A Modular Programmable Inorganic Cluster Discovery Robot for the Discovery and Synthesis of Polyoxometalates

The exploration of complex multi-component chemical reactions leading to new clusters, where discovery requires both molecular self-assembly and crystallization, is a major challenge. This is because the systematic approach required for an experimental search is limited when the number of parameters in a chemical space becomes too large, restricting both exploration, and reproducibility. Herein, we present a synthetic strategy to systematically search a very large set of potential reactions, using an inexpensive, high-throughput platform; modular in terms of both hardware and software, and capable of running multiple reactions with in-line analysis; for the automation of inorganic and materials chemistry. The platform has been used to explore several inorganic chemical spaces to discover new, and reproduce known, tungsten-based, mixed transition-metal polyoxometalate clusters, giving a digital code allowing the easy repeat synthesis of the clusters. Among the many species identified in this work, most significantly is the discovery of a novel, purely inorganic W₂₄Fe^III-superoxide cluster formed under ambient conditions. The Modular Wheel Platform (MWP) was then employed to undertake two chemical space explorations producing compounds [1-4]: (C₂H₈N)₁₀Na₂[H₆Fe(O₂)W₂₄O₈₂(H₂O)₂₅] (1, {W₂₄Fe}), (C₂H₈N)₇₂Na₁₆[H₁₆Co₈W₂₀₀O₆₆₀(H₂O)₄₀] (2, {W₂₀₀Co₈}), (C₂H₈N)₇₂Na₁₆[H₁₆Ni₈W₂₀₀ O_660-(H₂O)₄₀] (3, {W₂₀₀Ni₈}) and (C₂H₈N)₁₄[H₂₆W₃₄V₄O₁₃₀] (4, {W₃₄V₄}), along with many other known species, for example simple Keggin clusters and 1D {W₁₁M²⁺} chains.