Structure-Dependent Guest Recognition with Flexible Ferrocene-Based Aromatic Oligoamide β-Sheet Mimics

Article abstract of DOI:10.1002/chem.201904719

A series of aromatic oligoamides incorporating an inherently flexible ferrocene dicarboxylic acid unit was synthesized. Solid state, solution, and computational studies on these systems indicated that the aromatic strands can adopt a syn parallel stacked conformation. This results in modular β-sheet-like molecular clefts that display structure-dependent recognition of small polar molecules. NMR and theoretical studies of the host–guest interaction support an in cleft binding mode and allowed the selectivity of the oligomers to be rationalized on the basis of minor changes in functional-group presentation on the edge of the aromatic strands.

Full text of DOI:10.1002/chem.201904719

A Journal of
Accepted Article
Title: Structure Dependent Guest Recognition with Flexible Ferrocene
Based Aromatic Oligoamide β -Sheet Mimics
Authors: Yazhou Liu, Hu Wang, Chien-Kai Chan, Xiao Mu, Koen
Robeyns, Cheng-Chung Wang, and Michael Singleton
This manuscript has been accepted after peer review and appears as an
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To be cited as: Chem. Eur. J. 10.1002/chem.201904719
Link to VoR: http://dx.doi.org/10.1002/chem.201904719
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Structure Dependent Guest Recognition with Flexible Ferrocene
Based Aromatic Oligoamide β-Sheet Mimics
[
a]
[a]
[b]
[a]
[a]
[b]
Ya-Zhou Liu, Hu Wang, Chieh-Kai Chan, Xiao Mu, Koen Robeyns, Cheng-Chung Wang and
Michael L. Singleton*[a]
Abstract:
A
series of aromatic oligoamides incorporating an
forms for 1,1’ aromatic functionalized ferrocenes.[12] On the other
hand, ferrocene is a fluxional molecule and rotation of the Cp rings
or about the C-C bonds of the 1 or 1’ substituents, Figure 1B, has
inherently flexible ferrocene dicarboxylic acid unit was synthesized.
Solid state, solution, and computational studies on these systems
indicated that the aromatic strands can adopt a syn parallel stacked
conformation. This results in modular β-sheet like molecular clefts that
display structure dependent recognition of small polar molecules.
NMR and theoretical studies of the host-guest interaction support an
in cleft binding mode and allowed the selectivity of the oligomers to
be rationalized on the basis of minor changes in functional group
presentation on the edge of the aromatic strands.
potential to generate
a
rich conformational landscape.
Nevertheless, this flexibility may be advantageous, as it can
permit the strands to move for optimal stacking interactions.
Curved β-sheet motifs are common in the active sites of many
proteins, where they provide functionalized clefts important for
specific recognition and catalysis.[1] Nevertheless, synthetic
mimics of these curved β-sheet structures, of interest for
mimicking the above functions, are rare,[2] and most work on β-
sheets has remained focused on the synthesis and stability of
extended structures.[3] Recently however, a new class of β-sheet
mimics based on aromatic oligoamide foldamers[4] (AOF) has
been reported that allows access to curved motifs. Several
examples of extended and bent sheet-like structures comprised
of stacked aromatic strands have been described.[5]
Unlike their aliphatic analogs, where the chains are held together
primarily through hydrogen bonding, typically weaker π-π
interactions have been implicated in stabilizing the stacked
structures in AOF β-sheet mimics. As such, turn-units that direct
the aromatic strands in a parallel fashion at distances suitable for
π-stacking have been essential to the design of these molecules.
Some examples used with AOF include proline,[6] 1,8-
naphthalenes,[7] tertiary squaramides,
phenylenediamine,
[4b]
and 4,6-dinitro-1,3-
Figure 1. (A) Two examples of turn units previously used for β-sheet-like
aromatic oligoamides. (B) Turn unit used in this work. (C) Structures of the
pentamers 1-4.
[
4a,5]
Figure 1A. Still, for these turns, long
strands (larger π-surfaces) are needed to observe well-stacked
structures and obtaining bent or cleft-like structures with short
sequences remains a challenge.
To this end, ferrocene diacid is an intriguing candidate as a turn-
unit. This scaffold has been used previously for promoting
hydrogen bonding between aliphatic peptide sequences,[8] as well
as for the design of hydrogen bonding receptors/sensors[9] and
molecular machines.[10] For aromatic strands, the short distance
between the cyclopentadienyl (Cp) rings (3.3 to 3.4 Å)[11] is well-
suited for promoting stacking interactions between the strands.
