Artificial Receptors for the Extraction of Xanthines
FULL PAPER
X-ray crystallographic data
[1] J. M. Lehn, Supramolecular Chemistry,VCH,Weinheim, 1995.
[2] J. W. Steed,J. L. Atwood, Supramolecular Chemistry,John Wiley
and Sons,Chichester, 2000; P. Cragg, A Practical Guide to Supra-
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ing Constants,John Wiley and Sons,New York, 1987.
Suitable crystals were obtained upon diffusion of pentane into a damp
equimolar solution of 1 and 2 in CH2Cl2.
X-ray
crystal
structure
analysis
for
1i·2·H2O:
formula
C66H63N6O9Br3·C8H10N4O2·H2O·2CH2Cl2, Mr =1760.02,colourless crystal
0.250.150.05 mm, a=14.781(1), b=17.179(1), c=17.510(1) , a=
[3] H. J. Schneider,A. Yatsimirsky, Principles and Methods in Supra-
molecular Chemistry,Wiley,Chichester, 2000.
86.37(1), b=72.93(1), g=64.67(1)8, V=3831.7(4) 3, 1calcd =1.479 gcmÀ3
,
m=1.786 mmÀ1,empirical absorption correction (0.664 ꢁTꢁ0.916), Z=2,
[4] U. Spichiger-Keller, Chemical Sensors and Biosensors for Medical
and Biological Applications,Wiley-VCH,Weinheim, 2000.
[5] S. R. Waldvogel, Angew. Chem. 2003, 115,624–625; Angew. Chem.
Int. Ed. 2003, 42,604–605; G. A. Spiller, Caffeine,CRC Press LLC,
Boca Raton, 1998.
¯
triclinic,space group P1 (no. 2), l=0.71073 , T=198 K, w and f scans,
33861 reflections collected (Æh, Æk, Æl),[(sin q)/l]=0.59 À1,13449 in-
dependent (Rint =0.083) and 6367 observed reflections [Iꢂ2s(I)],957 re-
fined parameters, R=0.093, wR2 =0.291,max. residual electron density
0.98 (À0.82) eÀ3,hydrogen atoms at O50 from difference map; others
calculated and refined as riding atoms.
[6] B. H. Bech,E. A. Nohr,M. Vaeth,T. B. Henriksen,J. Olsen,
Epidemiol. 2005, 162,983–990.
Am. J.
Crystallisation occurred upon solvent diffusion into a solution of 1e and
4 in CH2Cl2 when it was covered with cyclohexane.
[7] P. Ballester,M. A. Barcelo,A. Costa,P. M. Deya,J. Morey,M.
Orell,C. A. Hunter, Tetrahedron Lett. 2000, 41,3849–3853; S. Gos-
wami,A. K. Mahapatra,R. Mukherjee, J. Chem. Soc. Perkin Trans.
1 2001,2717–2726; R. Fiammengo,M. Crego-Calama,P. Timmer-
man,D. N. Reinhoudt, Chem. Eur. J. 2003, 9,784–792; P. C. Ander-
son,S. Mecozzi, J. Am. Chem. Soc. 2005, 127,5290–5291.
X-ray
C72H78N6O9·C8H10N4O3·H2O·CH2Cl2·2C6H12, Mr =1652.86,light-yellow
crystal 0.500.500.10 mm, a=14.259(1), c=36.255(1) , V=
6383.8(7) 3, 1calcd =1.290 gcmÀ3 m=1.250 mmÀ1,empirical absorption
crystal
structure
analysis
for
1e·4·H2O:
formula
,
correction (0.574ꢁTꢁ0.885), Z=3,trigonal,space group P32 (no. 145),
l=1.54178 , T=223 K, w and f scans,22882 reflections collected ( Æh,
Æk, Æl),[(sin q)/l]=0.59 À1,9353 independent ( Rint =0.044) and 7141
observed reflections [Iꢂ2s(I)],995 refined parameters, R=0.072, wR2 =
0.203,max. residual electron density 0.55 ( À0.59) eÀ3,Flack parameter
0.09(7),CH 2Cl2 and cyclohexane refined with isotropic thermal parame-
ters,the latter also with geometrical restraints; hydrogen atoms at O101
from difference map; others calculated and refined as riding atoms.
[8] M. C. Schophol,C. Siering,O. Kataeva,S. R. Waldvogel,
Angew.
Chem. 2003, 115,2724–2727; Angew. Chem. Int. Ed. 2003, 42,2620–
2623.
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112,2580–2583; Angew. Chem. Int. Ed. 2000, 39,2472–2475.
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18,23–27.
[11] C. Siering,S. Grimme,S. R. Waldvogel,
1877–1888.
Chem. Eur. J. 2005, 11,
Crystallisation occurred upon solvent diffusion into a solution of 7c in
CH2Cl2 and methanol when it was covered with n-heptane.
[12] D. Mirk,H. Luftmann,S. R. Waldvogel, Z. Naturforsch. B: Chem.
Sci. 60,1077–1082.
[13] K. Gloe,P. Mühl, Isotopenpraxis 1983, 19,257–260; H. Stephan,S.
