Design based sensors for ionic substrates in sol gel media

Abstract

The dissertation entitled DESIGN-BASED SENSORS FOR IONIC SUBSTRATES IN SOL-GEL MEDIA embodies in detail the design and synthesis of new molecular scaffolds for the selective sensing and detection of ionic species [metal ions and anions] of biological significance in the solution and gel phases. This thesis covers a set of designed molecules that work towards the ionic substrates either through hydrogen bonding interaction or through metal coordination sites. The scaffolds in many cases act as low molecular weight supramolecular gelators in different solvents and the gel phases show responsive character towards the ionic substrates with moderate sensitivities. Tuning of the structures leads to the development of new gelators and helps us to understand the structure-property relationship in molecular aggregation and to build up ion-responsive sensing materials. In the area of molecular recognition, numerous efforts are directed by supramolecular chemists to develop artificial sensors for biologically relevant cationic and anionic substrates. The designs show the interaction with the guests involving various non-covalent forces (hydrogen bonding, charge-charge interactions, cation-and#960;, and anion and#960; interactions etc.) and govern the absorption, emission, or electrochemical changes in the solution. In recent times, substantial effort is given to developing ion-responsive supramolecular gelators in addition to the conventional probes. The use of gel phase to mark the recognition event by visualizing the phase transformation (sol-to-gel or vice versa) in naked-eye without any instrumental aids is less explored and is therefore challenging. Apart from recognition, such compounds find applications in biomedical and material science in capturing toxic materials and dyes from contaminated water etc. The work in this thesis covers the detailed study on self-aggregation, gel properties and ion responsive features of the newly designed molecular structures.