Inspired by the mechanism of the clock reaction, we rationally constructed a novel phosphomolybdenum blue (PMB) clock catalytic system for a highly efficient synthesis of benzimidazoles and benzothiazoles simply at ambient temperature. The current PMB clock catalytic system exhibits a sharp decoloration event to announce the depletion of the intermediateconstraint, making this synthetic approach selfindicating and TLC-free. 31 P NMR and XPS analysis of PMBcatalyst showed that only two Mo 6 + atoms are reduced to Mo 5 + atoms in the Keggin structure due to the moderate reducibility of benzimidazoline and benzothiazoline intermediates. Thus,the active Keggin-type POM cluster could be well maintained in DMSO during the redox cycling of phosphomolybdic acid (PMA) and PMB. 1 H NMR tracing experiment not only confirmed the proposed reaction mechanism but also showed that PMB exerts Lewis acid catalytic activityat the early phase of the reaction other than the expected redox catalytic activity.

An efficient method based on peroxo-Mo(VI)/Mo(VI) redox cycle for ambienttemperature synthesis of quinazolin-4(3H)-ones has been developed. Catalytic phosphomolybdic acid (PMA) exhibits Lewis acid and oxidative dehydrogenation activities at different phases of the reaction, and the true oxidative catalytic species was identified as peroxo-Mo(VI) Keggin cluster. Surprisingly, we found that aggregation-induced emission (AIE) is a generic property that has long been neglected for quinazolin-4(3H)-ones. Theoretical calculation results well rationalized their photophysical behaviors and elucidated their AIE mechanism as restriction of access to dark state (RADS). The crystallographic analysis of two representative quinazolin-4(3H)-ones not only revealed their packing mode and weak intermolecular actions but also supported the molecular conformations obtained by theoretical calculations.

An efficient method for ambient-temperature synthesis of a variety of 2-substituted and 1,2-disubstituted benzimidazoles from aldehyde and phenylenediamine substrates has been developed by utilizing Co(III)/Co(II)-mediated redox catalysis. The combination of only 1 mol% of Co(acac)2 and stoichiometric amount of hydrogen peroxide provides a fast, green, and mild access to a diversity of benzimidazoles under solvent-free conditions.

A peroxo-Mo(VI)/Mo(VI)-mediated redox synthesis of quinazolin-4(3H )-ones and their aggregation-induced emission property and mechanism