Photochemical Sciences Ph.D. Dissertations

Photophysical Studies of Luminescent Supra-Molecules and Their Application in Sensing of Anionic Analytes

Date of Award

2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Photochemical Sciences

First Advisor

Pavel Anzenbacher (Advisor)

Second Advisor

Ganming Liu (Other)

Third Advisor

Malcolm D.E. Forbes (Committee Member)

Fourth Advisor

H. Peter Lu (Committee Member)

Abstract

Analytical chemistry together with photophysical studies is a powerful tool for the detection and quantification of crucial chemical species involved in the environment and biological processes. Among analytical techniques, luminescent chemosensors are widely used in the development of new solutions to long-standing problems. Here, the main focus of this research is the recognition and quantification of important biological and organic/inorganic anions utilizing luminescent molecular sensors.

The first part of this work is focused on the recognition of ATP due to its pivotal role in many biological processes. Bisantrene, a molecule comprising imidazolium hydrazone receptor moieties and anthracene as a central fluorophore, was employed as a new sensor for ATP in water at neutral pH by displaying amplified fluorescence. This process was selective to ATP while other nucleotide phosphates such as AMP, GTP, UTP, and CTP did not elicit sensor response. Also, this sensor was used to sense other small anions such as F-, Cl-, AcO-, H2PO4- and HP2O73- in an organic solvent, where the sensor shows fluorescence quenching.

The second project is focused on the recognition and sensing of various phosphates and carboxylates in water using a metal-sensor coordination system. The sensors are based on fluorescent carboxamidequinoline chemosensors derivatized by phenol and benzothiazole. These sensors form non-fluorescent complexes with Eu3+ where the fluorescence is recovered when the phosphate anion sequesters the Eu3+ from the complex. The present sensors show selectivity for biological phosphates such as ATP, ADP, and AMP.

Arsenate (HAsO42-) is a highly toxic analyte to living organisms, and efforts toward sensing arsenate are an important area of research. The third project is aimed at the detection of arsenate (HAsO42-) in water by luminescence spectroscopy using a lanthanide/transition metal dyad. We have synthesized a cryptand molecule which binds Eu3+and displays a ligand-sensitized luminescence. This intense luminescence is quenched upon addition of Zn2+, only to be restored in the presence of arsenate. This lanthanide/transition metal dyad was used for the detection of arsenate in water utilizing an Off-to-On intensity switching of Eu3+ luminescence.

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