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Inclusion Complexes between a Macrocyclic Host Molecule and Aromatic Hydrocarbons in Aqueous Solution.

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proton noise decoupled): 7a : 6(CH,)= 19.2,6(C-2)= 57.0,6(C-3,4)= 80.8,
85.0,6(C-5)=62.1,6(C-6)= 132.4; 7b:6(CH3)= 19.3,6(C-2,5)=56.2, 57.5,
6(C-3,4)=82.4, 85.9, 6(C-6)= 131.7.
[5] a) H. Pommer, Angew. Chem. 89 (1977) 437; Angew. Chem. Int. Ed. Engi.
16 (1977) 423; b) H. J. Bestmann, Pure Appl. Chem. 51 (1979) 515; C)R. C.
Kerber in E. A. Koerner von Gustorf, F. W. Grevels, 1. Fischler: The Organic Chemistry of Iron, Vol. 2. Academic Press, New York 1981, d) M.
Schlosser, K. F. Christmann, Liebigs Ann. Chem. 708 (1967) 1.
+
Inclusion Complexes between a Macrocyclic Host
Molecule and Aromatic Hydrocarbons in Aqueous
Solution
O=$-CHJ
fN7
By FranGois Diederich* and Klaus Dick
We are interested in cyclophane-like macrocycles which
possess a hydrophobic cavity of definite size and which
permit the formation of stoichiometric inclusion complexes with apolar substrates in aqueous solution at room
temperature at pH = 7IZ1.The key reaction in the synthesis
of the novel host molecule 1 is the cyclization of two equivalents each of 7 and 8 to the macrocycle 9, which proceeds in 18% yield; 1 is obtained in good yield after four
subsequent steps[31.Over the range 2 x 1OP4-7 x l o p 3M,
the 'H-NMR signals of 1 in D20 (303 K, see Table 1) are
independent of concentration and are highly resolved. The
critical micellar concentration (CMC) of 1 in water was
M by 'H-NMR spectroscopy.
found to be 7.5 x
If a suspension of solid pyrene prepared by ultrasonification is stirred or shaken with a 2 x lo-' M aqueous solution of 1 and then centrifuged and filtered, the solution exhibits the intense fluorescence of monomeric pyrene.
In this solid-liquid extraction an inclusion complex between pyrene and 1,which possesses a hydrophobic cavity
of complementary size, is formed. A solution of 13 (with
smaller cavity) is considerably less effective. A 2 x lo-' M
solution of y-cyclodextrin has an even weaker effect, and a
2x
M solution of 12 produces no increase in fluorescence intensity compared to the extraction with water.
Aqueous solutions of the complex of 1-pyrene can also
be prepared by liquid-liquid extraction: e.g. a ~ O - ' M solution of pyrene in n-heptane is shaken with a 2 x lo-' M aqueous solution of 1.
Multiple extraction of an aqueous solution of the l-pyrene complex with n-hexane results in quantitative transfer
of pyrene into the organic phase; the concentration of 1
before complex formation can be determined from the absorption spectrum of the aqueous phase. The concentration of the complex is obtained from the concentration of
pyrene in the organic phase on consideration of the solubility of pyrene in water'"]. Using a 5.5 x
M solution
of 1, a concentration of complex of 2 . 9 ~l O p 3 ~was
achieved.
Evidence for the 1 :I-stoichiometry and information
about the geometry of the 1-pyrene complex in aqueous
solution were obtained by 'H-NMR spectroscopy (Table
1). The large difference in chemical shift between the solution of the complex and the solutions of the components
can best be explained by the following favored geometry
of the complex: the long pyrene C2-axis through C(2) and
C(7) lies along the direction of the C2-axis passing through
the cavity of 1 perpendicular to the mean molecular plane.
[*] Dr. F. Diederich, K. Dick
Ahteilung Organische Chemie
Max-Planck-Institut fur Medizinische Forschung
Jahnstrasse 29, D-6900 Heidelberg I (Germany)
Angew. Chem. Inr. Ed. Engl. 22 (1983) No. 9
R
2H3C-C
H3C-
A : KOH, [18]crown-6, tetrahydrofuran, 48 h, 65"C, 18%; E : 1) NaOH,
CH30CH2CH20H, 124"C, 85%; 2) HCHO, HCOOH, IOOT, 91%; 3)
FS03CH3, CHCI,, 2 5 T , 82%; 4) Dowex 1 x 8 Cle, 79%.
