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

Abstract

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 W 24 Fe 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]: (C 2 H 8 N) 10 Na 2 [H 6 Fe(O 2 )W 24 O 82 (H 2 O) 25 ] (1, {W 24 Fe}), (C 2 H 8 N) 72 Na 16 [H 16 Co 8 W 200 O 660 (H 2 O) 40 ] (2, {W 200 Co 8 }), (C 2 H 8 N) 72 Na 16 [H 16 Ni 8 W 200 O 660- (H 2 O) 40 ] (3, {W 200 Ni 8 }) and (C 2 H 8 N) 14 [H 26 W 34 V 4 O 130 ] (4, {W 34 V 4 }), along with many other known species, for example simple Keggin clusters and 1D {W 11 M 2+ } chains.