Masked Michael Acceptors in Poly(phenyleneethynylene)s for Facile Conjugation

TitleMasked Michael Acceptors in Poly(phenyleneethynylene)s for Facile Conjugation
Publication TypeJournal Article
Year of Publication2006
AuthorsBailey, GC, Swager, TM
Date Publishedapr
Keywordsmasked maleimide pendant group polyphenyleneethynylene conjugation enhanced, Michael acceptor side chain polyphenyleneethynylene conjugation enhanced, tetrahydroepoxyisoindoledione side chain polyphenyleneethynylene conjugation enhanced

Poly(phenyleneethynylene)s (PPEs) capable of reacting with thiol-contg. mols. have been designed and synthesized with no.-av. mol. wts. ranging from 8000 to 11,000. The PPEs contain pendent 3a,4,7,7a-tetrahydro-4,7-epoxy-1H-isoindole-1,3(2H)-dione groups available to participate in conjugate addn. and Diels-Alder chem. after being thermally activated. If the maleimide group is left unmasked during palladium-catalyzed cross-coupling polymn., it leads to side reactions and the prodn. only of short chain oligomers (Mn < 3000, DP ∼ 4). Reversible Diels-Alder reactions between the maleimides and furan were detd. to be a very effective method to produce a masked Michael acceptor that can be unveiled after polymn. under relatively mild thermal conditions. Cycloreversion to the maleimide has been monitored by thermogravimetric anal. (TGA), TGA-MS, IR, and NMR. A PPE contg. the masked maleimide unit has been modified with a thiolated carboxy-X-rhodamine (ROX) dye, and the resulting absorbance and fluorescence spectra as well as gel permeation chromatograms (GPC) are presented. [on SciFinder(R)]