A sensitive molecular probe exhibiting significant change in their photophysical and morphological behavior upon interaction with Fe ion.

An efficient molecular probe 8 has been designed and synthesized. The photophysical, electrochemical and morphological behavior of the probe has been examined in the absence and presence of different ions. The probe 8 at 90 % water fraction in acetonitrile showed aggregation induced emission (AIE). Probe 8 upon interaction with ions binds with Fe ion selectively in a 1:1 stoichiometry and showed fluorescence "turn-Off" response with good limit of detection (LOD = 92.2 nM). The particle size (DLS method) of probe upon increasing water fraction in acetonitrile showed a gradual increase while upon formation of a stable complex, 8 + Fe particle size decreased along with change in morphology of the probe. SEM and TEM studies showed that in pure acetonitrile probe self-assemble into a sheet like structure of uneven surface. While in aggregated state (fw, 90 %) it changes to a uniform hollow rectangular rod shape structure. Further interaction of the probe with Fe ions in aggregated state acquired a well-defined smooth sheet. Electrochemical (CV) studies suggested that the redox property of the probe incurred a marginal change in band gap upon complexation with Fe. The cell imaging studies were performed to detect Fe in HeLa cells. The paper strip test and real water sample analysis showed the potential analytical application of probe to detect Fe with a naked-eye sensitive visible color change. The formation of a complex, 8 + Fe involving N and O atoms of the probe molecule was confirmed by HNMR and HRMS data.