Creation of structures and functions of artificial DNAs directed towards nano-assembly of metal complexes

用替代碱基替换DNA天然碱基的策略允许以高度特异性和位点选择性的方式修饰DNA，因为DNA具有排列预先设计的构建块的结构基础。最近，我们设想通过金属介导的碱基配对来取代天然DNA中存在的氢键碱基配对。这种金属诱导的碱基对进入DNA不仅会影响DNA的组装-拆卸过程和双链结构，而且还会赋予DNA多种基于金属的功能。因此，化学接口与生命科学和材料科学沿着这条线，我们设计和合成金属介导的碱基对与核苷轴承苯二胺，邻苯二酚，2-氨基苯酚，吡啶，或羟基吡啶酮作为核碱基。它们中的一些被成功地整合到DNA中，并被发现稳定双链体或三链体结构。最近，我们报道了一系列以羟基吡啶酮核碱基（H）为平面双齿配体的人工寡核苷酸d（5 -GH_nC-3）（n = 1-5）的合成。寡核苷酸的右手双螺旋，nCu^<2+> d（5 -GH_nC-3）_2（n = 1-5）通过Cu^<2+>介导的交替碱基配对而定量形成（H-Cu^<2+>-H），其中掺入每个复合物中的Cu^<2+>沿双链体内部的螺旋轴沿着排列，Cu^<2+>-Cu^<2+>为3.7 - 0.1埃。Cu^<2+>离子通过未成对d电子相互铁磁耦合形成磁链。

The strategy of replacing DNA natural bases by alternative ones has allowed the modification of DNA in a highly specific and site-selective manner, because DNA has a structural basis to array predesigned building blocks. We have recently envisioned the replacement of hydrogen-bonded base pairing present in natural DNA by metalmediated base pairing. Incorporation of such metal-induced base pairs into DNA would not only affect the assembly-disassembly processes and the structure of DNA double strands but also confer a variety of metal-based functions upon DNA. The chemistry thus interfaces with both life sciences and materials scienceAlong this line, we designed and synthesized metal-mediated base pairs with nucleosides bearing a phenylenediamine, a catechol, a 2-aminophenol, a pyridine, or a hydroxypyridone as the nucleobase. Some of them were successfully incorporated into DNA and were found to stabilize the duplex or triplex structures. Recently, we reported the synthesis of a series of artificial oligonucleotides, d(5 -GH_nC-3 ) (n = 1-5), using hydroxypyridone nucleobases (H) as flat bidentate ligands. Right-handed double helices of the oligonucleotides, nCu^<2+> d(5 -GH_nC-3 )_2 (n = 1-5), were quantitatively formed through Cu^<2+>-mediated alternative base pairing (H-Cu^<2+>-H), where the Cu^<2+> incorporated into each complex were aligned along the helix axes inside the duplexes with the Cu^<2+>-Cu^<2+> of 3.7 -0.1 angstrom. The Cu^<2+> ions were coupled ferromagnetically with one another through unpaired d electrons to form magnetic chains.