ORGANIC SYNTHESIS

Acetylene in, PAHs out

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Science  01 Jun 2018:
Vol. 360, Issue 6392, pp. 977
DOI: 10.1126/science.360.6392.977-a

Electron density map of polycyclic aromatic hydrocarbons inside a zeolite cage

CREDIT: S. H. KO ET AL., J. AM. CHEM. SOC. 10.1021/JACS.8B00900 (2018)

Polyaromatic hydrocarbons (PAHs) are attractive for optoelectronics applications, but their synthesis can be challenging. Solution routes tend to have low yields, and high-temperature vacuum pyrolysis (∼1000°C) generates numerous carbonaceous side products. Ko et al. synthesized PAHs by polymerizing acetylene in Ca2+ ion–exchanged Linde type-A zeolites at ∼400°C. The Ca2+ ions appear to lower the barrier for carbon-carbon bond formation. The PAHs remained trapped in the α-cages of the zeolite but were recovered after dissolving the zeolite with acid. The product mixture exhibited white fluorescence in N-methylpyrrolidone solution. Column chromatography separation isolated violet, blue, green, and orange emitters, with coronene being the main component of the blue emitter.

J. Am. Chem. Soc. 10.1021/jacs.8b00900 (2018).

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