NBO Population Analysis and Electronic Calculation of Four Azopyridine Ruthenium Complexes by DFT Method

Abstract

The molecular structure, the Natural Bond orbital (NBO) and the Time Dependent-DFT of both isomers cis or γ-Cl and trans or δ-Cl of RuCl 2 (L) 2 , where L stands respectively for 2-phenylazopyridine (Azpy), 2,4-dimethyl-6-[phenylazo]pyridine (Dazpy), 2-[(3,5-dimethylphenyl)azopyridine] (Mazpy) and 2-pyridylazonaphtol (Nazpy) were calculated with DFT method at B3LYP/LANL2DZ level. The prediction of the frontier orbitals (Highest Occupied Molecular Orbital or HOMO and Lowest Unoccupied Molecular Orbital or LUMO) shows that the most active complexes suitable for electronic reactions are admitted to be the trans isomers. Moreover, δ-RuCl 2 (Azpy) 2 is discovered to react more actively as photo-sensitizer since its energy gap is the minimum. Besides, electronic structures of all complexes through NBO calculation indicate that Ru-N bonds are made of delocalization of occupancies from lone pair orbital of N atoms to the ruthenium. Moreover, Ru was assumed to have almost the same charge regardless the structure of the azopyridine ligands in the complex indicating that the ligands provide only a steric effect that is responsible for the ruthenium's selectivity. Concerning the transition state, NBO analysis also highlights that the transition LP(Ru)π*(N 1 -N 2 ) does correspond to t 2g π*(L). This transition is assumed to correspond to Metal to Ligand Charge Transfer (MLCT) that is responsible for the photo-sensitiveness of the metallic complex. Besides, TDDFT calculation of complexes showed that δ-RuCl 2 (Nazpy) 2 displays the largest band during the absorption. For that reason, it is admitted to be the best photosensitizer due to a large system of conjugation provided by Nazpy ligand.

Theoretical calculation of influence of halogen at-oms (F, Cl, Br, I) on arylazopyridine (Azpy) ruthenium complexes behaving as photo sensitizers by DFT method

“…Which confirms a symmetry that allows each pair of atom to be in the same environment as we indicated in a previous paper (Nobel et al 2017). Thus, those isomers are assumed to be C2 symmetrical.…”

Theoretical Determination of Influence of the Metallic State of Oxidation toward Cytotoxic Activity: Case of Ruthenium Complexes

“…Terpy and α-Rucl 2 (azpy) 2 present wavelengths in the visible domain up to 500 nm. This data is characteristic of MLCT transfer[43]. They present respectively 521.35 nm and 624.06 nm at Wb97xd/Lanl2dz level and 536.41 nm and 640.44 nm at B3lyp/Lanl2dz level.…”

Perfluorophenyl Derivatives as Unsymmetrical Linkers for Solid Phase Conjugation

“…The frequency calculations afforded no negative Eigen values indicating stability of the molecule. After optimization of the molecules, their atomic charges were calculated using natural bond orbital (NBO) analysis, another efficient tool for studying hyperconjugative interactions, intermolecular charge transfer, and electron density transfer (EDT), which are fundamentally linked for calculations of atomic charges (Drissi et al, 2015; Md Abdur Rauf et al, 2015; El-Faham et al, 2016; Kouakou Nobel et al, 2017). …”