Radicalized DNA Bases through Ring-Expansion Modification: An Intriguing Class of Building Blocks for the Magnetic DNA Nanowires

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• 作者：Li Han ; Hongfang Yang ; Jing Zhao ; Yuxiang Bu
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：November 8, 2012
• 年：2012
• 卷：116
• 期：44
• 页码：23214-23223
• 全文大小：487K
• 年卷期：v.116,no.44(November 8, 2012)
• ISSN：1932-7455

文摘

In the present work, cyclopentadienyl radicals are introduced to nucleobases to gain the building blocks of DNA-based molecular wires with novel electromagnetic characteristics. Calculations reveal that the radicalized DNA bases exist stably because their extended 蟺-conjugated structures are beneficial to spin delocalization, diradical base pairs possess open-shell singlet ground states, and magnetic coupling interactions of the multiradical systems are controlled by both intra- and intermolecular interactions. For the designed base pairs, the intra-base-pair magnetic interactions are weak, especially in the diradical rA鈥搑T base pair; as for the inter-base-pair magnetic interactions, different cases are observed depending on the relative position of the radicalized bases. The overlap-stacking diradical helices manifest variable degrees of ferromagnetic and antiferromagnetic characteristics, whereas the magnetic coupling interactions in the cross-stacking diradical helices are generally weak. The latter is attributed to the long spatial distances between the two spin centers. Thus, for the tetraradical helices, their magnetic characteristics can be viewed as a combination of two overlap-stacking diradical base pairs, and mostly are antiferromagnetic. This work provides a reasonable strategy of designing magnetic building blocks for the magnetic DNA molecular wires or DNA molecular magnets.