Highly Branched Polyphenylenes with 1,3,5-Triphenylbenzene Fragments via Cyclocondensation of Acetylaromatic Compounds and Ni⁰-Catalyzed Dehalogenation:  Synthesis and Light Emission

Abstract

Highly branched photoluminescent polyphenylenes (PP) containing 1,3,5-triphenylbenzene (TPB) fragments were prepared via combination of cyclocondensation of acetylaromatic compounds and Ni 0 -catalyzed dehalogenation. To develop optimal conditions for cyclocondensation of acetylaromatic compounds, we studied a model reaction of 1,3,5-triphenylbenzene formation using different solvents and catalysts. The maximum 85% yield of TPB was achieved using H 2SO4 as a catalyst in ethanoltoluene medium at 50 °C for 5 h. Cyclocondensation polymerization of 4,4′-diacetyl diphenyl ether or 4,4′-diacetylbenzene in the presence of equimolar amounts of acetophenone (in the optimal conditions with respect to the soluble polymer yield) did not produce photoluminescent PP due to various defects in the polymer chain. Defect-free PP with starlike fragments were synthesized using Ni 0 -catalyzed polymerization of aromatic bromides obtained by modification of 1,3,5-tri(p-bromophenyl)benzene. The molecular weights of the polymers were 6700 and 8600 Da. The maximum photoluminescence in solution (quantum yield of 96%) was obtained for the highly branched polymer with starlike TPB fragments, bearing no Br or acetyl groups. The PP of this kind also show very bright fluorescence in the solid state under UV irradiation at 360 nm so they can be considered as promising materials for OLED applications.

Crystallization characteristics of weakly branched poly(ethylene terephthalate)

“…With the progress in sophisticated synthesis methods, it becomes easier now to produce polymers with complicated macromolecular architecture [1][2]. As a matter of fact, the macromolecular architecture has become a tunable factor to change polymer properties and applications.…”

Star-like Aromatic Conjugated Polymers and Dendrimers for OLEDs

“…Synthesis of branched defect-free oligophenylene with 13 phenyl ring, (tridecaphenyl or 1,3,5-tri[1,3-diphenyl-(phenyl-5-yl)-phenyl-4'-yl]benzene (1) was described by us earlier [19] using cyclocondensation of [1-(4'-acetylphenyl)-3,5-diphenyl]-benzene. However these soluble PPs always contain some defect fragments and do not show photoluminescence.…”

“…We suggest here a combination of two techniques: (i) cyclocondensation of monoacetyl aromatic compounds with trimer formation (a central part of a star-like polymer) [18,19] and (ii) Ni 0 -catalyzed dehalogenation for synthesis of branched defect-free polymers. We suggest here a combination of two techniques: (i) cyclocondensation of monoacetyl aromatic compounds with trimer formation (a central part of a star-like polymer) [18,19] and (ii) Ni 0 -catalyzed dehalogenation for synthesis of branched defect-free polymers.…”

Phenylene dendrimers and novel hyperbranched polyphenylenes as light emissive materials for blue OLEDs

“…Polymers emit strongly, deep blue light at 380 nm. The quantum efficiency achieved in solution was about 96% relatively to quinine sulfate [8].…”