Quantitative and spontaneous formation of a doubly interlocking [2]catenane using copper(I) and palladium(II) as templating and assembling centers [7]

Full text of DOI:10.1021/ja992391r

11014
J. Am. Chem. Soc. 1999, 121, 11014-11015
Quantitative and Spontaneous Formation of a
Doubly Interlocking [2]Catenane Using Copper(I)
and Palladium(II) as Templating and Assembling
Centers
Fumiaki Ibukuro,†,‡ Makoto Fujita,*,†,§,
Kentaro Yamaguchi,| and Jean-Pierre Sauvage*,†
Figure 1. Prototypical interlocking molecules prepared by (a) template4
and (b) self-assembly5 strategies.
Laboratoire de Chimie Organo-Mine´rale
UMR 7513 du CNRS, UniVersite´ Louis Pasteur
Insitut Le Bel, 4 rue Blaise Pascal
Scheme 1. General Strategy for the Preparation of Doubly
Interlocking [2]Catenanes
67070 Strasbourg, France
The Graduate UniVersity for AdVanced Studies
Myodaiji, Okazaki 444-8585, Japan
Coordination Chemistry Laboratories
Institute for Molecular Science and CREST
Japan Science and Technology Corporation (JST)
Myodaiji, Okazaki 444-8585, Japan
Chemical Analysis Center, Chiba UniVersity
Inageku, Chiba 263-8522, Japan
ReceiVed July 9, 1999
Template strategies and self-assembly have recently undergone
on explosive development, making possible the synthesis of many
fascinating and complex structures using only relatively simple
procedures.1 By combining building blocks coming from various
families of molecules, the structure of the resulting multicom-
ponent systems can, in principle, be varied infinitely at will. Here,
we report a new strategy for catenane synthesis,2 which enabled
us to obtain a 4-crossing [2]catenane quantitatively incorporating
two different metal centers: 4 Pd(II) and 2 Cu(I).
in one chemical step sophisticated structures, including interlock-
ing rings, from very simple molecular fragments and under mild
conditions.2j The two prototypical molecules made using these
approaches are the copper(I) catenane4 and the four-palladium
interlocking ring system5 of Figure 1. Several previous reports
deal with catenane formation for which the ring-forming reaction
is based on transition metal coordination.6-11
Doubly interlocking catenanes are chiral, and have complex
topologies which have only been described recently.3 Our
approach is to combine the two methods, based on coordination
chemistry, which are termed as “template” and “self-assembly”
strategies. In the template strategy which has been developed in
the course of the last 15 years, copper(I) complexes have been
used as precursors, affording simple to topologically very complex
catenanes.2c On the other hand, the self-assembly process furnishes
The first strategy we have used is summarized in Scheme 1.
Ligand (1) contains both phenanthroline and pyridine units in its
structure. It was expected that phenanthroline units would
coordinate to Cu(I) and pyridine rings would interact with
Pd(II), leading to the sequence of reactions indicated in Scheme
1. In fact, the hypothetical simple [2]catenane built around one
Cu(I) center only would be highly strained and thus very unstable.
It was anticipated that the doubly interlocking dimer-like structure
of Scheme 1 would be favored.
† Universite´ Louis Pasteur.
‡ The Graduate University for Advanced Studies.
§ Coordination Chemistry Laboratories, Institute for Molecular Science.
Present address: Department of Applied Chemistry, School of Engineering,
Nagoya University, Chikusa, Nagoya 464-8603, Japan.
Indeed, following this route, the target catenane 310+ was
quantitatively obtained, first as nitrate salt and, after anion
exchange, as its hexafluorophosphate salt (Scheme 2). The
reaction of the pyridine-based ligand (1) (0.03 mmol) and
CREST, Japan Science and Technology Corporation (JST).
| Chemical Analysis Center, Chiba University.
(1) Sauvage, J.-P.; Hosseini, W., volume Eds. In ComprehensiVe Supramo-
lecular Chemistry; Lehn, J.-M., Ed.; Pergamon Press: Oxford, UK., 1996;
Vol. 9 and references therein.
