scholarly journals Influence of Varying Functionalization on the Peroxidase Activity of Nickel(II)–Pyridine Macrocycle Catalysts: Mechanistic Insights from Density Functional Theory

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 52
Author(s):  
Jerwin Jay E. Taping ◽  
Junie B. Billones ◽  
Voltaire G. Organo
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Stoichiometric Ratio ◽  
Functional Theory ◽  
Pendant Arm ◽  
Spin Singlet

Nickel(II) complexes of mono-functionalized pyridine-tetraazamacrocycles (PyMACs) are a new class of catalysts that possess promising activity similar to biological peroxidases. Experimental studies with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), substrate) and H2O2 (oxidant) proposed that hydrogen-bonding and proton-transfer reactions facilitated by their pendant arm were responsible for their catalytic activity. In this work, density functional theory calculations were performed to unravel the influence of pendant arm functionalization on the catalytic performance of Ni(II)–PyMACs. Generated frontier orbitals suggested that Ni(II)–PyMACs activate H2O2 by satisfying two requirements: (1) the deprotonation of H2O2 to form the highly nucleophilic HOO−, and (2) the generation of low-spin, singlet state Ni(II)–PyMACs to allow the binding of HOO−. COSMO solvation-based energies revealed that the O–O Ni(II)–hydroperoxo bond, regardless of pendant arm type, ruptures favorably via heterolysis to produce high-spin (S = 1) [(L)Ni3+–O·]2+ and HO−. Aqueous solvation was found crucial in the stabilization of charged species, thereby favoring the heterolytic process over homolytic. The redox reaction of [(L)Ni3+–O·]2+ with ABTS obeyed a 1:2 stoichiometric ratio, followed by proton transfer to produce the final intermediate. The regeneration of Ni(II)–PyMACs at the final step involved the liberation of HO−, which was highly favorable when protons were readily available or when the pKa of the pendant arm was low.

scholarly journals Pd/Pt embedded CN monolayers as efficient catalysts for CO oxidation

2019 ◽  
Vol 21 (46) ◽  
pp. 25743-25748
Author(s):  
Yong-Chao Rao ◽  
Xiang-Mei Duan
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Density Functional ◽  
Carbon Nitride ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Functional Theory ◽  
Spin Polarized ◽  
Planar Carbon

The catalytic performance of Pd/Pt embedded planar carbon nitride for CO oxidation has been investigated via spin-polarized density functional theory calculations.

scholarly journals Caryolene-forming carbocation rearrangements

2013 ◽  
Vol 9 ◽  
pp. 323-331 ◽  
Author(s):  
Quynh Nhu N Nguyen ◽  
Dean J Tantillo
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Energy Barrier ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Intramolecular Proton Transfer ◽  
The Other ◽  
Orbital Symmetry ◽  
Functional Theory ◽  
Biosynthetic Precursor

Density functional theory calculations on mechanisms of the formation of caryolene, a putative biosynthetic precursor to caryol-1(11)-en-10-ol, reveal two mechanisms for caryolene formation: one involves a base-catalyzed deprotonation/reprotonation sequence and tertiary carbocation minimum, whereas the other (with a higher energy barrier) involves intramolecular proton transfer and the generation of a secondary carbocation minimum and a hydrogen-bridged minimum. Both mechanisms are predicted to involve concerted suprafacial/suprafacial [2 + 2] cycloadditions, whose asynchronicity allows them to avoid the constraints of orbital symmetry.

scholarly journals Intracluster proton transfer in protonated benzonitrile–(H2O)n≤6 nanoclusters: hydrated hydronium core for n ≥ 2

2019 ◽  
Vol 21 (45) ◽  
pp. 25226-25246 ◽  
Author(s):  
Kuntal Chatterjee ◽  
Otto Dopfer
Keyword(s):  
Density Functional Theory ◽  
Infrared Spectroscopy ◽  
Proton Transfer ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Dopant Molecule

Infrared spectroscopy and density functional theory calculations of protonated benzonitrile–(H2O)n clusters reveal proton transfer to solvent for n ≥ 2 and the drastic effects of the aromatic dopant molecule on the network of H+(H2O)n+1.

CO oxidation over the polyoxometalate-supported single-atom catalysts M1/POM (Fe, Co, Mn, Ru, Rh, Os, Ir, and Pt; POM = [PW12O40]3–): a computational study on the activation of surface oxygen species

2019 ◽  
Vol 48 (18) ◽  
pp. 6228-6235 ◽  
Author(s):  
Chun-Guang Liu ◽  
Li-Long Zhang ◽  
Xue-Mei Chen
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Density Functional ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Single Atom ◽  
Oxygen Species ◽  
Surface Oxygen ◽  
Functional Theory

Density functional theory calculations have been carried out to explore the catalytic performance of a series of the M1/POM (M = Fe, Co, Mn, Ru, Rh, Os, Ir, and Pt; POM = [PW12O40]3−) single-atom catalysts for CO oxidation.

scholarly journals High-Pressure Phases of SnO and PbO: A Density Functional Theory Combined with an Evolutionary Algorithm Approach

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6552
Author(s):  
Long Truong Nguyen ◽  
Guy Makov
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Evolutionary Algorithm ◽  
Density Functional ◽  
Experimental Studies ◽  
Lone Pair ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Lead Monoxide ◽  
Tin Monoxide

Tin monoxide, SnO, and its analog, lead monoxide, PbO, have the same tetragonal P4/nmm structure, shaped by nonbonding dispersion forces and lone pairs. The high-pressure phases of SnO and PbO have been explored in several experimental and theoretical studies, with conflicting results. In this study, the high-pressure structures of SnO and PbO are investigated using density functional theory calculations combined with an evolutionary algorithm to identify novel high-pressure phases. We propose that the monoclinic P21/m SnO and orthorhombic Pmmn PbO phases, which are metastable at 0 GPa, are a slight rearrangement of the tetragonal P4/nmm-layered structure. These orthorhombic (and their closely related monoclinic) phases become more favored than the tetragonal phase upon compression. In particular, the transition pressures to the orthorhombic γ-phase Pmn21of SnO/PbO and the monoclinic phase P21/m of SnO are found to be consistent with experimental studies. Two new high-pressure SnO/PbO polymorphs are predicted: the orthorhombic Pbcm phase of SnO and the monoclinic C2/m of PbO. These phases are stabilized in our calculations when P > 65 GPa and P > 50 GPa, respectively. The weakening of the lone pair localization and elastic instability are the main drivers of pressure-induced phase transitions. Modulations of the SnO/PbO electronic structure due to structural transitions upon compression are also discussed.

Mechanistic insights into the dearomative diborylation of pyrazines: a radical or non-radical process?

2021 ◽  
Author(s):  
Liuzhou Gao ◽  
Hanyin Zhang ◽  
Xueting Liu ◽  
Guoqiang Wang ◽  
Shuhua Li
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Radical Process

The mechanisms of the dearomative diborylation of pyrazines were investigated via a combination of density functional theory calculations and experimental studies.

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