Abstract:
Push-pull chromophores (also, called donor-acceptor compounds) are delocalized π-electron
systems with a donor at one end of the molecule and an acceptor at the other. These compounds
are used as active materials in organic devices such as organic light emitting diodes (OLED),
organic photovoltaic cells (OPVC) and dye-sensitizing solar cells (DSSC). There are numerous
studies on heterocyclic push-pull compounds based on oxazoles, oxadiazoles and triazoles with
promising optical and photophysical properties. However, systematic study of the substituent
effect on the photophysical properties of tetrazole-based donor-acceptor compounds is scarce in
the literature. Thus, the aim of this project was to synthesize several push-pull tetrazole
compounds of the general structure 2,5-AD and 2,5-DA with varying strengths of donors (D) and
acceptors (A) and investigate their photophysical properties by UV-Vis and fluorescence
spectroscopy.
The key step in the synthesis of 2,5-AD and 2,5-DA involved a copper-catalyzed aerobic
C-N coupling reaction of the appropriately substituted aryl tetrazoles and aryl boronic acids. The
photophysical properties were analyzed in different organic solvents, using ultra-violet visible and
fluorescence spectroscopy. Our work so far shows that the UV-Vis absorption characteristics of
these molecules can be tuned with substituents. The 2,5-AD compounds studied showed weak
emission, while no fluorescence was observed from the 2,5-DA compounds. Our preliminary work
indicates that the synthesized compounds exhibit small solvatochromic behavior and cannot serve
as solvent polarity indicators.
