Coordination-Controlled Synthesis of Aluminum Nanoparticles: Insights from AlH3·(NMP) x Complexes.

The controlled chemical synthesis of Aluminum nanocrystals (Al NCs) is crucial for their applications in plasmonics, photocatalysis, and optoelectronics. However, there is still a lack of correlation between the precursor of Al hydride N-methylpyrrolidine (AlH3·(NMP)x) and the Al NC synthesis outcomes . Here, we report the synthesis of AlH3·(NMP)x complexes with different coordination numbers (x from 1.0 to 2.0) and their characterization as precursors regulating the morphology of Al NCs. We isolated AlH3·(NMP)1.0 single crystals from AlH3·(NMP)x mixtures and successfully elucidated the structure of H3Al·(NMP)1.0 through single-crystal X-ray diffraction. Importantly, H3Al·(NMP)1.0 exhibited the fastest decomposition rate, yielding highly monodisperse Al NCs with well-defined shapes and the narrowest size distribution, while higher coordination numbers led to increased polydispersity and irregular morphologies. Additionally, we observed distinct multipole plasmonic resonances in Al NCs synthesized from lower coordination number precursors, highlighting their superior optical properties. This work establishes a direct correlation between precursor coordination chemistry and Al NC synthesis outcomes, providing a foundation for optimizing nanoparticle production for advanced material applications.