Colorimetric and fluorescent sensing of transition metal ions in aqueous medium by salicylaldimine based chemosensor

The cation sensing property of highly sensitive chromogenic receptor N, N′-bis (salicylidine)-o-phenylene diamine (receptor 1) was studied by visual observation, UV–vis spectroscopy and fluorescence spectroscopy. The proposed study has been targeted to sense the first transition series metal cations like Fe3+, Co2+, Ni2+ and Cu2+. Binding affinity toward Cu2+ is found to be of higher magnitude compared to the other three cations mentioned. Receptor 1 on binding with Fe3+, Co2+ Ni2+ and Cu2+ ions shows fluorescence enhancement which is due to the inhibition of PET mechanism.

The cation sensing property of highly sensitive chromogenic receptor N, N′-bis (salicylidine)-o-phenylene diamine was studied by naked eye observation, UV–vis spectroscopy and fluorescence spectroscopy. The proposed study has been targeted to sense the first transition series metal cations like Fe3+, Co2+, Ni2+ and Cu2+. Binding affinity toward Cu2+ is found to be of higher magnitude compared to the other three cations mentioned. Receptor 1 on binding with Fe3+, Co2+ Ni2+ and Cu2+ ions shows fluorescence enhancement which is due to the inhibition of PET mechanism.Figure optionsDownload as PowerPoint slideHighlights
► Receptor 1 serves as a multi channel probe for different transition metal cations.
► Binding constant for Cu2+ is of higher magnitude compared to the other cations.
► The ions bind to the receptor through NONO centers forming 2:1 and 1:1 complexes.
► Paramagnetic ions show fluorescent enhancement due to the inhibition of PET mechanism.