Cheng-Liang Xiao,Qun-Yan Wu, Lei Mei, Li-Yong Yuan, Cong-Zhi Wang, Yu-Liang Zhao, Zhi-FangChai*, Wei-Qun Shi*, High Selectivity towards Small Copper Ions by aPreorganized Phenanthroline-Derived Tetradentate Ligand and New Insight intothe Complexation Mechanism.