Fullerene-Catalyzed Reduction of Azo Derivatives in Water under UV Irradiation

• Published in: Chemistry, an Asian journal Vol. 7; no. 12; pp. 2842 - 2847
• Main Authors: Guo, Yong, Li, Wengang, Yan, Jingjing, Moosa, Basem, Amad, Ma'an, Werth, Charles J., Khashab, Niveen M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-12-2012; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: amines; azo compounds; Chemistry; Dyes; electron transfer; fullerenes; heterogeneous catalysis; Ultraviolet radiation
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201200701

Metal‐free fullerene (C60) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH4. Use of NaBH4 by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C60 catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the NN bond. UV irradiation increases the ability of C60 to interact with electron‐donor moieties in azo dyes.
Filling a vacancy: Experimental and theoretical methods have been combined to show that C60‐catalyzed reductions of azo compounds form aromatic amines under UV irradiation (see scheme). The obtained results show that C60 acts as an electron acceptor to catalyze the reduction of azo compounds, and the role of UV irradiation is to increase the ability of C60 to interact with electron‐donor moieties in azo compounds.