TY  - THES
AB  - Fluorescence spectroscopy is an indispensable analytical method in modern research. The complexity of luminescent systems usually requires the combination of several techniques.
In this work, novel donor-acceptor fluorescence dyes with potential applications in electro-optical devices, materials with non-linear optical properties and fluorescence sensors were characterized spectroscopically. For the targeted synthesis of these fluorophores
with specific fluorescence properties, a detailed understanding of their optical characteristics is essential.
An important part of this work was the optimization of dynamic and static fluorescence techniques for the spectroscopic characterization of donor-acceptor dyes. In particular, an excitation-emission-spectrometer has been supplemented by an integration sphere for the detection of solid state fluorescence. Furthermore, a newly designed TCSPC-experiment enables the analysis of excited states in solution as well as in the solid state.
A low-temperature sample holder was integrated in both experiments for static and dynamic fluorescence spectroscopy at temperatures down to 77 K.
In the second part of this work, a number of boron-based donor-acceptor-dyes, containing a 1,3,2-benzodiazaborolyl or a dicarba-closo-dodecarborane unit, were investigated
spectroscopically. For a comprehensive understanding of the relationship between the structure of dyes and their fluorescence properties, the spectroscopic studies were
supplemented by the results of TD-DFT calculations and X-ray structure analysis. Benzodiazaborolyl-based donor-acceptor dyes exhibit intense luminescence accompanied
by large Stokes shifts. The distinct solvatochromism of the emission confirms a strong change in the dipole moment between the ground state and the excited state which is
characteristic for donor-acceptor dyes. By the variation of the substituents at the nitrogen atoms of the benzodiazaborole, the originally electron donating character can be changed to an electron accepting behaviour. As a result, the benzodiazaborolyl moiety
offers the unique opportunity to create donor-acceptor dyes in which both functionalities originate from the same group of substances.
Systematic measurements revealed that ortho-carboranebased donor-acceptor dyes possess unexpected and complex emission properties which include dual fluorescence. UVemissions are due to local transitions while the low-energy emissions could be traced back to a charge-transfer-transition to an excited state with a geometry significantly different to the ground state. Benzodiazaborolyl-substituted ortho-carboranes exhibit
yellow to red emission in the solid state. Because of the high quantum yields of up to 70 %, these compounds are a promising candidate for technical applications.
DA  - 2014
KW  - boron-based fluorescence dyes
KW  - carboranes
KW  - OLEDs
KW  - low-temperature measurements
KW  - static and dynamic fluorescence measurements
LA  - ger
PY  - 2014
TI  - Mehrdimensionale Fluoreszenzspektroskopie an borbasierten Donor-Akzeptor-Farbstoffen: Zusammenhang von Struktur und photophysikalischer Funktionalität
UR  - https://nbn-resolving.org/urn:nbn:de:hbz:361-26932407
Y2  - 2024-11-22T04:44:03
ER  -