Ce-mediated molecular tailoring on gigantic polyoxometalate {Mo(132)} into half-closed {Ce(11)Mo(96)} for high proton conduction

Precise synthesis of polyoxometalates (POMs) is important for the fundamental understanding of the relationship between the structure and function of each building motif. However, it is a great challenge to realize the atomic-level tailoring of specific sites in POMs without altering the major framework. Herein, we report the case of Ce-mediated molecular tailoring on gigantic {Mo(132)}, which has a closed structural motif involving a never seen {Mo(110)} decamer. Such capped wheel {Mo(132)} undergoes a quasi-isomerism with known {Mo(132)} ball displaying different optical behaviors. Experiencing an ‘Inner-On-Outer’ binding process with the substituent of {Mo(2)} reactive sites in {Mo(132)}, the site-specific Ce ions drive the dissociation of {Mo(2)(*)} clipping sites and finally give rise to a predictable half-closed product {Ce(11)Mo(96)}. By virtue of the tailor-made open cavity, the {Ce(11)Mo(96)} achieves high proton conduction, nearly two orders of magnitude than that of {Mo(132)}. This work offers a significant step toward the controllable assembly of POM clusters through a Ce-mediated molecular tailoring process for desirable properties.