Indeed, syn stacked conformations are often the most stable
To study the balance between these factors and the applicability
of ferrocene for generating functional β-sheet-like clefts, a series
of AOF pentamers containing ferrocene dicarboxylic acid, Figure
1C, as a central unit was synthesized. Coupling of two equivalents
of pyridine, quinoline, or diazaanthracene monomer acid
[13]
chlorides
with the diaminopyridine functionalized ferrocene
1,1’-dicarboxylic acid trimer[ gave the corresponding pentamers
as red-orange solids in moderate to good yield after
recrystallization.
14]
The structures, determined by X-ray diffraction, for all three
oligomers, Figure 2, show the central ferrocene unit connected to
two aromatic strands in a parallel offset stacked arrangement with
a largely eclipsed (torsion angle <8°) conformation for the Cp
rings. Values measured for the distance between the planes of
the aromatic strands are close to 3.4 Å, consistent with values
observed in other stacked aromatic systems.[15] The head to head
arrangement in the curved strands is expected to allow better
[
[
a]
b]
Y.-Z. Liu, H. Wang, X. Mu, Dr. K. Robeyns, Prof. M. L. Singleton
Institute of Condensed Matter and Nanosciences
Université catholique de Louvain
Place Louis Pasteur 1, Louvain-la-Neuve, 1348, Belgium
E-mail: m.singleton@uclouvain.be
Dr. C.-K. Chan, Prof. C.-C. Wang
Institute of Chemistry, Academia Sinica
Taipei 115, Taiwan
Supporting information for this article is given via a link at the end
of the document. ((Please delete this text if not appropriate))
overlap of the aromatic units, compensating for the parallel
[13b]
orientation of the dipole moments of the aromatic rings.
This
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-
90 °C in CD
2
Cl
2
no splitting of the Cp resonances was observed
with oligomers 1 and 2. Because of the lower solubility of 3,
cooling only led to its precipitation from solution. Nevertheless, a
number of observations suggest that the stacked conformation
still has an important contribution to the overall conformational
preferences in solution.
First, proton resonances for the aromatic strands in 1 – 3 are more
upfield shifted than in the corresponding dimers. This is consistent
with shielding from the neighboring strand, and is reported as
evidence for the stacked conformations in aryl functionalized
ferrocenes, as well as in aromatic β-sheet mimics.[6, 12c,
Additionally, using asymmetric oligomer 4, the 1H ROESY
spectrum shows a weak correlation between the iso-butoxy
methylene and the methyl group of the ester on the neighboring
16]
strand. This does not result from intermolecular contacts as 1
H
NMR concentration studies show minimal changes in chemical
shifts between 0.1 – 10 mM.
Computational studies also support that the stacked conformation
is favorable. DFT minimized structures match well with the crystal
structures of 1 – 3. Calculations of open form or head to tail
conformations, obtained by varying the dihedral angle of the Cp
rings or amides respectively, found only higher energy structures.
Indeed, Cp rotation from 0 – 180º, is strongly correlated to
increased energy, suggesting important stabilizing interactions
between the strands in the stacked structures.
Finally, the stacked confirmation appears important for the host-
guest properties of the oligomers. While examples of cleft-like
aromatic β-sheet mimics have been described, few functional
systems able to bind small molecules, have been reported.[13b] As
the cleft-like structures lined with polar groups can act as a
Figure 2. Side and top views of the X-ray structures of oligomers 1 (A&B),
2
(C&D), and 3 (E&F). Solvent molecules have been omitted for clarity.
unfavorable dipole alignment is further minimized in the solid state
by the anti-parallel packing of neighboring molecules in the crystal
lattice. The curvature of these sheet-like structures generates a
molecular cleft lined by
a
number of hydrogen bond
acceptor/donor sites coming from the amide N-H’s and endocyclic
nitrogens.
