Synthesis and Luminescence of 14-Aryl- or Alkyl-14H-dibenzo[a,j]xanthenes Catalyzed by 2-1′-Methylimidazolium-3-yl-1-ethyl Sulfate

Abstract

A facile and efficient synthesis of 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes has been accomplished by treatment of β-naphthol with aryl or alkyl aldehydes catalyzed by 2-1′-methylimidazolium-3-yl-1-ethyl sulfate in ionic liquid [BMIM][BF₄] at 80°C. The luminescence of products was studied in detail.

Keywords:

• Luminescence
• 2-1′-methylimidazolium-3-yl-1-ethyl sulfate
• synthesis
• xanthenes

ACKNOWLEDGMENTS

We are grateful to the National Natural Sciences Foundation of China (No. 20772103), the Natural Science Foundation in Jiangsu Province (No. BK2007028), the Surpassing Project in Jiangsu Province (No. QL200607), the Postgraduate Creative Project in Jiangsu Province (No. CX07S-0162), and the Postgraduate Scientific Research Project Foundation of Xuzhou Normal University (No. 08YLB029) for financial support.

Notes

^a Reaction conditions: 4-chlorobenzaldehyde (1.0 mmol), β-naphthol (2.0 mmol), and catalyst 2-1′- methylimidazolium-3-yl-1-ethyl sulfate (0.08 mol%) in [BMIM][BF₄] at 80°C.

^b Yield of isolated products.

^c No reaction.

^d [BPY] = 1-n-butylpridinum.

^a Relative fluorescence intensity.

^b Relative fluorescence quantum yield.