Anomalous phenomenon in pyridyl-imidazoperylene H_2gas sensor

摘要

Organic pigments were once extensively investigated as a photoconductor for the electrophotographic photoreceptor. Nowadays, they play an important role as colorants for color copies as well as materials for optical discs, electroluminescence, FET etc. Here, we report another novel application of organic pigments for H_2 gas sensors. We are involved in the research and development on H_2 gas sensors utilizing high proton affinity of the pyridyl rings integrated in the title compound (PIP). An anomalous phenomenon in PIP-based H_2 sensors has been observed that the sensor current increases even after H_2 interruption. Two N-sites in PIP are found to be involved in the protonation: N~1 at the pyridyl ring and N~2 at the five-membered ring. Among these, N~1 is especially sensitive to water moisture as well as H_2; whereas N~2 behaves as an ordinary proton acceptor as found in other pyridylring-integrted pigments. The anomalous effect is found to be due to the former N~1 behavior.