Breaking the Boundary of Gigantic Molybdenum Blue Clusters: From Half-Closed {Mo ₈₅ } to {Mo ₁₇₂ } Dimer

Cyclic assemblies represent an important class of functional structures due to their inherent porous architectures and diverse properties. However, the controlled synthesis of cyclic aggregates with precise size, achieved by modulating the oligomerization of fundamental building blocks (BBs), remains a formidable challenge. Here we report the synthesis of the previously elusive octameric member of molybdenum blue (MB) wheels, {Mo85} ( 1), and its dimer analogue {Mo172} ( 2), under the direction of novel BBs of {Mo1}, {Mo2}, and bent {Mo6} pentagon. The combination of these with existing BBs facilitates wheel contraction and distortion, resulting in the formation of an ellipitical and half-closed {Mo85} octamer, the smallest cyclic cluster in the MB family. The {Mo172} dimer exhibits cross-shaped architecture, composed of two {Mo86} clusters structurally analogous to {Mo85}. Moreover, the structural integrity of 1 and 2 was confirmed by mass spectrometry and other analytic techniques, enabling their exploration in photothermal conversion in both solution and the solid state.