Characterization of fluorescent conjugated polymer sensors with varying percentage loading of dipyrrolequinoxaline receptors for the detection of fluoride and cyanide ions

Simple methods to detect common inorganic anions represent a continuing challenge for the characterization of contaminants in the environment. Cyanide and fluoride anions have a significant negative impact on the environment. Rapid detection of these agents in a sensitive and selective manner is currently of great interest. While a number of analyses for these ions exist, there is a need for portable low-cost sensors for field-based detection. This research explores the characterization of fluorescent conjugated polymers as "turn-off" anion chemosensors.;Previous research done in the Jones group showed that when dipyrrolequinoxaline (DPQ) anion sensing systems are incorporated into a conjugated polymer backbone, the sensitivity of the system increases. The Jones group synthesized a series of new conjugated dipyrrolequinoxaline polymers containing a combination of pendant receptors or non-pendant receptors which were incorporated into the polymer backbone.1 These polymers were fully characterized and evaluated as fluorescent chemosensors in solution for the selective detection of fluoride and cyanide anions. In each polymer, the acidic pyrrole N-H protons serve as the receptor unit.;This research focuses on the loading dependence and molecular weight distribution of conjugated fluorescent polymer sensors. The NDPQ and PDPQ-PPETTE polymers, with increasing percentage loading of the receptor, were synthesized by my associates in the Jones group. Afterwards, the polymers were fully characterized by various spectroscopic techniques including gel permeation chromatography (GPC), multi angle laser light scattering (MALLS), ultraviolet-visible (UV-Vis) and nuclear magnetic resonance (NMR) spectroscopy. Successful characterization of the polymer systems provides insight to optimize the polymer synthesis and sensor design. The main focus of this research was on characterizing the molecular weight attributes of these polymers. UV-Vis and 1H NMR techniques were also used to verify the impact of receptor loading on the conjugation system and to determine the impact of different syntheses and aging on the structure of these polymers respectively.