||Structural investigation of polyoxometallates self-assembled architectures induced by crown ether supramolecular cations [an abstract of entire text]
Crystal engineering basedon polyoxometallates (POMs) hasintimate relationship with our daily lifebecause of their far ranging applications, whichinvolve catalysis, magnetism, nonlinear optics, medicine and so on. However, constructingthe desirable functional architectureis difficult,and the characteristics of building blocks should betaken into accountat first. POMs are discrete early transition metal-oxide cluster anions with many of structural characteristics. First, POMs have multiple hydrogen bonding sites, which promote them to construct versatileorganic-inorganic hybrids architecture. Second, POMs have giganticsize, whichallow them to embedlarge size of organic/supramolecular cation and construct multifunctional materials. Third, POMs with the large three dimensional structureand alternating short and long bond length distortion featuremake them be an excellent candidate to prepare chiral materials.The structurecharacteristics of POMs can be matched well with the structuralfeatures of crown ethers. Carbon atoms and donor oxygen atoms in crown ether are the potential hydrogen bonding sites, whichenable to construct self-assembledsupramolecularstructure with multiple hydrogen bonding sites POMs. Large cave of crown ethers have the ability to capture cations such as alkali metalsand organic ammonium cations, and construct large size supramolecularcations, whichmake it possible tobe filled into the large cave formed by POMs. Flexiblestructure of crown ethers allows them to construct diversesupramolecularstructures and adjust the charge of supramolecular cations by introducing different cations. Asymmetricstructural characteristicsof crown ethers improve the opportunity to construct chiral crystal with POMs.According to the structural characteristics ofPOMsand crown ethers, this thesis involvesthree aspects ofinvestigations. (1) Buildingvariouspacking structure by introducing differentsupramolecularcations and discoveringthe relationshipbetween the packing diagram and size of supramolecularcations. (2). Constructing supramolecular rotator by introducingsupramolecularcations into POMs. (3) Designing chiral crystalsby modifying POMs and crown ethers.Various supramolecular cations based on nine kindsof anilinium derivatesand three kindsof crown ethers have been constructed and were introduced into [SMo12O402–]or [PMo12O403–]. 17 POMsself-assembled architecturesbased on crown ether supramolecular cations have been synthesized. This thesis includessix chapters.Chapter one, two and six are introduction, experimental and conclusionsrespectively.In the chapter three, eight POMsself-assembled architecturesbased on different size supramolecular cations have been synthesized. The crystalline packing diagram has close relationship with the size of supramolecularcation, whichis that six monovalentsmall size supramolecular cationsencased one [SMo12O402–]and constructed hexagonal self-assembled structure, and four divalent large size supramolecularcationssurrounded one [SMo12O402–]and formed a rectangular self-assembled structure. In the chapter four, supramolecular cationscomposed of DBcrown-6(DBcrown-6＝dibenzocrown-6)and(m-XAni+)(X＝F, Cl, Br or I, Ani+＝anilinium) wereintroduced into [SMo12O402–]. Disorder of halogenatom was observed at meta-position of anilinium. Supramolecular rotation in terms ofintermolecular interactionswas investigated. Weak intermolecularinteraction between (m-XAni+) cation and its adjacent ions/molecules restricted the motional freedom of the (m-XAni+) cation, whichwas proved by the potential energy calculationand dielectric measurements.In the chapter five,chiral organic-inorganic hybrids based on POMs and achiralsupramolecular cations have been designedthroughimproving the asymmetricstructureof the starting materials. Divalent [SMo12O402–]and supramolecularcation based on symmetricDBcrown-6molecule constructed the crystal 13,whichbelonged to P21/n. Crystal 14was obtained by introducing supramolecularcation based on asymmetricbenzocrown-6 (Bcrown-6)into divalent [SMo12O402–], and the crystalcrystallized in the space group Pī.Crystal 15 was prepared by introducing asymmetric supramolecular cationof[(4-BrAni+)(Bcrown-6)]into trivalent[PMo12O403–], and belonged to thechiral crystallinegroup spacePc.According to this method, two novel chiral POMs-based crystals 16 and 17have been synthesized.The research in this thesis will promote the development in the future about designing (1)diversity crystalline packing structures by introducingdifferentsize of organic cationinto certain kind of inorganic building block.(2) supramolecular rotator based on crown ether and anilinium derivativeby selecting suitable POMs to avoid the weak intermolecular interaction.(3) many of versatile and functional chiral organic-inorganic hybrids based on POMs and crown ether derivates. All these results will promote the development of crystal engineering basedon POMs.
Hokkaido University（北海道大学）. 博士(環境科学)