Phenylene-2,5-dimethylpyrazine co-oligomers: synthesis by Suzuki couplings, X-ray structures of neutral and diprotonated teraryl species and efficient blue emission

Turksoy, F.; Hughes, G.; Batsanov, A.S.; Bryce, M.R.

Abstract

Phenylene-2,5-dimethylpyrazinyl co-oligomers and a dipyridylpyrazine derivative have been synthesised by Suzuki cross-coupling reactions starting from 2,5-dibromo-3,6-dimethylpyrazine. X-Ray crystal structures are reported for two teraryl derivatives, viz. 2,5-bis(2-methoxyphenyl)-3,6-dimethylpyrazine 2 and 2,5-bis(6-methoxypyridin-3-yl)-3,6-dimethylpyrazine 6, and a diprotonated pyrazinyl dication salt, viz. 2,5-bis(2-methoxyphenyl)-3,6-dimethylpyrazinium bis(tetrafluoroborate) salt 3. Compounds 2 and 6 and the dication in 3 have crystallographic C-i symmetry and adopt twisted conformations: dihedral angles between the aryl and pyrazine rings are 74.0degrees (2), 56.4degrees (3) and 44.6degrees (6). Violet-blue photoluminescence is seen for 2 lambda(max) 372 nm, 5 lambda(max) 418 nm and 6 lambda(max) 387 nm in ethanol solution. [Compound 5 is 1,4-dimethoxy-2,5-bis{2-(5-tertbutylphenyl-3,6-dimethylpyrazinyl)benzene }]. Blue electroluminescence, lambda(max) 444 nm, is observed for the device structure ITO/PEDOT/5/Ca with no long-wavelength emission from pi-aggregates or exciton states.

Citation

Turksoy, F., Hughes, G., Batsanov, A., & Bryce, M. (2003). Phenylene-2,5-dimethylpyrazine co-oligomers: synthesis by Suzuki couplings, X-ray structures of neutral and diprotonated teraryl species and efficient blue emission. Journal of materials chemistry, 13(7), 1554-1557

• Journal Article Type: Article
• Publication Date: 2003
• Journal: Journal of Materials Chemistry
• Print ISSN: 0959-9428
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 13
• Issue: 7
• Pages: 1554-1557