scholarly journals A DFT Study of Some Structural and Spectral Properties of 4-Methoxyacetophenone Thiosemicarbazone and Its Complexes with Some Transition Metal Chlorides: Potent Antimicrobial Agents

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Julius Numbonui Ghogomu ◽  
Nyiang Kennet Nkungli
Keyword(s):  
Transition Metal ◽  
Spectral Properties ◽  
Density Functional ◽  
Antimicrobial Agents ◽  
Population Analysis ◽  
Binding Energies ◽  
Rational Drug Design ◽  
Ethanolic Solution ◽  
Metal Chlorides ◽  
Chemical And Biological Systems

Recent studies have shown that 4-methoxyacetophenone thiosemicarbazone (MAPTSC) and its complexes with some transition metal chlorides are potent antimicrobial agents. To deepen the understanding of their structure-activity relationships necessary for rational drug design, their structural and spectral properties, along with thione-thiol tautomerism of MAPTSC, have been studied herein using the density functional theory (DFT). From our results, the thione tautomer of MAPTSC is more stable than the thiol counterpart in ethanolic solution, and thione-to-thiol tautomerization is highly precluded at ambient temperature (25°C) by a high barrier height ≈46.41 kcal/mol. MAPTSC can therefore exist as a mixture of the thione (major) and thiol (minor) tautomers in ethanolic solution at room and higher temperatures. Conformational analysis has revealed five possible conformers of the thione tautomer, of which two are stable enough to be isolated at 25°C. Based on our computed values of MAPTSC-metal(II) binding energies, enthalpies, and Gibbs free energies, the thione tautomer of MAPTSC exhibits a higher affinity for the d8 metal ions Ni(II), Pd(II), and Pt(II) and can therefore efficiently chelate them in chemical and biological systems. Natural population analysis has revealed ligand-metal charge transfer in the MAPTSC complexes studied. A good agreement has been found between calculated and experimentally observed spectral properties (IR, UV-Vis, and NMR).

Ab initio and DFT studies on the structures, binding energies and nature of bonds in X2Y3 metal clusters (X+ = Li+, Na+ and K+; ${\rm Y}_{3}^{2-} = {\rm Zn}_{3}^{2-}, {\rm Cd}_{3}^{2-}$ and ${\rm Hg}_{3}^{2-}$)

2015 ◽  
Vol 14 (06) ◽  
pp. 1550043 ◽  
Author(s):  
Masoud Hatami ◽  
Mehdi Bayat ◽  
Hassan Keypour ◽  
Sadegh Salehzadeh
Keyword(s):  
Ab Initio ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Theoretical Study ◽  
Population Analysis ◽  
Binding Energies ◽  
Energy Decomposition ◽  
Zinc Cadmium ◽  
Covalent Contribution ◽  
Wiberg Bond Indices

A comprehensive theoretical study on the structure and stability of linear and triangular isomers of anionic clusters of zinc, cadmium and mercury [Formula: see text] and their binding with one and two alkali metal cations ( X + = Li +, Na +, K +) has been investigated at the density functional (BP86 and B3LYP) and ab initio (MP2, MP4 and coupled cluster single and double (CCSD)) methods. The results showed that in all cases, the triangular geometry with D3h symmetry is more stable than linear one. The calculated values of interaction energies (IE) between [Formula: see text] anions and two X+ cations, Wiberg bond indices (WBI) and the electron densities at bond critical points (BCP), ρ(BCP), for Y–X bonds show that among all complexes investigated here at all levels of theory Zn 3 Li 2 and Hg 3 K 2 have the largest and the smallest values of IE, WBI and ρ(BCP), respectively. The natural charges of the atoms and WBI involved in the bonding as well as the global value of the charge transfer ΔQ from [Formula: see text] to X+ cation in X2Y3 clusters, evaluated through natural population analysis, confirmed that covalent contribution in Y–X bond formation increases from K + to Li +. Also the energy decomposition analyses (EDA) were used to detect the nature of interaction in the complexes. The results confirmed that the contribution of electrostatic interactions in present complexes is almost more than 70%.

scholarly journals Electronic and Magnetic Properties of One Dimensional Sandwich Transition Metal-Anthracene Molecular Wires

2021 ◽  
Author(s):  
Guang Yang ◽  
Huiyang Zhang ◽  
Yijun Yang ◽  
Yudi Wang ◽  
Xinzi Xv ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Transition Metal ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Molecular Wires ◽  
Binding Energies ◽  
One Dimensional ◽  
Electronic And Magnetic Properties ◽  
Antiferromagnetic Ordering ◽  
Potential Applications

