2025-06-032025-06-032025-05-19https://repository.tcu.edu/handle/116099117/67115Fluorescent small molecule environment-sensitive probes have photophysical properties such as emission wavelength, fluorescence intensity or lifetime that change based on their surroundings like temperature, pH, or viscosity. Viscosity is an important physical property of fluid media, which plays crucial roles in many chemical and biological systems. In biological settings such as a cellular environment, changes in viscosity could be indicative of cellular malfunction or abnormalities. Thus, utilization of these environment-sensitive molecular probes could be useful in assessing the changes in viscosity of the cells. Ratiometric probes have two components with different reactive spectral properties that allow for more consistent internal calibration that provides more accurate determination of viscosity. However, the synthesis of ratiometric probes is often challenging, requiring multiple purification steps for isolation of the desired compounds. Therefore, this research highlights our synthetic efforts to make ratiometric molecular viscometers in a facile, efficient and modular manner.