Ab Initio Chemical Synthesis of Designer Metal Phosphate Frameworks at Ambient Conditions

Abstract

Stepwise hierarchical and rational synthesis of porous zinc phosphate frameworks by predictable and directed assembly of easily isolable tetrameric zinc phosphate [Zn(dipp)(solv)]4 (dippH2 = diisopropylphenyldihydrogen phosphate; solv = CH3OH or dimethyl sulfoxide) with D4R (double-4-ring) topology has been achieved. The preformed and highly robust D4R secondary building unit can be coordinatively interconnected through a varied choice of bipyridine-based ditopic spacers L1-L7 to isolate eight functional zinc phosphate frameworks, [Zn4(dipp)4(L1)1.5(DMSO)]·4H2O (2), [Zn4(dipp)4(L2)1.5(CH3OH)] (3), [Zn4(dipp)4(L1)2] (4), [Zn4(dipp)4(L3)2] (5), [Zn4(dipp)4(L4)2] (6), [Zn4(dipp)4(L5)2] (7), [Zn4(dipp)4(L6)2] (8), and [Zn4(dipp)4(L7)2] (9), in good yield. The preparative procedures are simple and do not require high pressure or temperature. Surface area measurements of these framework solids show that the guest accessibility of the frameworks can be tuned by suitable modification of bipyridine spacers.

A [4+2] Condensation Strategy to Imine‐Linked Single‐Crystalline Zeolite‐Like Zinc Phosphate Frameworks

“…The presence of a single resonance in the CP‐MAS 31 P NMR spectra of 3 – 6 at around δ ≈4 ppm reveals the structural integrity of the cubane core in the final framework (Figure b, Figures S9–S13, Supporting Information, and Table ). The relative stoichiometry of the constituents of the framework is established by solution 1 H NMR spectroscopy through dissolution of 3 – 6 in [D 6 ]DMSO, to produce the parent cubane [Zn(dipp)(DMSO)] 4 ( 1 ) and the respective Schiff‐base linkers in solution. The spectra obtained further confirm the presence of −N=CH− linkages in 3 – 6 (Figures S14–S19, Supporting Information).…”

“…The fact that four zinc centers occupying the alternate corners of the cubane in 1 are highly Lewis acidic has led to the successful joining of these cubanes by structurally diverse substituted pyridines– or ditopic spacer ligands, such as 4,4′‐bipyridine (Scheme ) . An alternative strategy to build porous solids starting from D4R zinc phosphate cubanes would be by diligently combining the principles of both MOF and COF chemistries.…”

Network Formation via Anion Coordination: Crystal Structures Based on the Interplay of Non-Covalent Interactions

“…To this purpose, we are now considering the rigid and planar tetrazine molecule 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine (L, Figure 1 c), bearing two pyridine residues attached through their 4 position. This molecule, which is known for its use in the construction of metal–organic frameworks (MOFs) and coordination polymers [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ], has never arouse interest as anion receptor, although a few L–anion contacts were discernible in a few crystal structures [ 24 , 25 , 26 ]. Nevertheless, while the neutral L appears to be an effective element for the construction of MOFs, protonated forms of L combine structural and electronic characteristics that are promising for the formation of interesting supramolecular assemblies with anions.…”

Hexanuclear iron(iii) α-aminophosphonate: synthesis, structure, and magnetic properties of a molecular wheel

“…11,12 Molecular phosphonates have potential applications as precursors (building-blocks) for the synthesis of new organic-inorganic materials with predicted properties. [13][14][15] However, due to the facile formation of polymeric structures, synthesizing molecular metal phosphonates is a challenging task. Usually there are two main synthetic strategies for their preparation.…”