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Novel Host Structures for the Selective Inclusion of Aromatic and Aliphatic Guests in Aqueous Solution.

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tained by a difference Fourier synthesis. The C6C7 and
C6'C7' distances correspond to the length of a single bond.
2a, b were further characterized by elemental analysis as
well as by mass, IR, and '3C('H}-NMR spectra (Table I).
In 2a, the C atoms in the a- and p-positions, respectively,
are magnetically equivalent. In contrast, because of the
PPh3 ligand, in 2b four signals occur which are split into
doublets for C5, C7, and C8. The larger coupling constant
is ascribed to the trans-C8-Fe-P group. The assignment of
the signals is corroborated by studies of 2a, b in which the
P-positions of the ferracyclopentanes were labeled by deuterium (Table 1).
Table 1. Spectroscopic data and melting points for 2a, 2b, and 3b.
2a
Zb
3b
~
IR [cm-'1
W O ) [a1
''C('HJ-NMR 6
Ibl
MS (m/z)
M.p. ["C]
~-
~
2096 m-s
2032 s
2021 vs
2010 s-vs
22.1 (s, (253)
36.6 (s, C6,7)
2042 w
2024 vs
1977 vs
1965 s
1972 sh
1935 s-vs
21.0 (d, C8) [c]
37.4(s,C5,6)
26.8 (d, C5) [d]
35.0 (d, C7) [el
37.3 (s, C6)
212.1 (d,C2)[fl
216.3(s,C2,3)
205.1 (s, C2,3)
218.0 (d, C1,4) [g] 216.6(s,Cl)
212.2 (s, C1,4)
224 ( M " )
458 ( M e ) [h]
430 ( M " )
-35 (decomp.)
79
120 (decomp.)
[a] In n-hexane. [b] In CDCI,, 20.115 MHz, &value rel. TMS. [c]
zJ(CP)=10.2 Hz. [d] 'J(CP)=5.1 Hz. [el 'J(CP)=8.9 Hz. [fl *J(CP)=lO.O
Hz. [gl 'J(CP)= 14.0 Hz. [h] FD-MS (8 kV).
In the presence of CO, 2a is remarkably stable, and the
expected formation of cyclopentanone is observed only at
20°C['01.In the absence of CO, 2a decomposes already at
- 35 "C to afford Fe,(CO),, as well as cis- and trans-butene
in the molar ratio 1 : 2 .
The ethene complexes 3a["] and 3bf5]can be obtained
analogously and have been characterized by mass, IR, and
'3C{1H]-NMRspectroscopy (Table 1). 3a['I1has previously
been prepared from Fe2(C0)9 and C2H4, a method associated with tedious, laborious separation from Fe(C0)5. Xray structure analysis of 3bc7lconfirms the predicted equatorial arrangement['*] of ethene (Fig. 2).
[l] R. J. Puddephatt, Comrn. Inorg. Chem. 2 (1982) 69.
121 T. A. Manuel, S. L. Stafford, F. G . A. Stone, J. Am. Chem. Soc. 83 (1961)
249.
[31 H. H. Hoehn, L. Pratt, K. F. Watterson, G . Wilkinson, J. Chem. Soc.
1961, 2738.
[4] Recently, this compound was generated photochemically and detected
by IR spectroscopy in an alkane matrix at 77 K: J. C. Mitchener, M. S.
Wrighton, J. Am. Chem. Soc. 105 (1983) 1065.
[5] A. Stockis, R. Hoffmann, J . Am. Chem. Soc. 102 (1980) 2952.
[6] E. Lindner, H.-J. Eberle, Angrw. Chem. 92 (1980) 70; Angew. Chem. Inf.
Ed. Engl. I9 (1980) 73; E. Lindner, G. von Au, H.-J. Eberle, Chem. Ber.
114 (1981) 810.
