Mechanistic investigation of MOF-catalyzed intramolecular hydroamination of <i>o</i>-alkynylanilines using Zn-UiO-67-BPY as a catalyst

Hybrid quantum mechanics/molecular mechanics (QM/MM) calculations were used to determine the distribution of active catalytic sites in Zn-UiO-67-BPY and the mechanism behind the MOF-catalyzed intramolecular hydroamination of <i>o</i>-alkynylanilines. It was found computationally that the active sites were located at a distance from each other within the framework, promoting catalysis. Additionally, the fixation of Zn(II)-bipyridine to the MOF contributed to the barrier of the rate-determining step and stabilized the transition state. The study also revealed a series of linear relationships between the NPA charge of two counterions and the calculated barrier, which displayed ladder-like changes depending on the degree of orbital overlap between the counterion and the substrate. These relationships offer valuable insights into the counterion effect in complex catalytic systems and facilitate the design of anionic heterogeneous catalysts.