A Tale of Chaos and Colour Influencing the photophysical properties and glass forming abilities of BODIPY dyes via structural modification
Abstract
Organic dyes are everyday contributors in chemistry, physics and biology. BODIPY dyes
were used as model dye class in this thesis. They are well-known for their versatility,
which mainly originates from the tuneability of their photophysical properties upon
changes in their molecular structure. This thesis strives to deepen the knowledge of the
structure-to-photophysical properties relationship of those fluorophores. Furthermore, it
demonstrates how the intrinsic properties of the dye can be influenced by modifying the
molecular structure.
Structural homologues of the BODIPY and the aza-BODIPY class were synthesised. The
homologues differ only in the bridging atom. Moreover, they are decorated with electron
withdrawing and donating groups. The effects of those groups were analysed for each
class individually and additionally compared within the two classes. This revealed
different behaviours of the two dye classes that were previously unexplored.
To strategically decrease the singlet-triplet energy gap, a BODIPY-anthracene dyad,
which populates a charge separated state, and can then undergo charge recombination
into the triplet state, was oligomerised. Oligomerisation in a non-conjugated fashion
mimics a fixed J-aggregate thus facilitating strong exciton coupling. This lowers the
singlet state of the oligomers, without having a large effect on the triplet energy.
Therefore, the energy gap, which can be described as the energy loss of the system, can
be decreased.
Furthermore, a new dye material, a room temperature dye glass, was fabricated. BODIPY
derivatives equipped with different alkyl chains were synthesised and subsequently
mixed. Upon mixing the entropy of the system is increased, leading to a decrease in the
materials ability to crystallise and aggregate. The material now forms an amorphous solid
state, a glass, which inherits the monomeric optical properties of the dye components.
The results presented in this thesis highlight that by modifying the molecular structure of
a dye molecule, its intrinsic properties can be governed according to ones needs. This is
of great importance for the in vivo design of dyes as well as the fabrication of new
materials.
Parts of work
Paper I
Entropic Mixing Allows Monomeric-Like Absorption in Neat BODIPY Films
Clara Schäfer, Jürgen Mony, Thomas Olsson, and Karl Börjesson, Chem. Eur.
J. 2020, 26, 14295–14299.
https://doi.org/10.1002/chem.202002463 Paper II
The effect of the aza-N-bridge and push-pull moieties, a comparative study between
BODIPYs and aza-BODIPYs
Clara Schäfer, Jürgen Mony, Thomas Olsson, and Karl Börjesson, J. Org.
Chem. 2022, 87, 2569−2579.
https://doi.org/10.1021/acs.joc.1c02525 Paper III
Room Temperature Dye Glasses - A Guideline towards the Fabrication of
Amorphous Dye Films with Monomeric Absorption and Emission
Clara Schäfer, Sandra Hultmark, Yizhou Yang, Christian Müller, and Karl
Börjesson, Chem. Mater. 2022, 34, 20, 9294–9302.
https://doi.org/10.1021/acs.chemmater.2c02761 Paper IV
Selective reduction of the singlet excited state to decrease the singlet-triplet energy
gap via intramolecular exciton-exciton coupling
Clara Schäfer, Rasmus Ringström, Jörg Hanrieder, Bo Albinsson, and Karl
Börjesson.
Manuscript
Degree
Doctor of Philosophy
University
University of Gothenburg
Institution
Department of Chemistry and Molecular Biology ; Institutionen för kemi och molekylärbiologi
Disputation
Fredag 5 maj, 2023, kl. 9.15, KC-salen, Campus Johanneberg, Kemigården 4, Göteborg
Date of defence
2023-05-05
clara.schafer@chem.gu.se
Date
2023-04-04Author
Schäfer, Clara
Keywords
BODIPYs
structure-to-optical properties relationship
entropy
amorphous materials
exciton coupling
Publication type
Doctoral thesis
ISBN
978-91-8069-238-0 (PDF)
978-91-8069-237-3 (PRINT)
Language
eng