowest unoccupied molecular orbital energy (E LUMO ), energy gap(∆E), dipole moment ( and charges on heteroatoms were calculated using DFT at B3LYP level with 6-31+G (d) and LanL2DZ basis sets. Fukui indices were also determined and discussed. The theoretical results are consistent with the experimental data reported. DOI: http://dx.doi.org/10.17807/orbital.v8i2.804

Theoretical study of functionalized single-walled carbon nanotube (5, 5) with Mitoxantrone drug

Objective(s): First principles calculations were performed to study four multiple sclerosis drugs namely, Ampyra, Fingolimod, Mitoxantrone and Eliprodil in gas and liquid phases using Density Functional Theory (DFT). Computational chemistry simulations were carried out to compare calculated quantum chemical parameters for Ampyra, Fingolimod, Mitoxantrone and Eliprodil. Materials and Methods: All calculations were performed using DMol3 code which is based on DFT. The Double Numerical basis set with Polarization functions (DNP) was used.Results: Mitoxantrone has highest HOMO energy, global softness, solvation energy and molecular mass and lowest LUMO energy, energy gap, global hardness and total energy in comparison to Ampyra, Fingolimod and Eliprodil in gas and solvent phases. Calculations were carried out to study the interaction of covalently binding Mitoxantrone to functionalized carbon nanotube. The Mitoxantrone local reactivity was studied through the Fukui indices in order to predict both the reactive centers and the possible sites of nucleophilic and electrophilic attacks. The Mitoxantrone binding energy is calculated to be 6.507 eV in gas phase and -9.943 eV in solvent phase that is a decrease in BE as the drug phase changes from gas to liquid.Conclusion: The simulation results show Mitoxantrone is quite a reactive drug. The quantum chemical parameters of pristine nanotube and f-SWNT-Mitoxantrone showed that reactivity of f-SWNT-Mitoxantrone increased in comparison to pristine nanotube in both phases.

Theoretical Study of the Aliphatic-Chain Length’s Electronic Effect on the Corrosion Inhibition Activity of Methylimidazole-Based Ionic Liquids

Density Functional Theory based studies about the inhibition of corrosion affecting the cathode hematite surface by coverage with an methylimidazole-based ionic liquid, IL, were performed. Inhibition performance is tuned through the length of aliphatic chains Cn attached to the imidazolium aromatic ring, where n = 1, ..., 20. Frontier molecular orbitals and energy gaps for single ILs and a pristine (112) hematite surface, the energy difference between ILs and hematite-surface, Fukui indices for the ILs, and adsorption energies and charge transfers for ILs/hematite surface systems were calculated. Results show that adsorption activity is due to the donation/back-donation bonding among the imidazolium aromatic ring of the ILs and the exposed iron atoms of the hematite surface. Dispersive long-range interactions from the ILs alkyl tails allow a closer bonding of the corrosion inhibitor molecules to the hematite surface; the charge transfer between the IL and the hematite is in C18. The optimal alkyl chain s...