AAAA-DDDD quadruple hydrogen-bond arrays featuring NH···N and CH···N hydrogen bonds

David A Leigh, Craig C Robertson, Alexandra M Z Slawin, Patrick I T Thomson

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)


The X-ray crystal structure of a previously reported extremely strong quadruple NH···N AAAA-DDDD hydrogen-bond array [5·4] (K(a) = 1.5 × 10(6) M(-1) in CH3CN; K(a) > 3 × 10(12) M(-1) in CH2Cl2) features four short linear hydrogen bonds. Changing the two benzimidazole groups of the DDDD unit to triazole groups replaces two of the NH···N hydrogen bonds with CH···N interactions (complex [5·6]), but only reduces the association constant in CH3CN by 2 orders of magnitude (K(a) = 2.6 × 10(4) M(-1) in CH3CN; K(a) > 1 × 10(7) M(-1) in CH2Cl2). Related complexes without the triazole groups range in K(a) from 18 to 270 M(-1) in CH3CN, suggesting that the CH···N interactions can be considered part of a strong AAAA-DDDD quadruple hydrogen-bonding array. The NH···N/CH···N AAAA-DDDD motif can be repeatedly switched "on" and "off" in CDCl3 through successive additions of acid and base.

Original languageEnglish
Pages (from-to)9939-9943
Number of pages5
JournalJournal of the American Chemical Society
Issue number26
Publication statusPublished - 3 Jul 2013


  • benzimidazoles
  • crystallography, X-ray
  • hydrogen bonding
  • models, molecular
  • molecular structure
  • triazoles


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