Linked Life Data

19016560

Source:http://linkedlifedata.com/resource/pubmed/id/19016560

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
36
pubmed:dateCreated
2008-12-18
pubmed:abstractText
A series of oligoindole foldamers 1 a-d that are highly fluorescent were prepared by using a biindole derivative as the repeating unit, and their folding and anion-binding properties were revealed by (1)H NMR and fluorescence spectroscopy. The oligoindoles exist in an extended conformation, but adopt a compact helical structure in the presence of an anion. The anion is entrapped inside the tubular cavity of the helical strand, comprising four aryl units per turn, by multiple hydrogen bonds with the indole NHs. These structural features were confirmed by (1)H NMR and fluorescence spectroscopy. When folded by anion binding, 1 b-d show characteristic downfield shifts of the NH signals and upfield shifts of the aromatic CH signals by Deltadelta=0.1-1.0 ppm. The average chemical shift for all the aromatic signals of 1 a-d is more upfield shifted as the chain lengthens, as anticipated from the degree of overlapped aromatic surfaces in the helical strand. Moreover, 1 a-d are strongly fluorescent in the absence of an anion. Upon binding an anion such as a chloride, the shorter oligoindoles 1 a and b lead to negligible change in the emission spectra, whereas the longer ones 1 c and d result in dramatic changes, that is, large hypochromic and bathochromic shifts (Deltalambda=65 and 70 nm) of the emission band, confirming the helical folding. The association constants (K(a)) between oligoindoles and tetrabutylammonium chloride strongly depend on the chain length; <1 M(-1) for 1 a, 630 M(-1) for 1 b, 1.1x10(5) M(-1) for 1 c, and 2.9x10(5) M(-1) for 1 d in 20 % (v/v) MeOH/CH(2)Cl(2) at 24+/-1 degrees C. In addition, the association constants of 1 c and 1 d with other anions such as fluoride, bromide, iodide, azide, cyanide, acetate, and nitrate are determined to be in the order of 10(3)-10(6) M(-1) under the same conditions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1521-3765
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
14
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11406-14
pubmed:dateRevised
2009-8-4
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Folding and anion-binding properties of fluorescent oligoindole foldamers.
pubmed:affiliation
Center for Bioactive Molecular Hybrids and Department of Chemistry, Yonsei University, Seoul 120-149, Korea.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't