Substituent effects on the structure and properties of (para-C5H4X)Ir(PH3)3 complexes in the ground state (S0) and first singlet excited state (S1): DFT and TD-DFT investigations

2020 ◽  
pp. 174751982094286
Author(s):  
Gholamreza Ghane Shalmani ◽  
Reza Ghiasi ◽  
Azam Marjani
Keyword(s):  
Excited State ◽  
Ground State ◽  
Substituent Effects ◽  
Electron Localization Function ◽  
Basis Sets ◽  
Electron Localization ◽  
Singlet Excited State ◽  
Localization Function ◽  
Td Dft ◽  
Localized Orbital

The ground and lowest singlet excited state geometries of selected ( para-C5H4X)Ir(PH3)3 iridabenzene complexes ( para-substituent = NH2, OMe, Me, H, F, Cl, CCl3, CF3, NO2) are optimized using the MPW1PW91 procedure employing the LanL2DZ(Ir) and 6-311G(d, p) (C, H, N, O, P, F, Cl, P) basis sets. The excited state is generated using the time-dependent density function method. The effects of electron-donating groups and electron-withdrawing groups on the energy, atomization energy, rotational constants, and frontier orbital energies in the first singlet excited state (S1) of iridabenzene are investigated and compared to those of the ground state (S0). The Ir–C and Ir–P bonds in the studied molecules are analyzed by electron localization function and localized-orbital locator methods. The correlations between the Ir-C and Ir–P bond distances, electron localization function, and localized-orbital locator values Hammett constants (σp) and dual parameters (σI and σR) are given for the two studied states. The para-delocalization index is used for investigation of the aromaticity of the studied complexes.

The Electron Localization Function in Excited States: The Case of the Ultra-Fast Proton Transfer of the Salicylidene Methylamine

2019 ◽  
Author(s):  
Andrea Echeverri ◽  
Tatiana Gómez ◽  
Patricio Fuentealba ◽  
Boris Maulen ◽  
Carlos Cardenas
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Chemical Bond ◽  
Excited States ◽  
Ground State ◽  
Topological Analysis ◽  
Photochemical Reactions ◽  
Electron Localization Function ◽  
Electron Localization ◽  
Localization Function

The physical characterization of the chemical bond in the ground state has been a central theme to theoretical chemistry. Among many techniques, quantum chemical topology (QCT) has emerged as a robust technique to understand the features of the chemical bond and electron organization within molecules. One consolidate tool within QCT is the topological analysis of the electron localization function (ELF). Most research on ELF and chemical bond has focused either on singlet ground states or the first excited triplet. However, most photochemical reactions and photophysical processes occur in excited states with the same spin-symmetry as the ground state. In this work, we develop a proposal on how to compute the ELF in excited states of any symmetry within linear-response time-dependent density functional theory. Then, we study the evolution of the chemical bonds in the ground and excited state intramolecular proton transfer (ESIPT) of a prototypal Schiff Base (the salicylidene methylamine, Scheme 1). We found that the topological analysis of the ELF along reaction paths explain the presence of a barrier for the proton transfer in the ground state and the absence of it in the excited state. Briefly, in the ground state, the cleavage of the O-H bond results in a structure with high electrostatic potential energy due to an excess of electron lone-pairs (3) in the Oxygen atom, which explains the barrier. In the excited state, the electronic transition promotes an enhancement of the basicity of Nitrogen by allocating three nonbonding electrons in the basin of its lone-pair. This excess of electrons in the N exerts an electrostatic attraction of the proton, which we suggest as the primary driven-force of the barrierless reaction. Because in excited states the molecule can develop more vibrational kinetic energy than in the ground state, we perfumed an ab initio molecular dynamics of the proton transfer in the excited state and corroborate that our conclusions on the topology of the ELF do not change due to dynamic effects.

