Synthesis, spectroscopic analysis and photolabilization of water-soluble ruthenium(III)-nitrosyl complexes
Synthesis, spectroscopic analysis and photolabilization of water-soluble ruthenium(III)-nitrosyl complexes
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DOI：
10.1039/c2dt30464c
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发表时间：
2012-01-01
影响因子：
4
通讯作者：
Lehnert, Nicolai
中科院分区：
文献类型：
--
作者：
Merkle, Anna C.;McQuarters, Ashley B.;Lehnert, Nicolai
本文报道了一系列以TPA(三（2-吡啶基甲基胺）为配体的新型{RuNO}(6)型Ru(III)-亚硝基的合成、结构和光谱表征。以Ru（III）前驱体[Ru(TPA)Cl-2]ClO4(1)为原料，与NO气体简单反应制备了络合物[Ru(TPA)Cl-2(NO)]ClO4(2)。x射线晶体学证实，这导致TPA的一个吡啶（py）臂被NO取代（而不是氯阴离子被NO取代）。以TPA作为四齿配体的NO配合物是通过新的Ru（II）前体[Ru(TPA)(NO2)(2)](3)与强酸反应得到的。这导致亚硝酸盐脱水为NO+，并形成{RuNO}(6)配合物[Ru(TPA)(ONO)(NO)](PF6)(2)(4)，该配合物也进行了结构表征。用尿素(5)或水(6)代替亚硝酸盐的4衍生物也得到了。然后用红外光谱和傅里叶变换拉曼光谱进一步研究了这种方法得到的亚硝基配合物。两种阴离子氯配体的配合物2显示出最低的N-O和最高的Ru-NO拉伸频率，分别为1903和619 cm（-1）。在TPA作为四齿配体的配合物5和6中，较高能量的nu（N-O）分别为1930和1917 cm(-1)，较低能量的nu（Ru-NO）分别为577和579 cm（-1）。这些振动能，以及沿着这一系列配合物观察到的nu（N-O）和nu（Ru-NO）的负相关关系，再次支持了之前提出的{RuNO}(6)配合物的Ru(II)-NO+型电子结构。最后，我们研究了UV光照射下Ru-NO键的光性，以确定配合物2、4、5和其他水溶性配合物[Ru(H(2)edta)(Cl)(NO)](7)和[Ru(Hedta)(NO)](8)中NO的光释放量子产率（phi）。虽然{RuNO}(6)配合物经常被认为是体内NO递送剂，但研究phi如何受到溶剂水的影响的研究缺乏。我们的研究结果表明，中性水不是一种促进NO光解的溶剂，这将是设计{RuNO}(6)配合物作为体内光稳定的NO递送剂的主要障碍。
In this paper, the synthesis, structural and spectroscopic characterization of a series of new Ru(III)-nitrosyls of {RuNO}(6) type with the coligand TPA (tris(2-pyridylmethyl)amine) are presented. The complex [Ru(TPA)Cl-2(NO)]ClO4 (2) was prepared from the Ru(III) precursor [Ru(TPA)Cl-2]ClO4 (1) by simple reaction with NO gas. This led to the surprising displacement of one of the pyridine (py) arms of TPA by NO (instead of the substitution of a chloride anion by NO), as confirmed by X-ray crystallography. NO complexes where TPA serves as a tetradentate ligand were obtained by reacting the new Ru(II) precursor [Ru(TPA)(NO2)(2)] (3) with a strong acid. This leads to the dehydration of nitrite to NO+, and the formation of the {RuNO}(6) complex [Ru(TPA)(ONO)(NO)](PF6)(2) (4), which was also structurally characterized. Derivatives of 4 where nitrite is replaced by urea (5) or water (6) were also obtained. The nitrosyl complexes obtained this way were then further investigated using IR and FT-Raman spectroscopy. Complex 2 with the two anionic chloride coligands shows the lowest N-O and highest Ru-NO stretching frequencies of 1903 and 619 cm(-1) of all the complexes investigated here. Complexes 5 and 6 where TPA serves as a tetradentate ligand show nu(N-O) at higher energy, 1930 and 1917 cm(-1), respectively, and nu(Ru-NO) at lower energy, 577 and 579 cm(-1), respectively, compared to 2. These vibrational energies, as well as the inverse correlation of nu(N-O) and nu(Ru-NO) observed along this series of complexes, again support the Ru(II)-NO+ type electronic structure previously proposed for {RuNO}(6) complexes. Finally, we investigated the photolability of the Ru-NO bond upon irradiation with UV light to determine the quantum yields (phi) for NO photorelease in complexes 2, 4, 5, and additional water-soluble complexes [Ru(H(2)edta)(Cl)(NO)] (7) and [Ru(Hedta)(NO)] (8). Although {RuNO}(6) complexes are frequently proposed as NO delivery agents in vivo, studies that investigate how phi is affected by the solvent water are lacking. Our results indicate that neutral water is not a solvent that promotes the photodissociation of NO, which would present a major obstacle to the goal of designing {RuNO}(6) complexes as photolabile NO delivery agents in vivo.