Dimensionality Alteration and Intra- versus Inter-SBU Void Encapsulation in Zinc Phosphate Frameworks

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystallography

Background:

• 4,4'-Bipyridine-N-oxide (BIPYMO) is an underutilized linker in coordination polymer synthesis.
• Double-four-ring (D4R) zinc phosphate clusters offer potential for novel framework construction.

Purpose of the Study:

• To synthesize and characterize novel framework coordination polymers using BIPYMO and D4R zinc phosphate clusters.
• To investigate the encapsulation capabilities of the resulting frameworks for ions and small molecules.
• To explore the structural diversity and host-guest properties of these new materials.

Main Methods:

• Solvothermal synthesis involving zinc acetate, substituted diisopropylphenyl phosphate ligands (X-dippH2), and BIPYMO.
• Synthesis using preformed D4R cubanes [Zn(X-dipp)(DMSO)]4 and BIPYMO.
• Single-crystal X-ray diffraction for structural elucidation.
• In situ generation and isolation of host-guest complexes.

Main Results:

• Novel 2D coordination polymer networks [Zn4(X-dipp)4(BIPYMO)2]n were successfully synthesized.
• The frameworks exhibit distinct intra-D4R and inter-D4R voids suitable for encapsulation.
• Framework 6 represents the first structurally characterized fluoride-ion-encapsulated polymeric coordination compound/MOF.
• Framework 2 demonstrated selective host-guest behavior, encapsulating benzil via π-π interactions.

Conclusions:

• BIPYMO is an effective linker for constructing D4R zinc phosphate-based coordination polymers with diverse network topologies.
• The synthesized frameworks possess tunable voids for selective ion and small molecule encapsulation.
• This work expands the scope of metal-organic frameworks and coordination polymers for host-guest chemistry applications.