Pyrene only then fits completely into the cavity if its short
Cz-axis, which intersects the C(4)-C(5) and C(9)-C( 10)
bonds, runs in the direction of the C2-axis of 1through the
spiro carbon atoms of the two diphenylmethane moieties.
In this way, H-2,7 of pyrene project out of the cavity and
are shifted to the smallest extent; in contrast, H-1,3,6,8 and
H-4,5,9,10 are directed towards the diphenylmethane
moieties and are shifted markedly to high field.
The proposed geometry for the complex is corroborated
by the low-field shift of the protons of 1 in the pyrene molecular plane and by the high-field shift of the protons perpendicular to this plane. The unexpected high-field shift of
H-2' and N(l?-CH3 can be explained by the conformational mobility of the Cs bridges bearing the piperidinium
0 Verlag Chemie GmbH, 6940 Weinheim, 1983
0570-0833/83/0909-0715 $02.50/0
715
Table I. ’H-NMR spectra (360 MHz) of the complex 1-pyrene in D 2 0
([1]=5.5 x IO-’M, [I-pyrene]=2.9 x ~ O - ’ M ; 6 relative to sodium 2,2,3,3-tetradeuterio-3-(trimethylsilyl)propionate(TSP) in D 2 0 as ext. standard) and,
for comparison, of pyrene (6 relative to TSP,,, in [D&nethanol) and 1
([I]= 2 x 10-4-7 x lo-’ M, 6 relative to TSP,,, in D,O]). J in Hz.
H- 1
H-2
H-4
Pyrene in [DJMethanol
Complex 1-Pyrene in D20
303 K
8.21 (d, J=7.6, 4 H )
8.02 (t, J=7.6, 2H)
8.10 (s, 4 H )
7.19 (d, J=7.5, 4 H ) 7.19
7.58 (t, 5=7.5, 2 H ) 7.54
6.95 (s, 4H)
6.95
303 K
353 K
1 in D20
303 K
1.87 (m, 8 H )
1.96 (“t”,
J=7,8H)
Aryl-CH, 2.08 (s, 24H)
H-3”
2.73 (m, 8H)
N(I?-CH3 3.16 (s, 2 4 ~ )
N( 1“)-CH,
H-2‘
3.43 (m, 16H)
H-2”
H-3’
H-3
3.88 (“t”.
J=7,8H)
7.01 (s, 8 H )
H-2
H-10
353 K
1.87
I .96
2.08
2.68
3.15
3.41
1.13 (m, br, 8 H )
1.47 (m. br, 8 H )
2.10 (s, 24H)
la1
2.96 (S, 12H)
3.18 (s, 12H)
3.50 (m, 8 H)
3.88
[a]
6.95
7.30 (s, br, 8 H )
1.17 (m, 8 H )
1.45 (“t”,
J=7.5, 8 H )
2.09 (s, 24H)
2.86 (m, 8H)
2.96 (s, 12H)
3.17 (s, 12H)
2.94 (m, 8 H)
3.48 (“t”,
J=5.2, 8 H )
3.10 (“t”,
5=7.5, 8 H)
7.23 (s, 8 H )
[a] These signals are very broad and collapse at 6=2.6-3.1
2
2,6-dimethylphenol, 576-26-1 ; ethyl cyanoacetate, 105-56-6; piperidine-4,4diacetic acid, 86748- 14-3; pyrene, 129-00-0; y-cyclodextrin, 17465-86-0.
121 F. Diederich, K. Dick, Tefruhedron Lett. 23 (1982) 3167.
[3] Correct analytical results and appropriate spectra were obtained for
these compounds.
[lo] A 8 x IO-’M (0.162 mg/L) aqueous solution of pyrene can be prepared
at room temperature using the method described; this value, obtained
photometrically, is completely consistent with the literature data: H. B.
Klevens, J. Phys. Chem. 54 (1950) 283; W. W. Davis, M. E. Krahl, G. H.
