Construction And Properties Of Metal Complex-Based Materials

Supramolecular chemistry focuses on the study of high-order assemblies with specific structures and functional diversity formed by molecular recognition and noncovalent interactions(hydrogen bonding,π-π stacking,electrostatic interaction,metalligand interaction and hydrophobic-hydrophobic interactions).Among them,supermolecular self-assembly has been widely explored as an important building method in supermolecular chemistry.Due to non-covalent metal-metal interactions and unique geometric coordination modes,luminescent self-assembled materials based on d8 and d10 transition metals were endowed unique luminescent properties and anisotropic orientations,which has greatly promoted the rapid development of supramolecular self-assembly,and has achieved remarkable achievements in the fields of optoelectronic devices,catalysis,data storage,information encryption,and biomedicine.Herein,this thesis mainly studies on the photophysical properties and selfassembly behaviors of metal complex-based materials in solution,and further explores their potential applications in the fields of bioimaging,chiral materials,and singlemolecule conductance.This thesis mainly includes four parts as follows:(1)A series of spherical micelles(SAAu-n and EAAu-m)were prepared by selfassembled process through electrostatic connection of cationic binuclear gold(Ⅰ)complexes(Au-1 and Au-2)with poly(styrene-block-acrylate sodium)(Sn-b-Am)and poly(ethylene oxide-block-acrylate sodium)(En-b-Am),respectively.Keeping the degree of polymerization of the neutral block(Sn and En)unchanged,the size of both the spherical micelles and cores gradually decreased with increasing of the molecular weight of the Am block.Moreover,stronger luminescence was observed in intensity due to the increasing of Au(Ⅰ)…Au(Ⅰ)interaction.In addition,these metallosupramolecular polymer micelles could be used for cell imaging as bioluminescent probes.(2)Gold(Ⅰ)-containing polymeric composites have been constructed in water by coupling poly(ethylene glycol)-block-poly-(L-glutamic sodium)(PEGn-b-PLGSm)with bis(1,1’-dimethyl-3,3’-propylenediimidazol-2,2’-diylidene)digold(Ⅰ)dibromide(Au-1).Keeping the degree of polymerization of the neutral block(PEGn)unchanged,both the phosphorescence intensity and quantum yield of the composites would increase gradually with the molecular weight of the PLGSm block.Meanwhile,the chirality transfer and amplification from the chiral block copolymers to the gold(Ⅰ)complexes were demonstrated.These phenomena were closely related to the intramolecular aurophilic Au(Ⅰ)…Au(Ⅰ)interactions in Au-1.In addition,this is the first example of chiral composites exhibiting circularly polarized luminescence(CPL)emissions by self-assembly based on gold(Ⅰ)complexes and chiral block copolymers.(3)The rod-like nanomicelles(EnAm-(la-3))have been constructed from cation polypyridine/cyclometallic ligand platinum(Ⅱ)complexes(la-3)and poly(ethylene oxide-block-acrylate sodium)(En-b-Am)via electrostatic self-association.In the resulting micelles,platinum(Ⅱ)-based ionic microdomains were regarded as the micellar core and a poly(ethylene oxide)neutral block as the micellar shell.Keeping the degree of polymerization of the neutral block(En)unchanged,the short rod-like micelles gradually increased in size with increasing the molecular weight of the Am block,resulting in enhanced phosphorescence intensity and increased quantum yield.After screening these composite micelles,we found that strong near-infrared phosphorescence emissions originated from 3MMLCT excited state due to Pt(Ⅱ)…Pt(Ⅱ)and π-π stacking interactions.In addition,the cytotoxicity screening result showed that the micelle of EnAm-le possess strong cytotoxicity to human liver cancer cell(HepG2 and LM3)together with intensely near-infrared phosphorescent emissions.(4)A novel class of sulfur-containing platinum(Ⅱ)complexes(Sla-Slc and S2S4)were obtained by introducing thioether and thiol groups into platinum(Ⅱ)complexes.Upon adding different contents of a poor solvent to a good solvent,their unique color and spectral characteristics appeared and derived from intermolecular Pt(Ⅱ)…Pt(Ⅱ)and π-π stacking interactions.The interesting morphological transitions were caused by changing the solvent composition,which was the result of a subtle balances between multiple non-covalent interactions(hydrophobic-hydrophobic,Pt(Ⅱ)…Pt(Ⅱ)and π-π stacking interactions).In addition,the excellent conductance values of their single-molecule stacking junctions drived by intermolecular Pt(Ⅱ)…Pt(Ⅱ)and π-π stacking interactions could be measured using the mechanically controllable break junction technique.This is a first study of the charge transport properties of platinum(Ⅱ)complex related single-molecule conductance.