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The Multiple-Path Mechanism for 13C-13C Long-Range Coupling Constants of Bicyclic Hydrocarbons.

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[IOS] R. Goldstone, K. Martin, R. Zipser. R. Horton, Prostaglandins 22
(1981) 587.
[I091 K. U. Weithmann, Ric. Clin. Lab. I 1 (Supplement 1) (1981) 209.
[IIO] G. A. Fitzgerald, A. R. Brash, P. Faladeau, 1. A. Oates, J. Clin. Inuest.
68 (1981) 1272.
[ I 1 I ] 1. A. Blair, S. E. Barrow, K. A. Waddell, P. J. Lewis, C. T. Dollery, Prostaglandins 23 (1982) 579.
[I121 a) V. Int. Conf. Prostaglandins, Florence, May 18-21, 1982, Fondazione Giovanni Lorenzini 1982; b) G. Galambos, V. Simonidesz, 1. lvanics, G. Kovacs in [ I IZa], p. 513.
I1131 T. Toru, K. Bannai, T. Tanaka, N. Okamura, A. Hazato, Y. Okamiya,
T. Naruchi, S. Kurozumi in [ I 12a], p. 519.
1114) R. H. Bradbury, K. A. M. Walker, Tetrahedron Lett. 23 (1982) 1335.
[I151 R. Noyori in B. M. Trost, C. R. Hutchinson: Organic Synthes1.c Today
and Tomorrow. 3rd IUPAC Symp. Org. Synth., Pergamon, New York
1980, p. 284.
[I I61 P. A. Aristoff, A. W. Harrison, Tetrahedron Lett. 23 (1982) 2067
[I171 R. Ceserani, M. Colombo, M. Grossoni, L. Zuliani, N. Mongelli in
[112a],p. 511.
[ I 181 N. Mongelli, 0. Magni, R. Ceserani, C. Ciandolfi in [112a], p. 126
[ I I91 A. J. Dixon, R. J. K. Taylor, Tetrahedron Lett. 23 (1982) 327.
Il20l U. Seipp, W. Vollenberg, G. Michel, B. Miiller, Eur. Pat. 45842 (Prior.
August 8, 80). Griinenthal GmbH.
[I211 R. F. Newton, A. H. Wadsworth, J. Chem. Soc. Perkin Trans. I , 1982.
823.
[I221 R. R. Gorman, Fed. Proc. Fed. Am. Soc. Exp. Biol. 38 (1979) 83.
(1231 D. J. Levenson, C. E. Simmons, B. M. Brenner, Am. J. Med. 72 (1982)
354.
[I241 W. Creutzfeld, Scand. J. GastroenreroL Suppl. 77 (1982) 7.
C O M M U N IC A T I O N S
1
2
3
4
5
6
7
8
9
10
Table 1. Measured and calculated (according to the additivity rule) coupling
constants J , [Hz] of bicyclic hydrocarbons.
The Multiple-Path Mechanism for
13C-13CLong-Range Coupling Constants
of Bicyclic Hydrocarbons
Cpd.
1
2
By Martin Klessinger* and Jung-Huyck Cho
For the interpretation of the I3Gi3Clong-range coupling constants of cyclic hydrocarbons o n the basis of a
multiple-path mechanism we have recently assumed an algebraic additivity of the contributions of the various coupling pathways"]. It should be possible to check this assumption particularly well on bicyclic hydrocarbons in
which three coupling pathways are possible for the J 1 . ~ coupling between the bridgehead atoms. We have therefore synthesized the unlabeled compounds 1-10 and investigated their I3C-NMR spectra. The J,,,-coupling constants are collected in Table I .
