Exploring the Molecular Growth of Two Gigantic Half‐Closed Polyoxometalate Clusters {Mo₁₈₀} and {Mo₁₃₀Ce₆}

Abstract

Understanding the process of the self‐assembly of gigantic polyoxometalates and their subsequent molecular growth, by the addition of capping moieties onto the oxo‐frameworks, is critical for the development of the designed assembly of complex high‐nuclearity cluster species, yet such processes remain far from being understood. Herein we describe the molecular growth from {Mo150} and {Mo120Ce6} to afford two half‐closed gigantic molybdenum blue clusters {Mo180} (1) and {Mo130Ce6} (2), respectively. Compound 1 features a hat‐shaped structure with the parent wheel‐shaped {Mo150} being capped by a {Mo30} unit on one side. Similarly, 2 exhibits an elliptical lanthanide‐doped wheel {Mo120Ce6} that is sealed by a {Mo10} unit on one side. Moreover, the observation of the parent uncapped {Mo150} and {Mo120Ce6} clusters as minor products during the synthesis of 1 and 2 strongly suggests that the molecular growth process can be initialized from {Mo150} and {Mo120Ce6} in solution, respectively.

Ligand‐Directed Template Assembly for the Construction of Gigantic Molybdenum Blue Wheels

“…There are also six l ‐ornithine ligands attached on six {Mo 2 } units in 4 a 1 . Among them, two pairs of l ‐ornithine are orientated in tail‐to‐tail mode, with the terminal amino groups pointing to each other, while the remaining two are arranged freely . Similar to 1 – 3 , the positively charged l ‐ornithine ligands not only serve as charge buffers to glue the anionic {Mo 36 } template and {Mo 150 } host together, but also form a multiplicity of N−H⋅⋅⋅O (2.7642(1)–3.7894(2) Å) and C−H⋅⋅⋅O (2.7862(1)–3.5290(2) Å) hydrogen bonds with both the terminal and bridging O atoms on {Mo 36 }, to further stabilize the aggregate (Figure S9).…”

“…l ‐ornithine was initially introduced into a standard version of the lanthanide‐doped Mo Blue synthesis system (see SI for details), to establish whether it could assist in trapping an “intrinsic” template that directs the self‐assembly process. Crucially, no preformed anion templates, as established in previous studies, such as the Keggin‐type {M 12 } or Dawson‐type {M 18 } were added, yet crystals of 1 were obtained in two weeks.…”

Ligand‐Directed Template Assembly for the Construction of Gigantic Molybdenum Blue Wheels

“…[9a] There are also six l-ornithine ligands attached on six {Mo 2 }u nits in 4a 1 .A mong them, two pairs of l-ornithine are orientated in tail-to-tail mode,w ith the terminal amino groups pointing to each other, while the remaining two are arranged freely. [10] Similar to 1-3,t he positively charged…”

“…Herein we describe the template-based self-assembly of as eries of Mo Blue (MB) wheels showing as tructural evolution 1-4.T hese compounds are formed by using l-ornithine to direct the assembly electrostatically and via hydrogen bonding to stabilize the template&host architecture The{ Mo 17 }u nit is isolated for the first time,a lthough its framework has been seen previously in the {Mo 36 }cluster.All compounds were characterized crystallographically and the formulae were determined using an array of techniques (see SI). Compounds 1-4 can be formulated as: l-ornithine was initially introduced into as tandard version of the lanthanide-doped Mo Blue synthesis system (see SI for details), [10] to establish whether it could assist in trapping an "intrinsic" template that directs the self-assembly process.C rucially,n op reformed anion templates,a se stablished in previous studies,s uch as the Keggin-type {M 12 }o r Dawson-type {M 18 }w ere added, yet crystals of 1 were obtained in two weeks.Single-crystal X-ray structure analysis of 1 reveals ah ost-guest structure 1a in which a-[Mo 8 O 26 ] 4À ({Mo 8 }) is encapsulated by the {Mo 124 Ce 4 }h ost ( Figure 1). [11] {Mo 124 Ce 4 }i sc omposed of 12 {Mo 8 }u nits,8{ Mo 2 }u nits,1 2 {Mo 1 }u nits and 4{ Ce(H 2 O) 5 }u nits functionalized by l-ornithine ligands on the inner surface.T wo Ce 3+ ions are located on the upper rim and separated by one {Mo 2 }u nit while another two are situated on the opposite side and separated by two {Mo 2 }units,giving rise to an elliptical wheel.…”

Controlling the Reactivity of the [P8W48O184]40− Inorganic Ring and Its Assembly into POMZite Inorganic Frameworks with Silver Ions

“…[1] Over the years many synthetic strategies have been developed to control the self-assembly of the POMs as effective anionic molecular inorganic building blocks. [2,3] One of the most recent successes of this strategy was made possible by using the superlacunary cyclic heteropolyanion [P 8 W 48 O 184 ] 40À (abbreviated as {P 8 W 48 }) as ab uilding block for the construction of intrinsically porous all-inorganic framework materials,n amed POMzites. [4] Polyoxometalatebased framework materials,o rP OMzites,a re an emerging class of configurable all-inorganic porous materials.…”