Probing Mesoscopic Solvation Dynamics via Comparable-Sized Nanomolecular Clusters

Probing the solvation dynamics of electrolytes is essential for understanding mass transport processes in biological, chemical, and electrochemical systems, yet access to these mesoscopic interactions remains limited. Here, we develop a molecular design strategy that enables the interrogation of solvation dynamics using nanomolecular clusters engineered to match the size and chemical environment of solvation shells. As a proof of concept, we employ an (electro)chemically robust octamethyl polyhedral oligomeric silsesquioxane (octamethyl-POSS, ∼1.09 nm) to track Li⁺ solvation reorganization in real time. We show that solvated Li⁺ sheds coordinating ligands within ∼2 ps and stabilizes into a new configuration by ∼6 ps. The presence of POSS clusters suppresses ligand exchange and electrolyte decomposition while enhancing ion migration. This mesoscopic probing framework establishes a general design principle for electrolyte screening and opens new avenues for advancing next-generation energy storage technologies.