Gilch Synthesis of Poly(ortho -Phenylene Vinylenes): A Powerful Access to High-Molecular-Weight Blue-Emitting Polymers

Abstract

For the first time, the successful Gilch synthesis of poly(ortho-phenylene vinylenes) (ortho-PPVs) is reported. The molar mass of the constitutionally homogeneous ortho-PPVs reaches values as high as Mw ≈ 300 000 Da. The ortho-connectivity of the repeating units forces the chains to assume closely packed conformations even in good solvents. Significant perturbation of the π-electron systems and considerable shortening of the conjugation lengths are the consequences. UV-vis absorption and photoluminescence maxima consequently are shifted clearly toward shorter wavelengths compared to, e.g., classic para-PPVs.

Effects of Halogen and Hydrogen Bonding on the Electronics of a Conjugated Rotor

“…To this end, 1,2-bis­((2-ethylhexyl)­oxy)­benzene was iodinated using a common protocol then converted to intermediate 9 using a Sonogashira coupling and TBAF deprotection (Scheme ). Because the C–I bonds at the 2/5 positions of pyrazine are significantly more reactive than the C–I bond of 9 , this terminal alkyne could be selectively coupled to 2,5-diiodopyrazine in high yield.…”

Transition-Metal-Free Homopolymerization of Pyrrolo[2,3-d:5,4-d′]bisthiazoles via Nucleophilic Aromatic Substitution

“…The polymerization is free from transition metal catalysts and therefore much more environmentally friendly. Additional examples of transition-metal-free polymerization chemistry include the use of the Horner–Wadsworth–Emmons or the Gilch polymerization methods to synthesize vinylene-linked polymers. − The use of catalytic amounts of fluoride anion to initiate polymerization between arylsilanes and electron deficient perfluoroaryl groups has also been reported. − Other notable reports include the dehydrative and oxidative cross-coupling methods. , Modern high performing conjugated polymers are almost always composed of adjacently linked aromatic rings, and reports of transition-metal-free polymerizations are rare, particularly with electron-deficient aromatics which cannot readily oxidatively polymerized.…”

Polymer Valence Isomerism: Poly(Dewar-o-xylylene)s

“…Such functionalization has led to success in the preparation of alkoxy-or siloxy-substituted POXs of molecular weights ranging from 5 kDa to 11 kDa. 7 Gilch conditions have also recently been applied to the synthesis of poly(ophenylenevinylene)s. 8 In the 1960s, Errede discovered the dimerization of o-xylylene at low temperature to produce an unstable spiro-dimer. Upon warming this molecule autopolymerizes to afford POX, which is the first report on radical ringopening polymerization.…”