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

Abstract

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–Shäfer (QLS) films from three ambipolar sandwich tetradiazepinoporphyrazinato/phthalocyaninato europium double-decker complexes [^nBuPc]₂Eu (1), [^tBuPhDzPz][^nBuPc]Eu (2) and [^tBuPhDzPz]₂Eu (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.