171 Triclinic crystals of Zb (space group P i ) from n-butane. Refinement in
the non-centrosymmetric space group PI did not lead to a n improvement of the structure model and confirmed the assumption of a disorder
of atoms C(6) and C(7). Lattice constants at 183 K (MoKa radiation):
a=969.4(4), b=976.4(6), c = 1348.9(5) pm, a= 103.75(5), p= 108.77(3),
= 1.352 g/cm'. Structure solved with MULy=70.16(3)", 2 = 2 ,
TAN, R = 0.039, 3833 reflections with 12 3 u(0. Monoclinic crystals of
3b (C2/c) from n-pentane. Lattice constants at 193 K (MoKa radiation):
a=2350.4(3), b=1425.4(3), c = 1917.1(5) pm, p=140.99(4)", Z=8,
pC.,. = 1.414 g/cm'. Structure solved with MULTAN, R =0.039, 1639 reflections with I>3u(I). Further details on the crystal structure investigations can be obtained from the Fachinformationszentrum Energie Physik Mathematik, D-7514 Eggenstein-Leopoldshafen 2, by quoting the
depository number CSD 50942, the names of the authors, and the journal citation.
[8] Procedure: A solution of 10 mmol (F3CSO'CH2CH& o r (F,CS0,CH2)2
in 150 m L dimethyl ether is added dropwise at -50°C to a suspension
of l a , b (10 mmol) in 100 mL dimethyl ether. After 12 h, the dark red solution is concentrated to a third at -80°C in vacuo and diluted with nbutane to the original volume. After the residue is decanted off, the solution is concentrated in vacuo until the colorless (Za, 3a) or yellow (Zb,
3b) compounds precipitate; purification follows by recrystallization
from n-butane (Za, 3a: -78°C) and n-pentane (2b, 3b: -2S"C), respectively. Yields 60-90%.
191 a) C. Kruger, Y:H. Tsay, Cry.sl. Sfnrcr. Cornrnun. 5 (1976) 215; b) M. R.
Churchill, H. J. Wasserman, H. W. Turner, R. R. Schrock, J. A m . Chem.
Soc. 104 (1982) 1710.
[lo] F.-W. Grevels, D. Schulz, E. Koerner von Gustorf, Angew. Chem. 86
(1974) 558; Angew. Chem. In,. Ed. Engl. I3 (1974) 534.
[Ill a) H. D. Murdoch, E. Weiss, ffelu. Chim. Acta 46 (1963) 1588; b) D. D.
Beach, W. L. Jolly, Inorg. Chem. 22 (1983) 2137.
[12] a) M. I. Davis, C. S. Speed, J . Organomel. Chem. 21 (1970) 401; b) T. A.
Albright, R. Hoffmann, J. C. Thibeault, D. L. Thorn, J . Am. Chem. Soc.
I01 (1979) 3801; c) T. A. Albright, Tetrahedron 38 (1982) 1339.
Novel Host Structures for the Selective Inclusion
of Aromatic and Aliphatic Guests in Aqueous
Solution**
By Fritz Vogtle* and Walter M. Miiller
Tetraammonium salts of the [n.l.n.l]cyclophane type 1
(m= 1-3, X or R1-R4 may contain an N') with units derived from diphenylmethane form an elongated cavity and
are suitable, water-soluble host structures for neutral aromatic guest molecules['1.
Q
X-(CH,),-C-(CH,),X
/ \
Fig. 2. Molecular structure of 3b in the crystal. Selected distances [pm] and
angles ["I: Fe-C5 209.5(7), Fe-C6 210.2(7), C5-C6 139.8(8); Fe-C5-C6 70.8(4),
Fe-C6-C5 70.3(4), C5-Fe-C6 38.9(2), C2-Fe-C3 112.213).
R4
R3
1
[*] Prof. Dr. F. Vogtle, W. M. Muller
Received: May 21, 1984;
revised: July 10, 1984 [Z 841 IE]
German version: Angew. Chem. 96 (1984) 727
712
0 Verlag Chemie GmbH. 0-6940 Weinheim, 1984
Institut fur Organische Chemie und Biochemie der Universitat
Gerhard-Domagk-Strasse I, D-5300 Bonn 1 (FRG)
[**I Frau 0. Werner is thanked for her assistance
0570-0833/84/0909-0712 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 23 (1984) No. 9
We now report the host structures 2a-c, which differ
principally from 1, and which are just as effective as hosts.
They are marked by their propitious and variable syntheses-starting from standard reagents such as terephthaloyl dichloride, ethylenediamine, and pyridinecarbaldehyde.
