The effect of metal type and gamma irradiation doses on the VOC detection performance of new 1,3-bis(2-pyridylamino)isoindoline complexes

In this study, naphthoxy group substituted 1,3-bis(2-pyridylimino)isoindoline compounds containing nickel and copper metals were synthesized and characterized by NMR, FTIR, UV-vis, and mass spectroscopic methods. Thin film of these compounds is deposited on Plexiglas substrates decorated with Au interdigital electrode structure using spin coating method. The deposited films are then exposed to six doses of gamma irradiation between 1 kGy and 150 kGy using 60 Co as gamma source. The morphological and volatile organic compound (VOC) sensing properties of as-deposited and gamma-irradiated thin films are investigated using Atomic Force Microscopy (AFM) technique and current-time (I-t) measurement set up, respectively. The results of VOC sensing performance have shown that in naphthoxy group substituted 1,3-bis(2-pyridylimino)isoindoline compounds containing nickel and copper metals strongly dependence on the central metal. Under the same conditions, the maximum sensitivity was observed against methanol vapor in the NiBPI-based sensor, while the maximum sensitivity was observed towards ammonia vapor in the CuBPI-based sensor. The results obtained from examining the effect of gamma radiation dose on the VOC sensing performance of the sensors showed that gamma radiation dose has non-negligible effect on the VOC sensing properties of these compounds. For example, the response of CuBPI-based sensor towards ammonia vapors treated by 15 kGy gamma radiation was 18 times higher than that of bare CuBPI based sensor, the results obtained was correlated with the surface roughness of the films.