Synthesis of coordination polymers (CPs), driven by metal-directed self-assembly, represents a fascinating advance in supramolecular chemistry.1 For example, polyoxometalates (POMs) such as monolacunary Dawson anions (MDAs), characterised by desirable redox and catalytic properties,2 may conveniently interlink to form CPs after due functionalisation with metal-coordinating tethers.3 However, the process remains difficult to control: a promising, yet scarcely explored alternative is that of pre-synthesising smaller POM-based 2D coordination oligomers (akin to supramolecular building blocks), and allowing these to self-assemble into finite-size nanostructures at a later stage.4,5 In the present communication, we report our studies one such building block, occurring as a supramolecular triangle or square, which indeed forms nanoaggregates in solution. Triangles and squares consist of, respectively, 3 or 4 interlinked MDAs (modified from [P2W17O61]10-), brought together by Iron(II). To enable its coordination, the lacuna of each MDA is aptly equipped with two long alkynylterpiridine linkers, bound to it via a [−Si2+—O—Si2+−] anchorage. Using density functional theory (DFT) to treat MDAs, and tight-binding DFT to treat linkers, we thus carry out multi-level quantum mechanical calculations on the two polygons: upon comparing our computational results with spectroscopic data, we crucially identify which of the two blocks preferentially participates in aggregation. (1) Yamada, T.; Otsubo, K.; Makiura, R.; Kitagawa, H. Chem. Soc. Rev. 2013, 42, 6655-6669. (2) Song, Y.-F.; Tsunashima, R. Chem. Soc. Rev. 2012, 41, 7384-7402. (3) Proust, A.; Matt, B.; Villanneau, R.; Guillemot, G.; Gouzerh, P.; Izzet, G. Chem. Soc. Rev. 2012, 41, 7605-7622. (4) Santoni, M.-P.; Hanan, G. S.; Hasenknopf, B. Coord. Chem. Rev. 2014, 281, 64-85. (5) Izzet, G.; Macdonell, A.; Rinfray, C.; Piot, M.; Renaudineau, S.; Derat, E.; Abécassis, B.; Afonso, C.; Proust, A. Chem. - Eur. J. 2015, in press.

Of triangles and squares: Hierarchical self-assembly of interlinked polyoxometalates

251st National Meeting (2016)

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