Bielefeld University Department of Chemistry Biophysical Chemistry and Photochemistry deutsch

Dye Photochemistry and Polymer Chemistry

Organic dyes play an important role as fluorescence markers in spectroscopy and microscopy and as chromophores in sensory proteins and light-driven enzymes. Furthermore they have a great potential for application in the field of photovoltaics and in organic LEDs.

We monitor the reaction steps after excitation with light by time-resolved UV/vis and FTIR spectroscopy. Our aim is to identify intermediates and products as well as to determine the kinetics.

In the focus of our investigations are aqueous media, because water poses special challenges for infrared spectroscopy due to its high intrinsic absorption.

Fluorescence Markers for Super-Resolution Microscopy

The development of super-resolution light microscopy beyond Abbe´s diffraction limit is based on dyes which can be switched off transiently. These non-fluorescent states are often not chemically characterized.

Due to the high sensitivity of FTIR spectroscopy we can identify the products of these inefficient reations by a combination with quantum chemical calculations. In particular, we can record difference spectra in presence of a very high background signal from reaction partners (see J. Phys. Chem. Lett. 2010).

Model Compounds for Chromophores in Light Sensors

We need reference measurements of organic dyes in solution to understand photochemical reactions in proteins. However, the basic characterization by infrared spectroscopy of key transient intermediates is often missing (see PCCP 2013).

Furthermore, a comparison of our results in aqueous solution with those in organic solvents and in the protein enables us to isolate the influence of the protein environment.

Polymer Chemistry

FTIR spectroscopy allows us to investigate the structure and composition of organic polymers and other materials (see Angew. Chem. Int. Ed. 2010).

As applications we determine the monomer content in copolymers (siehe Polymer 2017) and resolve structural changes in thermoresponsive, colloidal particles in water.

As surface-sensitive technique we apply ATR difference spectroscopy on monolayers. By photopolymerization we obtain freestanding 2D nanomembranes with promising properties.

The employment of quantum cascade lasers allows us to enter totally new fields of application.

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