Aguirre J Dafhne, Lutterman Daniel A, Angeles-Boza Alfredo M, Dunbar Kim R, Turro Claudia
Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA.
Inorg Chem. 2007 Sep 3;46(18):7494-502. doi: 10.1021/ic700708g. Epub 2007 Aug 9.
The reactivities toward biomolecules of a series of three dirhodium(II,II) complexes that possess an increasing number of accessible axial coordination sites are compared. In cis-[Rh2(OAc)2(np)2]2+ (1; np=1,8-naphthyridine) both axial sites are available for coordination, whereas for cis-[Rh2(OAc)2(np)(pynp)]2+ (2; pynp=2-(2-pyridyl)1,8-naphthyridine) and cis-[Rh2(OAc)2(pynp)2]2+ (3) the bridging pynp ligand blocks one and two of the axial coordination sites in the complexes, respectively. The electronic absorption spectra of the complexes are consistent with strong metal-to-ligand charge transfer transitions at low energy and ligand-centered peaks localized on the np and/or pynp ligands in the UV and near-UV regions. Time-dependent density functional theory calculations were used to aid in the assignments. The three complexes exhibit metal-centered oxidations and reductions, localized on the aromatic ligands. The ability of the complexes to stabilize duplex DNA and to inhibit transcription in vitro is greatly affected by the availability of an open axial coordination site. The present work shows that open axial coordination sites on the dirhodium complexes are necessary for biological activity.
比较了一系列三种二铑（II,II）配合物对生物分子的反应活性，这些配合物具有越来越多可及的轴向配位位点。在顺式-[Rh2(OAc)2(np)2]2+（1；np = 1,8-萘啶）中，两个轴向位点均可用于配位，而对于顺式-[Rh2(OAc)2(np)(pynp)]2+（2；pynp = 2-(2-吡啶基)-1,8-萘啶）和顺式-[Rh2(OAc)2(pynp)2]2+（3），桥连的pynp配体分别在配合物中阻断了一个和两个轴向配位位点。配合物的电子吸收光谱与低能量下强烈的金属到配体的电荷转移跃迁以及紫外和近紫外区域中位于np和/或pynp配体上的以配体为中心的峰一致。使用含时密度泛函理论计算来辅助进行归属。这三种配合物表现出以金属为中心的氧化和还原，定域在芳族配体上。配合物稳定双链DNA和体外抑制转录的能力受到开放轴向配位位点可用性的极大影响。目前的工作表明，二铑配合物上的开放轴向配位位点对于生物活性是必需的。
