Journal of inclusion phenomena

, Volume 2, Issue 1–2, pp 377–389 | Cite as

Crystalline complexes of N,N'-ditritylurea (DTU) and N-tritylurea (NTU) hosts with molecular guests

  • Israel Goldberg
  • Lon-Tang W. Lin
  • Harold Hart
Original Papers

Abstract

This paper reports crystalline complexes of the new hosts N,N'-ditritylurea (DTU) and N-tritylurea (NTU) with various uncharged molecular guests. The crystal structures of the following complexes were elucidated by single crystal X-ray diffraction analysis at 115oK: (I) 1:1 DTU-propanamide — space group C2/c, a=15.839Å, b=9.088Å, c=24.584Å, β=111.05o, Z=4; (II) 1:1 DTU-ethyl N-acetylglycinate — space group P1, a=9.010Å, b=10.800Å, c=19.810 Å, α=105.29o β=94.33o, γ=93.03o, Z=2; (III) 2:1 NTU-N, N-dimethylformamide — space group Cc, a=29.614Å, b=8.906Å, c=16.127Å, β=121.04o, Z=4. The three crystal structures are stabilized mainly by a cooperative effect of hydrogen bonding between amide fragments displaced along the shortest axis of each crystal. This interaction occurs between host and guest in complexes I and II, and between host and host in complex III. The latter also represents a cage-type clathrate in which the guest molecules are accommodated in voids between the hydrophobic fragments of four neighboring NTU hosts. On the other hand, complexes of DTU are characterized by a more specific interaction between the two components, each guest molecule being inserted between two adjacent hosts (related by translation) and strongly bound to them via hydrogen bridges. These results illustrate a useful concept in the design of molecular species which can be potential hosts upon crystallization with neutral molecular guests.

Key words

Host-guest complexation of molecular guests Molecular design for hosts 

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Notes and References

  1. 1.
    H. Hart, L-T. W. Lin, and D. L. Ward:J. Am. Chem. Soc. 106, 4043 (1984).Google Scholar
  2. 2.
    F. Toda and K. Akagi:Tetrahedron Lett. 3695 (1968); F. Toda, K. Tanaka, and H. Ueda:Tetrahedron Lett. 22, 4669 (1981); F. Toda, K. Tanaka, T. Omata, K. Nakamura, and T. Ōshima:J. Am. Chem. Soc. 105, 5151 (1983); F. Toda, K. Tanaka, H. Ueda, and T. Ōshima:J. Chem. Soc., Chem. Commun. 743 (1983); F. Toda, K. Tanaka, and K. Mori:Chem. Lett. 827 (1983); K. Tanaka and F. Toda:J. Chem. Soc., Chem. Commun. 1513 (1983).Google Scholar
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    F. Toda, D. L. Ward, and H. Hart:Tetrahedron Lett. 22, 3865 (1981); F. Toda, K. Tanaka, H. Hart, D. L. Ward, H. Ueda, and T. Ōshima:Nippon Kagaku Kaishi 239 (1983).Google Scholar
  4. 4.
    Other rigid end groups (such as 9-anthracenyl) work well; H.Hart and L-T. W. Lin, unpublished results.Google Scholar
  5. 5.
    There was already in the literature an indication that DTU might form such complexes. DTU was reported to crystallize from ethanol with two molecules of solvent; B. Helferich, L. Moog and A. Jünger:Chem. Ber. 58, 872 (1925).Google Scholar
  6. 6.
    M. F. Bengen: German Patent Application, OZ 123438 (March 18, 1940); for reviews, see L. C. Fetterly:Non-Stoichiometric Compounds (Ed. L. Mandelcorn), pp. 497–530, Academic Press (1964); V. M. Bhatnagar,J. Struct. Chem. 8, 513 (1967); V. M. Bhatnagar,Clathrate Compounds, pp. 1–16, Chemical Publishing Co. (1970).Google Scholar
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    H. Hartley, N. G. Thomas:J. Chem. Soc. 1013 (1906); see also A. Allemand and R. Gerdil:Acta Cryst. A31, S130 (1975).Google Scholar
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    H. Bredereck and E. Reif:Chem. Ber. 81, 426 (1948).Google Scholar
  9. 9.
    However, during an attempt to prepare a DTU complex with ethyl 4-aminobenzoate in the usual way, the crystals which deposited were a 1:1 complex of DTU with ethyl acetate. Similarly, DTU does not form a complex when crystallized from pure tetrahydrofuran (THF). However, crystallization from THF containing 30% water gives a 1:1 DTU-THF complex that does not contain water.Google Scholar
  10. 10.
    A similar phenomenon has recently been also classified as ‘coordination-assisted clathration’ E. Weber, I. Csoregh, B. Stensland and M. Czugler:J. Am. Chem. Soc. 106, 3297 (1984).Google Scholar

Copyright information

© D. Reidel Publishing Company 1984

Authors and Affiliations

  • Israel Goldberg
    • 1
  • Lon-Tang W. Lin
    • 2
  • Harold Hart
    • 2
  1. 1.Department of ChemistryTel-Aviv UniversityRamat-AvivIsrael
  2. 2.Department of ChemistryMichigan State UniversityEast LansingUSA

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