Fast and accurate prediction of proton affinities: revisiting the extended Koopmans' theorem for protons

2017 ◽  
Vol 19 (37) ◽  
pp. 25324-25333 ◽  
Author(s):  
Laura Pedraza-González ◽  
Jorge Charry ◽  
William Quintero ◽  
Jorge Alí-Torres ◽  
Andrés Reyes
Keyword(s):  
Gas Phase ◽  
Molecular Orbital ◽  
Accurate Prediction ◽  
Quantitative Prediction ◽  
Proton Affinities ◽  
Koopmans Theorem

In this work we propose schemes based on the extended Koopmans' theorem for quantum nuclei (eKT), in the framework of the any particle molecular orbital approach (APMO/KT), for the quantitative prediction of gas phase proton affinities (PAs).

scholarly journals A Simple Computational Tool for Accurate, Quantitative Prediction of One–Electron Reduction Potentials of Hypoxia–Activated Tirapazamine Analogues

2020 ◽  
Vol 23 ◽  
pp. 231-242
Author(s):  
Hassan RH Elsaidi ◽  
Leonard I Wiebe ◽  
Piyush Kumar
Keyword(s):  
Gas Phase ◽  
Molecular Orbital ◽  
Density Functional ◽  
Polar Solvent ◽  
Single Point ◽  
Single Electron ◽  
Quantitative Prediction ◽  
Energy Calculation ◽  
Reduction Potentials ◽  
Electron Reduction

The reduction potentials of bioreductively-activated drugs represent an important design parameter to be accommodated in the course of creating lead compounds and improving the efficacy of older generation drugs.  Reduction potentials are traditionally reported as single–electron reduction potentials, E(1), measured against reference electrodes under strictly defined experimental conditions.  More recently, computational chemists have described redox properties in terms of a molecule’s highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), in electron volts (eV).  The relative accessibility of HOMO/LUMO data through calculation using today’s computer infrastructure and simplified algorithms make the calculated value (LUMO) attractive in comparison to the accepted but rigorous experimental determination of E(1).  This paper describes the correlations of eV (LUMO) to E(1) for three series of bioreductively–activated benzotriazine di-N-oxides (BTDOs), ring-substituted BTDOs, ring-added BTDOs and a selection of aromatic nitro compounds. The current computational approach is a closed–shell calculation with a single optimization.  Gas phase geometry optimization was followed by a single–point DFT (Density Functional Theory) energy calculation in the gas phase or in the presence of polar solvent.  The resulting DFT–derived LUMO energies (eV) calculated for BTDO analogues in gas phase and in presence of polar solvent (water) exhibited very strong linear correlations with high computational efficiency (r2 = 0.9925) and a very high predictive ability (MAD = 7 mV and RMSD = 9 mV) when compared to reported experimentally determined single–electron reduction potentials.

Prediction of proton affinities of organic molecules using the any-particle molecular-orbital second-order proton propagator approach

2016 ◽  
Vol 18 (39) ◽  
pp. 27185-27189 ◽  
Author(s):  
Laura Pedraza-González ◽  
Jonathan Romero ◽  
Jorge Alí-Torres ◽  
Andrés Reyes
Keyword(s):  
Gas Phase ◽  
Molecular Orbital ◽  
Organic Molecules ◽  
Second Order ◽  
Proton Affinities ◽  
Wide Range

We assess the performance of the recently developed any-particle molecular-orbital second-order proton propagator. Our results show that this method provides quantitative predictions of gas phase proton affinities for a wide range of organic molecules.

Gas-Phase Tautomerism in the Triazoles and Tetrazoles: A Study by Photoelectron Spectroscopy and ab Initio Molecular Orbital Calculations

1981 ◽  
Vol 36 (11) ◽  
pp. 1246-1252 ◽  
Author(s):  
Michael H. Palmer ◽  
Isobel Simpson ◽  
J. Ross Wheeler
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
Relative Stability ◽  
Photoelectron Spectra ◽  
Equilibrium Geometry ◽  
Molecular Orbital Calculations ◽  
Methyl Derivatives

The photoelectron spectra of the tautomeric 1,2,3,- and 1,2,4-triazole and 1,2,3,4-tetrazole systems have been compared with the corresponding N-methyl derivatives. The dominant tautomers in the gas phase have been identified as 2 H-1,2,3-triazole, 1 H-1,2,4-triazole and 2H-tetrazole.Full optimisation of the equilibrium geometry by ab initio molecular orbital methods leads to the same conclusions, for relative stability of the tautomers in each of the triazoles, but the calculations wrongly predict the tetrazole tautomerism.

Molecular orbital structures of sulfones

1982 ◽  
Vol 60 (6) ◽  
pp. 730-734 ◽  
Author(s):  
Russell J. Boyd ◽  
Jeffrey P. Szabo
Keyword(s):  
Crystal Structure ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Geometry Optimization ◽  
Membered Ring ◽  
Molecular Orbital Calculations ◽  
Bond Lengths ◽  
Comparison With Experiment ◽  
The Difference

Abinitio molecular orbital calculations are reported for several cyclic and acyclic sulfones. The geometries of XSO2Y, where X, Y = H, F, or CH3 are optimized at the STO-3G* level. Similar calculations are reported for the smallest cyclic sulfone, thiirane-1,1 -dioxide, as well as the corresponding sulfoxide, thiirane-1-oxide, and the parent sulfide, thiirane. Where comparison with experiment is possible, the agreement is satisfactory. In order to consider the possibility of substantial differences between axial and equatorial S—O bonds in the gas phase, as observed in the crystal structure of 5H,8H-dibenzo[d,f][1,2]-dithiocin-1,1-dioxide, STO-3G* calculations are reported for a six-membered ring, thiane-1,1-dioxide, and a model eight-membered ring. Limited geometry optimization of the axial and equatorial S—O bonds in the chair conformations of the six- and eight-membered rings leads to bond lengths of 1.46 Å with the difference being less than 0.01 Å.

Sign in / Sign up

Export Citation Format

Share Document