scholarly journals A DFT Study of Structural and Bonding Properties of Complexes Obtained from First-Row Transition Metal Chelation by 3-Alkyl-4-phenylacetylamino-4,5-dihydro-1H-1,2,4-triazol-5-one and Its Derivatives

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Hubert Jean Nono ◽  
Désiré Bikélé Mama ◽  
Julius Numbonui Ghogomu ◽  
Elie Younang
Keyword(s):  
Transition Metal ◽  
Gas Phase ◽  
Metal Atom ◽  
Density Functional ◽  
Antioxidant Activities ◽  
Metal Chelation ◽  
Topological Parameters ◽  
Bonding Properties ◽  
Neutral Ligands ◽  
Phase Water

Density functional calculations were used to explore the complexation of 3-alkyl-4-phenylacetylamino-4,5-dihydro-1h-1,2,4-triazol-5-one (ADPHT) derivatives by first-row transition metal cations. Neutral ADPHT ligand and mono deprotonated ligands have been used. Geometry optimizations have been performed in gas-phase and solution-phase (water, benzene, and N,N-dimethylformamide (DMF)) with B3LYP/Mixed I (LanL2DZ for metal atom and 6-31+G(d,p) for C, N, O, and H atoms) and with B3LYP/Mixed II (6-31G(d) for metal atom and 6-31+G(d,p) for C, N, O, and H atoms) especially in the gas-phase. Single points have also been carried out at CCSD(T) level. The B3LYP/Mixed I method was used to calculate thermodynamic energies (energies, enthalpies, and Gibb energies) of the formation of the complexes analyzed. The B3LYP/Mixed I complexation energies in the gas phase are therefore compared to those obtained using B3LYP/Mixed II and CCSD(T) calculations. Our results pointed out that the deprotonation of the ligand increases the binding affinity independently of the metal cation used. The topological parameters yielded from Quantum Theory of Atom in Molecules (QTAIM) indicate that metal-ligand bonds are partly covalent. The significant reduction of the proton affinity (PA) observed when passing from ligands to complexes in gas-phase confirms the notable enhancement of antioxidant activities of neutral ligands.

An ab initio and density functional theory study on neutral pterin radicals

Pteridines ◽  
2015 ◽  
Vol 26 (4) ◽  
pp. 135-142 ◽  
Author(s):  
Gilbert Reibnegger
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Electronic Structures ◽  
Density Functional ◽  
Electron System ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Molecular Systems ◽  
Phase Water ◽  
Planar Transition

AbstractThe electronic structures of the five radicals resulting from homolytic elimination of one of the hydrogen atoms from the most stable tautomeric form of neutral pterin were investigated in gas phase as well as in aqueous solution. Molecular wave functions obtained by density functional theory were analysed by quantum theory of atoms in molecules and electron localisation functions (ELF). Spin densities of the radicals as well as electrostatic potential functions were analysed. Radicals resulting from elimination of N-bonded hydrogen atoms are more stable in comparison with radicals obtained after abstraction of C-bonded hydrogen atoms. N-centred radicals show strong delocalisation of spin density over both heteroaromatic rings; in C-centred radicals delocalisation does not occur. ELF analyses showed that in N-derived radicals particularly the lone electron pair at N2′ is strongly involved into the bicyclic heteroaromatic π-electron system. Thereby, bonding geometry at N2′ in these radicals changes from pyramidal to planar. Transition from gas phase to solution phase (water) generally leads to increased polarity of the structures. Pterin-derived free radicals have been implicated in several biologically important reactions; so this investigation provides first insights into the detailed electronic structures of such molecular systems.

scholarly journals Concomitant Effects of Transition Metal Chelation and Solvent Polarity on the First Molecular Hyperpolarizability of 4-Methoxyacetophenone Thiosemicarbazone: A DFT Study

2016 ◽  
Vol 2016 ◽  
pp. 1-19 ◽  
Author(s):  
Nyiang Kennet Nkungli ◽  
Julius Numbonui Ghogomu
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Broad Band ◽  
Solvent Polarity ◽  
Dielectric Constants ◽  
Dft Study ◽  
Electromagnetic Spectrum ◽  
Metal Chelation ◽  
First Hyperpolarizability ◽  
Nlo Response

Nonlinear optical (NLO) properties of organic and metal-organic materials are of considerable interest to emerging optoelectronic and photonic technologies. Much work has been carried out on the former materials but the latter ones have received less attention till date. Herein, a density functional theory (DFT) study on the combined effects of transition metal chelation and solvent polarity on the first hyperpolarizability (βtot) of 4-methoxyacetophenone thiosemicarbazone (MAPTSC) is reported. MAPTSC exhibits a tautomeric form with higher optical nonlinearity rendering its NLO response in polar solvents potentially switchable. Our results have revealed significant modifications of the first hyperpolarizability of MAPTSC upon complexation with different transition metal chlorides in the presence of solvents with varying dielectric constants. Therefore, its second-order NLO response is highly tunable by the synergy of transition metal chelation and solvent polarity. MAPTSC and its Zn(II) and Pt(II) chloride complexes are promising NLO materials because their gas-phase βtot values are larger than those of the prototype push-pull molecules, para-nitroaniline (PNA) and urea, by factors of about 1.40–1.76 and 19.57–37.24, respectively; these factors greatly increase in polar solvent medium. Moreover, they possess high optical transparencies in the visible region of the electromagnetic spectrum which mitigate transparency/nonlinearity trade-offs, thereby increasing the likelihood of broad band NLO response.

Steady semiconducting properties of monolayer PtSe2 with non-metal atom and transition metal atom doping

2020 ◽  
Vol 22 (10) ◽  
pp. 5765-5773 ◽  
Author(s):  
Xu Zhao ◽  
Ranzhuo Huang ◽  
Tianxing Wang ◽  
Xianqi Dai ◽  
Shuyi Wei ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Electronic Structure ◽  
Transition Metal ◽  
Metal Atom ◽  
Density Functional ◽  
Transition Metal Atom ◽  
Functional Theory ◽  
Semiconducting Properties

Based on density functional theory, the electronic structure and magnetic properties of monolayer PtSe2 doped with different atoms were studied.

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