The Design，Synthesis And Mechanical Force Induced Fluorescence Swicthing Of Cyano Alkadiene Based D-A Compounds

In recent years,organic solid fluorescence molecules have attracted much attention due to its superior optical physical properties.It has wide application in many areas,such as organic electroluminescent（OLEDs）,organic light-emitting field-effect transistor（OLEFET）,organic fluorescence probe and fluorescence sensors.In most applications,the organic fluorescent molecules with thin film or the state of aggregation such as crystal forms are different from the single molecule luminescence,state of aggregation of organic molecules luminescent characteristics influenced by many factors,such as the dipole-dipole interaction between molecules（in）the charge transfer,energy transfer effect,and so on.Only realize the organic fluorescent molecule of the solid-state light control,to make its application in real life.Therefore,realizing the organic solid light regulation of fluorescent material,not only is a hotspot of research on modern organic optical function materials,but also a difficult problem of research.In order to further understand the relationship between the structure and performance of Organic luminescent material,and to achieve the regulation of the luminescence properties of fluorescent material,this thesis designed and synthesized D-A small molecules compounds based on the structure of the styrene acrylic organic solid light-emitting molecular system.This paper studies the external environmental factors（pressure）,state of aggregation structure of molecules and their optical link between physical properties.First,we designed and synthesized with characteristics of an AIE D-A small molecule structureβ-CN-TPA.The structure and properties were characterized,we found that switched color in the nature of the grinding force did not show up,but under the static liquid pressure presents the obvious piezo-chromic fluoresence behavior show up.Analysis result of the test of single crystal analytical molecular accumulation mode,powder X-ray diffraction and fluorescence spectrum.The piezo-chromic phenomenon under mechanical force grinding was not appear because of the strong interaction between the molecules that exist in the crystal.The situ Raman spectra further confirmed that the reason of high pressure cause piezo-chromic is subordinated bond between the molecules of enhancement and intra-molecular conformation change.And through the comparison of the fluorescent effect of isomers of the alpha-CN-TPA,cyano in compounds that replace position is different,can lead to accumulation patterns of molecular changes,thus affecting its optical physical properties of light.Then we make a change on A part of a molecule,the styrene acrylic was replaced with pyridine,to study the electron-accept group light of the physical properties of organic fluorescent molecule.We designed and synthesized organic light-emitting D-A structure of small molecules of alpha-ON-TPA and beta-ON-TPA.The material characterization of the structure and the optical performance of of alpha-ON-TPA,not only discovery with AIEE effect,also has the obvious pressure to change color.Single crystal molecular accumulation patterns and X-ray diffraction proved its obvious mechano-chromic fluoresence related to its loose,orderly crystal structure.Through the calculation of the front molecular orbital theory,we found that the cause of discoloration phenomenon is due to its apparent behavior of acid molecular excited states transition from HLCT state to the CT state.And although the beta-ON-TPA had an AIE effect obviously,but the piezochromic behavior appear but not a lot of displacement.We found that even the isomers,also have different nature of the pressure to change color,and the piezochromic behavior of with D-A part of a structure has a lot to do.Therefore,we then will be A part of the electronic absorption capability for more pairs of pyridine group,design synthesis D-A small molecules structure organic light-emitting TPA-N-N,and a portion of electronic absorption ability,will replace the base into methoxyl,design synthesis D-A small molecules structure organic light-emitting TPA-N-OCH₃,to study the piezochromic behavior and the substituent position and the relationship between the groups in polarity.TPA-N-N not only has the obvious AIE effect,but also has obvious piezochromic performance.And compound TPA-N-OCH₃ have no piezochromic performance.Via XPS spectra analysis,we found that the strong electric effect after grinding compound TPA absorption parts easier complanation,more effective conjugate degree and intra-molecular charge transfer is more obvious.By the frontier molecular orbital theory calculation,found this series compounds HOMO,LUMO energy level distribution are separation,low degree of electron cloud overlap had the characteristics of high efficiency light-emitting,and provide the conditions for preparation of high light emitting device.