Photocurrent responsive films prepared from a nickel-dithiolate compound with directly bonded pyridyl groups

Because the pyridyl group can act as a proton acceptor and a coordination biting unit, electrodes with films of dithiolene complex [ n -Bu 4 N][Ni(4-pedt) 2 ] ( 1 ) (4-pedt = 1-(pyridine-4-yl) ethylene-1,2-dithiolate) are prepared to investigate the photocurrent response behaviours of a metal dithiolene compound upon protonation and transition metal coordination. The morphologies of film 1 are characterized by SEM analysis. Photoelectrochemical measurements are carried out with the electrodes of film 1 . The results are as follows: (1) the stronger the medium acidity is, the weaker the photocurrent becomes. (2) Photocurrent intensities of Mn( ii ), Co( ii ) and Zn( ii ) treated film 1 are increased in comparison with that of the original film 1 due to the polymeric coordination. (3) When film 1 is treated by Fe( iii ) ions, it is oxidized to a neutral [Ni(4-pedt) 2 ] film that shows weaker photocurrent response. In addition, a new ionic pair compound MV[Ni(4-pedt) 2 ] 2 ( 2 ) (MV 2+ = methylviologen dication) synthesized by cation exchange shows good photocurrent response properties due to the improvement of electron transfer. Photocurrent response behaviours of a nickel dithiolene derivative upon protonation, transition metal coordination and cation exchange by photoactive MV 2+ are discussed.