Regioselective photodimerization of cinnamic acids in water: templation with cucurbiturils

Pattabiraman, Mahesh ; Kaanumalle, Lakshmi S. ; Natarajan, Arunkumar ; Ramamurthy, V. (2006) Regioselective photodimerization of cinnamic acids in water: templation with cucurbiturils Langmuir, 22 (18). pp. 7605-7609. ISSN 0743-7463

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Official URL: http://pubs.acs.org/doi/abs/10.1021/la061215a

Related URL: http://dx.doi.org/10.1021/la061215a

Abstract

Cinnamic acids upon irradiation in solution undergo geometric isomerization while dimerizing to different dimers in the crystalline state. Controlling the nature of the dimer formed upon irradiation remains a challenging task. We have aligned a variety of cinnamic acid molecules in a head-head fashion employing cucurbit[8]uril, a weakly water soluble host as a template. The water solubility of cucurbit[8]uril is enhanced by inclusion of water soluble cinnamic acids and positions the olefins in an arrangement that favors the formation of syn head-head cyclobutanes in near quantitative yields. This methodology works in both solid state as well as in aqueous solution. Irradiation of cinnamic acid complexes with γ-cyclodextrin has been carried out as a comparison. We find that while cucurbit[8]uril functions well both in solid state and aqueous solution, cyclodextrin works best as solid complexes only. Consistent with the postulated requirement of large cavities for templating olefins to dimerization, irradiation of complexes of cinnamic acid with cucurbit[7]uril resulted in only the corresponding cis isomers.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:55884
Deposited On:19 Aug 2011 07:50
Last Modified:19 Aug 2011 07:50

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