(2) For leading references in the field of catenanes, see: (a) Schill, G. In
Catenanes, Rotaxanes, and Knots; Academic Press: New York, 1971. (b)
Frisch, H. L.; Wasserman, E. J. Am. Chem. Soc. 1961, 83, 3789-3795. (c)
Dietrich-Buchecker, C. O.; Sauvage, J.-P. Chem. ReV. 1987, 759-810. (d)
Chambron, J.-C.; Dietrich-Buchecker, C. O.; Sauvage, J.-P. Top. Curr. Chem.
1993, 165, 131-162. (e) Amabilino, D. B.; Stoddart, J. F. Chem. ReV. 1995,
95, 2725-2828. (f) Hunter, C. A. J. Am. Chem. Soc. 1992, 114, 5303-5311.
(g) Vo¨gtle, F.; Du¨nnwald, T.; Schmidt, T. Acc. Chem. Res. 1996, 29, 451-
460. (h) Leigh, D. A.; Murphy, A.; Smart, J. P.; Deleuze, M. S.; Zerbetto, F.
J. Am. Chem. Soc. 1998, 120, 6458-6467. (i) Hamilton, D. G.; Davis, J. E.;
Prodi, L.; Sanders, J. K. M. Chem. Eur. J. 1998, 4, 608-620. (j) Fujita, M.
Acc. Chem. Res. 1999, 32, 53. (k) Sauvage, J.-P.; Dietrich-Buchecker, C. O.
In Catenanes, Rotaxanes, and Kots; Wiley-VCH: Weinhein, New York, Eds.
1999.
(4) Dietrich-Buchecker, C. O.; Sauvage, J.-P.; Kintzinger, J.-P. Tetrahedron
Lett. 1983, 24, 5098.
(5) Fujita, M.; Ibukuro, F.; Hagihara, H.; Ogura, K. Nature 1994, 367, 720-
723.
(6) Piguet, C.; Bernardinelli, G.; Williams, A. F.; Bocquet, B. Angew.
Chem., Int. Ed. Engl. 1995, 34, 582.
(7) Ca´rdenas, D. J.; Gavin˜a, P.; Sauvage, J.-P. J. Am. Chem. Soc. 1997,
119, 2656-2644.
(8) Ca´rdenas, D. J.; Sauvage, J.-P. Inorg. Chem. 1997, 36, 2777-2783.
(9) Batten, S. R.; Robson, R. Angew. Chem., Int. Ed. 1998, 37, 1460-
1494 and references therein.
(10) Whang, D.; Park, K.-M.; Heo, J.; Ashton, P.; Kim, K. J. Am. Chem.
Soc. 1998, 120, 4899-4900.
(11) Mingos, D. M. P.; Yau, J.; Menzer, S.; Williams, D. J. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 1894-1895.
(3) Dietrich-Buchecker, C. O.; Sauvage, J.-P. Chem. Commun., 1999, 615.
10.1021/ja992391r CCC: $18.00 © 1999 American Chemical Society
Published on Web 11/12/1999

Communications to the Editor
J. Am. Chem. Soc., Vol. 121, No. 47, 1999 11015
Scheme 2. Preparation of 310+ a
Figure 3. 1H NMR spectrum of catenane 310+
.
Scheme 3. Second Approach for the Preparation of Doubly
Interlocking [2]Catenanes via Preformed Ring Molecules
a
(i) Cu(CH3CN)4PF6 (0.5 equiv to 1); (ii) (en)Pd(NO3)2 (2.0 equiv to
2
2+).
data are clear evidence that the complex formed contains four
Pd(II), two Cu(I), and four molecules of 1 and that it cannot be
a simple [2]catenane. 1H NMR also strongly supported the
structure of 310+: (i) the four ligands of 310+ are all equivalent;
(ii) each ligand is disymmetric as evidenced by the presence of
the 14 individual signals in the aromatic region; and (iii) the two
protons of the PyCH2 group (see Figure 3) are diastereotopic.
