Spectroscopic Study of New Sensors for Organophosphates, Metals, and Cyanide Based on Rhodamine and Cholic Acid Derivatives
Date of Award
Doctor of Philosophy
Dr. Ekkehard Sinn
Dr. Guda Ramaknshna
Dr. Gellert Mezei
Dr. Pamela Hoppe
Despite the increasing interest in developing sensors for nerve gas agents, efficient detection remains challenging. Among the various sensors developed so far, fluorescence sensors play an important role due to their simplicity. We developed six new rhodamine-based compounds that can be used as fluorescent turn-on sensors. Compound 1 and 3 gave high fluorescent enhancement with diethyl chlorophosphate (DCP) compared to the other compounds. Very high selectivity and sensitivity were observed as these compounds did not show significant fluorescent enhancement with dimethyl methylphosphonate (DMMP), HC1 and transition metal ions. The potential sensor can be used in solution as well as on a solid surface.
In addition, rhodamine-based compounds have been used as sensors for metal ions. We used the same strategy to develop turn-ON sensors for some environmentally and biologically important metal ions. Fluorescent sensors were developed for trivalent chromium which is considered a common environmental pollutant. The high affinity of Cr3+ towards CN was employed to develop a fluorescent turn-OFF sensor for toxic cyanide based on the metal displacement approach. Similarly, sensors were developed for Ni2+, Hg2+, Fe3+, and Cu2+.
Siderophores are relatively small organic compounds with extremely high affinity for Fe3+. We synthesized and characterized three new siderophore analogs bearing a cholic acid core (23, 27, and 30). Cholic acid is a biologically available compound with three hydroxyl groups that can be used to attach catechol arms. The salicylate mode of metal complexes (Fe3+ and Al3+) were synthesized successfully and their properties studied using UV-Vis, IR, and NMR spectroscopy.
Weerasinghe, Arambe Gedara Aruna, "Spectroscopic Study of New Sensors for Organophosphates, Metals, and Cyanide Based on Rhodamine and Cholic Acid Derivatives" (2011). Dissertations. 479.