Advances in gas sensors of tetrapyrrolato-rare earth sandwich-type complexes — Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

In recent years, sandwich-type rare earth tetrapyrrole derivatives, have attracted more and more attention as material for conductimetric sensors. They have not only great chemical stability and processability, but also flexible molecular structure, which is a key to adjustable semiconductor properties. In this mini review, we focus mainly on the development of tetrapyrrolato-rare earth sandwich-type complexes as the semiconducting active layer in the gas sensors published in the last ten years (2010–2020). The main part includes two sections. In the single component gas sensing of sandwich rare earth tetrapyrrole complexes, we describe the influence factors of the single-component semiconducting active layer on the sensing performance of tetrapyrrolato-rare earth sandwich-type complexes, including substituents, central metals and π-conjugate systems. In the multi-component gas sensors, the synergistic effect between tetrapyrrolato-rare earth sandwich-type complex and other materials on improving sensitivity and conductivity has been discussed briefly.