Design,Synthesis And Characterization Of Organic Salts With Room-temperature Phosphorescence

Materials with room-temperature phosphorescence(RTP)have important applications in bioimaging,organic optoelectronic materials,anti-counterfeiting systems and chemical sensors due to their unique excited state properties.At present,most phosphorescent materials are mainly inorganic and coordination complexes that contain noble metals.Considering that these compounds are relatively expensive and toxic,pure organic room-temperature phosphorescent materials with low cost,low toxicity and high designability are in urgent need of development.Herein,quinolinium salts were selected as the main research objects.Heavy atom effect and conjugation effect on the luminescence properties of pure organic room temperature phosphorescent salts were investigated,respectively.The main contents are summarized as follows:(1)To investigate the influence of heavy atom effect on luminescent properties,N-allylquinolium halides with different anions such as Cl-,Br-,I-and PF6-were synthesized to test their luminescent properties.The results showed that the salt with Br-was weakly phosphorescent,and the N-allylquinolium salts with Cl-and PF6-counterparts were mainly fluorescent due to the absence of heavy atoms,and especially the organic salt with PF6-emitted strong fluorescence,while the rest compounds are barely luminescent.In addition,quantum yield(?em)of salt with Br-is promoted from almost zero to 2.76%after the addition of CHCl3,and the luminescent color is changed from the original orange to green.(2)To investigate the conjugated effect on the luminescent properties of the materials,a series of organic bromides with RTP based on different cations such as N-allylquinolinium,N-allylphthalazinium and N-allyl-1,10-phenanthrolinium were synthesized and studied.The results showed all the compounds were phosphorescent.The position of the nitrogen atom in the conjugated system of N-allylisoquinolinium bromide was changed,leading to that there was barely solvent stimuli response to CHCl3,and the addition of solvent only had an effect on the intensity of the luminescence.Compared with the former,N-allylpyridazinium bromide had one more nitrogen atom in the ortho position and they had similar properties.For N-allyl-1,10-phenanthrolinium bromide,the extension of conjugated system resulted in that it was difficult for CHCl3 to produce significant perturbation between molecules due to the steric hindrance,besides there were no obvious effect on the crystal arrangements.In conclusion,Br-showed the best performance to induce phosphorescence in organic salts while the compounds without heavy atoms were mainly fluorescent;combining the special external solvent stimuli response to CHCl3,the application of N-allylquinoline bromide in anti-counterfeiting materials has been developed;to investigate the effect of conjugation on the phosphorescence of organic salts,the positions of heteroatom nitrogen and allyl group lead to the distribution changes of the central conjugated electron cloud and crystal phase transition,which caused that the compounds did not have an obvious solvent stimuli response to CHCl3.