R
R
a
2a-d
a:R =
3
d:R
b:R
\ /
c:R = N<
CH,
The 30-membered sixfold acid amides 2a-c of the
[6.6.6]paracyclophane type, which are relevant for receptor- and enzyme-model studies, and which have, respectively, six a-,p-, and y-pyridylmethyl side arms[*I, exhibit
in aqueous acidic solution (e.g. pD= 1.2) similar guestbinding properties as hosts of the type 1, but have different substrate selectivity (vide infra). The large high-yield
shifts of the 'H-NMR signals of the aromatic guest molecules (resorcinol, 2,6- and 2,7-naphthalenediol) and of the
host protons differ little from those caused by the host l r 3 I .
In addition, Table 1 contains data on the new macrocycles
2d and 3 -the latter with pyrazine structural elementswhich also function as host compounds.
Under analogous conditions, 2b induces the largest
high-field shifts. A 1 :1-mixture of hosts 2b and 2c with
the guest 2,6-naphthalenediol exhibits predominantly the
characteristic high-field shift pattern of the 2b complex.
These differences in the hostlguest binding are possibly
attributable, inter alia, to the different spatial separation of
the six pyridine nitrogen atoms from the formally similar
cavity in 2a-c and to the presence of H bonds between the
OH groups of the naphthalenediols and the nitrogen atoms
of the pyridine rings, as indicated by inspection of molecular models.
Table 1. 'H-NMR high-field shifts M [ppm] of guest protons by the host
compounds 2a-d and 3 (400 MHz, in D,O/DCI at pD=1.2 and 21°C.
Standard defined as HDO at 6=4.8. Concentrations: host 2.5 x 1 0 - 2 ~ ,
guest: 1.25 x 1O-'M). The chemical shifts for the guests are 2,6-naphthalene3
7.06 (H-3), 7.61 (H-4); 2,7-naphthalenediol: 6=7.03 (Hdiol: 6 ~ 7 . 1 (H-I),
I), 6.93 (H-3), 7.69 (H-4); resorcinol: 6=6.35 (H-2), 6.42 (H-4), 7.11 (H-5).
Guests
dH
H
o
w
H
HO$OH
HO
\
/
Studies of comparable substances corroborate the conclusion that the high-field shifts in the system 2 indicate
molecular guest-inclusion in aqueous solution. The methyl-substituted 27- and 36-membered pyridinophanes 4a,
b, which are also water-soluble when protonated[", do
not-as pyridine and 2- and 3-methylpyridine-exhibit
analogous high-field shifts, although the H I D exchange
rate of added phenols is also-if only slightly-accelerated
(vide infra): the guest molecules described apparently require an approximately 30-membered macrocycle, such as
in ring 2, but not in 4 or 5 .
Of especial note for the novel host structures 2a-c is that
in addition to aromatic also aliphatic guests such as trans1,4-cyclohexanediol,
trans- 1,4-cyclohexanedicarboxylic
acid, adamantanecarboxylic acid, and adamantanethiol
are dissolved by complexation in aqueous acidic solution.
Accordingly, the high-field shifts of the cyclohexane- and
adamantane-CH protons can be taken as also indicating
the inclusion of those aliphatic guests into the cavity. Inspection of molecular models suggests that the cavity in
2a-c is more "circular" than in 1.
H-3
H-4
H-3
H-4
H-i
H-5
Host
H-l
H-3
H-4
H-l
H-3
H-4
H-2
H-4
H-5
2a
2b
2c
2d
3
0.61
0.76
0.61
0.34
0.26
0.44
0.54
0.32
0.23
0.26
0.58
0.78
0.60
0.23
0.24
0.52
0.64
0.63
0.26
0.31
0.20
0.35
0.21
0.24
0.30
0.41
0.53
0.42
0.25
0.31
0.27
0.42
0.26
0.21
0.32
0.23
0.36
0.19
0.19
0.32
0.25
0.38
0.20
0.20
0.32
Angew. Chern. Int. Ed. Engl. 23 (1984) No. 9
L
4a: n = l
4b: n:2
b:R
=
4
d:R = C H j
In contrast to the host system lC5],
rapid H/D-exchange
of the 1,5-(1,8)protons of 2,6-(2,7-)naphthalenediol and of
the 2-proton of resorcinol occur in the presence of the
hosts 2a-c. We ascribe this to a catalysis effected by the
pyridine nitrogen atoms of the side armsL6]
The hosts 2 and the analogously synthesized new ligand
3 are concipated to complex not only neutral guests but
also cations, just as in the cocomplexation in enzymes. An
illustration of their capacity to bind cations is the ability of
the hosts 2 to solvate sodium permanganate into lipophilic
phases (CH,Cl,), a phenomenon previously known only
for efficient crown ethers, cryptands, and podands. Host ligands of the type 2 should also function as catalysts for
proton transfers, nucleophilic substitution[71,and as models for NADH[~].
