Molad A, Goldberg I, Vigalok A * Tel Aviv University, Israel
Tubular Conjugated Polymer for Chemosensory Applications.
J. Am. Chem. Soc. 2012;
134: 7290-7292
Key words
NO sensing - conjugated polymers - bicalixarenes
Significance
A 5,5′-bicalixarene scaffold was incorporated into the linear backbone of a soluble
conjugated polymer 5 via Glaser-type coupling. Monomer 4 synthesis relies on oxidative coupling of calixarene 1, followed by deprotection and selective triflation. Next, the triflate was replaced
with TES-acetylene, because direct cross-coupling of 3 with 1,4-diethynylbenzene failed. Deprotection of the alkyne and installation of solubilizing
groups furnished the desired monomer in 5% overall yield.
Comment
Access to a closed (capsule-type) conformation in bicalixarenes greatly enhances complexation
properties of the calixarene scaffold. Indeed, polymer 5 fluorescence (λabs = 420 nm, λem = 450 nm, ΦFL = 0.37) is efficiently quenched by NO vapor. Importantly, a brief application of
low vacuum to remove NO completely restores the fluorescence, indicating that the
complexation is reversible.