Despite the well-folded structure in the solid state, solution 1
H
NMR studies show a high degree of mobility in the three oligomers. binding site for small molecules,[17] we studied the host-guest
Independent of the solvent used, the Cp protons of 1-3 appear as
only two signals indicating a fluxional process that equates the
properties of 1 and 2 with catechol, resorcinol, and benzoic acid
through H NMR titrations. Besides being structural motifs in a
number of biologically important molecules,[18] the variation in
1
2,5/2’,5’ and 3,4/3’,4’ protons on both rings. Even upon cooling to
Figure 3. (A) Part of 1H NMR titration experiment (300 MHz, 298 K) in chloroform-d of 1 (2 mM) in the presence of catechol (from 0 to 43 mM). (B) Chemical shifts
of amide protons in 1 or 2 versus increasing guest concentrations. Black squares represent catechol ⊂ 1; blue triangles represent benzoic acid ⊂ 2; pink triangles
represent resorcinol ⊂ 1; red circles represent catechol ⊂ 2; green squares represent resorcinol ⊂ 1. (C) Structure of 1 with catechol, key protons are shown in
colors, arrows represent observed interactions between the two molecules. (D) Part of 2D-NOESY spectrum of 1 (1 mM) with catechol (1 mM) in CDCl , blue and
3
black circles show NOE correlations. Colors are the same as for C.
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Figure 4 DFT optimized structures for the host-guest systems, (A-D) Lowest energy structures of A) 1 with catechol, B) 1 with resorcinol, C) 2 with benzoic acid
and D) 2 with catechol, potential hydrogen bonds are indicated with blue dashed lines. (E-H) Overlays of the lowest energy geometries for E) 1 with catechol, F)
1
with resorcinol, G) 2 with benzoic acid and H) 2 with catechol. For the overlay models, host molecules are shown in wire frame and guests in stick style; side
chains and protons not involved in forming hydrogen bonds are hidden for clarity.
donor/acceptor sites on the guests provides a way to study
different possible modes of binding in the hosts.
support binding of the guest into the cleft of the host, Figure 3D.
Correlations between the aromatic protons of the catechol and
both the Cp and methyl ester protons were observed. Similar
studies for the other host-guest combinations were inconclusive
due to the weak binding affinity and/or overlap of the host/guest
signals. Nevertheless, given the similar changes observed during
the titration with catechol and benzoic acid, we suggest that they
bind in a similar fashion with both 1 and 2, while with resorcinol
other binding modes may be involved. This is supported by
computational studies.
NMR titrations of 1 or 2 with different guests, Figures 3A and S11,
show shifts for several proton resonances with increasing guest
concentrations. In 1, the signals corresponding to the amide
between the pyridines (10.12 ppm) and the amide next to the
ferrocene (8.09 ppm) shift downfield by 0.32 and 1.19 ppm
respectively, suggesting their participation in hydrogen bonding.
Similar changes, though less pronounced, (Δδ of 0.07 and 0.39
ppm) are observed for the amides in 2. For both, small upfield
shifts are also observed for all of the remaining protons in the
oligomers Less marked changes occur with resorcinol as the
guest. The ferrocene amides remain almost unchanged, shifting
only 0.09 and 0.03 ppm for 1 and 2 with increasing guest
concentration while the pyridine amides shift more, (0.29 and 0.06
ppm). With benzoic acid, no significant changes were observed
for any of the proton resonances in 1. However, with oligomer 2,
increasing the concentration of benzoic acid results in similar
changes as observed with catechol, i.e. downfield shifting of the
amides (Δδ of 0.08 and 0.95 ppm).
To look at guest binding, 100 guest geometries, both in and
outside of the cleft, were randomly generated using molclus,[
and then optimized at the PM6+[21] level with MOPAC[22] resulting
in 43 different geometries. Of these, the 20 lowest energy were
then further optimized by DFT using Gaussian 09.[ Overlays of
the lowest energy geometries for the host-guest systems are
shown in Figure 4A-H and S13. For catechol and benzoic acid,
the guest was found bound inside of the clefts of the oligomers.
Geometries where the guest was outside of the cleft were higher
in energy by >23 kJ/mol.
