Date Thesis Awarded


Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)




Elizabeth J. Harbron

Committee Members

Robert J. Hinkle

John C. Poutsma

John Conlee


Rhodamine based dyes have grown in popularity for use as pH sensors in biological systems due to their sensitive and rapid response to changes in pH. However, these rhodamine dyes typically fluoresce at levels which are too acidic for most biological system. Since the pH at which the dyes fluoresce is a function of the steric and electronic effects of different substituents, different di-ortho Rhodamine B (RB) and Rhodamine 6G (R6G) derivatives were synthesized. Computational models were also used in order to develop a better understanding of the steric and electronic interactions which drive the pH-dependent fluorescence of rhodamine dyes. As a result of titrations of the RB and R6G series, a working equation for use in predicting the pKa of a derivative based on the substituents was drafted using both steric and electronic parameters. Ultimately, the pH response was tuned enough to allow for the development of a rhodamine pH probe capable of responding at a high enough pH for biological applicability. This pH probe was incorporated into conjugated polymer nanoparticles as proof of concept for a possible vector pathway for future biological studies.

On-Campus Access Only