FWF - Molekulare Thermometer - TADF-based Molecular Thermometers

In analytical chemistry, luminescent sensors represent an invaluable and flexible tool to measure a variety of analytes under conditions unsuitable for other detection methods. Undoubtedly, temperature is one of the most important parameters to be monitored. Knowing temperature is not only of highest interest of its own but also is crucial for compensation of chemical sensors for temperature cross-talk. With ongoing progress in luminescent sensors and their growing popularity in various fields of science and technology, optical temperature measurement gains increasing importance. Often, application of conventional analytical tools such as resistance thermometers is either almost impossible possible (e.g. in (intra)cellular measurements) or undesirable due to their invasiveness. Unfortunately, most state-of-the-art luminescent temperature sensors do not possess the desired resolution due to limited temperature sensitivity and often feature other drawbacks such as poor brightness and incompatibility with compact and low cost instrumentation. Related research for OLED technology has (re-)discovered thermally activated delayed fluorescence (TADF) as a type of luminescence with interesting properties combining the features of fluorescence and phosphorescence. The photophysical properties of these dyes, however, have not yet been adapted for optical sensing. Most of TADF OLED emitters are either excitable in the UV or blue part of the electromagnetic spectrum and/or possess low molar absorption coefficients making them less suitable for sensing applications. The flexibility in molecular design of TADF emitters, however, allows the tuning of photophysical properties over a wide range. The synthetic effort is comparably low and precious metals are not required, contrary to most phosphorescent dyes. Our recent discovery of the highly temperature-dependent character of the luminescence lifetime of TADF emitters makes us to believe that the current limitations of these dyes can be overcome by proper structural modification, making them highly promising for application as molecular thermometers. Thus, the main aim of the project is to design and synthesise new TADF dyes and develop high performance temperature sensing materials on their basis. We also plan to adapt the unique class of emitters featuring dual phosphorescence and TADF for simultaneous oxygen and temperature sensing. For this purpose, the group of Sergey Borisov from the Institute for Analytical Chemistry and Food Chemistry in Graz, will design and synthesize new TADF emitters with photophysical properties optimized for optical sensing of temperature and dual oxygen and temperature sensing. The dyes will be then used to manufacture new optical sensing materials realized in various formats (planar optodes and spots, fiber-optic sensors, nanoparticles) especially for bioanalytical applications.