Premium
Size‐Specific, Colorimetric Detection of Counteranions by Using Helical Poly(phenylacetylene) Conjugated to L ‐Leucine Groups through Urea Acceptors
Author(s) -
Kakuchi Ryohei,
Nagata Sachiko,
Sakai Ryosuke,
Otsuka Issei,
Nakade Hiroshi,
Satoh Toshifumi,
Kakuchi Toyoji
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200801235
Subject(s) - phenylacetylene , conjugated system , chemistry , urea , leucine , biochemistry , stereochemistry , organic chemistry , amino acid , polymer , catalysis
A colorimetric detection susceptible to the dimensions of guest counteranions has been demonstrated by using poly(phenylacetylene) with L ‐leucine and urea functionalities (poly‐PA‐Leu). Poly‐PA‐Leu was prepared from N ‐(4‐ethynylphenylcarbamoyl)‐ L ‐leucine ethyl ester (PA‐Leu) by using [Rh + {η 6 ‐C 6 H 5 )B − (C 6 H 5 ) 3 }(2,5‐norbornadiene)] as a catalyst. The biased helical conformation of poly‐PA‐Leu was demonstrated through Cotton effects in the circular dichroism (CD) spectra. The addition of ammonium salts, including tetra‐ n ‐butylammonium acetate, tetra‐ n ‐butylammonium chloride, and tetra‐ n ‐butylammonium bromide anions (CH 3 COO − , Cl − , and Br − ), into the poly‐PA‐Leu solution intensified the CD responses of poly‐PA‐Leu, which is indicative of the chiral adjustability of anion recognition by using urea groups. In addition, the combination of poly‐PA‐Leu with the CH 3 COO − , Cl − , and Br − anions promoted large redshifts in the absorption spectra, thus providing dramatic color changes from pale yellow to red. Guest dependency in the CD and UV/Vis spectra was clearly correlated with the size of the counteranions. Fundamentally, the addition of tetra‐ n ‐butylammonium nitrate, tetra‐ n ‐butylammonium hydrogen sulfate, tetra‐ n ‐butylammonium perchlorate, tetra‐ n ‐butylammonium azide, tetra‐ n ‐butylammonium fluoride, and tetra‐ n ‐butylammonium iodide anions (NO 3 − , HSO 4 − , ClO 4 − , N 3 − , F − , and I − ) has no effect on either the CD or UV/Vis profiles of poly‐PA‐Leu. The guest specificity observed in the CD and UV/Vis spectra clearly demonstrated the guest‐dimension selectivity of poly‐PA‐Leu in counteranion recognition.