General procedure for the macrocycles using the example of
2a-c
A solution of 40.0 mmol of the corresponding N,N'-substituted ethylenediamine (prepared from ethylenediamine and the corresponding pyridine
carbaldehyde and subsequent hydrogenation with 5% Pd/CaC03) in 250 mL
benzene is allowed to react at room temperature with a solution of 20.0 mmol
terephthaloyl dichloride in 250 mL benzene under high dilution conditions
(7 h simultaneous dropwise addition into 1 L benzene). The oligomers, which
were extracted with dichloromethane, are separated by chromatography, column chromatography (Al2O3,CHZC12/EtOHas eluent), dry column chromatography (AlzOs), or preparative thin-layer chromatography (AIzO,,
CHZCIZ/EtOHas eluent). 2a : Yield (in each case relative to the dicarboxylic
acid dichloride): 1.9%, m.p. = 149- 155°C; 2b: 3.6%, 143--149"C, phase
transition 205"C, 271-273°C; 2c: 1.0%, 163-170°C, phase transition
235"C, 263-266°C; 2d: 8.2%, 114-123"C; 3 : 7.8%, 115--126"C; 4a:
16.6%, 123-129°C; 4b: 7.9%, 132-136°C.
0 Verlag Chernie GrnbH, 0-6940 Weinheirn, 1984
Received: April 25, 1984 (2 809 IE]
German version: Angew. Chern. 96 (1984) 711
0570-0833/84/0909-0713 $ 02.50/0
713
[ I ] a) K. Odashima, A. Itai, Y. Iitaka, Y. Arata, K. Koga, Tefrahedrun Left.
21 (1980) 4347; K. Odashima, K. Koga: Cyelophanes, Vu/. 2, Academic
Press, New York 1983, S. 629; b) F. Diederich, K. Dick, Angew. Chem. 95
(1983) 730; Angew. Chem. In[. Ed. Engl. 22 (1983) 715; Angew. Chem.
Supp/. 1983, 957; c) H . J. Schneider, personal communication; d) J.
Winkler, E. Coutouli-Argyropoulou, R. Leppkes, R. Breslow, J . Am.
Chem. Sue. 105 (1983) 7198; e) Y. Murakami, Top. Curr. Chem. 115
(1983) 107; f) cf. 1. Tabushi, K. Yamamura, ibid. l l 3 (1983) 145; g) cf.
also C. J. Suckling, J . Chem. SOC.Chem. Cummun. 1982, 661.
[2] Correct elemental analyses, ‘H-NMR, and mass spectra were obtained
for all the new compounds.
[31 The shifts arise from anisotropic effects between host and guest as well as
from the influences of the positive charges on the pyridinium groups; cf.
[Ib, cl.
141 Since 2 ( R = benzyl), in contrast to 2a-c, is not soluble in acids, analogous inclusions in water are ruled out; cf. F. Vogtle, H . Puff, E. Friedrichs, W. M. Miiller, J . Chem. Sue. Chem. Commun. 1982, 1398.
151 Prof. K . Koga, Kyoto, is thanked for this personal communication.
[6] Cf. G. W. Kirby, L. Ogunkoya, J. Chem. SUC.1965. 69 14, and references
cited thcrcin.
171 Attempts to hydrolyze lipophilic p-nitrophenyl esters in the presence of
2a, b as catalyst in aqueous acidic solution indicate an inhibition attributable either to a strong host/guest binding or to an unfavorable position of the nucleophilic centers of the host.
[Sl Cf. R. M. Kellogg, Top. Curr. Chem. I01 (1982) 1 11.
Functionalized, Oligocyclic Large CavitiesA Novel Siderophore“”
290 “C) dissolves remarkably readily in chloroform, but
less well in dichloromethane.
