Construction And Properties Investigation Of Photo-functional Metal-organic Macrocycles

Photofunctional materials were defined as the integrations of optical materials which utilized the principle of changes of their photophysical properties to realize the detection and adjustment of incident light signals,and the transformation of energy or frequency.Photofunctional materials have attracted increasing interests due to their wide applications in energy,environmental protection,military areas,human health,telecommunications and so on.Photofunctional molecules are the most important physical basis of the photofunctional materials,and as we known,photochromic molecules and photosensitivers are two kinds of typical photofunctional molecules.In the past few decades,a variety of photofunctional supramolecular self-assemby systems have been constructed through introduction of the photofunctional molecules such as diarylethenes with photochromic properties,porphyrin and transition metal complex with photosensitive properties into the supramolecular self-assemby systems.To some extent,these photofunctional supramolecular self-assemby systems have exhibited more excellent properities than the simplex photofunctional small molecules and they showed wide range of potential applications in molecular recognition,photocatalysis,light-controlled chirality adjustment,biologics and so on.However,these reported photofunctional supramolecular self-assemby systems still face the problems such as uncontrollable properties and simplex structures.Thus,the development of photofunctional supramolecular self-assemby systems with light-controllability and the construction of novel and complex photofunctional supramolecular self-assemby systems which utilizes photosensitivers as the building blocks still remains challenging.Based on the above problems,combined with our previous work on functional metal-coordinated self-assemblies at the same time,this doctoral dissertation will center on the construction and properties investigation of the new photofunctional metal-organic macrocycles.Through reasonable structural design,on one hand,we have successfully constructed a serious of metal-organic macrocycles with light-controllability and further explored their applications on molecular ink,photodynamic therapy?PDT?etc.On the other hand,a serious of supramolecular metal-coordinated self-assemblies with complex topological structures were constructed using photofunctional molucules as the building blocks and further studies on their properties and functions were performed.The studies of this dissertation not only enriches the structural library of supramolecular coordination complexes?SCCs?,but also could integrate the advantages of supramolecular coordination complexes?SCCs?and photofunctional building blocks to reach the aim of“1+1>2”.The main content of this dissertation includes the following five chapters:In chapter one,recent developments of stimuli-responsive SCCs and the applications of photofunctional SCCs were reviewed.Then we put forward the projects in the dissertation.In chapter two,two kinds of metal-organic macrocycles with light-controlled luminescence switching were successfully constructed and it could be mainly divided into two parts.In the first part,we have realized the construction of“turn-off”photo-switchable fluorescent metallacycles.Through self-assembly of photochromic diarylethene unit and luminescent Ir complex unit,a new heterometallic macrocycle was formed,which features photoswitchable F?rster resonance energy transfer?FRET?behaviour.Thus,light-controlled luminescence switching of the Ir complex was realized,which could be further applicated in erasable molecular inks.In the second part,we have realized the construction of“turn-on”photo-switchable fluorescent metallacycles.Through the self-assembly of fluorescent diarylethene donors with the120°di-platium acceptors,a series of new photochromic metal-organic macrocycles were formed.Interestingly,the ring-open isomers of the metallacycles showed no fluorescence,but the ring-closed isomer of the metallacycles exhibited brilliant fluorescence with a relatively high quantum yield??_F=0.5?.It destroyed the limitation that metal-coordination resulted in the emission quenching of SCCs in most situations and in situ construction of highly emissive metal-organic macrocycles upon irradiation was realized.In chapter three,a new dual-stag metallacycle which integrates the porphyin photosensitiver and the diarylethene photochromic-switch was constructed through coordination-driven self-assembly.The metallacycle showed excellent photochromic property and light-controlled generation of singlet oxygen?¹O₂?was realized due to the photoswichable energy transfer from porphyrin to diarylethene.When the diarylethene was in the ring-open form,the metallacycle could efficiently generate ¹O₂.When the diarylethene was converted to its ring-closed isomer under UV irradiation,energy transfer from porphyrin to the ring-closed isomer of diarylethene occurred,resulting in the dramatic decline of the ¹O₂ generation ability of the ring-closed isomer of the metallacycle.Furthermore,to investigate the possibility of applications in biological systems,the metallacycle was encapsulated into an amphiphilic polymer mPEG-DSPE,leading to the formatin of nanoparticles,and the studies indicated that O-NPs?open form?showed a higher ¹O₂ generation ability than C-NPs?closed form?.Further in vitro and in vivo experiments both indicated that O-NPs showed stronger anti-tumor effects under irradiation than C-NPs,resulting from the higher ¹O₂ generation ability of C-NPs.Thus,for the first time,light-controlled generation of singlet oxygen was achieved in the discrete supramolecular coordination complexes?SCCs?including metallacycles or metallacages,which could be used in the light-controlled cancer cell killing.In chapter four,a series of trefoil-shaped multi-metallic macrocycles were successfully constructed for the first time through coordination-driven self-assembly and primary investigations on their applications in PDT were conducted.Self-assemby of the Ru complex containing six pyridines?as the center donor ligand?,the Ru complex containing two pyridines?as the peripheral donor ligand?and the 120°di-platium acceptors?as the linkage?in appropriate ratio led to the formation of a twisted tricyclic supramolecular structure which looks like a trefoil according to the entropy-driven self-assembly and maximum site occupancy rule.Through simply changing the peripheral donor ligands,five different trefoil-shaped multi-metallic macrocycles were obtained and the types of incorporated metal could reach three.These twisted tricyclic supramolecules were well characterized with ¹H NMR,³¹P NMR,2D NMR and ESI-TOF-MS.In addition,these multi-cyclic structures exhibited excellent luminescent property and efficient singlet oxygen generation because the building blocks of them?Ru and Ir complex?were typical photosensitizers.Furthermore,the tricyclic supramolecule whose building block showed the longest emission wavelength and the highest singlet oxygen generation ability was selected for PDT.The metallacycle was encapsulated into amphiphilic polymers mPEG-DSPE and PLGA for the formation of nanoparticles.In vitro experiments indicated the nanoparticles were mainly accumulated in lysosome and showed modest cancer cell killing ability under irradiation.In chapter five,a series of new twisted multicyclic supramolecular structures including monocyclic,bicyclic,tricyclic and tetracyclic supramolecules were successfully constructed efficiently through charge sepration.Self-assembly of the Ru complex which contains six pyridines?as the center donor ligand?,disodium terephthalate?as the peripheral donor ligand?and 90°platium acceptors in appropriate ratio led to the formation of twisted tricyclic supramolecular structure almost quantitatively.It should be noted that the strategy of charge sepration could completely rule out the formation of monocycles and oligomers in the system,providing a new method for the construction of multicyclic supramolecular coordination complexes?SCCs?.By replacing the center donor ligand into the saddle-shaped macrocyclic molecule which contains eight pyridines,a twisted tetracyclic supramolecular structure was successfully obtained through the above strategy.In addition,monocyclic and bicyclic supramolecules were readily prepared by changing the center donor ligand.The structure of these multicycles were fully characterized with ¹H NMR,³¹P NMR,2D NMR and ESI-TOF-MS.Furthermore,the two chiral isomers of the center ligand of the tricyclic supramolecule were obtained by stepwise chiral synthesis and susquently self-assembled into chiral tricyclic supramolecules.