Assemblies based on the directing effect of non-classical W18 anionic clusters and the rod-like trans-1,2-di-(4-pyridyl)-ethylen (bpe)

Two polyoxometalate (POM) supramolecular assemblies based on W18 clusters and the rigid organic trans-1,2-di-(4-pyridyl)-ethylen (bpe) have been synthesized and fully characterized, namely (H2bpe)3.5H2[SbW18O60].5H2O (1), and (H2bpe)5[Ni4(AsW9O34)2(H2O)2].3H2O (2). Compounds 1-2 are formed from organic bpe cations and different polytungstate anions: pseudo-Dawson-type [SbW18O60]9- in 1 and sandwich-type [Ni4(H2O)2(AsW9O34)2]10- in 2. Both of compounds 1-2 crystallize in a low-symmetrical space group of P-1 and consist of a complicated supramolecular network based on non-covalent intermolecular weak interactions, including hydrogen bonding and π...π stacking. The multipoint hydrogen bonding interactions constitute the structural feature in two supramolecular frameworks. The UV-vis, fluorescence and electrochemistry properties are also studied. -- Graphical abstract: Two polyoxometalate-based supramolecular assemblies built upon W18 clusters and the rigid organic trans-1,2-di-(4-pyridyl)-ethylen (bpe) have been synthesized and characterized. Research highlights: → Sb3+ has a larger ionic radius to prevent the formation of the sandwich-type polyoxometalate cluster. → Non-covalent interactions play important roles in the self-organization process. → Polyanion can structure the conjugated organic molecule into a parallel and ordered arrangement. → Polyanion-based hybrid is a potential candidate in the modified material for electrode.