Organometallic sandwich complexes have been attracting tremendous interest for their potential applications in electronics and spintronics. Here, we systematically studied the structures, electronic and magnetic properties of one dimensional (1D) transition metal (TM)-anthracene (Ant) sandwich molecular wires (SMWs), [TM2Ant]∞ and [TM3Ant]∞ (TM=Ti, V, Cr, Mn), based on density functional theory calculations. Our results showed that all the 1D SMWs display normal sandwich configurations with their binding energies closely related to the choice of TM atoms. Excepting 1D [Mn2Ant]∞ and [Fe3Ant]∞ favoring antiferromagnetic ordering, most 1D [TM2Ant]∞ and [TM3Ant]∞ SMWs display robust ferromagnetic feathers. Particularly, 1D [Cr3Ant]∞ SMW is revealed to be ferromagnetic half-metal with large magnetic moment of 28.0µB per unit cell. Further spintransport calculations double proved that 1D [Cr3Ant]∞ SMW are good spintransport molecular devices. Our findings shed light on the properties of 1D Ant based SMWs and propose a new way to design potential electronic and spintronic devices.

Density functional theory study on silver clusters using dimers, trimers, and tetramers as building units

2015 ◽  
Vol 93 (3) ◽  
pp. 318-325 ◽  
Author(s):  
T.N. Rekha ◽  
Beulah J.M. Rajkumar
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Nearest Neighbor ◽  
Population Analysis ◽  
Growth Patterns ◽  
Binding Energies ◽  
Silver Clusters ◽  
Mulliken Population ◽  
Functional Theory

We systematically investigate growth patterns of small silver clusters, Agn (n ≤ 10), using density functional theory (DFT) and time-dependent density functional theory (TDDFT), considering Ag2, Ag3, and Ag4 as basic building units. Nearest-neighbor distances increase gradually with increasing n. Compared with an earlier study, where the clusters were developed by adding one atom at a time, the clusters derived in this investigation had considerably higher computed binding energies, confirming increased stability and suggesting possible growth patterns using these basic units. We used TDDFT methods to simulate the ultraviolet–visible spectra of the silver clusters, which are in good agreement with the reported experimental absorption spectrum of Ag nanoparticles. Our study indicates that the clusters formed with units of Ag3 tend to form more reactive clusters, particularly if an odd number of atoms is involved. Further, the higher level of computations employed gives better insight into the process of particle growth. The disproportionation energies of clusters built using this scheme are compared with those built one atom at a time. Mulliken population analysis of the distributions indicates the presence of polarities among the atoms in some of the cluster isomers, suggesting sites of increased activity. In addition, patterns established for the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and HOMO–LUMO energy gaps may be used to model stable clusters with modified optoelectrical properties.

scholarly journals Interaction of intermediates with transition metal surfaces in the dehydrogenation of ethanol to ethyl acetate: A theoretical investigation

2019 ◽  
Vol 44 (1) ◽  
pp. 74-91 ◽  
Author(s):  
Adel Boualouache ◽  
Ali Boucenna ◽  
Ghazi Otmanine
Keyword(s):  
Transition Metal ◽  
Ethyl Acetate ◽  
Metal Surfaces ◽  
Density Functional ◽  
Binding Mode ◽  
Potential Method ◽  
Binding Energies ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Transition Metal Surfaces

By employing a combined approach of the unity bond index–quadratic exponential potential method and density functional theory within the generalized gradient approximation, we have studied the interaction of intermediates in the ethanol dehydrogenation process to ethyl acetate on Cu, Ag, Ni, Pd, Pt, Co, Au and Ir(111) transition metal surfaces. Binding energies and geometries were optimized for the main intermediates of this process. Electronic structures were computed for some intermediates/transition metal systems. We also calculated the activation energies for the elementary steps of the reactions. The results show that amid the studied surfaces, Cu(111) stabilizes ethoxy and acetyl species, preventing their dissociation. Inducing the η2 binding mode of acetaldehyde by alloying Cu with Ni, Co, Pd, Pt or Ir can enhance the catalytic proprieties of the Cu(111) clean surface.

scholarly journals A DFT Investigation of Tris-(4´-(Amino)(1,1´-biphenyl)-3,4-diol) Fe(III) Complex

