Alkyne Metathesis with Simple Catalyst Systems:  Efficient Synthesis of Conjugated Polymers Containing Vinyl Groups in Main or Side Chain

Abstract

The synthesis of novel conjugated polymers by acyclic diyne metathesis (ADIMET) is reported. These polymers are hybrids between poly(p-phenylenevinylene) and poly(p-phenyleneneethynylene) (PPE). They contain phenylene, ethynylene, and vinylene groups (⋮PhPh, PPVE). Simple in situ catalysts formed from Mo(CO)6 and 4-chlorophenol were used to metathesize the dipropynyl(tetraalkyl)stilbene monomers. The monomers are made by a combination of Horner reactions and Heck-type couplings. The PPVEs form in high yields and are structurally defined. They show degrees of polymerization (P n ) of 30−220 repeating units (i.e. 60−450 benzene rings), demonstrating that the presence of the double bonds does not interfere with alkyne metathesis. The PPVEs were structurally characterized by XRD and electron microscopy. They show fibrillar and network-type morphologies, which should make them interesting for applications in molecular electronics. Solid samples of PPVEs display powder XRD patterns almost identical to those of the PPEs. PPVEs thus assume similar doubly lamellar structures as the PPEs. The aggregation behavior of PPVEs was studied. In addition, ADIMET to a poly(2,7-fluorenyleneethynylene) carrying unsaturated side chains is reported. In this case the presence of unsaturation does neither interfer with efficient alkyne metathesis.

Poly(aryleneethynylene)s

“…[59,60] PPE 91 detected cancer cells, while 93 is crosslinked by interaction with streptavidin. In a similar vein, Swager [15] demonstrated that carboxylate groups in the side chains of PPEs could be coupled to oligopeptides to give peptide-PPE constructs. For the attachment to DNA, Schanze et al [61] prepared an oligonucleotide on a controlled porosity glass bead.…”

“…Best results are obtained for the synthesis of dialkyl-PPEs 3 and poly(dialkyl-fluorenyleneethynylene)s 6 as well as for PPE-PPV hybrid polymers. [15] The reaction yields are quantitative. Spectroscopically pure, well soluble dialkylPPEs 3 are obtained after precipitation from methanol and washing with acid and base to remove both molybdenum containing impurities as well as the phenol co-catalyst.…”

Luminescent and Electronic Properties of Stilbenoid NCN‐Pincer PtII Compounds

“…Phosphonate ester 8a was synthesized by reduction of 4-dimethylaminobenzaldehyde with sodium borohydride to form 4-dimethylaminobenzyl alcohol, [40] which was then in situ reacted with methanesulfonyl chloride and subsequently converted into the phosphonate ester by an Arbuzov reaction [41] (Scheme 2).…”

Photoinduced Electron Transfer and Photovoltaic Devices of a Conjugated Polymer with Pendant Fullerenes

“…The presence of both double and triple bonds in the backbone make 3 a hybrid polymer of poly(p-phenylene vinylene) and poly-(p-phenylene ethynylene), similar to those recently reported. 9 The polymerization reaction was followed by absorption spectroscopy, as a red-shift in time of the π-π* transition of the polymer with respect to that of monomer 2 (λ max ) 428 nm). The three hexyloxy chains ensure that 1 is a highly soluble C 60 derivative, but its reactivity toward 2 under these conditions is less than that of 1,4-diiodo-2,5-bis(2′-ethylhexyloxy)benzene (4).…”