20]
23]
Plots of changes in amide chemical shift versus guest
For the lowest energy structure of 1 with catechol, one guest
hydroxyl group forms hydrogen bonds with both a ferrocene
amide NH and a pyridine endocyclic nitrogen, while the second
hydroxyl appears to interact mostly with the carbonyl of a methyl
ester. This latter interaction may explain the difference in affinity
of 1 vs 2 for catechol. Indeed, the lowest energy structure for 2
with catechol shows both guest hydroxyl groups forming OH-N
hydrogen bonds with the pyridine nitrogens, while the catechol
oxygens form hydrogen bonds with the nearby amides. For almost
all structures the shortest NH-O distances are observed for the
interaction with the ferrocene amide, fitting well with the larger
experimental shifts observed for this proton resonance in the
presence of the guest. This is similarly true for the lowest energy
structure of 2 with benzoic acid. In this case, this interaction
results in the aromatic portion of the guest being in close proximity
to the 8-position C-H of the quinoline unit. In 1, this space is
occupied by the esters, likely explaining the lack of affinity
between 1 and benzoic acid.
concentration fit to 1:1 binding isotherms.[
19]
Association
-1
-1
constants of 238 M and 41 M were found for catechol with 1
and 2, respectively. By contrast, the binding constants for
resorcinol are substantially lower. For 1, K
1,
while for 2 no good fit could be modeled. A similar 1:1 binding
a
was found to be 80 M-
-1
a
(K = 108 M ) was found for the interaction of 2 with benzoic acid,
while surprisingly no interaction was observed between this guest
and 1. This structure dependent binding is intriguing, especially
given the high similarity between the core structures of 1 and 2.
Additionally, the presence of the two strands in the oligomers also
appears important for the interaction with the guests. Indeed, for
the interaction of the single stranded pyridine dimer 5 (See SI)
-1
with catechol the association constant was found to be 115 M ,
while no interaction was found with resorcinol.
To better understand how the guests interact with the oligomers,
we turned to a combination of solution studies and computational
modeling. NOESY NMR studies of 1 with catechol in CDCl
3
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The calculated structures with resorcinol suggest that different
binding modes are possible. The lowest energy geometries for 1
and 2, Figure 4F and S13, showed guest binding both inside and
outside the clefts. Energy differences between these
conformations are about 11 and 4 kJ/mol for resorcinol with 1 and
John Wiley & Sons, 2007. d) B. Gong, Acc. Chem. Res. 2008, 41, 1376-
1
386.
a) L. Sebaoun, B. Kauffmann, T. Delclos, V. Maurizot, I. Huc, Org. Lett.
014, 16, 2326-2329; b) L. Sebaoun, V. Maurizot, T. Granier, B.
[5]
2
Kauffmann, I. Huc, J. Am. Chem. Soc. 2014, 136, 2168-2174; c) A.
Lamouroux, L. Sebaoun, B. Wicher, B. Kauffmann, Y. Ferrand, V.
Maurizot, I. Huc, J. Am. Chem. Soc. 2017, 139, 14668-14675; d) J.
Atcher, A. Nagai, P. Mayer, V. Maurizot, A. Tanatani, I. Huc, Chem.
Commun. 2019.
2, respectively. Multiple guest binding equilibria may explain the
difficulties fitting the titration data with 2.
In conclusion, a series of aromatic oligoamides containing
ferrocene as a turn-unit was synthesized. Despite the flexible
nature of the central unit, the oligomers show stable stacked
structures in the solid state. Still, in solution, the molecules are
fluxional. Nevertheless, spectroscopic and theoretical studies
suggest that the stacked structure may be one of the important
conformations that exist in solution. The resulting clefts are
functional hosts for binding small molecules and thus mimic this
aspect of biological curved β-sheets. Interestingly, even with
these relatively short oligomers, subtle changes in monomer
composition are able to invert guest preferences from oligomer 1
to 2. The increased flexibility in these oligomers and their ability
to interact with guests is intriguing for the possibility to switch
between multiple conformations, e.g. sheet to helix. Such
conformational changes are of interest for sensing and
information storage.[24] Studies on stabilizing different
conformations and the exchange between them are ongoing in
our lab and will be reported in due course.
[6]
R. V. Nair, S. Kheria, S. Rayavarapu, A. S. Kotmale, B. Jagadeesh, R.
G. Gonnade, V. G. Puranik, P. R. Rajamohanan, G. J. Sanjayan, J. Am.
Chem. Soc. 2013, 135, 11477-11480.
