Synthesis,Photophysics And Self-assembly Properties Of Amphiphilic Schiff Base-Pt(Ⅱ) Complexes

Supramolecularly assembled functional materials are constructed by a"bottom-up"assembly method based on various non-covalent interactions and arecharacterized by high-ordered structures.Apart from the design and synthesis of various organic supramolecular scaffolds,the transition metal complexes as building blocks for the construction of higher-order supramolecular structures has attracted increasing attention.The diversity of coordination numbers in metal complex systems and the diversity of transition metal centers provide the basis for the diverse regulation of coordination geometry.Platinum(Ⅱ)complexes are an important class of transition metal complexes with a d~8 electron configuration and a square planar geometry.The spin-orbit coupling between the metal and the ligand unit gives the resulting organic Pt(Ⅱ)complexes a wealth of photophysical significance.Single-and multi-dentate(bi-,tri-and tetra-dentate)organoplatinum(Ⅱ)complexes have been used to construct ordered supramolecular assemblies.The multi-dentate organic complexes terpyridine platinum(Ⅱ)as well as bzimpy platinum(Ⅱ)complexes systems have been receiving extensive attention.Highly ordered supramolecular materials are constructed by changes in temperature,solvent composition,and metal gel formation.The aggregation process is accompanied by drastic color and spectral changes,which can be used for the development of sensing systems.Self-assembly studies of terpyridyl platinum(Ⅱ)as well as bzimpy platinum(Ⅱ)complex systems have been extended to include many functionalized metal amphiphiles.Schiff base platinum(Ⅱ)complexes are easy to synthesize and structurally modify,thermally stable,with rich photophysical properties as well as square planar geometry,and can be used in organic light-emitting diodes(OLEDs),dye-sensitized solar cells,and energy storage.However,schiff base Pt(Ⅱ)complexes need to be further explored in the field of amphiphilic self-assembled functional molecular materials.Based on the self-assembly studies of the amphiphilic systems of terpyridyl platinum(Ⅱ)and bzimpy platinum(Ⅱ)complexes and the photophysical properties and planar geometry properties of schiff base Pt(Ⅱ)complexes,this paper designs amphiphilic schiff base metal Pt(Ⅱ)complexes to investigate their photophysical properties and self-assembly behavior in solution and under non-covalent interaction forces to construct different supramolecular nanoassemblies materials.First,we designed and synthesized schiff base metal Pt(Ⅱ)complexes modified with alkyl chains and triethylene glycol chains using schiff base metal Pt(Ⅱ)complex1 as the core moiety in this thesis.The n-octyl,n-dodecyl,n-hexadecyl and triethylene glycol chains were modified in complexes 2–5.The n-octyl,n-dodecyl,n-hexadecyl and triethylene glycol chains were modified in complexes 2–5.Complexes 6 and 7 were designed to modify two n-octyl alkyl chains,and their synthetic routes were new,and the final synthesis of complexes 1–7 was performed by one-pot method.The complexes were obtained by column chromatography as well as recrystallization,and tested by NMR hydrogen and carbon spectroscopy,MALDI-TOF mass spectrometry,and elemental analysis,and determined to be consistent with the structure of the designed complexes 1–7.Secondly,the crystal structure of complex 1 was obtained by mixing acetone and water in solvent,and it was determined that the molecules of complex 1 have a planar square structure and crystal stacking mode,and the Pt···Pt,π-πinteractions were found to exist in the intermolecular stacking of complex 1.The spectral properties of complexes 1–7 were investigated with the effect of triethylene glycol chains and alkyl chains on the spectral properties.The relationship between the spectral changes and the self-assembly behavior of complexes 1–7 in different ratios of acetone and water mixed solvents was investigated.Dynamic light scattering was used to further determine the aggregation of the complexes under mixed solvents.The morphological structures of the complexes were observed by transmission electron microscopy under mixed solvent versus single solvent conditions.Then,the assembly of complexes 2–7 in mixed solvents was tested by X-ray diffraction to analyze the different molecular structures in the same solvents,and further studied how the molecules of the complexes stacked with each other by 2D NOESY nuclear magnetic hydrogen spectroscopy.Finally,a model for the assembly and stacking of complexes 2 and 3 was proposed based on the above analysis results.This work realized the modification of amphiphilic schiff base platinum(Ⅱ)complex 1 by adding triethylene glycol chains or alkoxy chains to make the complexes more amphiphilic and achieve different morphologies of the assembled materials.The alkyl chain chain length has an important role in regulating the assembly properties.The n-octyl alkyl chain was found to be a more suitable chain length to achieve an ordered and stable nanostructure.The number of triethylene glycol chains and n-octyl alkyl chains were varied to achieve repeated transformation of the assemblies from spherical to sheet shapes.Therefore,the amphiphilic modulation of schiff base platinum(Ⅱ)complexes enables the construction of supramolecular assemblies with different morphologically ordered materials,providing experience in the construction of complex supramolecular assemblies structural materials by amphiphilic schiff base platinum(Ⅱ)complexes and an in-depth understanding of material assembly stacking.