The Electron Localization Function in Excited States: The Case of the Ultra-Fast Proton Transfer of the Salicylidene Methylamine

2019 ◽  
Author(s):  
Andrea Echeverri ◽  
Tatiana Gómez ◽  
Patricio Fuentealba ◽  
Boris Maulen ◽  
Carlos Cardenas
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Chemical Bond ◽  
Excited States ◽  
Ground State ◽  
Topological Analysis ◽  
Photochemical Reactions ◽  
Electron Localization Function ◽  
Electron Localization ◽  
Localization Function

The physical characterization of the chemical bond in the ground state has been a central theme to theoretical chemistry. Among many techniques, quantum chemical topology (QCT) has emerged as a robust technique to understand the features of the chemical bond and electron organization within molecules. One consolidate tool within QCT is the topological analysis of the electron localization function (ELF). Most research on ELF and chemical bond has focused either on singlet ground states or the first excited triplet. However, most photochemical reactions and photophysical processes occur in excited states with the same spin-symmetry as the ground state. In this work, we develop a proposal on how to compute the ELF in excited states of any symmetry within linear-response time-dependent density functional theory. Then, we study the evolution of the chemical bonds in the ground and excited state intramolecular proton transfer (ESIPT) of a prototypal Schiff Base (the salicylidene methylamine, Scheme 1). We found that the topological analysis of the ELF along reaction paths explain the presence of a barrier for the proton transfer in the ground state and the absence of it in the excited state. Briefly, in the ground state, the cleavage of the O-H bond results in a structure with high electrostatic potential energy due to an excess of electron lone-pairs (3) in the Oxygen atom, which explains the barrier. In the excited state, the electronic transition promotes an enhancement of the basicity of Nitrogen by allocating three nonbonding electrons in the basin of its lone-pair. This excess of electrons in the N exerts an electrostatic attraction of the proton, which we suggest as the primary driven-force of the barrierless reaction. Because in excited states the molecule can develop more vibrational kinetic energy than in the ground state, we perfumed an ab initio molecular dynamics of the proton transfer in the excited state and corroborate that our conclusions on the topology of the ELF do not change due to dynamic effects.

scholarly journals Quantum theory of atoms in molecules, electron localization function, and localized-orbital locator investigations on trans-(NHC)PtI2(para-NC5H4X) complexes

2020 ◽  
Vol 44 (7-8) ◽  
pp. 482-486
Author(s):  
Sarvin Hossien Saraf ◽  
Reza Ghiasi
Keyword(s):  
Quantum Theory ◽  
Substituent Effect ◽  
Atoms In Molecules ◽  
Electron Localization Function ◽  
Electron Localization ◽  
Localization Function ◽  
Hammett Constants ◽  
Localized Orbital ◽  
In Trans ◽  
Electron Donating Groups

In this study, the MPW1PW91 method is applied to analyze the quantum theory of atoms in molecules, the electron localization function, and the localized-orbital locator in trans-(NHC)PtI2( para-NC5H4X) (X = H, F, COOH, CN, NO2, Me, OH, NH2) complexes. The substituent effect is assessed in the presence of electron-withdrawing groups and electron-donating groups and their influence on the Pt–C and Pt–N bonds of the molecules is analyzed using quantum theory of atoms in molecules, electron localization function, and localized-orbital locator methods. In addition, the eta index (η) is used to evaluate the Pt–C and Pt–N bonds in the studied complexes. The correlations between electron localization function, localized-orbital locator, and the η index values of Pt–C and Pt–N bonds with Hammett constants (σp) and dual parameters (σI and σR) are given.

Prediction of hypervalent molecules: investigation on MnC (M = Li, Na, K, Rb and Cs; n = 1–8) clusters

2017 ◽  
Vol 19 (37) ◽  
pp. 25289-25297 ◽  
Author(s):  
Peng Shao ◽  
Bo-Le Chen ◽  
Li Ping Ding ◽  
Dao-Bin Luo ◽  
Cheng Lu ◽  
...  
Keyword(s):  
Density Of States ◽  
Ground State ◽  
Electron Localization Function ◽  
Electron Localization ◽  
Localization Function ◽  
Hypervalent Molecules

The density of states (DOS) and electron localization function plots of the ground state Li6C cluster.

scholarly journals On the Importance of Clar Structures of Polybenzenoid Hydrocarbons as Revealed by the π-Contribution to the Electron Localization Function

Symmetry ◽  
2010 ◽  
Vol 2 (3) ◽  
pp. 1653-1682 ◽  
Author(s):  
Jun Zhu ◽  
Christian Dahlstrand ◽  
Joshua R. Smith ◽  
Sébastien Villaume ◽  
Henrik Ottosson
Keyword(s):  
Electron Localization Function ◽  
Electron Localization ◽  
Localization Function ◽  
Clar Structures
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