Lanthanide-organic Hybrid Materials Based On Preyssler-type Polyoxometalates: Synthesis,crystal Structures And Properties

Polyoxometalates?POMs?-based inorganic-organic hybrid materials have been attracted much attention due to their wide applications in the fields of magnetism,catalysis,biomedicine,and nonlinear optics.POMs building units are crucial for the construction of extended structural compounds with various functionalities.Preyssler-type POMs show unique and outstanding properties such as large volume,large amount of bridge oxygen atoms and terminal oxygen atoms on the surface,high negative charge,and strong stability in acidic or alkaline solutions.Thus the design and synthesis of novel inorganic-organic hybrid materials based on Preyssler-type POMs building units as well as lanthanide organic complex remains a hot topic in POMs chemistry.In this thesis,we choose Preyssler-type POMs {P₅W₃₀} as the building unit,and it was modified by complexes of lanthanide cations featuring high coordination numbers and strong oxytropic properties.Seven crystalline extended structural compounds were successfully obtained through the hydrothermal strategy:Na₂[{Tb₂?H₂O?₆?Hina?₂}{Tb₂?H₂O?₇?Hina?₃}{Na?H₂O?P₅W₃₀O₁₁₀}]·15H₂O?1?Na₂[{Ho₂?H₂O?₈?Hina?₂}{Ho₂?H₂O?₇?Hina?₃}{Na?H₂O?P₅W₃₀O₁₁₀}]·8H₂O?2?Na[{Na?H₂O?₃}{Ce₄?H₂O?₁₅?Hina?₇}{Na?H₂O?P₅W₃₀O₁₁₀}]·19H₂O?3?Na[{K?H₂O?₆}{Pr₄?H₂O?₁₄?Hina?₇}{Na?H₂O?P₅W₃₀O₁₁₀}]·2H₂O?4?Na[{K?H₂O?₆}{Nd₄?H₂O?₁₄?Hina?₇}{Na?H₂O?P₅W₃₀O₁₁₀}]·13H₂O?5?Na[{K?H₂O?₆}{Eu₄?H₂O?₁₂?Hina?₈}{Na?H₂O?P₅W₃₀O₁₁₀}]·14H₂O?6?[{Gd?H₂O?₆}₂{Gd₄?H₂O?₁₈?pydc?₂}{Na?H₂O?P₅W₃₀O₁₁₀}]·4H₂O?7?These compounds were characterized by elemental analysis,XRD,PXRD,TGA,IR and UV-Vis.Compounds 1 and 2 show isostructural 2D monolayer configurations composed of three secondary building units: the {Ln₂?ina?₂} subunit,the {Ln₄?ina?₆} metal-chain subunit,and {P₅W₃₀}.Compounds 3-6 represent isostructural 2D bilayer configurations constituted by three secondary building units: the {Na} or {K} subset,the {Ln₄?ina?_n} metal-chain subset,and {P₅W₃₀}.Compound 7 remains a 3D extended configuration built by the {Gd₂} subset,the {Gd₄?pydc?₂} metal-chain subset,and {P₅W₃₀}.It is worth noting that compounds 3-6 are first examples of 2D bilayer structures in the Preyssler-type POMs-based extended crystal materials.Their successful synthesis enriches the structure types of Preyssler-type POMs-based crystal materials.The results of fluorescence texts reveal that the photoluminescence properties of compounds 1 and 6 are derived from the characteristic emission of Tb³⁺and Eu³⁺ions,respectively.