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E3Te3Hal Mixed Valency Tellurohalides of Gallium and Indium with One-Dimensional Structural Units.

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Table I. Permeation rates (P)of the water-soluble dye 2 across bilayerimmobilized films upon application of a n electric field ( 4 V between two Pt
electrodes) at SO "C.
P [ I O - 9 em's-'1
Film
Method B
Method A
Po [a1
lao/PSSQ
2.0
1b O/PSSQ
1.8
l c a/PSSe
I .6
2 c , x i 3 2 c , / P s s e 12
P
10
11
16
12
P
PO
5.0
6. I
10
10
Po la1
P
P
-
2.0
1.8
I .6
12
3.5
2.2
2. I
120
I .4
I .3
10
groups by contact with the polyanions, but still have the
fluid bilayer properties. These artificial membranes, whose
permeability is controllable by application of an electric
field, may provide a new tool to study transport mechanisms in biological membranes.
Received: February 17, 1986;
revised: Apirl 15, 1986 [Z 1671 IE]
German version: Angew. Chem 98 (1986) 723
Po
1.8
CAS Registry numbers:
la"/PSSe, 103368-69-0; Ibe/PSSe, 103368-71-4; Ic/PSSo, 103368-73-6; 2 ,
103368-74-7; 2C,,N2C, '/PSSe, 99742-69.5.
[a] P,=permeation rate in the absence of an electric field.
of the chain length of the spacer and the alkyl end groups.
The permeability change occurred within 30 s after application of the electric field, and there was no induction period due to swelling of the membrane. This permeability
change could be observed at various temperatures (between 10 and 60 "C), irrespective of the phase-transition
temperature of the bilayers, and could be reproduced repeatedly without damaging the films. The increase in permeability was observed only above 1.5 V (50 FA) and increased linearly with increasing potential in the range 1.58.0 V (50-500 PA).
When a potential of 4 V was applied across the membrane (method B), the permeability of the 1 @/PSSQfilms
was only slightly increased by a factor of 1.3-1.8. For
films prepared from dimethyldioctadecylammonium
(2C,8N@2C,)amphiphile and PSSO, the permeability is
largely enhanced (10 times) when the electric field is applied across the membrane (method B).I3=I In the latter
case, the film acts as a capacitor because of its poor conductivity; the electric transmembrane potential can produce transient pores in the fluid bilayers by electrically induced "breakdown," which results in permeability enhancement. In contrast, the 1 @/PSS" films contain highly
conductive chromophores in the bilayers, so that a high
transmembrane potential cannot form and no "breakdown" occurs.
When a potential is applied parallel to the l@/PSS"
films, the orientation of the azobenzene chromophore in
the bilayers presumably changes, and the permeability of
the resulting disordered bilayers increases. The orientation
of mesogenic azobenzene chromophores in bilayers of 1
is well known to be sensitive to temperature changes;
moreover, the UV/VIS spectra of the chromophores
change upon phase transition of the bilayers.lsl The absorption spectra of the l@/PSSQfilms, however, d o not
change, irrespective of whether the electric field is parallel
or perpendicular to the film plane. The permeability of
2Cl8N@2Cl/PSSefilms does not change when the electric
field is applied parallel to the. membrane because the
poorly conductive, "dialkyl" bilayers are not oriented by
the electric field. Thus, the permeability of the bilayer-immobilized film containing the conductive, liquid-crystalline chromophores changes when the electric field is applied parallel to the membrane; on the contrary, the permeability of the film from the poorly conductive, dialkyl
bilayers changes when the electric field is applied perpendicular to the membrane.
The fluid bilayer structure is very important for the electrically controlled change in permeability, because the
change is not observed when rigid, polymeric liquid crystals such as poly(benzy1 glutamate) are employed. The bilayers of 1' are immobilized at the hydrophilic head
@
752
0 VCH Verlagsgesellschafr mbH. 0-6940 Weinheim. 1986
[ I ] Y. Okahata, Acc. Chem. Res. 19 (1986) 57; 1 Kunitake, A. Tsuge, N. Nakashima, Chem. Lett. 1984. 1783; T. Kajiyama, A. Kumano, M. Takayanagi, T. Kunitake, Y. Okahata, Ber. Bunsenges. Phys. Chem. 88 (1984)
1216.
[2] Y. Okahata, S. Hachiya, T. Seki, J . Chem. SOC. Chem. Commun. 1985.
1377; Y. Okahata, S. Hachiya, K. Ariga, T. Seki, J . Am. Chem. SOC. 108
(1986) 2863.
[3] a ) Y. Okahata, K. Taguchi, T. Seki, J . Chem. SOC.Chem. Commun. 1985.
1122: b) Y. Okahata, G. En-na, K. Taguchi, T. Seki, J. Am. Chem. Sor.
I07 (1985) 5300.
[4] T. Kunitake, Y. Okahata, M. Shimomura, S. Yasunami, K. Takarabe, J.
Am. Chem. Sor. 103 (1981) 5401: M. Shimomura, R. Ando, T. Kunitake,
Ber. Bunsenges. Phys. Chem. 87 (1983) 1134.
[5] T. Kunitake, S. Shimomura, T. Kajiyama, A. Harada, K. Okuyama, M.
Takayanagi, 7 X n Solid Films 121 (1984) 89.
[61 Y. Okahata, N. lizuka, G. Nakamura,T. Seki, J. Chem. SOC.Perkin Trans.
2 1985. 1591.
E,Te3Hal, Mixed Valency Tellurohalides of Gallium
and Indium with One-Dimensional Structural
Units**
By Sabine Paashaus and Riidiger Kniep*
The ternary systems E-Te-Hal ( E = G a , I n ; Hal=Cl, Br,
I) contain the phases ETeHal, having incongruent melting
behavior, on the E,Te3-EHal, sections.['I Along the sections from these ternary phases to the binary chalcogenides ETeIZ1we have been able to identify thermodynamically stable, mixed valency compounds of the formula
E3Te3Hal. The following compounds have so far been obtained in pure form: Ga3Te3C1 (m.p. =718"C, congruent),
Ga3Te3Br (m.p. = 733"C, congruent), and Ga,Te31
(m.p. = 692"C, congruent) by crystallization from the melt
according to the Bridgman method and In3Te3Br
(m.p. = 381 " C, incongruent) and In3Te31(m.p. =394"C, incongruent) by annealing of stoichiometric mixtures at
240°C. The intense red crystals have high reflecting power
and an acicular habit and are very easily cleaved aIong the
fibers.
The first crystal structure analysis was carried out on
GaTe,I.I3l Figure I shows the macromolecular elements of
the structure, in which GaTe3,,I tetrahedra and Ga,TehI3
structural units (staggered conformation) are linked. The
shortest Ga-Ga distances in the central six-membered
rings (2.454(2) A) are comparable to the Forresponding
bond lengths in Ga2I3 (Ga:Ga:'I,; 2.388(5) A'41) and GaTe
(2.434 Arz'), so that the oxidation state + 2 has to be assumed for these G a atoms; on the other hand, for the iodine-bonded G a atoms (Ga-I: 2.536(1) A) the oxidation
[*I
Prof. Dr. R. Kniep, Dipl.-Chem. S. Paashaus
lnstitut fur Anorganische Chemie und Strukturchemie der Universitat
Universitatsstrasse 1, D-4000 Dusseldorf (FRG)
[**I This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
0570-0833/86/0808-0752 $ 02.50/0
Angew. Chem. In!. Ed. Engl. 25 (1986) No. 8
state is +3. Thus, Ga3Te31is the first mixed valency compound that contains an element of the third main group
with the oxidation states + 2 and +3. The macromolecular
connection corresponds to the following structural formula:
Fig I. View along [OOlJ in the one-dimensional structural element of
Ga,Te,l: G a = 0 , I = 0.T e = O ; each tellurium atom forms a trigonal pyramid with three gallium atoms (bond lengths Ga-Te: 2.633(1) to
2.693(5) A)
In the structural arrangement, the strands that are extended parallel in the [OOl] direction are approximately
hexagonally close-packed with respect to their central
axes. The successive macromolecules are each translationally equivalent in the [IOO] direction. The shortest intermolecular distances (3.863(5) A) are found between the terminal iodine atoms and between those tellurium atoms that
are involved in the tetrahedral coordination of the Ga"'
centers.
Received: March 10, 1986;
revised: May 6, 1986 [Z 1696 IE]
German version: Angew. Chem. 98 (1986) 7 2 5
dral and octahedral sites,['-31 and are not reduced on treatment with H2 even at high temperatures (770 K). In calcined Cu/y-A1,03 catalysts, copper is similarly present in a
spinel-like p h a ~ e , [ ' . ~CuO
. ~ ] segregating out at high copper
loading^;'^] in this catalyst, however, the C u z @ions are reducible on treatment with H,. We considered it worthwhile
investigating the nature of species in reduced samples of
bimetallic Ni-Cu/y-A1,03, which are used as catalysts for
hydrogenation and other reactions. It has been reported
that the presence of copper favors the formation of Ni" in
reduced samples.'61 Presence of nickel similarly seems to
promote the reduction of supported copper. The actual nature of the nickel and copper species in reduced bimetallic
catalysts has not been described hitherto except for the
identification of the Nio species in Ni23-Cu77/y-AI2O3
samples by Erfl et aI.['l
We have investigated Ni-Cu/y-Al,03 catalysts over the
entire composition range by means of X-ray photoelectron
spectroscopy (XPS) and Auger electron spectroscopy
(AES)."] The total metal loading in the catalysts studied was
5 wt-Yo; samples with C u to Ni ratios 75:25, 50:50, 25:75,
were studied along with the catalysts containing only C u
and Ni. The catalyst samples were first calcined at 870 K
for 8 h in air. The spectra of the catalysts were recorded
after reducing them in situ in the sample preparation
chamber of the spectrometer (720 K, 6 h, 300-torr hydrogen pressure). The 2p level of A1201 (74.0 ev) and the
4f,,, level of Au (83.6 eV) were used as references for the
XPS binding energies.
Calcined Ni-Cu/y-AI2O, catalysts show the presence of
Ni?@in
. the form of NiA1204 with a Ni(2p3,,) binding energy of -856.6 eV. The Cu(2p3,,) binding energy in the
calcined samples was close to that of CuA1,04. On reduction, XPS in the core level region clearly reveals the nature
of the nickel species. The N i ( 2 ~ , , ~spectra
)
show the presence of both Nio and Ni2@with binding energies of 853.2
eV and 856.3 eV respectively, in samples with high copper
content (Fig. 1). The relative concentration of Ni" increases with increasing copper content, the Ni" being totally absent in reduced Ni/y-Al,O,. Variation of the rela-
[ I ] InTeHal: R. Kniep, A. Wilms, H.-J. Beister, K. Syassen, Z. Naiurforsch.
836 (1981) 1520: GaTeHal: R. Kniep, A. Wilms, H.-J. Beister, Muler
Res. Bull. 18 (1983) 615.
[2] 1nTe: J. H. C . Hogg, H. H. Sutherland, Acra Crystallogr. Sect. 832 (1976)
2689; GaTe: M. Julien-Pouzol, S. Jaulmes, M. Guittard, F. Alpini, ibid.
835 (1979) 2848.
[3] Crystallographic data of Ga,Te,l: 1408 (1462) reflections; R =4.8%;
P n ~ 2 , U: = 11.168(4), b = 19.529(10), c=4.102(2) A; Z = 3 : pcnlcd=4.00g/
cm'. Further details of the crystal structure investigation may be obtained
from the Fachinformationszentrum Energie, Physik, Mathematik GmbH,
D-7514 Eggenstein-Leopoldshafen2 (FRG), OR quoting the depository
number CSD-52010, the names of the authors, and the journal citation.
[4] G. Gerlach, W. Honle. A. Simon, Z. Anorg. Allg. Chem. 486 (1982) 7 .
Ni
N I 75- Cu2S
N I 50 - C U 50
Nature of Ni and Cu Species in
Reduced Bimetallic Ni-Cu/Alz03 Catalysts
By Gopinathan Sankar and C. N . Ramachandra Rao*
It is well known that NiZOions in calcined Ni/y-A1203
catalysts are in a spinel-like phase, occupying both tetraheN. R Rdo, G. Sankar
Solid State and Structural Chemistry Unit
lndian institute of Science
Bdngalore 560 012 (India)
I
I
I
I
1
851
8 55
859
863
867
[*] Prof. I>r. C
Angew. Chem. Int Ed. Engl. 25 11986) No. 8
fb
Lev1
-
Fig. I. Ni(Zp,,,,) spectra (ESCA) of reduced Ni-Cu/y-Alz03 catalysts:
Eb=binding energy.
0 VCH Veriagsgesel1,schajimbH. 0-6940 Weinheim, 1986
0570-0833/86/0808-0753 $ 02.50/0
753
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unit, gallium, structure, dimensions, valence, one, e3te3hal, indium, mixed, tellurohalides
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