Homologous size-extension of hybrid vanadate capsules – solid state structures, solution stability and surface deposition

Abstract

surface on a sub-monolayer scale giving rise to a 2D supramolecular structure that is comparable to the packing arrangements of the capsules in the crystal structures.The synthesis and characterisation of metallo-supramolecular cages and molecular capsules have received significant scientific attention. 1,2In the last few decades preparative efforts were directed towards the synthesis of new cage topologies or homologous species with controllable inner cavities whose chemical, geometrical and electronic attributes may give rise to unique properties that can be exploited in homogeneous catalytic processes, size-and shape-restrictive chemical transformations, separations, drug delivery and sensing devices. 2,3Importantly, for the majority of these and other advanced applications, the stability of the assembled molecular species in solution is a key requirement. (Fig. 1). We highlight the solution stability of this class of compounds and demonstrate that individual cluster entities can be deposited on the Au(111) surface and imaged using a scanning tunneling microscope (STM).Polyoxometalates constitute an interesting class of compounds for the preparation of cages. 6 The chemistry of polyoxovanadates in aqueous reaction systems as developed by Müller, Zubieta and others is characterised by condensation reactions whereby V IV and to a certain extent V V species in predominantly square pyramidal coordination environments aggregate to form oligonuclear and polynuclear clusters. The geometrical restraints associated with the square pyramidal {OQVO 4 } building unit often lead to convex oligonuclear species

Atomically precise vanadium-oxide clusters

“…For an expansive view of the development and applications of POM-organic hybrids, the readers are referred to the following relevant review articles. [97][98][99][100][101][102] Similarly, the organofunctionalization of POVs has been reported with carboxylate [103][104][105][106][107] and phosphonate 108,109 groups (Fig. 6).…”

“…In both cases, the cluster framework is formed from mononuclear precursors in the presence of the organic ligand. Due to the high diversity of carboxylate-and phosphonate-containing organic molecules available, supramolecular structures based on POV building blocks, such as cages, [105][106][107] rings, 104 and capsules, 108,109 have all been reported. The size and shape of these structures can be tuned with a high degree of precision, allowing researchers to envision applications of these materials in chemical separation through hostguest interactions.…”

Ligand-Directed Assembly of Polyoxovanadate-Based Metal–Organic Polyhedra

“…Subsequently, remarkable hexavanadate–organic hybrid molecules were reported by Wei’s group and Hill’s group, respectively . Inspiringly, Schmitt et al made a series of interesting POV-based molecular capsules built from {V 5 O 9 } subunits and organoarsenic or organophosphonic acids . Subsequently, Zaworotko and co-workers reported a family of prominent polyvanadate-based hybrids constructed from {V 4 O 8 Cl} or {V 5 O 9 Cl} clusters and carboxylate ligands .…”

Synthesis of Some Di‐ and Tetraphosphonic Acids by Suzuki Cross‐Coupling

“…The synthesis of the V‐shaped arylphosphonate linkers 3 and 4 is especially useful with respect to the formation of molecular cage structures in conjunction with the corner forming auxiliary ligands. The concurrent use of 1 , 3 , 4 , and 5 for the preparation of MOFs would be significant to form expanding macrocycle or cage molecules following up the mechanism previously reported . Likewise, the anthracene core in 2 has significant potential to form void spaces due to the T‐shape of the central aryl core and difficulty of such linker arrangements to form dense pillared layered networks.…”