[
7]
8]
P. Prabhakaran, V. G. Puranik, J. N. Chandran, P. R. Rajamohanan, H.-
J. Hofmann, G. J. Sanjayan, Chem. Commun. 2009, 3446-3448.
a) R. S. Herrick, R. M. Jarret, T. P. Curran, D. R. Dragoli, M. B. Flaherty,
S. E. Lindyberg, R. A. Slate, L. C. Thornton, Tetrahedron Lett. 1996, 37,
5289-5292; b) D. R. van Staveren, N. Metzler-Nolte, Chem. Rev. 2004,
104, 5931-5986; c) S. Chowdhury, G. Schatte, H.-B. Kraatz, Angew.
Chem. Int. Ed. 2008, 47, 7056-7059; Angew. Chem. 2008, 120, 7164-
[
7167.
[
9]
a) T. Saji, I. Kinoshita, J. Chem. Soc., Chem. Commun. 1986, 716-717.
b) J. Westwood, S. J. Coles, S. R. Collinson, G. Gasser, S. J. Green, M.
B. Hursthouse, M. E. Light, J. H. R. Tucker, Organometallics 2004, 23,
946-951; c) C. L. Beck, S. A. Berg, A. H. Winter, Organic & Biomolecular
Chemistry 2013, 11, 5827-5835; d) L. Pisciottani, M. Douarre, B. Bibal,
C. Davies, H. Roberts, B. Kauffmann, S. L. Horswell, J. H. R. Tucker, N.
D. McClenaghan, Supramol. Chem. 2018, 30, 869-875.
[10] a) S. Ø. Scottwell, J. D. Crowley, Chem. Commun. 2016, 52, 2451-2464;
b) X.-B. Wang, B. Dai, H.-K. Woo, L.-S. Wang, Angew. Chem. Int. Ed.
2005, 44, 6022-6024; Angew. Chem. 2005, 117, 6176-6178.
[
[
11] R. K. Bohn, A. Haaland, J. Organomet. Chem. 1966, 5, 470-476.
12] a) A. Iordache, M. Oltean, A. Milet, F. Thomas, B. Baptiste, E. Saint-
Aman, C. Bucher, J. Am. Chem. Soc. 2012, 134, 2653-2671; b) J. D.
Crowley, I. M. Steele, B. Bosnich, Chem. Eur. J. 2006, 12, 8935-8951; c)
S. Ø. Scottwell, A. B. S. Elliott, K. J. Shaffer, A. Nafady, C. J. McAdam,
K. C. Gordon, J. D. Crowley, Chem. Commun. 2015, 51, 8161-8164.
13] a) B. Baptiste, J. Zhu, D. Haldar, B. Kauffmann, J.-M. Léger, I. Huc,
Chem. Asian J. 2010, 5, 1364-1375; b) A. Lamouroux, L. Sebaoun, B.
Wicher, B. Kauffmann, Y. Ferrand, V. Maurizot, I. Huc, J. Am. Chem. Soc.
Acknowledgements
This work was supported in part through the Concerted Research
Action (ARC16/21-074). Y.-Z.L., H.W., and X.M. were supported
through China Scholarship Council fellowships. Computational
resources have been provided by the supercomputing facilities of
the Université catholique de Louvain (CISM/UCL) and the
Consortium des équipements de Calcul Intensif en Fédération
Wallonie Bruxelles (CPCI) funded by the Fond de la Recherche
Scientifique de Belgique (F.R.S.-FNRS) under convention
[
2017, 139, 14668-14675; c) J. Y. Bass, J. A. Caravella, L. Chen, K. L.
Creech, D. N. Deaton, K. P. Madauss, H. B. Marr, R. B. McFadyen, A. B.
Miller, W. Y. Mills, F. Navas, D. J. Parks, T. L. Smalley, P. K. Spearing,
D. Todd, S. P. Williams, G. B. Wisely, Bioorg. Med. Chem. Lett. 2011, 21,
2.5020.11. We also thank Dr. Gabriella Barozzino for help with
1206-1213.
NMR measurements.
[
14] H. S. Sørensen, J. Larsen, B. S. Rasmussen, B. Laursen, S. G. Hansen,
T. Skrydstrup, C. Amatore, A. Jutand, Organometallics, 2002, 21, 5243-
Keywords: Ferrocene • Aromatic Oligoamides • Foldamers •
Structural Stability • Host-Guest Chemistry
5
253.
[15] A. Takai, T. Yasuda, T. Ishizuka, T. Kojima, M. Takeuchi, Angew. Chem.
Int. Ed. 2013, 52, 9167-9171; Angew. Chem. 2013, 125, 9337-9341.
