Thiol-Linked Anthraquinone Anthryl Acetylene Molecule:  Synthesis, Self-assembly, and Photoelectrochemical Properties

A novel self-assembling molecule with coplanar anthraquinonyl and anthryl moieties linked by an acetylenic unit has been designed and synthesized as an electron acceptor for efficient photocurrent generation. The high-resolution scanning tunneling microscopy (STM) images showed that the self-assembled monolayer (SAM) of this molecule forms highly ordered two-dimensional (2D) arrays on Au(111) with an oblique lattice and graphite-like stacking at room temperature. The electrochemical study of this molecule and its SAM on Au showed reversible characteristics. The SAMs generated by co-assembling this acceptor with an oligo(pyrrolethiophene) donor show very promising photoelectrochemical properties. The amount of photocurrent generated (up to 1425 nA/cm 2, 23.1% of quantum yield) under the illumination of 360 nm light is comparable to that obtained from using a C 60 -based molecule as the electron acceptor (1700 nA/cm 2 ). This result demonstrates the feasibility of using anthraquinone-anthrylacetylene-thiol linked molecule as an efficient electron acceptor for constructing a monochromatic light-to-current molecular converter.