Theoretical Studies on the Excited States, DNA Photocleavage, and Spectral Properties of Complex [Ru(phen)2(6-OH-dppz)]2+

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• 作者：Lian-Cai Xu ; Jun Li ; Yong Shen ; Kang-Cheng Zheng ; Liang-Nian Ji
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：January 18, 2007
• 年：2007
• 卷：111
• 期：2
• 页码：273 - 280
• 全文大小：450K
• 年卷期：v.111,no.2(January 18, 2007)
• ISSN：1520-5215

文摘

The structures and related properties of the complex [Ru(phen)₂(6-OH-dppz)]²⁺ (phen = 1,10-phenanthroline;dppz = dipyrido [3,2-a:2',3'-c]phenazine) in the ground state (S₀), the first singlet excited state (S₁), and thefirst triplet excited state (T₁) have been studied using density functional theory (DFT), time-dependent (TD)DFT, Hartree-Fock (HF), and configuration interaction singles (CIS) methods. Three electronic absorption-spectral bands (¹MLCT, ¹LL, and ¹LL) lying in the range of 250-550 nm in vacuo and in aqueous solutionwere theoretically calculated, simulated, and assigned with TDDFT method. In particular, the theoreticalresults show the following: (1) The positive charges of central Ru atom in the excited states (S₁ and T₁) aregreatly increased relative to those in the ground state (S₀), and thus the Ru atom in the excited states can beregarded as Ru(III). (2) The positive charges on the main ligand (6-OH-dppz) in the excited states areconsiderably reduced, and thus the interaction between the main ligand (intercalative ligand) and DNA basepairs is considerably weakened. (3) The geometric structures in excited states are also distorted, resulting inobvious increase in the coordination bond length. It is advantageous to the complex forming a high oxidizingcenter (i.e., Ru(III) ion). On the basis of these results, a theoretical explanation on photoinduced oxidationreduction mechanism of DNA photocleavage by [Ru(phen)₂(6-OH-dppz)]²⁺ has been presented.