Electrical conductivity of π-complexes of metal 8-hydroxy-quinolinates

Abstract

Studies of the electrical conductivity of single crystals of the chloranil complexes of palladium and copper 8-hydroxyquinolinates are described. The preparation, analysis, and photoconductivity of a series of palladium 8-hydroxyquinolinate–chloranil complexes doped with 0–30% of the corresponding copper complex are also reported. Curves showing photoconduction as a function of wavelength have two regions of response, one to each side of the intermolecular charge-transfer band. The ratio of the responses in these two regions, and the resistivities of the samples, are strongly dependent on the concentration of the copper complex in the sample. The mechanim of photoconduction in molecular complexes is discussed in the light of these results, and it is shown that all the known results can be accommodated by the assumption that the low- and high-energy responses are due to the production of carriers by two different mechanisms. The effect of the copper complexes is discussed in terms of an electron-trapping mechanism for the production of charge carriers in the low-energy region.