Photoelectrochemical behavior of azobenzene self-assembled monolayers on gold

A novel azobenzene derivative was synthesized and self-assembled into monolayer on gold. The photochromic:and electrochemical behavior of thus formed azobenzene SAMs were studied by investigating the different redox properties before or/and after irradiating the film with 350 nm UV light. In the large scan range (-0.6 similar to+0.5 V), clear-cut electrochemical response of trans-azobenzene/hydrazobenzene was obtained in B-R buffer (0.1 mol/L NaClO4, pH: 2), while no discernible faradic response can be observed in a small scan range(-0.3 similar to+0.5 V). However, after 5 min irradiation of UV light, redox peaks corresponding to cis-azobenzene/hydrazobenzene raised up in the cyclic voltammogram, It should be noted that: (1) The conversion ratio of trans/cis isomerization is very low in the highly-organized monolayers due to the inhibition of rigid SAMs' structure, (2) The cis-azobenzene is much easier to be reduced than trans-form, enable the unique ''one way hybrid photoelectrochemical cycle'' to be available in SAMs as we obtained previously in LB monolayer.