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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Photophysical study of a family of [Ru(phen)_2(Me_ndpq)]~(2+) complexes in different solvents and DNA: a specific water effect promoted by methyl substitution
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Photophysical study of a family of [Ru(phen)_2(Me_ndpq)]~(2+) complexes in different solvents and DNA: a specific water effect promoted by methyl substitution

机译：[Ru（phen）_2（Me_ndpq）]〜（2+）配合物在不同溶剂和DNA中的光物理研究：甲基取代促进的特定水效应

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The synthesis and spectroscopic characterisation of a family of ruthenium complexes [Ru(phen)_2(Me_ndpq)]~(2+) (n = 0,1,2) are reported and the photophysical effect of the progressive methyl substitution on the dpq ligand ascertained in a range of solvents and in the presence of DNA: [Ru(phen)_2(dpq)]~(2+) (1),[Ru(phen)_2(Medpq)]~(2+) (2) and [Ru(phen)_2(Me_2dpq)]~(2+) (3) (where dpq is dipyrido[3,2-f:2',3'-h]-quinoxaline;Medpq is 2-methyldipyrido[3,2-f:2',3'-h]-quinoxaline;Me_2dpq is 2,3-dimethyldipyrido[3,2-/:2',3'-h]-quinoxaline and phen is 1,10-phenanthroline).The increase in electron density following substitution renders the quinoxaline nitrogen atoms more basic in the ground state to yield pK_a values of -1.9,-2.3,and -2.7 for 3,2,and 1,respectively.The methyl groups have a pronounced effect on the excited state photophysics of 1-3.In organic solvents,the non-radiative decay constant correlates well with the solvent polarity parameter pi~*,with the effect being more pronounced with increasing methyl substitution.On the contrary,in aqueous solution there is a ca.four-fold decrease in the non-radiative decay constant upon methyl substitution.This 'specific water effect' may be explained in terms of deactivation of the excited state by hydrogen bonding interactions between water and the quinoxaline nitrogen atoms,which is reduced on moving from 1 to 3.The excited state lifetimes and luminescence intensities for 1 substantially increase when bound to DNA in aerated aqueous solutions,with a six-fold increase,compared to a more moderate three-fold increase for 2 and 3.
机译：报道了钌配合物[Ru（phen）_2（Me_ndpq）]〜（2+）（n = 0,1,2）的合成和光谱表征，并且逐步甲基取代对dpq配体的光物理效应在一定范围的溶剂中和存在DNA的情况下确定：[Ru（phen）_2（dpq）]〜（2+）（1），[Ru（phen）_2（Medpq）]〜（2+）（2）和[Ru（phen）_2（Me_2dpq）]〜（2+）（3）（其中dpq是双吡啶[3,2-f：2'，3'-h]-喹喔啉; Medpq是2-甲基双吡啶[3， 2-f：2'，3'-h]-喹喔啉; Me_2dpq是2,3-二甲基二吡啶并[3,2-/：2'，3'-h]-喹喔啉，而phen是1,10-菲咯啉）。取代后电子密度的增加使喹喔啉的氮原子在基态更碱性，分别对3,2和1产生-1.9，-2.3和-2.7的pK_a值。 1-3的激发态光物理。在有机溶剂中，非辐射衰减常数与溶剂极性参数pi〜*有很好的相关性，其中w的影响更为明显。相反，在水溶液中，甲基取代后的非辐射衰变常数降低约四倍。这种“特定水效应”可以用激发态的失活来解释。水与喹喔啉氮原子之间的氢键相互作用从1移至3时会减少。与充气水溶液中的DNA结合时，1的激发态寿命和发光强度显着增加，相比之下增加了六倍。 2和3的增加幅度是中等的三倍。

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