X-ray
crystal
structure
analysis
for
7c·3MeOH:
formula
C57H84N6O9·3CH3OH·0.25H2O, Mr =1097.93,colourless crystal 0.50
0.400.40 mm, a=17.103(1), c=12.938(1) , V=3277.5(4) 3, 1calcd
=
Juran,B. Antonioli,K. Gloe,
Extraction Methods in Analytical
1.113 gcmÀ3, m=0.624 mmÀ1,empirical absorption correction (0.746 ꢁTꢁ
Methods in Supramolecular Chemistry (Ed.: C. A. Schalley),Wiley-
VCH,Weinheim, 2007,pp. 79–103.
¯
0.789), Z=2,trigonal,space group P3 (no. 147), l=1.54178 , T=223 K,
w and f scans,17262 reflections collected ( Æh, Æk, Æl),[(sin q)/l]=
0.59 À1,3356 independent ( Rint =0.051) and 2058 observed reflections
[Iꢂ2s(I)],248 refined parameters, R=0.076, wR2 =0.244,max. residual
electron density 0.53 (À0.24) eÀ3; the hydrogen atoms of the water mol-
ecule were not located; others were calculated and refined as riding
atoms.
[14] a) M. Petrich,L. Beyer,K. Gloe,P. Mühl,
Anal. Chim. Acta 1990,
228,229–234; b) C. F. Baes,Jr., Solv. Extr. Ion Exch. 2001, 19,193–
213.
[15] M. C. Schopohl,A. Faust,D. Mirk,R. Frçhlich,O. Kataeva,S. R.
Waldvogel, Eur. J. Org. Chem. 2005, 14,2987–2999; S. R. Waldvo-
gel,D. Mirk, Tetrahedron Lett. 2000, 41,4769–4772.
Data sets were collected with Nonius KappaCCD diffractometers,in the
case of Mo-radiation equipped with a rotating anode generator. Pro-
grams used: data collection: COLLECT (Nonius B.V.,1998),data reduc-
tion: Denzo-SMN (Z. Otwinowski,W. Minor, Methods in Enzymology
1997, 276,307–326),absorption correction: SORTAV (R. H. Blessing,
Acta Crystallogr. Sect. A 1995, 51,33–37; R. H. Blessing, J. Appl. Cryst.
1997, 30,421–426) and Denzo (Z. Otwinowski,D. Borek,W. Majewski,
W. Minor, Acta Crystallogr Sect. A 2003, A59,228–234),structure solu-
tion: SHELXS-97 (G. M. Sheldrick, Acta Crystallogr. Sect. A. 1990, 46,
467–473),structure refinement SHELXL-97 (G. M. Sheldrick,Universität
Gçttingen,1997),graphics: DIAMOND 3.0d (Crystal Impact GbR,
Bonn,Germany).
[16] S. R. Waldvogel,A. R. Wartini,P. H. Rasmussen,J. Rebek,Jr.,
rahedron Lett. 1999, 40,3515–3517.
Tet-
[17] W. Traube, Chem. Ber. 1900, 33,3035–3056.
[18] 95.3% (CHCl3) and 89.7% (CH2Cl2) of caffeine (110À4
m in
HEPES/NaOH buffer,pH 7.4) was extracted into the organic phase.
[19] A solubility of the individual receptor in the organic solvent of at
least 0.0025m is required.
[20] cligand =0.005m in toluene;
cxanthine =0.0001m in aqueous solution
(pH 7.4).
[21] D is defined as the quotient of the analytical concentrations of xan-
thine derivatives in the organic and aqueous phases; points in Fig-
ures 2–4 represent the experimental data; lines were calculated for
1:1 complex formation using a nonlinear regression program.[13a]
[22] Determination of binding constants for the system 2·1c in the tem-
perature range 25–658C and subsequent vanꢁt Hoff analysis yields
DHass =(À76Æ9) kJmolÀ1 and DSass =(À140Æ30) JKÀ1 molÀ1. There-
fore,the complex formation is definitely enthalpy driven. However,
the differences between the receptors will also have entropic contri-
butions. These are a matter of detailed ongoing investigations and
will be further discussed in due course.
CCDC-618021–CCDC-618023 contain the supplementary crystallograph-
ic data for this paper. These data can be obtained free of charge rom the
request/cif.
[23] For the water-free binding of caffeine,the spiro ketals have to bend
towards the triphenylene by approximately 10–158.
Acknowledgements
[24] J. E. Ladbury, Chem. Biol. 1996, 3,973–980; J. Janin, Structure
Struct. Fold. Des. 1999, 7,R277–R279; F. A. Quiocho, Pure Appl.
Chem. 1989, 61,1293–1306; F. A. Quiocho, Nature 1989, 340,404–
408; W. I. Weiss,K. Drickamer, Ann. Rev. Biochem. 1996, 65,441–
Financial support from the Deutsche Forschungsgemeinschaft (SFB 624)
and the University of Bonn is highly appreciated. The authors are indebt-
ed to Ms. R. Ruske for her careful experimental assistance in the prepa-
ration of 14C-labelled 1,3,7-trimethyluric acid.
Chem. Eur. J. 2007, 13,3724 – 3732
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA,Weinheim
3731