Anion-anion assembly: A new class of anionic supramolecular polymer containing 3,4-dichloro-2,5-diamido-substituted pyrrole anion dimers

Article abstract of DOI:10.1021/ja027118v

Two molecules containing two 2,5-diamido,3,4-dichloropyrrole units linked via 1,3- or 1,4-substituted benzene rings have been synthesized. The pyrrole groups in these compounds deprotonate in the presence of tetrabutylammonium fluoride and form pyrrole an

Full text of DOI:10.1021/ja027118v

Published on Web 08/29/2002
Anion-Anion Assembly: A New Class of Anionic Supramolecular Polymer
Containing 3,4-Dichloro-2,5-diamido-substituted Pyrrole Anion Dimers
Philip A. Gale,* Korakot Navakhun, Salvatore Camiolo, Mark E. Light, and Michael B. Hursthouse
Department of Chemistry, UniVersity of Southampton, Southampton, UK, SO17 1BJ
Received May 31, 2002
The use of anionic components to direct self-assembly is a
relatively new area of supramolecular chemistry but one which is
expanding the available noncovalent and coordinate bonding motifs
for the construction of interlocked materials and new noncovalently
linked molecular architectures.1 Early examples include de Mendoza
and co-workers’ sulfate-directed double helix2 and Lehn and co-
workers’ chloride-templated pentametallic circular helicate.3 Stod-
dart and co-workers4 and Beer and co-workers5 have reported
examples of anion-assisted formation of pseudorotaxanes using
hexafluorophosphate and chloride, respectively, while Vo¨gtle and
co-workers6 have used an anion-template approach to the synthesis
of rotaxanes. Sessler and co-workers have shown that calixpyrroles
and sapphyrins containing appended carboxylate groups form
anionic dimers,7 while in the inorganic arena, Mingos, Vilar, and
co-workers8 and McCleverty, Ward, and co-workers9 have used
anions to direct the formation of new inorganic complexes. In the
solid state, Hosseini and co-workers have used amidinium-
carboxylate interactions to assemble molecular rods, tapes, and
sheets,10 while Ward and co-workers have studied in detail the
factors influencing guanidinium-sulfonate interactions.11 We have
recently reported the synthesis and anion-binding properties of 2,5-
diamidopyrrole cleft species12 and the dimerization of 3,4-dichloro-
analogues which when deprotonated change conformation and form
dimers via NH-N- hydrogen bonds (Figure 1).13 Unlike the
hydrogen-bonding arrays found in systems such as DNA, the two
components in the pyrrole anion dimer are almost orthogonal, and
this system could be regarded as an organic analogue of Cu(I)
phenanthroline complexes used in the construction of various
complex supramolecular architectures.14 In this communication we
report the first examples of new interlocked materials based upon
this hydrogen-bonding motif consisting of supramolecular polymers
consisting of purely anionic components.
Figure 1. Hydrogen-bonding array between 2,5-diamidopyrrole anions.
coupled with 0.5 equiv of either 1,3-phenylenediamine or 1,4-
phenylenediamine using 1.05 equiv of PyBOP, HOBt (cat.), and
triethylamine in dry DMF to afford the dimers 1 and 2 in 50 and
69% respective yields.
Compounds 1 and 2 have limited solubility; however, it was
1
possible to obtain H NMR spectra of the materials in DMSO-d6.
Molecules 1 and 2 were synthesized in a stepwise procedure.
3,4-Dichloro-1H-pyrrole-2,5-dicarboxylic acid diethyl ester was
synthesized by literature methods.15 This material was reacted with
1 equiv of the aluminum amide formed by reacting 1 equiv of
trimethylaluminum with aniline,16 affording 3,4-dichloro-5-phen-
ylcarbamoyl-1H-pyrrole-2-carboxylic acid ethyl ester in 13% yield.
Subsequent saponification in an aqueous ethanolic solution of
sodium hydroxide afforded the acid in 75% yield. This was then
Solubility was improved upon addition of tetrabutylammonium
fluoride, allowing 13C NMR and mass spectroscopic characterization
studies to be completed.
Crystals of compounds 1 and 2 were obtained by slow evapora-
tion of acetonitrile solutions of the amidopyrroles in the presence
of excess tetrabutylammonium fluoride.17 Both compounds crystal-
lize as doubly deprotonated pyrrole anions (1-2H+ or 2-2H+)
forming interlocked chains of anions via NH-N- hydrogen bonds
(Figures 2 and 3). In bis-tetrabutylammonium (1-2H+), the anionic
chains consist of a single crystallographically unique molecule with
NH-N- interactions in the range 3.10(4)-3.239(13) Å and extend
* To whom correspondence should be addressed. Telephone: +44 23 80593332.
Fax: +44 23 80596805, E-mail: philip.gale@soton.ac.uk.
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J. AM. CHEM. SOC. 2002, 124, 11228-11229
10.1021/ja027118v CCC: $22.00 © 2002 American Chemical Society

