Presentation Information
[17p-M_123-7]Mechanical Control of Electrical Conductance and Thermopower in Single-Molecule Junctions of a π-Extended Three-Dimensional Carbohelicene
〇Shintaro Fujii1, Futo Morita1, Kanato Takahashi1, Juntaro Nogami1, Yuko Kishida1, Haruki Goto1, Ryota Shimizu1, Tomoaki Nishino1, Hidehiro Uekusa1, Ken Tanaka1 (1.Science Tokyo)
Keywords:
molecular junction,break junction,mechanical modulation
Helicenes possess a three-dimensional π-conjugated framework formed by ortho-fused benzene rings, enabling electron delocalization both through bonds and through space between π planes. Although theory predicts that electrical conductance and thermopower in helicene single-molecule junctions can be mechanically tuned by modifying interplanar interactions, experimental verification has been limited. In this study, we designed and synthesized a π-extended carbo[11]helicene and constructed stable single-molecule junctions using metal-π interactions with gold electrodes. Scanning tunneling microscopy confirmed the formation of an ordered monolayer on Au(111). Statistical analysis of conductance–distance traces obtained by the break-junction method revealed reproducible molecular plateaus longer than 1 nm, demonstrating stable junction formation. Compared with heteroatom-anchored helicene junctions, higher conductance was observed. Notably, during the pushing process, molecular compression led to a clear increase in conductance. Thermopower measurements under a temperature gradient further showed large negative values reaching approximately −40 μV/K, indicating strong mechanical modulation of orbital alignment in the junction.