4th EucheMs chemistry congress

Poster Session 1
s1088
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - organic chemistry
P - 0 4 5 3
SyntheSiS And oPtiCAL ProPertieS of
BiS(terPyridine)oLiGothioPheneS And
reLAted MetALLo-SuPrAMoLeCuLAr
dynAMerS
P. StenCLovA 1 , J. zedniK 1 , J. vohLidAL 1 ,
J. SvoBodA 1
1 Faculty of Science Charles University in Prague, Department
of Physical and Macromolecular Chemistry, Prague 2, Czech
Republic
Reversible linking of α,ω-functionalized oligomer
molecules by noncovalent interactions or appropriately labile
covalent or coordination bonds transforms the oligomers into
constitutional-dynamic polymers, co called dynamers. Main
advantages of dynamers are possibilities of additional
modification (in order to tune or tailor their properties) or
self-healing of the main chains by an exchange or reshuffling of
their components. Ideal systems of this constitution can be
repeatedly switched, in contrast to classical permanent polymers
composed of irreversible macromolecules.
Novel, fully π-conjugated ditopic oligomers: α,ωbis(terpyridine)oligothiophenes
(bithiophenes and terthiophenes,
unsubstituted, methyl- or hexyl- substituted), were synthesized
via Pd-catalyzed organic cross-coupling reactions from
monoterpyridine compounds. The obtained products were fully
characterised and their optical properties (absorption and emission
maxima, lifetimes of excited states and photoluminescence
efficiency) are presented as function of their structure. Interaction
of soluble compounds with Zn2+ ions were studied with
absorption and emission spectroscopy. Metallo-supramolecular
dynamers were obtained from the reaction of
bis(terpyridine)oligothiophenes with Zn2+ salts and additional
exchange of counterions.
On the basis of our results, we can draw several principal
conclusions: (i) the wavelength of the longer-wavelength
maximum of the oligomer absorption increases with
oligothiophene linker prolongation and (ii) decreases with
introduction of alkyl group onto thiophene ring, (iii) the emission
maximum in photoluminescence spectra increases with
conjugated chain prolongation. The lifetimes of excited states are
relatively short (0.55–0.77 ns) and the photoluminescence
emission quantum yields are 33–43% for bis-terpyridines with
non-substituted oligothiophene linker and 12–23% for compounds
with alkyl-substituted oligothiophene linker. Detailed
characterization of metallo-supramolecular dynamers is currently
underway in our laboratory.
Both π-conjugated oligomers as well as related
supramolecular dynamers might be, after additional detailed study
of their electronic properties in solution and solid phase suitable
materials for light emitting devices or dye-sensitized solar cells.
Keywords: C-C coupling; N-ligands; supramolecular
chemistry; UV/Vis spectroscopy; fluorescence;
4 th EucheMs chemistry congress
P - 0 4 5 4
ASyMMetriC dieLS-ALder reACtion witn
nitroACryLAte
o. StePAneK 1 , M. KotorA 1
1 Charles University in Prague Faculty of Science, Department
of Organic and Nuclear Chemistry, Prague, Czech Republic
Diels-Alder reaction of nitropropenoates with various dienes
constitutes one of the approaches to regioselectively substituted
cyclohexenes. Interestingly, its enantioselective variant that would
open a route to asymmetrically substituted cyclohexenes remains
hitherto a rather unexplored area. Since there are numerous
interesting compounds possessing chiral cyclohexene scaffold
(e.g. Tamiflu, [1] carbasugars, etc), this method is of considerable
synthetic interest. We focused on asymmetric Diels–Alder
reaction of the nitroacrylate bearing chiral ester auxiliary group
with 1-alkoxydienes. Although the formation up to eight possible
stereoisomers could be expected as the result of the Diels-Alder
reaction, only two of them were preferentially formed owing to
structural features (steric and electronic) of both reactants [2] .
Influence of reaction conditions on the stereoisomer ratio, and
asymmetric induction will be discussed. In addition, further
transformation of the obtained products into advanced synthetic
building blocks and their application in organic synthesis will be
presented as well.
references:
1. Farina, V.; Brown, J. D. Angew. Chem. Int. Ed. 2006, 45,
7330.
2. Kakushima, M.; Scott, D. J. Can. J. Chem. 1979, 57, 1399.
Keywords: Asymmetric synthesis; Cycloaddition; Chiral
auxiliaries;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc