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Docking of a Second Functional Protein Layer to a Streptavidin Matrix on a Solid Support Studies with a Quartz Crystal Microbalance.

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Our findings demonstrate once again the high tendency of
formation of transition metal-copper-sulfur clusters and
their structural variants. The driving force for the reactions
studied is the preferred formation of p3S compared to p2S
moieties in the presence of soft metal centers, which corresponds to the formation of the prismane type cage [CuPPh,),(MoOS,),] from two halves of it, that means from the
butterfly type species [ C U , ( P P ~ ) , ( M O O S , ) ]Subunits
. ~ ~ ~ ~ of
M-Cu-S complexes seem to be suitable for the synthesis of
various molecular structures. Whereas the synthesis of transition-metal clusters like 2 and 3 with sulfido-bridges by
"spontaneous self-assembly" reactions from simple inorganic reagents is highly unlikely, in some cases smaller clusters
can be used as building blocks in cluster synthesis.
2: A mixture of 0.20g (0.165 mmol) of 1 and 0.032g (0.17mmol) of
Cu(S,COEt)-obtained from 2.0 g of CuI in saturated K1 solution (30 g KI in
30 mL H,O) and 1.7 g KS,COEt (in 10 mL H,O) as a yellow precipitate, which
was washed with saturated KI solution, water, ethanol and ether-was dissolved in 15 mL CH,C1, and stirred for 3.5 h. The orange reaction solution was
then filtered and the filtrate treated with 60 mL diethyl ether. This solution was
allowed to stand for about 12 h at ca. 5 "C and 0.15 g of pure red crystals were
obtained (yield: 65 %); satisfactory C,H,Cu,P,S analysis.
3: A mixture of 0.20 g (0.165 mmol) of 1 and 0.027 (0.18 mmol) of Cu(SCMe,)
--obtained by reaction of 5.0 g Cu(NO,),. 3 H,O with 5 mL HSCMe, and
5 mL NEt, in 50 mL ethanol as a yellow precipitate, which was washed with
ethanol and ether-was dissolved in 30 mL of CH,CI, and stirred for 25 min.
The orange-red solution was filtered and the filtrate was treated with 30 mL of
diethyl ether. The filtrate was allowed to stand for ca. 12 h at 5 - 10 "C, orange
crystals were obtained. The orange-red crystals that separated out were recrystallized from 25 mL of CH,CI, solution by gaseous diffusion of diethyl ether.
Yield: 0.10 g (55%); satisfactory C,H,P,S analysis.
Received: January 30, 1992 [Z 5160 IE]
German version: Angew. Chem. 1992, 104, 1098
1141 A. Muller, U. Schimanski, J. Schimanski, Inorg. Chim. Acta 1983, 76,
[15] a) 2: IR (KBr pellet, C [cm-'1): 6(C-H) in Ph,P, 750(s), 745(s), 705(s),
695(vs); bonds due to stretching vibratios of the following type: Cu-P.
525(s), 515(shoulder), 510(s), and 495(s); W-p3-S, 440(s); W-0, 930(vs).
UV/Vis (in CH,CI,): i= 286 nm. Crystallographic data: triclinic, space
group PI (No. 2), a = 12.732(5), b = 22.896(6), c = 10.499(5)A, rn =
99.92(3), = 109.51(3), y = 86.86(3)", V = 2842(2) A', 2 = 2; R = 0.049
for 5823 observed reflections with I > 5 o(I) and 402 variables [I 5 c]. b) 3:
1R (KBr pellet, ? [ern-']): B(C-H) in Ph,P, 755(s), 745(vs), 705(shoulder),
and 695(vs); bonds due to stretching vibrations of the following type:
Cu-P, 530(vs), 510(s), and 500(s);W-p3-S, 460(s); W-0: 940(vs). UV/Vis
(in CH,Cl,): 1 = 348 nm. Crystallographic data: triclinic. space group Pi
(NO.2). u = 14.206(2), b = 14.729(3), c = 12.428(2) A, u = 110.43(1), fl =
90.45(1), y = 62.93(1)", V = 2134.1(6) A'; Z = 1; R = 0.040 for 5998 observed reflectionswith I z 3o(I)and460 variables[15c]. c) Furtherdetails
of the crystal structure investigations are available on request from the
Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlichtechnische Information mbH, W-7514 Eggenstein-Leopoldshafen 2
(FRG), on quoting the depository number CSD-56 196, the names of the
authors, and the journal citation.
[I61 G. Wilkinson, R. D. Gillard, J. A. McCleverty, Comprehensive Coordination Chemistry, Vol. 2, Pergamon, Oxford 1987. pp. 579-593.
[17] a) R. Hesse, U. Aava, Acta Chem. Scand. 1970.24, 1355; b) P. Jennische,
R. Hesse. ibid. 1971, 25, 423.
[18] a) I. G . Dance, Polyhedron, 1986, 5, 1037; b) P. J. Blower, J. R. Dilworth,
Coord. Chem. Rev. 1987, 76,121.
(191 T. Shibahara, H. Akashi, H. Kuroya, J. Am. Chem. Soc. 1988, fI0, 3313.
Docking of a Second Functional Protein Layer
to a Streptavidin Matrix on a Solid Support:
Studies with a Quartz Crystal Microbalance
CAS Registry numbers:
1, 125302-32-1; 2, 142700-17-2; 3, 142700-18-3
By Hiroshi Ebato, James N . Herron, Wolfgang Miiller,
Yoshio Okahata, Helmut Ringsdorf,* and Peter Suci
[I] A. Miiller, E. Diemann, R. Jostes, H. Bogge, Angew. Chem. 1981,93,957;
Angeu,. Chem. Int. Ed. Engl. 1981. 20, 934.
[2] M. P. Coughlan. Molybdenum and Molybdenum Containing Enzymes,
Pergamon Press, Oxford, 1980.
(31 C. F. Mills, Chem. Br. 1979, 15, 512.
[4] a) R. E. Palermo. R. Singh, J. K. Bashkin, R. H. Holm, J. Am. Chem. Soc.
1984. 106, 2600, and references therein. b) Q.-T. Liu, L.-R. Huang, H.-Q.
Liu, X.-J. Lei, D.-X. Wu. B.-S. Kang, and J.-X. Lu, Inorg. Chem. 1990,29,
4131. and references therein.
[5] S. Ciurli, S.-B. Yu, R. H. Holm, K. K. P. Srivastava, E. Miinck, J. Am.
Chem. Sac. 1990. 112, 8169.
[6] J. A. Kovacs. R. H. Holm, J Am. Chem. Sac. 1986,108,340; Inorg. Chem.
1987, 26. 71 1.
[7] a) T. E. Wolff, J. M. Berg, K. 0. Hodgson, R. B. Frankel, and R. H. Holm,
J. Am. Chem. SOC.1979, 101, 4140. (b) G. Christou, C. D. Garner, F. E.
Mabbs. and T. J. King, J. Chem. Sac. Chem. Commun. 1978, 740.
[X] a) Review: S. Sarkar, S. B. S. Mishra, Coord. Chem. Rev. 1984, 59, 239;
b) S. R. Acott, C. D. Garner, J. R. Nicholson, W. Clegg, J. Chem. Soc.,
Dalton Trans. 1983,713; c) J. R. Nicholson, A. C. Flood, C. D. Garner, W.
Clegg, J. Chem. Soc., Chem. Commun. 1983,1179; d) C. D. Garner, J. R.
Nicholson, W. Clegg, Acta Crystallogr. Sect. C , 1983, 39, 552.
[9] a) X.-T. Wu, S.-F. Lu, N.-Y. Zhu, Q.-J. Wu, J:X. Lu, Inorg. Chim. Acta.
1987. 133,39; b) S:F. Lu, N.-Y. Zhu, X:T. Wu,Q.-J. WU,J.-X. Lu,J. Mol.
Struc. 1989, 197, 15; c) H.-Q. Zhang, Y.-F. Zheng, X.-T. Wu, J.-X. Lu,
Inorg. Chim. Acta, 1989,156,277; d) Y-F. Zheng, H.-Q. Zhang, X.-T. Wu,
J.-X. Lu, Transition Met. Chem. (London) 1989, 14, 161.
[lo] a) N.-Y. Zhu, Y.-F. Zheng, X.-T. Wu, J. Chem. SOC.,Chem. Commun. 1990,
780; h) N.-Y. Zhu, R.-C. Wu, X.-T. Wu, Acta Crystallogr. Sect. C, 1991,
47, 1537.
[Ill a) A. Miiller, H. Bogge, U. Schimanski, J. Chem. SOC.Chem. Commun.
1980,91; h) A. Miiller, H. Bogge, U. Schimanski, Inorg. Chim. Acta 1983,
69,5;c) X.-T. Wu, Y.-F. Zheng, S-W. Du, Acra Crystallogr. Sect. C , 1989,
45, 1070; d) X.-T. Wu, Y-F. Zheng, S.-W. Du, N.-Y. Zhu, Transition M e t .
Chem. (London) 1989, 14, 157; e)N.-Y Zhu, J.-H. Wu, X.-T. Wu, Acta
Crystallogr. Sect. C , 1991, C47, 856.
[I21 a) X.-T. Lin, Y.-H. Lin, J.-L. Huang, J.-Q. Huang, Kexue Tongbao (Foreign
Lung. Ed.) 1987,32,810; b) H.-Q. Zhang, Master thesis of Fujian Institute
of Research on Structure of Matter, 1989 (Chinese).
(131 W.-H. Pan,T. Chandler, J. H. Enemark, E. I. Stiefel, Inorg. Chem. 1984,23,
The specific interaction of streptavidin[ll with biotinylated lipids at the air/water interface leads to the formation of
optically anisotropic two-dimensional streptavidin crystals.[z-4]This perfectly ordered matrix of the protein streptavidin, with two of its original four binding sites remaining
free, can be functionalized in various ways with biotinylated
subunits.['] Recently, it has been shown by Ward et al. that
it is possible to detect the binding of biotinylated moieties to
unspecifically adsorbed avidin and streptavidin layers with a
quartz crystal microbalance (QCM) for biosensor applications.''] In the study presented here, the possibility of using
a streptavidin film, specifically bound via biotin to a solid
support, as a template for docking a second functional
protein layer was explored. A quartz crystal microbalance[61
was utilized to study both the interaction of streptavidin with
biotinlipid membranes and the docking of biotinylated antifluorescyl-antibody fragments (Fab fragments)"] to streptavidin.
Previous monolayer experiments with biotinlipids at the
air/water interface revealed that it is necessary to have sufficient mobility and free space around the biotin headgroups
of the lipids for proper binding of the ligand.[3*41
One would
expect, that on a solid support, mobility and access of the
Angew. Chrm. Int. Ed. Engl. 1992, 31, No. 8
Prof. Dr. H. Ringsdorf, DipLChem. W. Muller, Dr. P. Suci
Institut fur Organische Chemie der Universitat
J. J. Becherweg 18-20, D-W-6500 Mainz 1 (FRG)
Dr. J. N. Herron
Department of Pharmaceutics, University of Utah
421 Wakara Way, Salt Lake City, UT 84101 (USA)
DipLChem. H. Ebato, Prof. Dr. Y Okahata
Department of Polymer Chemistry, Tokyo Institute of Technology
2-12-1 Ookayama, Meguro-ku, Tokyo 152 (Japan)
0 VCH Vrrlagsgesell.~chaftmbH, W-6940 Weinheim, 1992
0570-0833/92/0808-I087 $3.50+ .25/0
biotin headgroups will be even more important and hence
biotin lipids with a short (1) and a long (2) hydrophilic spacer
were compared in the studies. For all the experiments presented below, three monolayers of the corresponding lipids
mixed with L-a-dipalmitoylphosphatidylethanolamine(L-c(DPPE) in varying amounts were deposited by means of the
Langmuir-Blodgett (LB) technique on the gold electrode of
a QCM. All measurements with the QCM were performed in
buffer solution (50 mmol phosphate, pH = 7.5).
This is confirmed by experiments to determine the amount
of biotinlipid needed for a total protein coverage of the surface in mixed DPPE/2 layers. It could be shown (Fig. 2) that
with approximately 1 mol-YOof 2 in the DPPE matrix the
saturation frequency change of 65 Hz is already found.
' 5 40
0 1
[Hzl 3o
20 ?
Fig. 2. Dependence of the change in resonance frequency on the content (c in
mol-%) of biotinlipid 2 in the membrane.
As expected the spacer length plays an important role in
the docking process of streptavidin on solid supports. The
frequency change observed with the long spacer lipid 2
( 5 mol-% in DPPE[*I; Fig. 1 filled circles) is strongly
dependent on the protein concentration up to the saturation
of the membrane, which occurs between 2.5 x lo-' and
3.5 x lo-' M streptavidin in the buffer solution. The result-
When the biotinlipid 2 content was increased further no difference in the equilibrium frequency change was observed,
even when the content was 10 mol-%, indicating that under
these conditions no further protein can be induced to adsorb
once the surface is saturated.
The protein used for the docking of a second protein layer
to the streptavidin matrix is a Fab fragment of a monoclonal
antifluorescyl antibody (clone 4-4-20).17] Two different biotinylation procedures of the Fab were used: the results presented in Figure 4 were obtained with a Fab fragment biotinylated nonspecifically with an amino-reactive reagent
(BioFab) (see Experimental);the measurements presented in
Figure 5, on the other hand, were performed using a Fab
fragment specifically monobiotinylated in the hinge region
via a disulfide bridge (Fab) (see Experimental).This results
in formation of a layer structure (Fig. 3), in which the antigen-binding sites face the adjacent solution.
Fig. 1. Interaction of streptavidin with different lipid membranes, measured
via the change in resonance frequency Afof a quartz crystal microbalance as a
function of the streptavidin concentration c . o : pure DPPC membrane; A:
DPPE with 5 mob% of biotinlipid 1; 0 : DPPE with 5 mob% of biotinlipid 2.
ing saturation frequency change of 65 Hz is in agreement
with the frequency change expected for a monolayer of streptavidin as predicted by the Sauerbrey equation (in air).['' In
contrast to this, for the biotin-free (pure DPPE) membrane
and the membrane with 5 mol-% of the short spacer lipid 1,
a maximum frequency change of only 15 Hz is found (Fig. 1
open circles, triangles). With the pure DPPE membrane, a
specific interaction with the biotin ligand is excluded, and
therefore the frequency changes produced can be assumed to
result from nonspecific adsorption of streptavidin to the
membrane surfaces. Apparently, sufficient spacer length between the biotin-headgroup and the membrane-forming
alkyl chains of the biotinlipids can compensate for the reduced mobility and close packing of the headgroups on the
surface and allow proper binding of a streptavidin layer.
Verlugsgesellschujt mDH. W-6940 Wemheim, 1992
Fig. 3. Schematic representation of the docking of a Fab fragment which was
specifically biotinylated in the hinge region to a two-dimensional streptavidin
layer. The F a b layer can serve as a matrix for further binding of fluoresceincontaining molecules.
Figure 4 shows the course of the streptavidin interaction
with time with a biotinlipid-containing membrane ( 5 mol- YO
of lipid 2 in DPPE) before and after addition of the Fab- and
0570-0833/92/0808-l088 $3.50f.25/0
Angew. Chem. Int. Ed. Engl. 1992,31, N o . 8
Binding of streptavidin (5 x lo-' M) to the biotinlipids is
very fast and the equilibrium frequency change of 65 Hz
described above is reached after six minutes. The streptavidin covered membrane was rinsed with buffer, transferred
into a fresh buffer solution and incubated with streptavidin
a second time to see whether washing affects the coverage of
the surface. No frequency change could be detected during
this process, indicating that the streptavidin layer is tightly
bound to the membrane surface. The surface was then
washed as before and now incubated with non-biotinylated
Fab (1.8 x lo-' M). No significant frequency change was detected indicating no or only a negligible amount of nonspecific adsorption. Thereafter 3.5 x lo-' M of biotinylated
Fab was added to the buffer; this resulted in a slow but
significant frequency change reaching saturation at 55 Hz
relative to the original saturation frequency change (Fig. 4),
pointing to a dense packing of the Fab molecules onto the
streptavidin layer, as already shown with ellipsometry measurements at the air/water interface." O1
A f 60
streptavidin injection
Fig. 4. Course of streptavidin binding with time to a lipid membrane containing 5 mol-% of lipid 2 and interaction of non-biotinylated antifluorescyl-Fab
and biotinylated antifluorescyl-Fab with a streptavidin matrix.
It was interesting to see whether the same extent of binding
could be attained using the site-specifically monobiotinylated Fab fragment. The results of these docking experiments
are presented as a binding curve in Figure 5. This specific
interaction leads to an increasing frequency change with increasing F a b concentration, reaching again a saturation value of 50 Hz for a Fab' concentration of 1 x lo-' M. As beQ
The resonance frequency of the quartz crystal of the QCM is sensitive to the
mass bound to the surface of the gold electrode, although in liquids the relation
between adsorbed mass and frequencychange may bequite complex [ll]. In air,
the frequency change expected from aquantity of adsorbed mass is given by the
Sauerbrey equation [9]. Thus, in principle, the QCM technique allows one to
quantify the binding process of proteins to various membranes. Furthermore,
the course of the interaction with time can be followed in real time. The experimental setup used by us has already been described elsewhere [6]. The crystals
used in the experiments had a resonance frequency of 9 MHz.
LB-deposition of the lipid membranes was performed at a speed of 1 cmjmin
and a surface pressure of 40mNm-' ( T = 22") from the solid analogous
phase of the lipid monolayer. This resulted in a close packing and low lateral
mobility of the lipids on the support. For the mixed membranes (DPPE/biotinlipid) adequate amounts of chloroform solutions of the corresponding lipids
were mixed prior to spreading. For the measurements thecrystal was immersed
in buffer solution (50 mmol phosphate buffer, pH 7.5). The starting frequency
(f,,) and the change in resonance frequency of the crystal (A! - f ( r ) )
was monitored as a function of the protein concentration in the buffer
The nonspecific biotinylation of the Fab fragment was performed with 6-(6(biotinoy1)amino)-hexanoy1amino)hexanoic acid succinimidyl ester (8-1606
Molecular Probes, Inc., Eugene, OR 97402, USA). The selective biotinylation
of the F a b fragment in the hinge region was achieved with N-(6-(biotinamidohexyl)-3-(2-pyridyIdithio)propionamide (21341 Pierce, Rockford. IL 61 105,
USA) via formation of a disulfide bridge.
Biotinlipid 1 was synthesized as described earlier [12].
Biotinlipid 2 was synthesized in the following way [13]: 4 g (6.3 mmol) of N,Ndioctadecyldiglycolic acid monodmide (DODA-GSA) was refluxed with 1.1 g
(6.8 mmol) of carbonyldiimidazole in 30 mL of dry THF for 2 h to yield the
corresponding imidazole-active ester. The resulting solution was then added
dropwise to a stirred solution of 8 g (54 mmol) of 1,8-diamino-3,6-dioxaoctane
in 50 mL of dry T H E The reaction was monitored by TLC (CHC1,:MeOH:
Sjl). After completion (20 min), the solvent was evaporated off and the residue
taken up in CHCI,, extracted with water to remove the excess of diamine, and
purified by chromatography to yield 2.8 g of 1-N,N-dioctadecyl-14-amino-5oxo-3,9,12-trioxa-6-azatetradecanoic
acid amide (DODA-€0,-NH,). 300 mg
(0.39 mmol) of DODA-E0,-NH, and 133 mg (0.39 mmol) of N-hydroxysuccinimidobiotin were dissolved in 10 mL of dry D M F and allowed to react at
room temperature until no DODA-E0,-NH, could be detected by TLC
(CHCIJMeOH: l O / l ) . The solvent was removed by evaporation in vacuo; the
residue was then taken up in CHCI, and purified by chromatography to yield
220mg of pure 2 . Its structure was confirmed by elemental analysis and
'HNMR spectroscopy (400 MHz).
Received: December 27, 1991;
revised: February 20, 1992 [Z 5096 IE]
German version: Angew. Chrm. 1992, f04,1064
Fig. 5 . Binding of a site-specifically monobiotinylated Fab fragment (Fab) to
a streptavidin matrix as monitored with the QCM (each symbol represents
averaged data of three independent measurements).
Angen.. Chrm. Int. Ed. Engl. 1992, 31, No. 8
fore, the control experiment with non-biotinylated Fab fragment resulted in no detectable frequency change (not
In conclusion it has been shown that the QCM is able to
differentiate between specific binding and nonspecific adsorption of streptavidin to different biotinlipid membranes.
Employing this first streptavidin layer as a template, docking
of monoclonal antibody Fab (biotinylated by two different
methods) was followed using the QCM. In general, surface
bound, highly organized protein matrices, having a vast variety of binding specificities, can be constructed using this
CAS Registry numbers:
1, 122567-70-8; 2, 142260-90-0; quartz, 14808-60-7; streptavidin, 901 3-20-1 ;
DPPE, 923-61-5.
[I] Methods in Enzymology, Vol. 184 (Eds.:E. A. Bayer, M. Wilchek).
Academic Press, San Diego, 1990, p. 5.
[2] S. A. Darst, M. Ahlers, P. Meller, E. W. Kubalek, R. Blankenburg, H. 0.
Ribi, H. Ringsdorf, R. D. Kornberg, Biophys. J. 1990,59, 387.
[3] M. Ahlers, W Miiller, A. Reichert, H. Ringsdorf, J. Venzmer, Angew.
Chem 1990,29, 1310; Angen,. Chem. Int. Ed. Engl. 1990, 29, 1269.
141 a) M. Ahlers, M. Hoffmann, H. Ringsdorf, A. M. Rourke, E. Rump,
Mukromol. Chem. Mukromoi. Q m p . 1991, 46, 307; b) M. Ahlers. R.
Blankenburg, H. Haas, D. Mobius, H. Mohwald. W. Miiller. H. Ringsdorf, H.-U. Siegmund, Adv. Mar. 1991, 3, 39.
VCH Verlugsgeselischajt mbH, W-6940 Weinheim, 1992
OS70-0833j92j080X-tOS9 S 3.50+ ,2510
[5] R. C. Ebersole, J. A. Miller, J. R. Mordn, M. D. Ward, L Am. Cheni. Suc.
1990, 112, 3239.
[6] Y . Okahata, H. Ebato, Anal. Chem. 1991, 43, 203.
[7] J. N. Herron, X.-M. He, L. Mason, E. W. Voss, Jr.. A. B. Edmundson,
Proteins 1989, 5, 211.
[El Since LB-transfer of the homogeneous lipid mixtures was performed in the
solid condensed state of the monolayer at 40 mN/m the space required for
one lipid molecule is approximately 40 A‘. 5 mol-% biotinlipid content
will thus result in approximately seven biotinlipid molecules on an area
convered by two streptavidin molecules (5000 A2).
[91 G. Sauerbrey, Z . Phys. 1959, 155, 206. According to the Sauerbrey equation the change of resonance frequency of a piezo quarr crystal is proportional to the change in mass on the electrode surface. For the crystals used
here, calibration revealed that a frequency change of 1 Hz corresponds to
a mass increase of 1.05 5 0.01 ng. The gold electrode has a diameter of
4.5 mm resulting in a sensitive area of 15.9 mm2. A monolayer coverage
with streptavidin (2500 A2 per molecule) should thus result in a frequency
decrease of 63 Hz. But due to the electrode surface roughness this can only
be a rough estimation.
[lo] J. N. Herron, W. Miiller, M. Paudler, H. Riegler, H. Ringsdorf, P. Suci,
Lungnzuir 1992, 18, 1413.
[ l l ] a) P. W. Walton, M. E. Butler, M. R. OFlaherty, Blochem. Sue. Trans.
1990, 19, 44; b) M. Thompson, U. J. Krull, Anal. Chem. 1991,43, 393 A;
c) K. K. Kanazawa, J. G. Gordon 11, Anal. Chim. Actu 1985,175,99; d) R.
Schumacher, Angew. Chem. 1990, 102, 347; Angen. Chem. Inr. Ed. Engl.
1990,29.329; e) R. C. Ebersole, M. D. Ward, J Am. Chem. SUC.1988,110,
(121 R. Blankenburg, P. Meller, H. Ringsdorf, C. Salesse, Biuchemistr.y 1989.
28. 8214.
[I31 M. Ahlers, Dissertation, Universitat. Mainz, 1990.
position was performed, and although the remaining H atom
was not located, bond valence calculationd6]showed that it
is attached to 0(3), as are those in MnPO;H,O[’] and LiMnAsOJOH), 14] confirming the formulation as a phosphate hydroxide rather than as a hydrogen phosphate oxide.
Polyhedral[81 representations of the structures of
(X = P, As), LiMnAsOJOH) and LiMnPO,(OH) are shown in Figures 1 a, 1 b and 1c, respectively.
A Remarkable Change in Framework Cation
Positions upon Lithium Exchange:
the Crystal Structure of LiMnPO,(OH)
By Miguel A . G. Aranda,* J. Paul Attj?eld
and Sebaslian Bruque
In the search for new battery materials, molecular sieves,
and ionic conductors and exchangers, reactions involving
the insertion or exchange of lithium into the channels or
interlamellar spaces of precursor structures are of great interest.“, ’] We have recently reported the synthesis and structure of a new material, manganese(rI1) arsenate hydrate
MnAsO,. H,O, 13] which undergoes a topotactic lithium exchange reaction with solid LiNO, to give LiMnAs0,(OH).t41This reaction is accompanied by an unusual switch
in the framework geometry as the Jahn-Teller distortions of
the MnO, octahedra change although the topology is unaltered. In this communication we describe the analogous lithium exchange reaction of MnPO,.H,O to give LiMnP0,(OH), which is accompanied by a different, remarkable
change in the framework, as the Mn3+ cations are displaced
to alternative octahedral sites within the PO,(OH) sublattice.
LiMnPO,(OH) was prepared in the form of a microcrystalline powder by solid-state reaction of MnPO; H,O with
LiNO,. The use of low temperatures and long reaction times
furnished a sufficiently crystalline material for crystal structure determination from laboratory X-ray powder diffraction data to be successful (see Experimental). A restrained
Rietveld[’I refinement of the MnPO, framework and the Li
[‘I Dr. M. A. G. Arandd, Prof. Dr. S. Bruque
Departamento de Quimica Inorganica
Universidad de Malaga, Aptd. 59
E-29071 Malaga (Spain)
Dr. J. P. Attfield
Department of Chemistry
University of Cambridge
Lensfield Road. GB-Cambridge CB2 lEW, (U.K.)
VCH ~ r l u g s g e s e l l s c h umbH,
W-6940 Weinheim, 1992
Fig. 1. Polyhedral near-(001) views (haxis vertical) ofa) MnXO,.H,O (X = P,
As), b) LiMnAsO,(OH), and c) LiMnPO,(OH) with lithium atoms shown as
open circles. Hydrogen atoms are not included.
In the first two structures, the MnO, octahedra are linked
via opposite vertices by H,O or OH- groups to form infinite
zigzag chains in the [I011direction that are interconnected by
XO, tetrahedra, resulting in a three-dimensional framework.
This encloses small channels parallel to the c-axis into which
the hydrogen atoms project in MnXO;H,O (X = P, As),
and in which the lithium ions are located in LiMnAsO,(OH).
In the LiMnPO,(OH) structure, the MnO, octahedra are
also linked through opposite vertices by OH- groups to give
infinite zigzag chains, but these now lie in the [OOl] direction.
This structural rearrangement is due to a migration of the
manganese atoms from the octahedral sites at 114,114 ,O and
related positions in MnXO; H,O to alternative octahedral
holes in the channels at 0, 0, 0 and equivalent positions.
Remarkably, this change in Mn positions results in little
change to the cell parameters or the coordinates of the other
atoms (Table 1). The two possible octahedral sites in the
MnX0,-H,O structure type are shown in Figure 2. The vacant sites in LiMnPO,(OH) are also connected to form channels in which the lithiums reside, but these run in a [I011
direction rather than [OOl] in the starting material. This re-
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crystals, second, matrix, solis, microbalance, support, streptavidin, quarta, protein, layer, docking, function, studies
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