2018 ◽  
Vol 66 (1) ◽  
pp. 67-71
Author(s):  
Mohammad A Matin ◽  
Mohammed A Aziz ◽  
M Saiful Islam
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Density Functional ◽  
Structural Parameters ◽  
Chelating Agent ◽  
Transition Metal Ions ◽  
Binding Energies ◽  
Molecular Properties ◽  
Electronic Band

Phenolic compounds, known as the pyrocatechol act as a metal chelating agent. Molecular details of cross-linking of pyrocatechol by transition metal ions are largely unknown. In the present study, the molecular properties of the tris-(4´-(amino)(1,1´-biphenyl)-3,4-diol)- Fe(III) complex have been investigated using density functional theory (DFT) at 6-311G(d,p). Calculated molecular properties of the optimized structure, the binding energies and spectroscopic properties are compared with the available experimental results. For the tris-complex investigated, the binding of Fe (III) with the catechol derivative is not as strong as the binding of other metal ions with catechol. The IR stretching bands show that the strong IR intensities is due to large charge polarization. Calculated electronic band gap is 2.45 eV which is in the range of transition metal ion-tris-(4´-(amino)(1,1´-biphenyl)-3,4-diol) complexes. The metal-ligand binding energy is 513.54 kcal mol-1, which could be used in understanding the speciation of Fe(III)-catechol complex. Structural parameters obtained from the DFT calculations are in good agreement with the crystallographic data. Dhaka Univ. J. Sci. 66(1): 67-71, 2018 (January)

Density Functional Theory Study of the Interaction of Nitric Oxide with 3D Transition Metal Dimers

2014 ◽  
Vol 804 ◽  
pp. 145-148 ◽  
Author(s):  
Jing Nie ◽  
Rui Jie Li ◽  
Li Jun He ◽  
Jin Li
Keyword(s):  
Nitric Oxide ◽  
Density Functional Theory ◽  
Transition Metal ◽  
Periodic Table ◽  
Density Functional ◽  
Vibrational Frequencies ◽  
Binding Energies ◽  
Functional Theory ◽  
Experimental Values ◽  
The Right

Density-functional theory (DFT) has been used to calculate the interaction of nitric oxide with 3d metal dimers (scandium through zinc) and determine the ground-state geometrical configurations and vibrational frequencies. Results are compared to the relevant experimental values and to other theoretical investigations when available, and the overall agreement has been obtained. On going from left to right side of the Periodic Table, the preference for the coordination mode of NO to transition-metal dimers is from side-on-bonded mode (Sc, Ti, V), via semibridging (Cr), to end-on-bonded mode (Mn, Fe, Co, Ni, Cu). The N-O stretching vibrational frequencies in the ground states of M2NO (M = Sc to Zn) increase generally from the left to the right side of the Periodic Table, whereas the N-O bond lengths decrease generally. The binding energies exhibit an overall decrease trend. These general trends in the interaction of nitric oxide with 3d metal dimers mirror the main features of NO adsorption on transition metal surfaces.

A DFT study of 3d (d1–d10) transition-metal phthalocyanines (TMPcs): Bonding natures, electronic adsorption spectroscopy

2017 ◽  
Vol 16 (04) ◽  
pp. 1750036
Author(s):  
Xiyuan Sun ◽  
Jiguang Du
Keyword(s):  
Transition Metal ◽  
Density Function ◽  
Density Functional ◽  
Function Theory ◽  
Structural Parameters ◽  
Population Analysis ◽  
Density Function Theory ◽  
Conceptual Density Functional Theory ◽  
Dft Methods ◽  
Metal Phthalocyanines

The structures, electronic properties, bonding characters and UV–Vis spectra of [Formula: see text] ([Formula: see text]–[Formula: see text]) transition-metal phthalocyanines (TMPcs) molecules have been studied with different density function theory (DFT) methods. The calculated structural parameters agree well with previous experimental or theoretical values. Natural Population Analysis (NPA) charge revealed that [Formula: see text]–[Formula: see text] hybridizations occur when [Formula: see text] TM atoms are involved in chemical bondings. The spin magnetic moments of TMPcs are mainly from the contribution of [Formula: see text] electrons. Conceptual density functional theory (CDFT) results indicate that [Formula: see text] TMPcs molecules are willing to accept further electrons. The TM–N chemical bonds show very weak covalent nature, and are consistent with bond order analyses. Time-dependent density function theory (TD-DFT) calculations were carried out to simulate the UV–Vis spectra, and corresponding electronic transfers for dominant peaks were also obtained.

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