Discrimination and detection of NO₂, NH₃ and H₂S using sensor array based on three ambipolar sandwich tetradiazepinoporphyrazinato/phthalocyaninato europium double-decker complexes

Developing a room-temperature operated gas sensor for highly efficient discrimination of various toxic gases, is highly desirable but remains challenging to date. Herein, the successful development of a novel sensor array is reported, which discriminates between three gases using solution-based quasi-Langmuir-Shafer (QLS) films from three ambipolar sandwich tetradiazepinoporphyrazinato/phthalocyaninato europium double-decker complexes [Pc-nBu](2)Eu (1), [(tBuPh)DzPz][Pc-nBu]Eu (2) and [(tBuPh)DzPz](2)Eu (3). For the three oxidizing and reducing gases: NO2, NH3, H2S at the sub-ppm level, 1 showed a response to NO2 and NH3, 2 responded to the three gases, and 3 responded to NO2 and H2S. Because of the synergistic effect between film-conductivity from the highly conjugated phthalocyanine ligands and the effective binding sites from the diazepine moieties, the QLS film 2 showed the best gas-sensing performance of all the sensors in terms of both sensing response to the three toxic gases, and the highest sensitivities (% ppm(-1)) of 46.84, 0.39 and 2.34 for NO2, NH3 and H2S, respectively. Furthermore, by combining the distinct response patterns of the devices, a sensor array was established to qualitatively and quantitatively distinguish NO2, NH3 and H2S gases with ultralow detection concentrations (20 ppb of NO2, 1 ppm of NH3 and 100 ppb of H2S), with a fast response time (1 min) and good stability at room temperature.