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Advances in polyoxometalate (POM) self-assembly chemistry are always accompanied by new developments in molecular blocks. The exploration and discovery of uncommon building blocks offer great possibilities for generating unprecedented POM clusters. An intriguing Sb III -W VI -cotemplated antimonotungstate [H 2 N(CH 3 ) 2 ] 11 Na[SbW 9 O 33 ]Er 2 (H 2 O) 2 Sb 2 [SbW VI W 15 O 57 ]·22H 2 O ( 1 ) was synthesized, which comprises a classical trivacant Keggin [SbW 9 O 33 ] 9- ({SbW 9 }) fragment and an unclassical lacunary Dawson-like [SbW VI W 15 O 57 ] 15- ({SbW VI W 15 }) subunit. Notably, the Dawson-like {SbW VI W 15 } subunit is the first example of a [SbO 3 ] 3- and [W VI O 6 ] 6- mixed-heteroatom-directing POM segment. Hexacoordinated [W VI O 6 ] 6- can not only serve as the heteroatom function but its additional oxygen sites can also link to lanthanide, main-group metal, and transition-metal centers to form the innovative structure. {SbW VI W 15 } and {SbW 9 } subunits are joined by the heterometallic [Er 2 (H 2 O) 2 Sb 2 O 17 ] 22- cluster to give rise to an asymmetric sandwich-type architecture. To further realize its potential application in electrochemical sensing, a conductive 1 @rGO composite was obtained by the electrochemical deposition of 1 with graphene oxide (GO). Using a 1 @rGO-modified glassy carbon electrode as the working electrode, an electrochemical biosensor for detecting the antidepressant drug paroxetine (PRX) was successfully constructed. This work can provide a viable strategy for synthesizing mixed-heteroatom-directing POMs and demonstrates the application of POM-based materials for the electrochemical detection of drug molecules.

Template-directed assembly of giant cluster-based nanomaterials is an everlasting theme in cluster science. In this work, ethylenediamine tetramethylphosphonic acid [H 8 EDTPA = (POCH 2 (OH) 2 ) 4 C 2 H 4 N 2 ] and [B-α-SbW 9 O 33 ] 9- were, respectively, used as an organic template and an inorganic template to prepare an organophosphonic acid-regulating P V -Sb III -heteroatom-inserted polyoxotungstate aggregate [H 2 N(CH 3 ) 2 ] 5 Na 11 H 9 [CeW 4 O 10 (HEDTPA)SbW 15 O 50 ][B-α-SbW 9 O 33 ] 2 ·36H 2 O ( 1 ). Noteworthily, organophosphonic acid ligand not only works as an organic template leading to the assembly of a [HEDTPASbW 15 O 50 ] 14- building block but also further bridges the sandwich-type [CeW 4 O 10 (B-α-SbW 9 O 33 ) 2 ] 11- entity. To extend its potential application in electrochemical sensing properties, we prepared a three-dimensional 1 @EGO composite (EGO = reduced graphene oxide functionalized by ethylenediamine) with porous architecture and a prominent conducting ability. Furthermore, the 1 @EGO composite was explored as a modification material for glassy carbon electrodes to build a dual-signal readout electrochemical aptasensor for carcinogens, which shows much better detection performance for aflatoxin B1 compared with traditional single-signal biosensors.