Abstract
We have prepared and reporting a new cyanide colorimetric and turn-on fluorescent chemo sensor L. Naked-eye colorimetric studies shows the prepared receptor is selectively sensing cyanide ion in acetonitrile medium. The sensor L shows very weak fluorescence in acetonitrile medium. The emission intensity of L gets reduced (quenching of fluorescence) upon addition of one equivalent of cyanide. Meanwhile further gradual addition of more than one equivalents of cyanide onto 1:1 cyanide complex of L shows remarkable fluorescence enhancement. The weakly emissive receptor L show drastic enhancement in fluorescence intensity upon addition of excessive cyanide ion which is mainly attributed due to the restriction of intramolecular rotation of 1:1 L•CN- complex and intermolecular aggregation of host: guest complex. This enhanced fluorescence emission is attributed due to the aggregation induced enhanced emission (AIEE) is subsequently supported with UV-Vis, emission and 1H-NMR spectroscopic studies. The preferential binding of cyanide by electron deficient receptor L through hydrogen bonding and anion···π interaction over benzene analogue of L is also analyzed with help of MEP surface analyses. To the best of our knowledge, this is the first example for selective colorimetric and turn- on cyanide sensor through AIEE mechanism. This type of fluorine rich organic material having such an aggregation enhanced emission properties in response to cyanide addition will be useful to construct the new type of material for various sensory applications.
A Turn-on Fluorescent Sensor For Cadmium Ion Detection In Aqueous Solutions
