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Volumn 5, Issue , 2003, Pages 507-513

Molecular self-assembly: 4-formylcoumarins as versatile skeletons for complementary multipoint association via weak (C-H ⋯O, C-H⋯F and C-X⋯O=C) interactions

Author keywords

[No Author keywords available]

Indexed keywords

COUMARIN DERIVATIVE; HALOGEN;

EID: 15944391772     PISSN: 14668033     EISSN: None     Source Type: Journal    
DOI: 10.1039/b315065h     Document Type: Article
Times cited : (15)

References (43)
  • 27
    • 0037244412 scopus 로고    scopus 로고
    • We have treated all the contacts with dH O 3.0 Å (0.3 Å greater than the sum of the van der Waals radii of hydrogen and oxygen atoms) and C-H O > 120° as hydrogen bonds. Further, the contacts for which the C O distances fall in the range 3.0-4.0 Å are also accepted; of course, the C-H O angle must be near linear for contacts with longer C O distances. The C-H O hydrogen bonds encompass a wide range of energies, with the interaction energies being highest for contacts with short O H distances and near-linear (180°) C-H O angles and vice versa. The limits set above for an interaction to be termed a C-H O hydrogen bond were justified from the following considerations: (i) the contacts with C-H O distances larger than the sum of the van der Waals radii are treated (subject to linearity) as hydrogen bonds owing to the weak, but highly directional nature of the C-H O bonds. It has been shown that the assessment of the strength of an interaction based on distance criterion alone can be misleading. Incidentally, the position of minimum in the intermolecular potential is ca. 0.4 Å larger than the van der Waals distance, see I. Dance, New J. Chem., 2003, 27, 22. (ii) The C-H O interaction fall-off with deviation from linearity (180°) is unlike that for O-H O hydrogen bonds because of the soft nature. It has been shown from statistical database analysis that the mean C-H O angle, for example C-H O hydrogen bonds involving methyl hydrogen and carbonyl oxygen is 137.1° while it is 154.0° for analogous O-H O C contacts, see T. Steiner and G. R. Desiraju, Chem. Commun., 1998, 891. Thus we believe that the contacts with poor geometric angles (<120°) may merely constitute van der Waals contacts. In a similar vein, the contacts that are near linear and longer should be considered weak, yet significant (cf. ref. 9).
    • (2003) New J. Chem. , vol.27 , pp. 22
    • Dance, I.1
  • 28
    • 0002432140 scopus 로고    scopus 로고
    • We have treated all the contacts with dH O 3.0 Å (0.3 Å greater than the sum of the van der Waals radii of hydrogen and oxygen atoms) and C-H O > 120° as hydrogen bonds. Further, the contacts for which the C O distances fall in the range 3.0-4.0 Å are also accepted; of course, the C-H O angle must be near linear for contacts with longer C O distances. The C-H O hydrogen bonds encompass a wide range of energies, with the interaction energies being highest for contacts with short O H distances and near-linear (180°) C-H O angles and vice versa. The limits set above for an interaction to be termed a C-H O hydrogen bond were justified from the following considerations: (i) the contacts with C-H O distances larger than the sum of the van der Waals radii are treated (subject to linearity) as hydrogen bonds owing to the weak, but highly directional nature of the C-H O bonds. It has been shown that the assessment of the strength of an interaction based on distance criterion alone can be misleading. Incidentally, the position of minimum in the intermolecular potential is ca. 0.4 Å larger than the van der Waals distance, see I. Dance, New J. Chem., 2003, 27, 22. (ii) The C-H O interaction fall-off with deviation from linearity (180°) is unlike that for O-H O hydrogen bonds because of the soft nature. It has been shown from statistical database analysis that the mean C-H O angle, for example C-H O hydrogen bonds involving methyl hydrogen and carbonyl oxygen is 137.1° while it is 154.0° for analogous O-H O C contacts, see T. Steiner and G. R. Desiraju, Chem. Commun., 1998, 891. Thus we believe that the contacts with poor geometric angles (<120°) may merely constitute van der Waals contacts. In a similar vein, the contacts that are near linear and longer should be considered weak, yet significant (cf. ref. 9).
    • (1998) Chem. Commun. , pp. 891
    • Steiner, T.1    Desiraju, G.R.2
  • 30
    • 15944363010 scopus 로고    scopus 로고
    • For example, see ref. 13 and references therein.
    • For example, see ref. 13 and references therein.
  • 31
    • 20544433165 scopus 로고
    • C: 1.70; H: 1.2; O: 1.52; F: 1.47; Cl: 1.75; Br: 1.85 Å.
    • The van der Waals radii of various atoms are as follows (see: A.Bondi, J. Phy.Chem.,1964, 68, 441): C: 1.70; H: 1.2; O: 1.52; F: 1.47; Cl: 1.75; Br: 1.85 Å.
    • (1964) J. Phy.Chem. , vol.68 , pp. 441
    • Bondi, A.1
  • 32
    • 15944403091 scopus 로고    scopus 로고
    • note
    • Although the distance is larger than the sum of the van der Waals radii (3.27 Å), the observed angle is strongly indicative of the halogen bond, see ref. 22.
  • 36
    • 15944405619 scopus 로고    scopus 로고
    • note
    • The van der Waals sum of H and F is 2.67 Å. The experimentally observed distances and angles in Table 2 are undoubtedly suggestive of the hydrogen bonding character.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.