[
16]
a) V. Maurizot, S. Massip, J.-M. Léger, G. Déléris, Chem. Commun.
[
1]
E. Marcos, B. Basanta, T. M. Chidyausiku, Y. Tang, G. Oberdorfer, G.
Liu, G. V. T. Swapna, R. Guan, D.-A. Silva, J. Dou, J. H. Pereira, R. Xiao,
B. Sankaran, P. H. Zwart, G. T. Montelione, D. Baker, Science, 2017,
2009, 5698-5700. b) A. Petitjean, L. A. Cuccia, M. Schmutz, J.-M. Lehn,
J. Org. Chem. 2008, 73, 2481-2495.
[
[
17] J. Rebek, B. Askew, N. Islam, M. Killoran, D. Nemeth, R. Wolak, J. Am.
Chem. Soc. 1985, 107, 6736-6738.
355, 201-206.
[
[
2]
3]
S. Rana, B. Kundu, S. Durani, Chem. Commun. 2004, 2462-2463.
a) D. J. Hill, M. J. Mio, R. B. Prince, T. S. Hughes, J. S. Moore, Chem.
Rev. 2001, 101, 3893-4012. b) J. S. Nowick, Acc. Chem. Res. 2008, 41,
18] a) B. N. Singh, S. Shankar, R. K. Srivastava, Biochem. Pharmacol. 2011,
82, 1807-1821; b) D. G. Gardner, D. Shoback, F. S. Greenspan,
Greenspan's basic & clinical endocrinology, McGraw-Hill Medical, 2007;
c) W. F. Symes, C. R. Dawson, J. Am. Chem. Soc. 1954, 76, 2959-2963.
19] P. Thordarson, Chem. Soc. Rev. 2011, 40, 1305-1323.
1
319-1330. c) A. A. Fuller, D. Du, F. Liu, J. E. Davoren, G. Bhabha, G.
Kroon, D. A. Case, H. J. Dyson, E. T. Powers, P. Wipf, M. Gruebele, J.
W. Kelly, Proc. Natl. Acad. Sci. USA, 2009, 106, 11067-11072. d) F.
Freire, A. M. Almeida, J. D. Fisk, J. D. Steinkruger, S. H. Gellman, Angew.
Chem. Int. Ed. 2011, 50, 8735-8738; Angew. Chem. 2011, 123, 8894-
[
[
20] T.
Lu,
in
molclus
program,
1.5
ed.,
2018,
p.
http://www.keinsci.com/research/molclus.html.
[
[
21] J. J. Stewart, J. Mol. Model. 2007, 13, 1173-1213.
8897.
22] J. J. P. Stewart, Stewart Computational Chemistry, Colorado Springs,
CO, USA, 2016, p. HTTP://OpenMOPAC.net
[
4]
a) G. Guichard, I. Huc, Chem. Commun. 2011, 47, 5933-5941. b) D.-W.
Zhang, X. Zhao, J.-L. Hou, Z.-T. Li, Chem. Rev. 2012, 112, 5271-5316.
c) S. Hecht, I. Huc, Foldamers: structure, properties and applications,
[
23] M. J. Frisch, G. W. Trucks, H. B. Schlegel, e. al, Wallingford, CT, 2016.
This article is protected by copyright. All rights reserved.

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[
24] A. Owais, A. M. Djerdjev, J. M. Hook, A. Yuen, W. Rowlands, N. G. White,
C. Neto, J. Mater. Chem. A, 2019, 7, 12713-12722.
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Entry for the Table of Contents (Please choose one layout)
Layout 1:
COMMUNICATION
Ferrocene was found to be an efficient
turn-unit in the development of a series
of curved aromatic oligoamide β-sheet
mimics. Solid state, NMR, and
Ya-Zhou Liu, Hu Wang, Cieh-Kai Chan,
Xiao Mu, Koen Robeyns, Cheng-Chung
Wang and Michael L. Singleton*
computational results support
a
Page No. – Page No.
stacked conformation of the strands
giving cleft-like structures able to bind
small molecules. Spectroscopic and
theoretical studies allowed the binding
modes and structure dependent
selectivity to be rationalized based on
minor changes in the cleft surface.
Structure
Dependent
Guest
Recognition with Flexible Ferrocene
Based Aromatic Oligoamide β-Sheet
Mimics
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