Fig. 1

Schematic diagram of electrochemical scanning tunneling microscopy break junction (ECSTM-BJ) and molecular structures. a Schematic illustration of the ECSTM-BJ approach for the conductance measurement of single-molecule junctions (red balls, Cu; green balls, Au; blue balls, O; gray balls, C) and b the target molecular structure of 2-M-1,3-BDC, 1,3-BDC, 5-M-1,3-BDC, and 1,3-BDCA