Controllable Assembly And Host-guest Properties Of Metal-organic Polyhedra Containing Face-capped Ligands

Metal-organic polyhedra(MOPs)as supramolecular assembly systems have abundant host-guest interactions,which showed promising application in the field such as molecular recognition,size-selective catalysis and molecular machine.The following problems still exist:(1)It's difficult to optimize the catalytic function of MOPs whose structure can be expected;(2)The supramolecular behavior between the MOPs and specific guest molecular or ions was not clear;(3)The reported method in the construction of heteroleptic complex cannot satisfy the requirement of more sophisticated functions associated with structural complexity.In this thesis,through subcomponent assembly,a diverse range of MOPs were controllable constructed from different metal ions and the tripodal or quadrupod face-capped ligands,which showed the superiority in controllable self-assembly and host-guest interaction.The relationship between the chemical structure,size,counterions of building block and the three-dimensional architecture into which it self-assembles is discussed.The new method of designing specific heteroleptic complex is explored.And the reasearch about host-guest interaction in the cavity of MOPs is done to expand the application in the field of biological and energy.The assembly of two cubes Cage 1 and 2 with an FegL6 formula were reported through the direct combination of C4-symmetric tetraphenylethylene-based ligands,different aldehyde groups and iron(II)centers.The robust metal-organic cubes are rich in ?-electron density and provide favourable interactions with the planar polycyclic aromatic hydrocarbons.Within the confined space of the host,the aromatic hydrocarbons molecules are forced closer to the redox active host,and the photoinduced electron transfer(PET)is modified into a pseudo-intramolecular pathway.Thes iron vertices within the cubes exhibit suitable redox potential and the well-modified PET is further tailored to create artificial systems for light-driven hydrogen evolution from water via the encapsulation of fluorescein dye.Control experiments based on a mononuclear compound Fe?(bpy)3(PF6)2 showed that the efficiency of Cage 2 was improved with a fourfold increase.It suggests that the increased molarity of the reaction within the confined space render these supramolecular systems superior to other relevant systems.And Cage 2 with more F1 inclusion showed a threefold enhancement in hydrogen evolution as compared to the same system in Cage 1.It was due to the host-guest inclusion changed the electron transfer pathway,which was benefit for the hydrogen production.It offered a novel pathway for the construction of efficient artificial photocatalytic hydrogen evolution systems.Through subcomponent self-assembly,new triply interlocked metal-organic catenanes Cat-1 and Cat-2 were created via self-assembly from the C3 symmetric tris(4-aminophenyl)amine groups,a bidentate 5-bipyridinealdehyde chelatlor and dynamics active zinc(II)ions in presence of BF4-and ClO4-.In presence of CF3SO3-,an isolated tetrahedron Tet-1 was formed and transfer to the interlocked species with addition of BF4-or ClO4-.The thermodynamic equilibrium constant was calculated as 7.0×104 M-2 in the precence of ClO4-.The kinetic constants of the structure transform processes from isolated tetrahedron Tet-1 to interlocked Cat-1 were also investigated by the temperature-dependence 1H NMR.The fitting curves exhibit a second-order kinetic behaviour,and the activity energy was calculated as 58 kJ/mol.Moreover,the formation of the interlocked structure Cat-3 could be driven by halide anions reached equilibrium immediately at room temperature,and unlocked to Tet-1 with the Br-or I-removed.This catch/release strategy regulates the capturing of fluorescence guest DSA.The strong binding ability for halide ions and dynamics allostery between locked/unlocked conformers efficiently promoted the elimination of bromo-hydrocarbons echoing the properties of dehalogenase enzymes.Utilizing a clever design on the basis of steric benefits and entropy driven,we realised high field and controlled construction of a heteroleptic triangular prism complex C3 by combining the triphenylamine LA,tetraphenylethylene ligand LB and zinc(II)ions by the subcomponent self-assembly.Zn-Zn distance in the triangle face of C3 is 11.9 A,and the distance between two parallel triangle face is 10.0 A.Using larger but similar configuration 1,3,5-triphenylbenzene ligand LC in accordance with tetraphenylpyrene LD or tetraphenylporphyrin ligands LE,two new heteroleptic triangular prisms C6 and C8 were successfully achieved via subcomponent assembly under same design idea which expand the assembly method to construct metal-coordination driven dynamic heteroleptic architectures.Zn-Zn distances in the triangle face of C6 and C8 are 14.6 A,and the distances between two parallel triangle face are 13.7 A and 15.1 A,respectively.It offered novel method for achieving the more sophisticated functions associated with structural complexity.