C O M M U N I C A T I O N S
Figure 2. X-ray crystal structure of 1-2H+ (tetrabutylammonium countercations are omitted for clarity). Color key: carbon - green, chlorine - yellow,
oxygen - red, nitrogen - blue, hydrogen - white.
Figure 3. X-ray crystal structure of 2-2H+ (tetrabutylammonium countercations are omitted for clarity). Color key: carbon - green, chlorine - yellow,
oxygen - red, nitrogen - blue, hydrogen - white.
(2) Sa´nchez-Quesada, J.; Seel, C.; Prados, P.; de Mendoza, J. J. Am. Chem.
along the a direction. In bis-tetrabutylammonium (2-2H+) there are
one and two half unique amidopyrrole anions in the unit cell. These
anions form chains that repeat in a 1232123212... sequence
Soc. 1996, 118, 277.
(3) Hasenknopf, B.; Lehn, J. M.; Kniesel, B. O.; Baum, G.; Fenske, D. Angew.
Chem., Int. Ed. Engl. 1996, 35, 1838. Hasenknopf, B.; Lehn, J. M.;
Boumediene, N.; Dupont-Gervais, A.; van Dorsselar, A.; Kniesel, B.;
Fenske, D. J. Am. Chem. Soc. 1997, 119, 10956.
extending in the 101h direction.
(4) Fyfe, M. C. T.; Glink, P. T.; Menzer, S.; Stoddart, J. F.; White A. J. P.;
The two half molecules are essentially planar, while the complete
Williams, D. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 2068.
(5) Wisner, J. A.; Beer, P. D.; Drew, M. G. B. Angew. Chem., Int. Ed. 2001,
40, 3606.
molecule, occurring at every other position in the chain, is twisted
such that the angle between the least-squares planes of the pyrrole
rings is 61.79(5)° and the NH-N interactions are in the range 3.112-
(9)-3.491(9) Å. In both cases the tetrabutylammonium counter-
cations occupy the spaces between the chains.
These two structures demonstrate the generality of 2,5-
diamidopyrrole anion dimer and its potential as a new motif for
the construction of interlocked hydrogen-bonded molecular as-
semblies formed by orthogonal components. We are currently
investigating the formation of other interlocked materials based
upon this motif and also the role of the countercation in the
assembly process. The results of these studies will be reported in
due course.
(6) Hu¨bner, G. M.; Glaser, J.; Seel, C.; Vo¨gtle, F. Chem. Eur. J. 1999, 38,
383.
(7) Sessler, J. L.; Andrievsky, A.; Gale P. A.; Lynch, V. Angew. Chem., Int.
Ed. Engl. 1996, 35, 2782.
(8) Rais, D.; Yau, J.; Mingos, D. M. P.; Vilar, R.; White A. J. P.; Williams,
D. J. Angew. Chem., Int. Ed. 2001, 40, 3464.
(9) Fleming, J. S.; Mann, K. L. V.; Carraz, C.-A.; Psillakis, E.; Jeffrey, J. C.;
McCleverty, J. A.; Ward M. D. Angew. Chem., Int. Ed. 1998, 37, 1279.
(10) Hosseini, M. W.; Ruppert, R.; Schaffer, P.; DeCian, A.; Kyritsaka, N.;
Fischer, J. J. Chem. Soc., Chem. Commun. 1994, 2135. Brand, G.;