The ‘H-NMR spectrum reflects the symmetry of the mol e ~ u l e [The
~ ~ .singlet of the methoxy protons is shifted characteristically to high field. On the NMR time scale, the
OCH3 groups apparently rotate relatively unhindered
about the p-phenylene axis and thus gain access to the anisotropic region of the two I ,3,5-substituted benzene rings,
At - 109°C the high-field shift is still marked; all signals
are broadened. Inspection of space-filling models indicates that not all of the six methyl groups of l a can be accommodated simultaneously in the interior of the molecule.
Accordingly, this provides an explanation why la, unlike
other neutral ligands, is not able to solvate inorganic salts
into lipophilic phases.
Cleavage of the methoxy groups in l a by BBr, in dichloromethane liberates the hexahydroxy compound l b
(decomp. 285OC). l b fluoresces intensely bright blue in
light of wavelength 366 nm, both in the solid state and in
solution in dimethyl sulfoxide. Alkaline solutions are
scarcely air sensitive. The FAB mass spectrum of l b in a
glycerine matrix exhibits a significant [ M + HIe peak[61.
Examination of molecular models suggests that in the
hexaanion of l b an octahedral donor geometry for metal
cations is formed; upon complexation, a helical-chiral
configuration results (Fig. 1).
By Wolfgang Kiggen and Fritz Vogtle*
We have succeeded in synthesizing a novel complex ligand-type 1, which cannot be described as a crown ether,
cryptand, or spherand. Moreover, the new ligand is a cagelike macrooligocycle which exhibits a cavity bounded on
three sides and has functional groups suitable for complex
formation“].
52
(6-n)@
H
1
co
H!/
yNJ2+cH2
oc
\
I
Fig. 1. Octahedral metal complex 01’ Ib.
0
$oRO
R:
1
o:R:CH3
H2
b : R:H
COR‘
2
”
a:R=CH,
R’= CH$
c : R = CH3
R’= CI
b : R z CH3
R‘= NaO
d :RE H
R’= H O
The colorless hexalactam l a can be synthesized by two
routes using high dilution conditions[*]via Stetter cyclization131: a) from 2,3-dimethoxyterephthaloyl d i c h l ~ r i d e [ ~ ]
and 1,3,5-benzenetriyltris(methaneamine) in 1.5% yield;
and b) from the new tris(acid chloride) 2c and 1,3,5-benzenetriyltris(methaneamine) in 13% yield (790 mg per
charge!). The hexamethoxy compound l a (decomp.
[*I Prof. Dr. F. Vogtle, Dip].-Chem. W. Kiggen
lnstitut Fiir Organische Chemie und Biochemie der Universitat
Gerhard-Domagk-Strasse 1, D-5300 Bonn 1 (FRG)
[**I
This work was supported by the Minister fur Wissenschaft und Furschung des bandes Nordrhein-Westfalen.
714
0 Verlag Chemie GmbH, D-6940 Weinheim, 1984
“Siderovhores” (iron carriers) which contain catechol’
moieties form octahedral complexes with Fe3QL71.
That l b
is a remarkably stronger complexing ligand emerges from
the observation that moist Ib attacks 1818 stainless steel,
producing a blue-black coloration. Iron and nickel powder
are dissolved in minutes, and chromium powder is dissolved within a few hours to form blue-green, green-grey,
and pink solutions, respectively, on exposure to air.
Addition of Fe3@salts to a solution of the novel ligand
l b in water at pH 11 leads to the characteristic red-violet
tint (Amax = 544 nm, E = 4680). For comparison, we prepared from 2a the colorless, open-chained, hexadentate ligand 2d, whose solution in water at p H 11-in contrast to
l b -becomes red-brown (ilmax
= 508 nm, E = 5120) upon
addition of Fe3Qsalts. Titrations of the two ligands against
Fe3@,with UV/VIS monitoring, indicate a 1 : 1 stoichiometry. Upon acidification of the Fe3@-complexsolutions of
l b and 2d, blue-black compounds precipitate out. The occurrence of a [(lig)H3Fe + HI@ peak in the FAB mass spectrum of the Fe3@complex of l b in a diethanolamine matrixr61corroborates the 1:1 stoichiometry, which suggests
the presence of one cation in the cavity, as shown in Figure
1[81
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Angcw. Chem. I n t . Ed. Engl. 23 (1984) No. 9
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