Studies on 6,6‘-Disubstitution Effects of the dpq in [Ru(bpy)₂(dpq)]²⁺with DFT Method

Abstract

Theoretical studies on 6,6‘-disubstitution effects of the dpq in [Ru(bpy)2(dpq)]2+ are carried out by using DFT method at the B3LYP/LanL2DZ level. The substituent effects caused by the electron-pushing group (OH) and the electron-withdrawing group (F) on the electronic structures and the related properties, e.g., the energies and the components of some frontier molecular orbitals, the spectral properties, and the net charge populations of some main atoms of the complexes, etc., have been investigated. The computational results show that the substituents have some interesting effects on the electronic structures and related properties of the complexes. First, on the basis of the analysis of the frontier molecular orbitals, the substituents influence the first excited-state properties of the substitutive derivates. The electron-withdrawing group (F) can activate the main ligand and passivate the co-ligands in the first excited state of [Ru(bpy)2(2F-dpq)]2+, whereas the electron-pushing group (OH) does not have this effect in this system. Second, the ground band wavelength of electronic spectra of each of complexes [Ru(bpy)2(2R-dpq)]2+ (R = OH, H, or F) is shorter slightly than that of well-known complex Ru(bpy)3 2+. The substitution of electron-pushing group (OH) or electron-withdrawing group (F) on 6,6‘ sites of dpq in [Ru(bpy)2(dpq)]2+ can cause a slight red shift in the ground band of the complex. Third, some interesting characteristics of atomic net charge populations on the main ligands of the three complexes occur, and they can be simply and satisfactorily interpreted applying the schematic map expressed by several series of arrowheads, based on the law of polarity alternation and the idea of polarity interference. The above theoretical results should be important to further inquiry into the interaction mechanism of the complexes with DNA active units from both the molecular orbital interactions and the atomic charge interactions.

QSAR Studies on a Series of 7,8‐Dialkyl‐1,3‐diaminopyrrolo‐[3,2‐f]quinazolines with Anticancer Activity

“…Furthermore, the stable configurations of the compounds can be confirmed by the frequency analysis, in which no imaginary frequency is found for all configurations at the energy minima. Some frontier molecular orbital compositions were analyzed 17 and the natural orbital population analysis (NPA) 15 was carried out. The above-mentioned calculations were all performed with the Gaussian 98 program-package.…”

Synthesis, Spectral Properties and DFT Calculations of new Ruthenium (II) Polypyridyl Complexes; DNA Binding Affinity and in Vitro Cytotoxicity Activity

“…the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are varied and when they intercalating in the DNA base pairs, the energy of the transition conformation will different. According to the frontier molecular theory, an electron will transfer more easily from a high HOMO to a lower LUMO, and resulting those complex have the lowest LUMO (in generally, the HOMO of DNA is higher than that of ruthenium complexes) will bind to DNA the strongest [16][17][18].…”

A Theoretical Investigation into the Photophysical Properties of Ruthenium Polypyridine‐Type Complexes

“…In the case of ruthenium compounds, the influence of diimine-type ligands has been investigated to interpret photonic [13] or electrochemical properties, [14] as well as the ability to interact with DNA. [15,16] More recently, time-dependent density functional theory (TDDFT) [17] has proven its aptitude for calculation of the vertical electronic excitation energies responsible for the absorption spectra of Ru II complexes. [18][19][20] The solvatochromism phenomenon has even been evaluated for some systems.…”