Switchable Optical Probes for Simultaneous Targeting of Multiple Anions

Traditional optical probes primarily work on the concept of one-to-one recognition strategy. Therefore, simultaneous detection of multiple anions is difficult using this kind of sensory systems. Similarly, designing of multi-responsive array-based materials is synthetically challenging as well as difficult to optimize. Thus, researchers across the globe became interested in developing single molecular probes, capable of detecting multiple anions (or anionic biomolecules) by simultaneously activating optically distinguishable output channels. Here, the modes of interaction largely depend on the structural features of the binding sites (cleft size, number of available coordination sites etc.), characteristics of the anions (ionic radius, hydration enthalpy, basicity, coordination number, pk_a of corresponding acids etc.) and the microenvironment around the probe molecules (micropolarity, viscosity, dielectric constant etc.) in the host matrix. In this review, we are mostly focusing on the structure-activity relationships of such multiple anions sensing optical probes and their stimuli-responsive properties.