In summary, we successfully designe

In summary, we successfully designed and synthesized the unique bi-chelating structure of "M4L3" Ni4 cubane cluster utilizing the flexible multidentate Schiff base ligand. The results of crystallographic and ESI-MS analysis showed that the outer-sphere organic ligands protect the key cluster core structure, and the cubane molecular cluster exhibited robust activity under harsh reaction conditions. Single site mechanism is proposed for both OER and UOR reaction according to the DFT calculation, which ensure the high catalytic efficiency and avoid the deactivation of the catalyst. To the best of our knowledge, this is the first coordination molecular cluster function as the bifunctional electrocatalyst with both high efficiency OER and UOR activity, which exhibits a satisfactory activity with a low potential of 1.585 V for OER and 1.338V for UOR to achieve 10 mA·cm-2. The potential of UOR is superior to most catalysts that have been reported. Our study suggests that the process-dependent solid-liquid structural information correlation provides new opportunities for in-depth study of the structure-activity relationship of coordination molecular clusters under electrocatalytic conditions. Utilizing common Schiff base ligands and transition metal, single metal site is successfully anchored. Its catalytic activity exceeds that of existing commercial precious metal catalysts. With rational catalyst design, we achieved a win-win situation between stability and catalytic activity and created a new strategy for preparing single-site catalysts, which is expected to contribute to the development of new efficient and stable molecular cluster catalysts in the future.