The coupling constants of the norbornane and bicycIo[2.2.2]octane series differ by about 5-7 Hz, as is to be
expected on replacement of the two-bond coupling pathway A by the three-bond pathway B on the basis of the increments 'JA= - 1 Hz and 'JB= 4 Hz"]. A comparison of
the data for 1, 2, and 3, and for 6,7,and 8, shows, as expected, that the influence of a methyl group on 'JAand 3JB
can be neglected, while an exocyclic methylene group
(pathway C ) reduces the coupling by about 2 Hz to 3Jc.=2
Hz. The comparison of the coupling constants of 4 and 2
and of 5 and 3, as well as of 9 and 7 and of 10 and 8
[*] Prof. Dr. M. Klessinger, J.-H. C h o
Organisch-chemisches Institut der Universitat
OrlCans-Ring 23, D-4400 Munster (Germany)
764
0 Verlag Chemie GmbH, 6940 Weinheim. 1982
3
4
5
Cpd.
Jw
J ,1
(exp.) [a1
(calc.1 [bl
6.8
5.9 (endo)
6.0 (exo)
4.4
5.5 (endo)
5.7 (exo)
4.0
7
6
7
7
5
8
9
6
10
4
J5.4
J,i
(exp.1 [a1
(calc.1 [bl
12.9
I2
12
12.8
11.1
13.4 (endo)
13.3 (exo)
11.3
10
13
II
[a] Measured in C,,Do (75%) with a Bruker WM-300 spectrometer at 75.47
MHz in the PFT method. [b] Calculated additively with the increments
quoted in the text.
shows that the introduction of a double bond into the norbornane series lowers the coupling by ca. 1 Hz, while in
the bicyclo[2.2.2]octane series it increases it by ca. 1 Hz.
This can be explained in terms of the valence angle dependence of the coupling via a three-bond pathway.
A
B
C
D
Quantum chemical calculations according to the INDOSCPT methodl4]show that for decreasing CCC valence angles the contribution to the coupling is expected to increase both for the coupling pathway B as well as for D.
the effect in the case of B with about 3 Hz for a valence
angle change of about 5" being almost twice as large as in
the case of D[".As a result, in the norbornane series the
valence angle effect dominates in the case of the saturated
and correspondingly a desystem, so that here 'JD<'JB
0570-0833/82/101#-0764 $ 02.50/0
Angew. Chem. Inr. Ed. Engl. 21 (1982) No. I #
crease of the coupling J,,4is observed in going from the
saturated to the unsaturated system, whereas the opposite
behavior is found in the bicyclo[2.2.2]octane series. If, in
agreement with these results, one puts ' J n = 3 Hz for the
increment of the coupling pathway D for the norbornene
derivative and 3J0 = 5 Hz for the bicyclo[2.2.2]octene derivative then excellent agreement is found between the measured data and the Jl,4-coupling constants calculated on
the basis of a multiple-path mechanism, also given in Table I.
Thus, o n taking into consideration the ring strain effects
an algebraic additivity of the contributions of the various
coupling pathways to the coupling constant is strictly fulfilled also in the case of the bicyclic systems. Hence, on using suitable increments the long-range couplings of complicated systems can be estimated, while deviations of the
additivity permit conclusions to be drawn regarding ring
strain and similar effects.
Table 1. Morphological and hydrodynamic parameters of DODAC vesicles
in aqueous solution: pH 7.0; 0.01 mol/L Tris-HCI.
13.8kO.5
3 3 5 k 1.5
4.4k 0.05
0.86
35.03~0.I
0 8561
1.72 f0.05
2510
Radius of gyration R, [nm]
Molecular weight M ,x 10'
Thickness of double layer R , [nm]
Degree of hydration [g HrO/g DODAC]
Maximum dimension D,.,,[nm]
Partial specific volume 0, [mL/g]
Diffusion coefficient D x lo-' [cm'/s]
Mass per unit area [M,/nm2]
Received: May 10, 1982 [Z 38 IE]
revised: July 9, 1982
German version: Angew. Chem. 94 (1982) 787
~
[I] M. Klessinger, H. van Megen, K. Wilhelm, Chem. Ber. I15 (1982) 50.
[2] According to S. Berger, Org. Magn. Reson. 14 (1980) 65, a Karplus-like
relationship with 'J($=O").;'J($= 180").;4 Hz holds for 'J. On the basis of the same relationship the 'J increment must be reduced by 3 Hz for
a change of the interplanar angle from 0 to 60': cf. [I].
