Preeti Saluja

Imine-linked chemosensors for the detection of Zn2+ in biological samples

A chemosensor 1 with a long hydrocarbon chain and polar end group is synthesized by the simple condensation reaction of a long chain amine with salicylaldehyde. A long chain hydrocarbon with a polar end group is used because of its solubility in an aqueous surfactant solution, which ensures that it can be used in a neutral water medium. The rationale for choosing an aryl aldehyde with –OH functionality is based upon the fact that a chelate ring consisting of an –OH group and an sp2 nitrogen donor is always better for the selective recognition of Zn2+. The sensor shows selective binding to Zn2+ in 1% Triton-X-100 solution. Binding of Zn2+ by sensor 3 leads to an approximately 300% enhancement in the fluorescence intensity of the sensor, due to the combined effects of excited state intramolecular proton transfer (ESIPT) and the inhibition of the photo-induced electron transfer (PET) process by the –OH group. The fluorescence emission profiles of sensor 1 show some changes in the low and high pH ranges, however the sensor remains stable in the pH range 4–9, which makes it appropriate for use in biological fluids.

Nanoaggregates of benzothiazole-based amidine-coupled chemosensors: a chemosensor for Ag+ and the resultant complex as a secondary sensor for Cl−

Nanoaggregates of benzothiazole-based amidines were prepared for study as sensors in aqueous medium. Sensor N2 was found to behave as a selective primary sensor for Ag+, and the subsequent complex N2·Ag+ acted as a secondary sensor for Cl− in aqueous medium through a cation displacement mechanism. The cation displacement mechanism was further supported by a CV titration of complex N2·Ag+ with Cl−.

Quantum Dot Based Chemosensors: Selective Estimation of Cu2+in Semi‐aqueous Medium

Quantum dots are the semiconducting nanocrystals whose exicitons are restricted in all the three dimensions within a range of 2–10 nm. Due to the phenomenon called quantum confinement they have unique optical and photo physical properties which makes them useful as chemosensors. Since quantum dots provide a useful framework for the surface confinement of the receptors thereby resulting in changes in the receptor binding affinity. Therefore capturing this feature of the quantum dots different ligands are synthesized and then attached to the quantum dots. Finally studying the surface modification of the quantum dots helps us to make chemosensorsors.