Hosseini, M. W.; Ruppert, R.; DeCian, A.; Fischer, J.; Kyrsitsaka, N.
New J. Chem. 1995, 19, 9.
(11) Russell, V. A.; Ward, M. D. J. Mater. Chem. 1997, 7, 1123.
(12) Gale, P. A.; Camiolo, S.; Chapman, C. P.; Light M. E.; Hursthouse, M.
B. Tetrahedron Lett. 2001, 42, 5095; Gale, P. A.; Camiolo, S.; Tizzard,
G. J.; Chapman, C. P.; Light, M. E.; Coles S. J.; Hursthouse, M. B. J.
Org. Chem. 2001, 66, 7849; Denuault, G.; Gale, P. A.; Hursthouse, M.
B.; Light, M. E.; Warriner, C. N. New J. Chem. 2002, 811.
(13) Camiolo, S.; Gale, P. A.; Hursthouse, M. B.; Light, M. E.; Shi, A. J.
Chem. Commun. 2002, 758.
(14) Sauvage, J. P. Acc. Chem. Res. 1998, 31, 611.
(15) Motekaitis, R. J.; Heinert, D. H.; Martell, A. E. J. Org. Chem. 1970, 35,
2504.
(16) Basha, A.; Lipton, M.; Weinreb, S. M. Tetrahedron Lett. 1977, 48, 4171.
(17) Cell dimensions and intensity data were recorded at 120 K, using a Bruker
Nonius KappaCCD area detector diffractometer mounted at the window
of a molybdenum rotating anode (λ ) 0.71073) following standard
procedures. Crystal data for 1: Colorless block, C62H90N8O4Cl4, Mr )
1153.22, T ) 120(2) K, orthorhombic, space group P212121, a ) 13.3899-
Acknowledgment. We thank the EPSRC for a project student-
ship (to S.C.) and for use of the crystallographic facilities at the
University of Southampton. P.A.G. thanks the Royal Society for a
University Research Fellowship. K.N. thanks Universities UK for
an O.R.S. award.
Supporting Information Available: CIF files for the two crystal
structures together with characterization and preparation data for
compounds 1 and 2 and space filling models of the polyanionic chains
(PDF). This material is available free of charge via the Internet at http://
pubs.acs.org.
(3) Å, b ) 16.3267(3) Å, c ) 28.0813(7) Å, V ) 6138.9(2) Å3, Fcalc
)
1.248 g cm -3, µ ) 0.246 mm-1, Z ) 4, reflections collected: 29984,
independent reflections: 7462 (Rint ) 0.1000), final R indices [I > 2σI]:
R1 ) 0.1119, wR2 ) 0.2814, R indices (all data): R1 ) 0.1866, wR2 )
0.3306. Crystal data for 2: Colorless block, C124H180N16O8Cl8, Mr
)
2306.44, T ) 120(2) K, triclinic, space group P-1, a ) 16.472(5) Å, b )
18.028(5) Å, c ) 24.398(5) Å, R ) 69.036(5)°, â ) 76.520(5)°, γ )
73.183(5)°, V ) 6408.0(3) Å3, Fcalc ) 1.195 g cm -3, µ ) 0.235 mm-1
,
Z ) 2, reflections collected: 31321, independent reflections: 17550 (Rint
) 0.0616), final R indices [I > 2σI]: R1 ) 0.1107, wR2 ) 0.2954, R
indices (all data): R1 ) 0.2051. wR2 ) 0.3389.
References
(1) Gale, P. A. Coord. Chem. ReV. 2001, 213, 79; Gale, P. A. Coord. Chem.
ReV. 2000, 199, 181; Beer, P. D.; Gale, P. A. Angew. Chem., Int. Ed.
2001, 40, 486.
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