Biscalix[4]arene Derivative As a Very Efficient Phase Selective Gelator for Oil Spill Recovery. - Tsai, Chia-Chen; Cheng, Ying-Tsai; Shen, Li-Ching; Chang, Kai-Chi; Ho, I-Ting; Chu, Jean-Ho; Chung, Wen-Sheng (Organic Letters, 2013)