Molecular Design,Synthesis And Properties Of Solid-solution Dual-efficient Organic Luminescent Materials

Organic luminescent materials have broad application prospects in many fields such as cell-imaging,OLED,chemical-sensing and so on.Traditional organic luminescent materials are prone to the phenomenon of aggregation-caused quenching?ACQ?,at high concentrations and in the aggregation state,the luminescence is weak or no-emitting.The rapidly developing AIE materials only emit light in the aggregation state,and emit light weakly or noemitting in the dilute solution.In order to meet the needs of application,it is of great scientific significance and application value to design and develop a new kind of luminescent materials which can emit light effectively in both solution and solid state.Based on the principle of quantum chemistry,this paper provides a molecular design strategy for solution-solid dual-state efficient emission luminescent material?DSE?.The specific work is as follows:?1?From the experimental point,the fundamental reason for the weak emitting of organic photoelectric material triphenylamine in solid state is the triplet-excitons generated by intersystem crossing are easily quenched by outside factors such as water and oxygen.Based on the analysis of the weak intermolecular interaction,it is explained that the reason of the effective emission of the twisted triphenylamine in solution is that there is a strong steric effects between the benzene rings of triphenylamine.A molecular design method for constructing DSE luminescent materials by using steric effects synergy with forbidding intersystem crossing was first proposed.The DSE literature based on triphenylamine was analyzed,and the general luminescence characteristics of DSE based on triphenylamine were summarized,such as high vibrator strength and small molecular configuration difference?RMSD?between ground state?S₀?and excited state?S₁?.?2?In order to verify the molecular design strategy for DSE luminescent materials,compounds TPA-BT,TPA-BBT and CZ-BT were synthesized.Theoretical calculation shows that the synthesized compounds have high oscillator strength and low RMSD value.The optical properties show that the compounds are emitting effectivily in solution and solid,in different polar solvents,in different aggregation state solutions and in PMMA doped film.For example,the efficiency of TPA-BBT in solution,crystal,amorphous state and doped film is 56.80%,60.92%,31.81%and 100%respectively,which proves the correctness of the proposed DSE molecular design method.?3?Compared with yellow,green and blue light luminescent materials,red light materials have low light efficiency.In this paper,TZ-DAP and TZ-MAP are designed and synthesized.By calculation,two compounds all have a twisted molecular configuration,low oscillator strength of S₁ state,small RMSD value,and the theory calculation verifies that the luminous color belongs to red or near-infrared light.The optical property test showed that the two red fluorescent compounds exhibited red emission in powder,low polarity solvent and PMMA doped film,for example,the luminous efficiency of TZ-DAP in solution,crystal and film reached 3.35%,8.62%and 3.98%.The DSE characteristics were found in different aggregation state solutions,which proved that the novel molecular design strategy could effectively design DSE red light materials.?4?Explore the design of anthracene luminescent materials TPA-AN and TZ-AN,and conduct research on geometric configuration optimization,transition orbit,spectrum,spin-sin coupling constant and other quantum chemical calculations.The results show that the coupling constant between S₁ and T₁ is small and the energy difference is large.The twisted configuration shows that it can avoid the strong pi-pi interaction to form excimer or complex in solid state,and can obtain high luminous efficiency.The medium RMSD value and oscillator strength as well as the molecular steric effect make them have better luminous efficiency in solution state.Both compounds are charge-transfer excitation,which are described by NTO 121-122 and MO121-122 orbitals respectively,indicating that the two compounds have solvatochromism effect.In short,the anthracene compounds TPA-AN and TZ-AN are expected to have DSE characteristics.