756
H. Seyler, A. Kilbinger / Tetrahedron Letters 54 (2013) 753–756
plane of neighboring phenyl rings twisted by ca. 35°
O
N
H
O
N
H
O
N
H
HO
O
N
N
N
H
H
N
H
O
O
H
O
O
H
O
O
- intramolecular
hydrogen bond
aggregation due to
solvophobic effect
- steric hindrance
O
H
N
H
O
H
O
O
H
O
O
H
O
N
N
N
N
H
N
H
HO
N
H
O
O
O
neighboring phenyl rings coplanar
Figure 4. Left: Proposed aggregation model shown for oligomer 6. Right: Side-on view of the proposed stacking of the dimers.
self-associating solvent DMSO.32 Micellation of alkyl group bearing
amphiphiles in DMSO has been reported previously.33–35
References and notes
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In 6 the edge opposite the hexyloxy side chains consists of car-
bonyl and N–H hydrogen bond acceptors and donors and can
therefore interact strongly with the solvent DMSO. Compound 7
forms aggregates via the same mechanism. The higher number of
hexyloxy side chains in 7 compared to 6 leads to a stronger solvo-
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p
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Acknowledgments
The authors thank Florian Wolf for MALDI-ToF MS measure-
ments. AFMK thanks Maren Schulze for helpful discussions and
the Deutsche Forschungsgemeinschaft (DFG) and the Swiss Na-
tional Science Foundation (SNF) for funding.
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Supplementary data
Supplementary data (sol–gel transition temperature measure-
ments (dropping ball) of the gels 6 and 7, Fmoc UV-absorption
cleavage elugrams for the automated synthesis of 6 and 7, MALDI
ToF MS data for 6 and 7 and a full experimental section) associated
with this article can be found, in the online version, at http://