Photochemistry and Spectroscopy Department
Institute of Physical Chemistry, Polish Academy of Sciences
MAESTRO highlights
1. Synthesis of several dozen new porphyrinoids (derivatives of porphyrin, porphycene, hemiporphycene and corficene) designed to (i) increase photostability; (ii) modifying the strength of the intramolecular hydrogen bond; (iii) changes in the quantum yield of the emission (see next section).
2. Demonstration of the correlation between the fluorescence quantum yield and the strength of intramolecular hydrogen bonds in porphycenes.
3. Demonstration of a huge increase in photostability (2-3 orders of magnitude under anaerobic conditions) for a series of cyclooctatetraene-substituted porphyrins.
4. Demonstration for a number of indoleacridine and indolopyrazine derivatives that the formation of intermolecular hydrogen bonds with alcohol leads to a large increase in photostability (even a 200-fold reduction in the photodestruction quantum efficiency).
5. Proposing a model according to which the quantum effect - delocalization of internal hydrogen atoms in porphycenes - triggers fast non-radiative transitions between the lowest excited singlet state and the ground state.
6. Comparison of single-molecule photostability for three porphycenes: the unsubstituted parent molecule and derivatives "screened" by tert-butyl substituents. Observation of a very heterogeneous photostability distribution.
7. Demonstration that measurements of single molecules by confocal fluorescence microscopy for chromophores with a negligible efficiency of transition to the triplet state distinguish molecules with a shortened triplet lifetime (quenched by the oxygen molecule adjacent to the fluorophore). The above model is confirmed by measuring fluorescence lifetimes in cryogenic oxygen-doped matrices.
8. Increasing the photostability of the phthalocyanine derivative by placing the chromophore in an optical microcavity.
9. Understanding the mechanisms of photodegradation of porphyrins in normal and deoxygenated solutions. Comparison of photostability of porphyrins and metalloporphyrins. Increasing photostability by complexation with dimethyl sulfoxide.
10. Detection of huge differences in the photostability of porphycenes substituted with electron donors and acceptors.
11. Development of a methodology for accurately determining the quantum efficiency of photodestruction.
12. Demonstration of the effectiveness of porphycenes in photoinduced destruction of bacteria.
13. Use of thin porphycene films as fast and reversible acidity sensors.
14. Application of a simple modification of the spectrofluorimeter, which allows for a more accurate measurement of fluorescence quantum yield than before.
