Concentrated and Rapid Heat Release in AP Decomposition: Reductive Ligand-Metal Synergy in Energetic Metal-Organic...

Ammonium perchlorate (AP), the primary solid propellant oxidizer, suffers from high decomposition temperatures, sluggish kinetics, and low heat release due to multistep decomposition. Traditional CuO catalysts agglomerate, organic neutral red additives show limited activity, and energetic metal-organic frameworks (EMOFs) exhibit dispersed energy output. Herein, we report a reductive ligand-metal center synergy strategy to streamline AP decomposition. By employing reductive dicyanamide (DCA^-) to facilitate electron transfer and energetic imidazol-1-yl-acetonitrile (Imat) to augment heat release, [Co(DCA)₂(Imat)₂]_n 1 and [Cu(DCA)₂(Imat)₂]_n 2 were assembled. With a 3 wt % loading of 1 in AP (3%-1-AP), the peak temperature decreases from 439.3 to 325.5 °C, and the decomposition heat release increases from 537 to 1301 J g^-1. Remarkably, the exothermic peak width of the 3%-1-AP composite is narrowed to merely 8 °C, which represents a 23-fold reduction compared to pure AP and signifies a remarkably concentrated energy release. Mechanistic studies reveal that strong Co-3d orbital hybridization with the reductive DCA^- ligand in 1 accelerates proton-coupled electron transfer, thereby converging the multistep decomposition of AP into a single, sharply concentrated heat release. This work establishes a robust structure-property relationship for designing advanced energetic catalysts through precise coordination chemistry.