Abstract
Complex formation between several crown ethers and the cryptand (222) and α-amino acids in methanol was studied by calorimetric titration. The ligand structure and the donor atoms of the ligands play an important role in determining the measured values of the reaction enthalpies and entropies. However, with the exception of the diaza crown ether (22) all stability constants are of the same order of magnitude. The enthalpic and entropic contributions to the stabilities of the complexes formed compensate each other. In methanolic solution the amino acids exist in their zwitterionic form. This equilibrium can be influenced. Under acidic, neutral or basic conditions different values of the reaction enthalpies are measured for the complexation of some amino acids with 18-crown-6. These results demonstrate that the concentration of the zwitterionic form of the α-amino acids can be influenced. Thus the reaction between macrocyclic and macrobicyclic ligands and amino acids should be described by at least two different reaction schemes.
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D.J. Cram, R.C. Helgeson, L.R. Sousa, J.M. Timko, M.L.A. Domeier, S.C. Peacock, K. Modan, and L. Kaplan: Pure Appl. Chem. 43, 327(1975).
R.M. Izatt, J.D. Lamb, N.E. Izatt, B.E. Rossiter, Jr., J.J. Christensen, and B.L. Haymore: J. Am. Chem. Soc. 101, 6273 (1979).
J.D. Lamb, J.E. King, J.J. Christensen, and R.M. Izatt: Anal. Chem. 53, 2127 (1981).
F. Vögtle, H. Sieger, and W.M. M¨ ller: Top. Curr. Chem. 98, 143 (1981).
C. Seel and F. V¨gtle: Angew. Chem. Int. Ed. Engl. 4, 442 (1991).
J.M. Timko, R.C. Helgeson, M. Newcomb, G.W. Gokel, and D.J. Cram: J. Am. Chem. Soc. 96, 7097 (1974).
J.-M. Lehn: Supramolecular Chemistry, VCH, Weinheim (1995).
H.-J. Buschmann: Polyhedron, 11, 559 (1992).
H.-J. Buschmann and L. Mutihac: Thermochim. Acta 237, 203 (1994).
J.A.A. de Boer and D.N. Reinhoudt: J. Am. Chem. Soc. 107, 5347(1985).
G. Wipff, P. Weiner, and P. Kollman: J. Am. Chem. Soc. 104, 3249 (1982).
M.G.B. Drew and P.C. Yates: Pure Appl. Chem. 61, 835 (1989).
M.H. Mazor, J.A. McCammon, and T.P. Lybrand: J. Am. Chem. Soc. 112, 4411 (1990).
H.-J. Buschmann, G. Wenz, E. Schollmeyer, and L. Mutihac: Thermochim. Acta 261, 1 (1995).
J.-M. Lehn and P. Vierling: Tetrahedron Lett. 21, 1323 (1980).
M. Newcombe, J.M. Timko, D.H. Walba, and D.J. Cram: J. Am. Chem. Soc. 99, 6392 (1977).
H.W. Colquhoun, D.F. Lewis, J.F. Stoddart, and D.J. Williams: J. Chem. Soc., Dalton Trans. 607 (1983).
M.R. Johnson and I.O. Sutherland: J. Chem. Soc. Perkin Trans. I 357 (1979).
J.P. Behr, J.-M. Lehn, and P. Vierling: Helv. Chim. Acta 65, 1853 (1982).
A.F. Danil de Namor: Pure Appl. Chem. 62, 2121 (1990).
A.F. Danil de Namor, M.C. Ritt, M.-J. Schwing-Weill, F. Arnaud-Neu, and D.F.V. Lewis: J. Chem. Soc., Faraday Trans. 87, 3231 (1991).
H.-J. Buschmann and L. Mutihac: Colloids Surfaces A: Physicochem. Eng. Aspects (1997) in press.
L. Mutihac, D.O. Popescu, and R.-I. Stefan: Anal. Lett. 28, 835(1995).
L. Mutihac, R. Mutihac, and H.-J. Buschmann: J. Incl. Phenom. 23, 167 (1995).
D.J. Eatough, J.J. Christensen, and R.M. Izatt: Experiments in Thermometric Titrimetry and Titration Calorimetry, Brigham Young University Publications, Provo (1973).
H.-J. Buschmann: Thermochim. Acta 102, 179 (1986).
H.-J. Buschmann: Inorg. Chim. Acta 195, 51 (1992).
N.E. Tayar, R.S. Tsai, P.A. Carrupt, and B.J. Testa: J. Chem. Soc., Perkin Trans. 2, 79 (1992).
W.P. Jencks and J. Regenstein: in G.D. Fasman (ed.), CRC Handbook of Biochemistry and Molecular Biology: Physical and Chemical Data, CRC Press, Boca Raton, Vol. 1, p. 305 (1976).
M. Czekalla, K. Goe, B. Habermann, T. Kr¨uger, H. Stephan, F.P. Schmidtchen, and R. Tr¨ ltzsch: Poster PB37, XXI International Symposium on Macrocyclic Chemistry, Montecatini Terme (Italy) (1996).
H.-J. Buschmann, E. Schollmeyer, and L. Mutihac: Supramol. Sci., in print.
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Buschmann, HJ., Schollmeyer, E. & Mutihac, L. The Complexation of Amino Acids by Crown Ethers and Cryptands in Methanol. Journal of Inclusion Phenomena 30, 21–28 (1998). https://doi.org/10.1023/A:1007941023186
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DOI: https://doi.org/10.1023/A:1007941023186