The classic inorganic polymer flocculant—polyaluminum chloride (PAC)—was used as an environmentally friendly, efficient, and recyclable catalyst in the synthesis of Bis(indolyl)methanes (BIMs) compounds for the first time. The strategy of catalysis is to use PAC as a Lewis acid, which contains different structures of Al–O polynuclear cations. These Al atoms may have a special synergistic catalytic effect for synthesis of BIMs compounds. PAC exhibits excellent catalytic activity in both solution (Yield: 95%) and solid phase (Yield: 99%). In addition, the PAC catalyst possesses outstanding stability and can be reused at least 4 times. Therefore, PAC may have wider applications in the synthesis of other organic compounds.

经典的无机高分子絮凝剂-聚氯化铝（PAC）–首次在双（吲哚基）甲烷（BIM）化合物的合成中用作环保，高效且可回收的催化剂。催化策略是使用PAC作为路易斯酸，其中包含Al-O多核阳离子的不同结构。这些铝原子可能对合成BIMs化合物具有特殊的协同催化作用。PAC在溶液（产率：95％）和固相（产率：99％）中均表现出优异的催化活性。此外，PAC催化剂具有出色的稳定性，可以重复使用至少4次。因此，PAC在其他有机化合物的合成中可能具有更广泛的应用。