A. Clowes, J. Am. Chem. SOC.64 (1942) 108.
1161 The ’H-NMR experiment was performed using a similar concentration
ratio [l]:[pyrene] and a concentration of complex of 5 . 5 ~IO-’M (303
K); here, almost identical chemical shifts (e.g. of the pyrene protons at
6=7.57, 7.19, and 6.95) and similar line widths for the signals of 1 are
obtained-an important piece of evidence for the same complex form at
concentrations below the CMC of 1.
Synthesis and Reactions of
q5-Cyclopentadienylbis(ethene)cobalt
By Klaus Jonas*, Etienne Deffense, and
Dietrich Habermann
Metallocenes react with alkali metals and olefins, with
elimination of alkali-metal cyclopentadienides, to give
transition metal-olefin or alkali metal-transition metal-olefin complexes[31.Thus, reaction of cobaltocene (Cp2Co)
with potassium and ethene in diethyl ether leads to formation of the bis(ethene) complex l .
CP2Co + K + 2C2H4
Et20
-20toOCC
’ CpCo(C2HS2 f
KCp
1
lo@;
9
This unusually facile entry to 1 (one-step synthesis, yield
85%), whose ethene ligands are readily replaceable, makes
1 a very useful starting material in organometallic chemistry (cJ Supplement). Of particular interest are the reactions
of 1 with alkynes or nitriles since, with C ~ C O ( C Oor
)~
CpCo(C,H,,) at temperatures > lOO”C, cobalt-catalyzed
alkyne cycl~trimerization[~~~
or cocyclization of alkynes
and nitriles to afford pyridine derivatives occurs1261.
At - 10 “C, 1 reacts with 2-butyne in n-hexane to afford
a new deep-red complex, which can be recrystallized from
boiling n-hexane, and which, according to the elemental
analysis and mass spectrum, has the composition 9.
7
Pyrene
12
rings which, favored by additional hydrophobic interactions, can approach the pyrene. In contrast to the highly
resolved pyrene signals between 273 and 353 K, the signals
of 1 in the complex are very broad below 333 K. This
probably arises from the exchange of pyrene on the ‘HNMR time scale with the host molecules present in excess[16!
By analogy, inclusion complexes were prepared from 1
and water-insoluble aromatic hydrocarbons such as perylene, fluoranthene, naphthalene, and durene. ’H-NMR
and optical spectra confirm the results obtained from the
complexation of pyrene.
Received: April 28, 1983 [Z 363 IE]
German version: Angew. Chem. 95 (1983) 730
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1983, 730
CAS Registry numbers:
1, 86765-98-2; 2, 32161-06-1; 3, 86748-13-2; 4, 86748-15-4; 5, 86748-16-5;
4 86748-17-6; 7,86748-18-7: 8, 86748-12-1; 9, 86748-19-8; 10, 86748-20-1;
11, 86748-21-2: 11. 4FS03CH,, 86765-97-1 ; 12, 86748-22-3; 13, 86748-23-4;
716
0 Verlag Chemie GmbH, 4940 Weinheim, 1983
The product 9 (yield 46%) was investigated crystallographically but, because of disorder in the crystal lattice, an
accurate description of the molecular geometry could not
be obtained. However, these results indicate that the cobalt
atom in 9 is sandwiched between a cyclopentadienyl ring
and a hexamethylbenzene ring”’]. The magnetic moment,
peff=2.85 pB,of solid 9 is almost exactly that expected for
two unpaired electrons according to the spin-only formula.
We assume, therefore, that 9 exists as qs-CSHsCo-q6C6(CH&, which is isoelectronic with the cation of
[(C6(CH3)6)2Co]PF,[Z71,
and in which the krypton electronic
configuration is exceeded by two electrons. This probably
accounts for the ease of displacement of the hexamethylbenzene ligand, e.g., with CO, and why 9 is the first reported (CsHs)Co-compound that can catalyze the cyclotrimerization of alkynes and cocyclization of alkynes and nitriles at room temperature.
[*] Priv.-Doz. K. Jonas, Dr. E. Deffense, Dr. D. Habermann
Max-Planck-Institut fur Kohlenforschung
Postfach 01 1325, D-4330 Miilheim an der Ruhr 1 (Germany)
0570-0833/83/0909-0716
S 02.50/0
Angew. Chem. Int. Ed. Engl. 22 (1983) No. 9
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