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Photoluminescence and Photochromism in Solution and in Solid Matrices - Interaction Kit Photo-Mol

Hotspots with particularly relevant contents for "Chemistry with Light" can be found in this thesis on the following pages with the respective contents :

  • p. 7 to p. 12: excited states and photoluminescence
  • li>p. 21 to p. 25: photochromism, photo steady state, solvatochromism
  • S. 29 to p. 44:  photoluminescence of esculin in tartaric acid, PVA, and gelatin
  • p. 45 to p. 48(+S .91): upconversion of photons via TTA
  • p. 60 to p. 67: model experiment on the RESOLFT concept
  • p. 83 to p. 67. 91: energy level model in didactic concise variations
  • p. 93 to p. 98: experiments and accompanying material in the "Photo-Mol" kit

Get the thesis (in German): urn:nbn:de:hbz:468-20190102-153948-6

Abstract

In this thesis, the experimental and material kit "Photonen und Moleküle (Photo-Mol)" was developed for the integration of photoprocesses, especially fluorescence, phosphorescence and photochromism, into school curricula. The experiments meet the requirements for the safe use of experiments. The observations are didactically concise due to the apparent material changes (colour shifts) and are suitable for use in class due to the use of harmless chemicals.

During the research of new experiments on fluorescence and phosphorescence, investigations were carried out to determine which conditions are advantageous for inducing an effect analogous to the heavy atom effect in organic molecules. For this purpose, two similar fluorophores (esculin and esculetin) were introduced into different inorganic and organic matrices and the changes in both fluorescence and phosphorescence spectra were investigated. Thus, the ability of the fluorophores to form hydrogen bonds with the matrix could be identified and confirmed as an important criterion for achieving this effect.

During the development of the photochromic experiments different solid matrices (polystyrene PS, polyvinyl alcohol PVA, polymethyl methacrylate PMMA and gelatine) were tested and characterized as a rigid medium for the fixation of the molecular switch spiropyrane/merocyanine. Polystyrene has been proven to be a trouble-free medium for teaching and learning. In the model experiment on RESOLFT nanoscopy, developed for the first time in collaboration with Sebastian Spinnen, PMMA is best suited.

For the upconversion of photons, an experiment was developed which has not been known in the literature so far. It implements the concept of triplet triplet annihilation with TPFPP-Pt(II) and DPA. By storing the oxygen-free solution in an ampoule, it was also possible to produce a sample that can be easily presented in demonstration lectures and at conferences. The upconversion from green light to blue light in this experiment meets the requirements for a didactically concise and scientifically consistent experiment.