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 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.

Competitive excited-state single or double proton transfer mechanisms for bis-2,5-(2-benzoxazolyl)-hydroquinone and its derivatives

2015 ◽  
Vol 17 (18) ◽  
pp. 11990-11999 ◽  
Author(s):  
Jinfeng Zhao ◽  
Junsheng Chen ◽  
Jianyong Liu ◽  
Mark R. Hoffmann
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Proton Transfer ◽  
Density Functional ◽  
Intramolecular Proton Transfer ◽  
Time Dependent ◽  
Functional Theory ◽  
Double Proton Transfer ◽  
Transfer Mechanisms ◽  
Dependent Density

The excited state intramolecular proton transfer (ESIPT) mechanism of HBO, BBHQ and DHBO have been investigated using time-dependent density functional theory (TDDFT).

scholarly journals Density Functional Theory Applied to Excited State Intramolecular Proton Transfer in Imidazole-, Oxazole-, and Thiazole-Based Systems

Molecules ◽  
2018 ◽  
Vol 23 (5) ◽  
pp. 1231 ◽  
Author(s):  
Fabricio de Carvalho ◽  
Maurício Coutinho Neto ◽  
Fernando Bartoloni ◽  
Paula Homem-de-Mello
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Proton Transfer ◽  
Density Functional ◽  
Intramolecular Proton Transfer ◽  
Functional Theory

Density Functional Theory on NV Center in 4H SiC

2017 ◽  
Vol 897 ◽  
pp. 269-274 ◽  
Author(s):  
András Csóré ◽  
Ádám Gali
Keyword(s):  
Density Functional Theory ◽  
Ground State ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Vacancy Defect ◽  
The Other ◽  
Nitrogen Vacancy ◽  
Functional Theory ◽  
Triplet Ground State ◽  
Nv Center

Paramagnetic defects in solids have become attractive systems for quantum computing as well as magnetometry in recent years. One of the leading contenders is the negatively charged nitrogen-vacancy defect (NV center) in diamond proposed to be highly promising with respect the afore-mentioned applications. In our study we investigate the NCVSi defect in 3C, 4H and 6H SiC as alternative choices with superior properties. Electronic structure of NV center in SiC exhibits S = 1 triplet ground state with the possibility of optical spin polarization. On the other hand, our results obtained by density functional theory calculations may contribute to unambiguously identify the possible defect configurations.

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.

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