Why are solutions of C-60-piperazine purple at pH 11?

作者：Xu Hanying^*; Tian Jun; Korobov Mikhail V; Sohlberg Karl; Smith Allan

来源：Fullerenes, Nanotubes, and Carbon Nanostructures, 2007, 15(4): 267-277.

DOI：10.1080/15363830701421512

• C-60-piperazine mono adduct
• vibronic coupling
• Jahn -Teller active
• vibrational mode
• PM3
• ZINDO(s)

The C-60-piperazine mono adduct was synthesized by the reaction of C-60 and piperazine. The saturated C-60-piperazine aqueous solution was colorless when pH is 8 or below. A purple color was developed when pH is around 9 and the pink color is most intense at pH 11. The color of the C-60-piperazine solution fades out when pH is approaching 12 from 11, and the solution remains colorless when pH is 13 or higher. The UV-Vis spectra of the C-60-piperazine solution were recorded at pH 4, 11 and 14. The mono-protonated C-60-piperazine was identified to be responsible for the purple color observed. The computational investigation of the un-protonated, mono-protonated and di-protonated C-60-piperazine was conducted at the PM3 and ZINDO( s) levels of theory. Vibronic coupling of the Jahn-Teller active vibrational mode to the electronic transition was applied to re-generate the weak absorption between 550-600 nm in the UV-Vis spectrum of the mono-protonated C-60-piperazine.

• 出版日期2007
• 单位上海大学