Figure 2. A molecular modeling of 310+ optimized by MM2 force-field
calculation with Cerius2 3.5 package program. For simplicity, only one
enantiomer is represented throughout the paper.
1
Furthermore, 2D H NMR afforded the expected linkage con-
nectivity of the ligand.
The second approach is based on the catenation reaction from
preformed Pd(II)-linked components, thus taking advantage of
the reversible nature of the Pd(II)-N bond (Scheme 3). Bipy (2,2′-
bipyridine) was selected as an ancillary palladium(II) ligand
instead of en so as to avoid coordination of the Pd centers to the
phenanthroline unit of 1, making the formation of square planar
complexes very unlikely because of steric reasons. When 1 and
(bipy)Pd(NO3)2 were mixed in CD3CN:D2O (1:1), quantitative
formation of a monomer ring was observed.14 Subsequent addition
Cu(CH3CN)4PF6 (0.015 mmol) in acetonitrile (1 mL) immediately
gave the catenane precursor (2+). To this mixture, an aqueous
solution (1 mL) of (en)Pd(NO3)2 (en ) 1,2-diaminoethane, 0.03
mmol) was added, and the reaction mixture was stirred for 1 h at
room temperature to give the doubly interlocking catenane
compound (310+). This quantitative catenane formation was
monitored by NMR experiment when the reaction was carried
out in a deuterated solvent. The reaction solution was poured into
aqueous KPF6 (0.6 mmol, 5 mL) to give a red-brown precipitate,
which was filtered and dried. With this simple method, catenane
310+ was isolated in almost quantitative yield as PF6 salt (92%).
It was fully characterized by elemental analysis and various
spectroscopic methods (1D- and 2D-NMR, and ESI-MS) as
discussed later.12
This remarkable assembly process leads in a surprisingly
efficient fashion to a 10-component architecture ( six metals and
four ligands). Catenane 310+ consists of two doubly interlocked
50-membered rings. An optimized structure is depicted in Figure
2, which shows the absence of any distortion in the framework.
The possibility of a simple, two-crossing [2]catenane consisting
of the same components is excluded because this molecule is
unable to chelate two Cu(I) centers at the same time due to too
large distortion of the chelated structure.
+
of Cu(CH3CN)4 led to the formation of a doubly interlocking
catenane, which is analogous to 310+, with bipy on each Pd(II).14
The formation of the same product by the two different routes
confirms that it is a strict self-assembled unit. This reaction was
also quantitative within the mixing time. As expected, bipy units
are all equivalent, but each of them is disymmetric in good
accordance with the expected structure. This procedure shows
the potentiality of reversible ring-closing and -opening processes
for constructing interlocking rings, analgous to previous work.5
Acknowledgment. We thank Dr. C. O. Dietrich-Buchecker for helpful
discussion. We are also grateful to Dr. T. Kusukawa and J. D. Sauer for
NMR. JSPS is appreciated with financial support to F.I.
Supporting Information Available: Experimental details, NMR (1D
and 2D) and ESI-MS data of catenane complexes 3 and its bipy-protected
analogue, and the optimized geometry of 3 (PDF). This material is
available free of charge via the Internet at http://pubs.acs.org.
The 4-crossing [2]catenane structure was evidenced by ESI-
MS and NMR spectroscopy. ESI-MS showed prominent peaks
corresponding to [310+‚nPF6
]
- (10-n)+ with n ) 3, 4, and 5.13 These
JA992391R
(12) Characterization of 310+: also see Supporting Information.
(13) ESI-MS data of compound 310+
ESI-MS (CH3CN) m/z 1289.1
[310+ - (PF6-)3]3+, 930.4 [310+ - (PF6-)4]4+, 715.3 [310+ - (PF6-)5]5+
(14) Physical properties of the bipy monomer ring and the bipy catenane
(ESI-MS, 1H and 13C NMR, Elemental Analysis, etc.): see Supporting
Information.
:
.