Sulfonatocalix[8] arene as a Potential Reaction Cavity

Photo- and electro-active dicationic guests arrest conformational equilibrium

Raja Kaliappan, Yonghua Ling, Angel Kaifer, Vaidhyanathan Ramamurthy

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Smaller members of water-soluble sulfonated calixarenes have been extensively explored in the context of host-guest complexation, supramolecular chemistry, and potential sensors. However, larger members especially eight-membered calixarene (CA[8]) has received much less attention because of its floppy nature and tendency to exist as a mixture of conformational isomers. Our continued interest in identifying molecules with an internal cavity as reaction vessels has led us to examine the host-guest complexation of CA[8] with photoactive bispyridyl ethylenes. We find that 4,4'-bispyridyl ethylene and 3,3'-bispyridyl ethylene upon complexation to CA[8] arrest the conformational equilibrium and force the latter to adopt a single conformation in solution. During complexation, bispyridyl ethylenes are protonated by the sulfonic acid groups of CA[8]. The host-guest complex is stabilized via an electrostatic interaction between the cationic bispyridyl ethylenes and anionic sulfonated calix[8]arene, and we propose the complex to have an inverted capsular structure. This model is also consistent with the electrochemical behavior of 4,4'-dimethylviologen included within CA[8]. Rigidification of bispyridyl ethylenes by the host has a consequence on the excited-state chemistry of the former. Generally, prevalent geometric isomerization of bispyridyl ethylenes are prevented by CA[8] upon complexation.

Original languageEnglish
Pages (from-to)8982-8992
Number of pages11
JournalLangmuir
Volume25
Issue number16
DOIs
StatePublished - Aug 18 2009

Fingerprint

Ethylenes
Complexation
Ethylene
ethylene
cavities
Calixarenes
Supramolecular chemistry
Sulfonic Acids
Isomerization
Coulomb interactions
chemistry
Excited states
Isomers
Conformations
sulfonic acid
isomerization
vessels
Molecules
Water
tendencies

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy

Cite this

Sulfonatocalix[8] arene as a Potential Reaction Cavity : Photo- and electro-active dicationic guests arrest conformational equilibrium. / Kaliappan, Raja; Ling, Yonghua; Kaifer, Angel; Ramamurthy, Vaidhyanathan.

In: Langmuir, Vol. 25, No. 16, 18.08.2009, p. 8982-8992.

Research output: Contribution to journalArticle

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