Newly developed conjugated polymer systems for nitroexplosive detection: Insights into the mechanistic investigations

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The content of this synopsis report entitled "Newly Developed Conjugated Polymer Systems for Nitroexplosive Detection: Insights into the Mechanistic Investigations" is divided into six chapters. Chapter 1 specifically describes the respective rescarch area where the scope and significance of the subsequent chapters are discussed. Chapter 2 discusses about the synthesis and characterization of conjugated polymer (PFAM) and its application in the rapid and specific recognition of nitroexplosive-picric acid (PA) on solid support and solution based on IFE/PET mechanism. Chapter 3 describes the synthesis of a new water-soluble non-fluorescent cationic conjugated polyelectrolyte PPPY, which selectively recognized nitroexplosive PA by fluorescence "turn-on" in the presence of closely related nitroexplosive compounds via fluorescence indicator displacement assay (IDA) technique in water at pH 7.0. Chapter 4 highlights the synthesis of cationic CP PFBT via oxidative polymerization and displayed dual state emission in DMSO as well as in water, a phenomenon very rarely observed, and tested for nitroexplosive analytes detection to observe a remarkable fluorescence quenching response for picric acid (PA) in the both solvents. Contact mode detection of PA was also accomplished using easy, economical and portable fluorescent test strips for on-site detection, which can detect upto (0.22 attogram level of PA. Vapor phase detection of PA was also established, which can detect up to 42.6 ppb level of PA vapors. Interestingly, the mechanism of sensing in DMSO solvent was attributed to strong inner filter effect (IFE) and photo induced electron transfer (PET), while in H2O the sensing occurs via possible resonance energy transfer (RET) and photoinduced electron transfer (PET), which is exceptional and not reported earlier for a single probe. Chapter 5 discusses the synthesis of the neutral "receptor-free" highly fluorescent conjugated polymers (PF1 and PF2), which detects PA by a fluorescence tum-off response, and was found as a result of exclusive IFE and was further confirmed via IFE corrections. Chapter 6 summarizes the thesis overview and the importance of various sensing mechanisms that can probably exist for nitroexplosive detection but not limited to these chemical entities. Additionally the design principle of probes that can result in efficient sensing of picric acid via these mechanisms was also studied and presented.
Supervisor: Parameswar Krishnan Iyer