{Mo 4 }-directed structural evolution of highly reduced molybdenum red clusters for efficient proton conduction.

A series of highly reduced Mo red clusters {Mo 28 } (1), {Mo 30 } (2), and {Mo 40 } (3) are synthesized from the rational assembly of planar {MoV4} building blocks and employed for proton conduction. 3 exhibits the best conductivity of 7.56 × 10 -3 S cm -1 under optimal conditions due to the most efficient hydrogen-bonding network.