Cheng, Xiu-Fen; Li, Yan; Su, Yi-Ming; Yin, Feng; Wang, Jian-Yong; Sheng, Jie; Vora, Harit U.; Wang, Xi-Sheng; Yu, Jin-Quan Journal of the American Chemical Society, 2013, vol. 135, # 4 p. 1236 - 1239 doi: 10.1021/ja311259x