Construction Of Supramolecular Room Temperature Phosphorescence System Based On The Synergistic Effect Of Ion Pair-Bromopyridine

Long-lived organic room temperature phosphorescence（RTP）materials have attracted extensive attention due to their applications in information encryption,bioimaging and smart sensors.Compared with traditional fluorescence,the RTP phenomenon originates from the slow radiative transition of triplet excitons.Therefore,increasing the intersystem crossing（ISC）rate from the lowest excited singlet state（S₁）to the excited triplet state and suppressing the nonradiative relaxation dissipation of the lowest excited triplet state（T₁）are reasonable methods to achieve efficient RTP in pure organic materials.In the past few decades,many strategies have been designed based on the above two key factors.It has been shown that the introduction of heavy atoms,aromatic carbonyls,and other heteroatoms with a large number of lone pairs of electrons can enhance spin-orbit coupling（SOC）,thereby successfully promoting the ISC process.In addition,a rigid environment is usually constructed by crystal engineering to limit intramolecular motion and intermolecular collisions and reduce excited state energy dissipation.In this paper,two kinds of organic room temperature phosphorescence systems with synergistic strategies were designed and synthesized.Different from the traditional host-guest interaction methods,this subject constructed a supramolecular organic room temperature phosphorescence system based on ion pair-bromopyridine synergy by a simple,efficient and easy-to-operate method.The following is the main content of this paper:（1）Organic room temperature phosphorescence system based on ion pair-bromopyridine synergistic:The organic cation solution was prepared by using 4-（4-bromophenyl）pyridine with benzene ring structure as raw material.Four kinds of crystal salts were obtained by crystallization with benzoic acid,phthalic acid,trimesic acid and pyromellitic acid.They showed different photophysical properties under different light source conditions.The experimental data and theoretical analysis showed that the maximum phosphorescence lifetime could reach 143.7 ms.（2）Supramolecular enhanced organic room temperature phosphorescence system:Based onthe previous work,a supramolecular organic cationic solution（BPCD）was prepared by simple organic synthesis usingβ-cyclodextrin and 4-（4-bromophenyl）-pyridine as raw materials by introducing the structure of macrocyclic cyclodextrin.A series of crystalline salts were formed by slow volatilization of organic cation solution and benzene carboxylic acid derivatives.The basic structure of the product was characterized by XRD and FT-IR,and the excitation emission phosphorescence spectrum was explored.The phosphorescence lifetime of the product was obtained by steady-state transient fluorescence spectrometer.The experimental results show that the phosphorescence lifetime can be increased by about 2 times after the introduction of supramolecular.In summary,a series of RTP materials were synthesized in this paper.Firstly,a simple strategy to achieve high-efficiency RTP was developed by introducing heavy atoms and benzene rings.On this basis,supramolecular macrocycles were introduced to obtain BPCD series of new high-efficiency RTP materials.The photophysical properties and phosphorescence emission mechanism were explored respectively,which provided a new idea for realizing supramolecular organic room temperature phosphorescence.