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Amphiphilic Platinum Complexes With Aggregation-induced Emission (AIE) Properties And Their Circularly Polarized Luminescence Properties

Posted on:2022-10-03Degree:MasterType:Thesis
Country:ChinaCandidate:N LiFull Text:PDF
GTID:2511306341483084Subject:Material Science
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Circularly polarized luminescence(CPL)is the phenomenon of left-handed or right-handed CPL emitted from chiral luminescence system with different intensity by photon or electron excitation.In recent years,CPL optical materials with both chirality and luminescence properties have become a new kind of materials showing broad application prospects in 3D displays,optical information storage and processing,liquid crystal display,molecular optical switches,biological probes,asymmetric synthesis and other fields.In CPL systems,quantum efficiency(?PL)and dissymmetry factor(glum)are two vital parameters to evaluate the properties of CPL materials for promoting their application prospects.Therefore,developing a simple and effective strategy to construct chiral luminescent materials with excellent glum and ?PL and further expand their applications is still an important research focus in this field.Compared to the other types of CPL materials,transition metal complexes with phosphorescent emission characteristics have gradually become an excellent choice for the construction of CPL materials due to their long luminescence lifetime,high luminescence efficiency and adjustable spectroscopic properties.In addition,the assembly and luminescence properties of platinum complexes are dynamically responsive to the changes of microenvironment such as temperature,light and mechanical force.Therefore,the self-assembly behavior of platinum complexes can be tuned by external stimuli and then the CPL properties of platinum complexes can be dynamically regulated.It provides a novel strategy for preparing CPL materials with excellent performances.In view of the above,an amphiphilic platinum complex with chiral centers and aggregation-induced emission(AIE)property was designed and synthesized by using a strategy of chemical synthesis plus self-assembly.The combination of the high luminescence efficiency of platinum complex and its dynamic response to microenvironment changes resulted in excellent performances.By changing the system temperature,the weak intermolecular interactions,such as Pt…Pt interaction,hydrophobic interaction,and hydrogen bonding between the tetraethylene glycol chains and water molecules,can be adjusted well to regulate the luminescence and CPL properties of platinum complexes,and ?PL and glum values of platinum complexes can be synchronously amplified.In particular,the thesis is divided into following two parts:The first part represents the design,synthesis,characterization,self-assembly behavior and photophysical properties of an amphiphilic platinum complex L-Pt with ether oxygen chain as hydrophilic tail chain and tridentate ligand as hydrophobic head group.The obtained L-Pt was characterized by LC-MS,1H NMR,13C NMR,FT-IR and elemental analysis.By changing the ratio and temperature of water/1,4-dioxane mixed solution in the system,the weak intermolecular interactions can be effectively regulated,and ?PL and glum of L-Pt can be simultaneously amplified.On this basis,the supramolecular self-assembly behavior and photophysical properties of L-Pt were studied by using UV-vis spectra,fluorescence spectra,CD spectra and CPL spectra.The results reveal that when the molecules are dissolved in 90%water/1,4-dioxane solution,the L-Pt produces AIE phenomenon,and the fluorescence intensity is enhanced by 99.4 times compared to the pure solution of 1,4-dioxane,greatly improving the luminescence efficiency of L-Pt.Indeed,the increase in temperature results in further self-assembly of L-Pt molecules.The mixture system shows remarkable increase of CD and CPL signals,|glum| value as high as 0.058,which indicates that the temperature has a significant effect on the aggregation pattern and supramolecular chirality of the L-Pt,and hydrogen bonding,Pt…Pt interaction and hydrophobic interaction are the main driving forces for the enhancement of CPL signal.In order to further optimize the luminescence properties of the CPL material and expand its application fields,the solid fluorescent film of L-Pt was successfully fabricated which is described in the second part of this thesis.The effect of L-Pt aggregation state on its CPL properties was studied by UV-Vis spectroscopy,fluorescence spectroscopy,CD and CPL spectroscopy.The results show that CPL behavior of the synthesized amphiphilic platinum complex L-Pt is closely related to its aggregation mode,and the amphiphilic platinum complex in solid film has more excellent glum,|glum| value as high as 0.19,which is the maximum in metal complex system reported so far.Further studies are being carried out in order to examine the self-assembly mechanism of L-Pt in solid film with chiral enhancement.
Keywords/Search Tags:Circularly polarized luminescence, self-assembly, amphiphilic platinum complex, supramolecular chirality
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