Temperature measurement using fluorescent molecular rotors
The introduction provides a brief overview of the problem of developing nano-sized devices for temperature detection. Fluorescent molecular rotors are considered as potential prototypes of temperature sensors. The spectral-fluorescent properties of thioflavin T (Tht) derivative (BTA-2 cation), a compound that belongs to the class of fluorescent molecular rotors (FMR), are described. The purpose of this work is to study temperaturesensitive fluorescence of BTA-2 cation and the possibility of using it as a temperature sensor. The main part discusses spectral-kinetic parameters of the fluorescence of BTA-2 cation and possibility of using this molecule as a sensor element in temperature sensors. The data obtained in this work (the fluorescence lifetime of BTA-2 cation in water-glycerol solutions and polyvinyl alcohol films, the determination of the rate constants for radiative and non-radiative transitions of the derivative under study, etc.) made it possible to elaborate the model of excited state deactivation for thioflavin Tht derivatives (additional nonradiative transition was found). The results of spectral-kinetic studies of the BTA-2 cation in water-glycerol solutions were used to solve the practical problem of measuring the distribution of the temperature field along the capillary with the test solution. In the course of these studies, the apparent dependence of the fluorescence lifetime of the BTA-2 cation on temperature was shown. The scientific novelty of the obtained results consists in elaborating the deactivation scheme of the excited state of ThT derivatives in viscous media, as well as in identifying the temperature-dependent nature of the fluorescence of the studied molecule, which can be used as nanoscale fluorescent thermometers. The field of application of the obtained results is nanotechnology (microfluidics), medicine, biology and microscopy.