Coding the Assembly of Polyoxotungstates with a Programmable Reaction System

Chemical transformations
are normally conducted in batch or flow mode, thereby allowing the
chemistry to be temporally or spatially controlled, but these approaches
are not normally combined dynamically. However, the investigation
of the underlying chemistry masked by the self-assembly processes
that often occur in one-pot reactions and exploitation of the potential
of complex chemical systems requires control in both time and space. Additionally, maintaining
the intermediate constituents of a self-assembled system “off
equilibrium” and utilizing them dynamically at specific time
intervals provide access to building blocks that cannot coexist under
one-pot conditions and ultimately to the formation of new clusters.
Herein, we implement the concept of a programmable networked reaction
system, allowing us to connect discrete “one-pot” reactions
that produce the building block­{W11O38} ≡
{W11} under different conditions and control, in real time,
the assembly of a series of polyoxometalate clusters {W12O42} ≡ {W12}, {W22O74} ≡ {W22} 1a, {W34O116} ≡ {W34} 2a, and {W36O120} ≡ {W36} 3a, using pH and ultraviolet–visible monitoring. The programmable
networked reaction system reveals that is possible to assemble a range
of different clusters using {W11}-based building blocks,
demonstrating the relationship between the clusters within the family
of iso-polyoxotungstates, with the final structural motif being entirely
dependent on the building block libraries generated in each separate
reaction space within the network. In total, this approach led to
the isolation of five distinct inorganic clusters using a “fixed”
set of reagents and using a fully automated sequence code, rather
than five entirely different reaction protocols. As such, this approach
allows us to discover, record, and implement complex one-pot reaction
syntheses in a more general way, increasing the yield and reproducibility
and potentially giving access to nonspecialists.