A recently introduced linker-mediated strategy that decouples network formation from properties of the inorganic nanocrystal cores has proven effective in achieving reversible bonding and controlled gelation. In this approach, a link is created when a small bifunctional molecule forms dynamic bonds to functional terminal groups on surface ligands of two neighboring nanocrystals. Using complementary dynamic covalent bonding pairs on the ligand and linking molecules allows for chemoreversible, and in some cases thermoreversible, bonding equilibria. Decoupling the interactions driving assembly from the properties of the inorganic core enables flexible tuning of nanocrystal size, shape, and elemental composition without altering the overall gel structure. Moreover, the identity and chemical structure of surface ligands and linker molecules offer extra levers for controlling kinetics and structure, or manifesting spectroscopic signals for quantitative characterization of link formation during the assembly process. Importantly, macroscopic control of nanocrystal phase behavior and dynamics is achievable by modifying the macroscopic linker-to-nanocrystal ratio or by adding monofunctional ligand caps to compete with linker bonding. Kang et al. developed a thermoreversible ITO nanocrystal gel using a cobalt-terpyridine Co(Tpy) 2 linkage that is thermodynamically stable at lower temperatures but dissociates to form cobalt(II) tetrachloride in a ligand exchange reaction under elevated temperatures and in the presence of Cl -(Figure ). A reversible transition of nanocrystals between dispersed and gel states was demonstrated, with the collective plasmon resonance of the gel redshifted and broadened relative to the nanocrystal LSPR. As demonstrated by modeling using Brownian dynamics and MPM simulations, these changes in the far-field spectra are predictable and reflect enhanced LSPR coupling due to the close local spacing of nanocrystals in the gel structure. The reversible nature of the links ensured consistent gel networks and optical properties as measured by SAXS and UV-vis-NIR spectroscopy when gels were formed and disassembled over repeated thermal cycles (Figure ). Coarse-grained molecular dynamics simulations revealed that percolated networks formed when there was more than one effective link per nanocrystal. As a result, the experimental gel point could be chemically tuned to lower temperatures by adding chloride and shifting the ligand exchange equilibrium toward cobalt(II) tetrachloride.