Fig. 3: Energy landscape and the role of coordination gradient.

a A simplified energy landscape of the assembly of the Ti₂₄ MOP. The reaction pathway involves i) kinetically trapped intermediates (intermediate 1 and intermediate 2) and ii) a high kinetic barrier corresponding to the dimerization step. The Ni²⁺ ion acts to stabilize the reaction energy, facilitating intermediate capture, while the dynamic nature of the Ti⁴⁺ ion promotes structural reorganization along the pathway. b Coordination lability gradient directs assembly pathway. The Ti⁴⁺ ion, a hard acid, exhibits high lability with rapidly exchanging coordination bonds (dotted line), driving structural reorganization. In contrast, the borderline acid Ni²⁺ ion displays intermediate lability, forming more stable coordination bonds that act as a kinetic trap and stabilize transient intermediates.