Engineering nanometre-scale coherence in soft matter

• Published in: Nature chemistry Vol. 8; no. 10; pp. 941 - 945
• Main Authors: Liu, Chaoren, Xiang, Limin, Zhang, Yuqi, Zhang, Peng, Beratan, David N, Li, Yueqi, Tao, Nongjian
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.10.2016
• Subjects: DNA - chemistry; Electric Conductivity; Electrons; Energy; Engineering; Guanine - chemistry; Nucleic Acid Conformation; Quantum Theory; Symmetry; United States > US; Arizona
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/NCHEM.2545

Electronic delocalization in redox-active polymers may be disrupted by the heterogeneity of the environment that surrounds each monomer. When the differences in monomer redox-potential induced by the environment are small (as compared with the monomer-monomer electronic interactions), delocalization persists. Here we show that guanine (G) runs in double-stranded DNA support delocalization over 4-5 guanine bases. The weak interaction between delocalized G blocks on opposite DNA strands is known to support partially coherent long-range charge transport. The molecular-resolution model developed here finds that the coherence among these G blocks follows an even-odd orbital-symmetry rule and predicts that weakening the interaction between G blocks exaggerates the resistance oscillations. These findings indicate how sequence can be exploited to change the balance between coherent and incoherent transport. The predictions are tested and confirmed using break-junction experiments. Thus, tailored orbital symmetry and structural fluctuations may be used to produce coherent transport with a length scale of multiple nanometres in soft-matter assemblies, a length scale comparable to that of small proteins.