Automatic polarographic elucidation of electrode

After validation, the previously described expert system has been employed in the investigation of reduction mechanisms of two metallomacrocylic compounds that have not been electrochemically studied before: a nickel salen derivative and a binapthyl-uranyl salen crown ether. The system has found that on a mercury electrode in DMSO, under experimental conditions (concentration in the range of 5 × 10−4 −2 × 10−3 M, time scale corresponding to scan rates 0.15–8.0 V s−1) the nickel salen derivative undergoes a reversible electron transfer followed by a fast, reversible chemical reaction. Additional experiments performed outside the expert system suggest that another very slow chemical step takes place, either subsequent or parallel, resulting in a product accumulated on the electrode surface. In the chemical processes most probably traces of water, oxygen or other impurities are involved. For binapthyl-uranyl salen crown ether the elucidated mechanism is a fast, reversible electron transfer followed by a weak adsorption of the reduction product (studied concentration range 2 × 10−4 −2 × 10−3 M, time scale corresponding to scan rate 0.11–5.0 V s−1. In both cases the expert system provided results which supported a single hypothesis about the mechanism much more than all others, giving a clear, unambiguous conclusion. The full elucidation cycle took approximately one working day.