Fig. 3 TM-AFM images on a gold substrate after dropcasting a
MCH solution of either OPV–s (a) or OPV (b) on a substrate having
a monolayer of OPV–s.
Fig. 4 Proposed model for the transfer of self-assembled p-conju-
gated fibrils on a gold substrate.
evaporation of the solvent to yield the monolayers. Subsequently
the supramolecular assemblies have been transferred to the surface
by dropcasting the MCH solution. Irrespective of the underlying
monolayer, the TM-AFM images show in all cases the presence of
self-assembled fibrils on the surface. However, the morphology
differs for the two systems at hand, where micrometer sized thick
bundles of fibrils are observed for OPV–s, OPV yields much
shorter fibril-like structures that are less high (Fig. 3a versus 3b).
These results show that the presence of a monolayer is crucial for
retaining the fibrils at the surface, while the orientation of the
molecules in the monolayer seems to be less important (see ESIz).
In order to establish the strength of the monolayers formed
by either OPV or OPV–s, the surface containing the mono-
layer was placed back in chloroform for either 10, 20 or
30 seconds and dried. Subsequently a MCH solution having
self-assembled structures of OPV is dropcast to transfer
the self-assembled structures on the surface. Irrespective of
the residence time in chloroform, fibril-like assemblies are
observed when the monolayer consists of OPV–s. However,
when the OPV monolayer is used, already 10 seconds
submerged in a chloroform solution is enough to remove the
OPV monolayer to such an extent that fibril formation is
severely hampered (ESIz). The removal of this monolayer has
been confirmed by FM-AFM. This shows that the stability of
the OPV–s monolayer is significantly enhanced with respect to
the OPV monolayer.
(FNRS-CGRI/CNRS 20182). Ph.L. is a Research Associate of
the FRS-FNRS (Belgium). The Dutch team acknowledges the
Netherlands Foundation for Scientific Research (NWO).
I.D.C. and S.D.F. acknowledge the Fund of Scientific
Research––Flanders (FWO), K.U.Leuven (GOA), the Belgian
Federal Science Policy Office through IAP-6/27. I.D.C. is
grateful to the Agency for Innovation by Science and
Technology in Flanders (IWT).
Notes and references
1 F. J. M. Hoeben, P. Jonkheijm, E. W. Meijer and A. P. H. J.
Schenning, Chem. Rev., 2005, 105, 1491; J. Wu, W. Pisula and
K. Mullen, Chem. Rev., 2007, 107, 718; S. Gunes, H. Neugebauer
¨
¨
and N. S. Sariciftci, Chem. Rev., 2007, 107, 1324.
2 E. W. Meijer and A. P. H. J. Schenning, Nature, 2002, 419, 353;
P. Leclere, E. Hennebicq, A. Calderone, P. Brocorens,
A. C. Grimsdale, K. Mullen, J. L. Bredas and R. Lazzaroni, Prog.
´
¨
Polym. Sci., 2003, 28, 55; A. P. H. J. Schenning and E. W. Meijer,
Chem. Commun., 2005, 3245.
3 T. F. A. de Greef, M. M. J. Smulders, M. Wolffs, A. P. H. J.
Schenning, R. P. Sijbesma and E. W. Meijer, Chem. Rev., 2009,
109, 5687; Z. Chen, A. Lohr, C. R. Saha-Moller and F. Wurthner,
¨
¨
Chem. Soc. Rev., 2009, 38, 564.
4 E. Gomar-Nadal, J. Puigmartı-Luis and D. B. Amabilino, Chem. Soc.
´
Rev., 2008, 37, 490; L. C. Palmer and S. I. Stupp, Acc. Chem. Res., 2008,
41, 1674; I. Radivojevic, I. Likhtina, X. Shi, S. Singh and C. M. Drain,
Chem. Commun., 2010, 46, 1643; K. Yoosaf, A. Llanes-Pallas,
T. Marangoni, A. Belbakra, R. Marega, E. Botek, B. Champagne,
D. Bonifazi and N. Armarol, Chem.–Eur. J., 2011, 17, 3262; G. De
Based on these results, we propose the following mechanism
for the deposition of the fibrils on a gold surface (Fig. 4). Due
to the cooperative nature of the self-assembly process an
equilibrium between supramolecular fibrils and monomers
exists in solution. It is likely that the stronger interaction of
the OPV–s monomers with the gold surface leads to a faster
formation of a stable monolayer, thereby counteracting the
destructive influence of gold for the fibers, while monolayer
formation is probably too slow for OPV monomers.
Luca, A. Liscio, P. Maccagnani, F. Nolde, V. Palermo, K. Mullen and
¨
P. Samorı, Adv. Funct. Mater., 2007, 17, 3791.
5 S. Xiao, J. Tang, T. Beetz, X. Guo, N. Tremblay, T. Siegrist,
Y. Zhu, M. Steigerwald and C. Nuckolls, J. Am. Chem. Soc., 2006,
128, 10700.
6 J. P. Hill, W. Jin, A. Kosaka, T. Fukushima, H. Ichihara,
T. Shimomura, K. Ito, T. Hashizume, N. Ishii and T. Aida,
Science, 2004, 304, 1481.
7 P. Leclere, M. Surin, P. Viville, R. Lazzaroni, A. F. M. Kilbinger,
O. Henze, W. J. Feast, M. Cavallini, F. Biscarini, A. P. H. J.
Schenning and E. W. Meijer, Chem. Mater., 2004, 16, 4452.
8 P. Jonkheijm, F. J. M. Hoeben, R. Kleppinger, J. van Herrikhuyzen,
A. P. H. J. Schenning and E. W. Meijer, J. Am. Chem. Soc., 2003,
125, 15941; M. Durkut, M. Mass-Torrent, P. Hadley, P. Jonkheijm,
A. P. H. J. Schenning, E. W. Meijer, S. George and A. Ajayaghosh,
J. Chem. Phys., 2006, 124, 154704.
9 M. Surin, P. Leclere, S. De Feyter, M. M. S. Abdel-Mottaleb,
F. C. De Schryver, O. Henze, W. J. Feast and R. Lazzaroni,
J. Phys. Chem. B, 2006, 110, 7898.
10 L. Piot, C. Marie, X. Dou, X. Feng, K. Mullen and D. Fichou,
¨
J. Am. Chem. Soc., 2009, 131, 1378; L. Piot, C. Marie, X. Dou,
In conclusion we have shown that the presence of a mono-
layer can be a crucial factor for retaining the solution
morphology and connectivity of fibrils on a surface. For
cooperative self-assembled systems, the remaining monomers,
inherently present in the solution, significantly influence the
organization of the self-assembled structures on the surface. It
can be anticipated that electronic (nano)devices made from
p-conjugated systems could have a monolayer that is arranged
differently than the bulk of the active layer, thus potentially
influencing the performance of the device.
X. Feng, K. Mullen and D. Fichou, Adv. Mater., 2008, 20, 3854.
¨
11 P. Jonkheijm, P. van der Schoot, A. P. H. J. Schenning and
E. W. Meijer, Science, 2006, 313, 80.
12 B. Grevin, R. Demadrille, M. Linares, R. Lazzaroni and P. Leclere, Adv.
´
Mater., 2009, 21, 4124.
The collaboration between Mons and Grenoble has been
carried out in the frame of a joint bilateral research program
c
This journal is The Royal Society of Chemistry 2011
Chem. Commun., 2011, 47, 9333–9335 9335