Construction And Properties Of Metal Organic Cage Based On Truxene

Metal organic cages are discrete three-dimensional supramolecular metal organic assemblies formed by coordination-driven self-assembly of metal ions and organic ligands.Due to the unique three-dimensional structure of metal organic cages,its distinctive cavities can provide a controlled microenvironment for binding of the guest molecules,enabling it to be widely used in the fields of molecular recognition,gas storage and drug loading.In addition,metal organic cages have the advantages of adjustable structure and easily functionalization,and can be obtained with unique properties and functions through the rational design of ligands and the introduction of functionalized motifs.The truxene not only has good photoluminescence and two-dimensional planar chirality,but also can be modified by multi-site functionalization,which is an ideal substrate for the design and construction of functionalized metal organic cages.Based on this,this thesis introduces truxene as functionalized substrate into metal organic cages,synthesizes two ligands with the same length,angle,symmetry and chirality,and thoroughly investigates their self-sorting behavior and mechanism;in addition,photo-functional metal organic cages with stimulus response are synthesized,and realizing the reversible regulation of circularly polarized luminescence by acid-base stimulation.The research content of this thesis is divided into the following parts:Chapter one.Firstly,we have summarized the construction strategies of metal organic cages systematically,then listed the representative applications of metal organic cages in the fields of separation,catalysis and fluorescence sensing,and finally proposed the research topic based on the above discussion.Chapter two.Two ligands with the same length,angle,symmetry and chirality are designed and synthesized by modifying the ethyl and propyl chains on truxene,respectively,and these two highly similar ligands can achieve narcissistic self-sorting after coordinating with Zn²⁺.The ligand exchange experiments of propyl and ethyl cages showed that the self-sorting phenomenon attributed to the difference in thermodynamic stability between two cages.To further prove the conclusion,we have synthesized ligands of larger size based on truxene for the study of self-sorting and ligands exchange,which further confirmes the above conclusion.Finally,we performe theoretical calculations and variable temperature NMR measurements for the ligand exchange experiments of metal organic cage to further quantify the magnitude of the difference in thermodynamic stability between the two cages,and the results showed that there is indeed a large difference in the thermodynamic stability between the two cages and leads to the self-sorting phenomenon.Chapter three.The truxene ligand is designed and synthesized,and then metal organic cage with CPL is successfully constructed by coordination-driven self-assembly.Subsequently,F（?）rster resonance energy transfer（FRET）system is successfully constructed with the metal organic cage as the FRET donor and Ni R as the FRET acceptor.The wavelength of the CPL signal is redshifted from 520 nm to600 nm by FRET process.Finally,based on the reversibility of dynamic covalent bonds,the CPL signal switching of the metal organic cage and FRET system was realized by acid-based stimulation.