131 V. Wray, J. Am. Chem. SOC.100 (1978) 768; M. Klessinger, M. Stocker,
Org. Magn. Reson. 17 (I98 I ) 97.
[4] A. C. Blizzard, D. P. Santry, J. Chem. Phys. 55 (1971) 950.
[S] M. Klessinger, J.-H. Cho, Urg. Magn. Reson.. in press: f x standard valence angles 'Js = 5.46 Hz and 'J0 =4.54 Hz, whereby according to [2] the
calculated value for 'Je is to large.
A
"3
Determination of the Structure of
Dimethyldioctadecylammonium Chloride in Solution
by Small Angle X-Ray Scattering;
Reversible Phase Transition**
By Hasko H . Paradies*
Phospholipid vesicles are of great importance as models
for biological membranes. The use of surfactant vesicles,
formed from simple amphiphiles upon sonication, can be
anticipated as artificial vesicles mimicking cell membrane
functions".21. Dimethyldioctadecylammonium chloride
(DODAC, (CH3)2(n-C,8H37)2NfC1-)and dihexyldecyl
phosphate ((n-C16H330)2P(0)OH)[41
have been characterized by Kunitake et a/.(']and FendlerI2l. I n spite of their potential for utilization in catalysis, energy conversion, and
substrate partitioning no detailed information is available
on the size and shape of DODAC surfactant vesicles in solution, nor on the factors which influence them. Unambiguous structural data have been obtained showing the formation of a lamellar bilayer structure as well as the internal structure of DODAC vesicles, including its phase transition behavior under varying pressures and temperatures.
The structural data of DODAC-vesicles (see Table 1) indicate that the amphiphile in aqueous solution is a random
distribution of'lamellas with a thickness of 4 . 4 f 0 . 2 nm,
which is consistent with a hollow vesicular structure with
an outer diameter of 35.0k0.1 nm (Fig. 1). The electron
density profile perpendicular to the DODAC lamellar
plane is shown in figure 1C.
[*] Prof. Dr. H. H. Paradies
[**I
Fachrichtung Biochemie der Pflanzen, Freie Universitat Berlin
Konigin-Luise-Str. 12- 16a, D- 1000 Berlin 33 (Germany)
Part of this work was carried out in the Department of Chemistry, Cornell University, Ithaca, N Y 14853 (USA).
Angew. Chem. Inr. Ed. Engl. 21 (1982) No. I 0
50
E
\
%
s
a
a
6.0
4.0
2.0
2,0
4.0
6.0
Fig. 1. A) Thickness factor, 1,(h)h2of DODAC vesicles obtained from the
uncorrected data by assuming a one-dimensiond cross section distance distribution function: h=(4n/d)sinO; d = 1.54 A, B=scattering angle, and
I,(h)= scattering intensity. B) Distance distribution function, Q(R), obtained
from the data in Fig. IA. C) Electron density profile, @ ( R ) , across the bilayer thickness obtained from the structure amplitudes.
The results obtained strongly support the view that a
certain interdigitation of inner and outer DODAC molecules occurs since the thickness of 4.4 nm is shorter than
the length of two octadecyl chains.
DODAC vesicles show a reversible transition at
T,, = 38 "C at constant pressure and varying temperature,
or vice versa (Fig. 2). The vesicle sizes changed from
D,,,=35 nm to D,,,=40 nm, consistent with recent results by Ceuterick et al.I4]for dimyristoylphosphatidylcholbut different from those of Watrs ef ~ l . [ ~ ] .
The changes in the effective hydrodynamic radii R ,
(DmaJ2) with pressure and temperature are due to
changes in the isopotential partial specific volume from
@=0.8561 f0.003 mL/g at 293 K to 0.8361 k0.002 mL/g
at 303 K. However, DODAC vesicles containing 11%
0 Verlag Chemie GmbH, 6940 Weinheim. 1982
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165
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