Characterization and Application of Self-Assembly Porphyrin with Four “Clips” on Gold Surface

Self-assembled monolayers (SAMs) of thiol-derivatized porphyrin molecules on Au substrate have attracted extensive interest for use in sensing, molecular recognition, and molecular electronics. Here, we synthesized tetra[ p -(3-mercaptopropyloxy)phenyl]porphyrin (PPS 4 ) with four “clips” for SAMs. The results demonstrated that PPS 4 could form excellent SAMs on gold surface wherein the molecules oriented on substrates with a tilted angle. Self-assembled nanojunctions of PPS 4 were fabricated by using gold nanogap electrodes (gap width: ca. 100 nm), which exhibited nonlinear current−voltage characteristics, indicating tunneling injection of current from Au electrodes into PPS 4 . With the light on/off, the nanojunctions switched between low/high impedance states as nanometer scaled photoswitchers.