4th EucheMs chemistry congress

Poster Session 1
s1028
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - organic chemistry
P - 0 3 3 3
CoMBinAtoriAL SyntheSiS, SCreeninG And
PhotodeGrAdAtion of PhoSPhoreSCent
MetAL CoMPLexeS for oLedS.
A. hohenLeutner 1 , S. SChMidBAuer 1 , r. vASoLd 1 ,
B. KÖniG 1
1 Institute of Organic Chemistry, Chemistry and Pharmacy,
Regensburg, Germany
While there have been thousands of reported transition metal
complexes for OLED applications in the last decade, an accurate
prediction of their photophysical properties and especially their
device stabilities/degradation mechanisms is not yet feasible.
Therefore the laborious synthesis, purification characterization
and testing of a larger number of compounds is still inevitable for
the development of new phosphorescent emitters with improved
performances.
We report the combinatorial synthesis and screening of
phosphorescent iridium complexes as solution processable
emitters for OLEDs. Our approach allows for the rapid library
synthesis, as well as the isolation, spectroscopic characterization
and identification of the compounds based on chromatographic
methods. Subsequent analysis of the irradiation induced
degradation provides insight on the stability of the complexes
under continuous excitation. Utilizing the developed screening
methodology we purified and characterized a larger number of
potential emitters. We examined the photophysical properties of
the compounds by obtaining absorption and emission spectra
directly from the chromatographic separation. Important trends in
the dual emission behavior of selected heteroleptic complexes
were observed that upon further studies might lead to the
development of promising new compounds for white OLEDs. By
investigating the photodegradation of the libraries in solution, we
found surprising trends and could identify compounds with
increased stabilities compared to the rest of the libraries. Further
studies into degradation mechanisms and to elucidate possible
connections between the device- and photo-stabilities are in
progress. The gained insight into degradation mechanisms and
structure property relationships will help in the design of
phosphorescent dopants with improved performances. The
reported chromatography based screening of organo-transition
metal complexes is by no means restricted to the development of
new OLED emitters but may be easily applied for the accelerated
discovery of other metal complexes or organic dyes for various
applications, e.g. in electroluminescence, photovoltaics and
sensing.
Keywords: Phosphorescence; combinatorial synthesis; Iridium
Complexes; Screening; Oled;
4 th EucheMs chemistry congress
P - 0 3 3 4
Photoswitchable Monolayers: A dynamic Control over Cell
Adhesion
M. hoLz 1
1 Otto-Diels-Institut für Organische Chemie,
Organic Chemistry, Kiel, Germany
Photoswitchable monolayers of azobenzene derivatives
mounted on glass, quartz or silicon surfaces offer an effective
control over cell adhesion. The light induced reversible
cis-/trans-isomerization of azobenzenes permits a precise
temporal and spatial control of surface properties.
We employed three strategies:
1. Switching of wettability
Upon isomerization of the azobenzene derivative, the
surface wettability changes due to different dipole moments of
the azobenzene isomers. This is especially the case when using
polar head groups.
2. fast oscillations
Upon irradiation with white light, azobenzenes with
push/pull substitution patterns are known to undergo a fast
continuous switching between their cis- and trans-isomers. [1]
We intend to utilize this effect to create a fast oscillating
monolayer on surfaces.
3. integrin mediated adhesion
The establishment of an arginine-glycine-aspartate (RGD)
tripeptide squence cell binding domain on surfaces offers the
opportunity to target specific integrins of cells. We have chosen
the c(-RGDfK-) peptide [2] as our future head group for this
purpose, due to its specific binding to α β integrin.
v 3
references:
1. T. Asano J. Am. Chem. Soc. 1980, 102, 1205; S. Hvilsted
et al. J. Mater. Chem. 2009, 19, 6641; B. Schmidt et al.
J. Phys. Chem. A. 2004, 108, 4399.
2. R. Haubner et al. J. Am. Chem. Soc. 1996, 118, 7461.
Keywords: Cell Adhesion; azobenzene; monolayers on glass;
photoswitchable monolayers;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc