Design And Properties Of Organic Room Temperature Phosphorescence Induced By Crystalline Al-DMSO Complexes

Room temperature phosphorescent?RTP?materials have received increasing attention due to their unique character of continuing to shine for a period of time after removal of the excitation source,which has made RTP materials extremely attractive in the fields of display devices,chemical sensing,anti-counterfeiting and bio-imaging.The early RTP phenomenon was mainly observed in some inorganic compounds,while the discovery of organic RTP compounds was relatively late,mainly due to the weak spin-orbit coupling?SOC?of the organics.In addition,the limited triplet energy was also easily to be deactivated by non-radiative transitions.In the 1960s and 1970s,it was found that some organics could exhibit strong RTP emission when they were slightly loaded on the surface of some inorganic salts,which could be attributed to the abundant weak interaction between the substrate and the organics.With the introduction of the concept of aggregation-induced emission?AIE?in 2001,people's exploration of the luminescence phenomenon of organics in the crystalline state has been greatly developed.By appropriately design,a small amount of organic compounds can exhibit RTP in crystalline state.This is due to the effective intersystem crossing?ISC?and inhibition of non-radiative transitions of organic molecules rich in heavy atoms under crystalline conditions,thus triggering RTP emission.In recent years,host matrix induced RTP based on guest species have been extensively studied.Researches have shown that many organics can be strongly induced to emit strong RTP in some heavy atomic matrices.However,the mismatch between matrices and guest molecules?such as solubility,harsh reaction conditions,etc.?leads to strict requirements on the configuration of organic matter.In addition,the RTP performance is not well tuned,making these matrices inherently flawed in practical applications.Based on this,in this thesis,dimethyl sulfoxide?DMSO?as the starting point of organic solvent,two kinds of crystalline metal-DMSO matrices,namely[Al?DMSO?₆]Cl₃?1?and[Al?DMSO?₆]Br₃?2?were designed and synthesized.It was found that that they have a good induction effect on the RTP emission of benzoic acid-containing phosphors.Besides,1 and 2 have good lever tuning effects on lifetime and quantum yield in inducing RTP due to different heavy atomic effects?different halogens?.The specific research contents are divided into the following parts:?1?17 aromatic acid molecules were screened,and then doped them into the matrices 1and 2,respectively.It was found that they were all able to exhibit strong RTP emission under the induction of matrices and shown the adjustment of RTP color from dark-blue to yellow-green.The lifetime of the single crystal complex Bba-m/-Cl was 1.9 s.The same organics has similar RTP emission peaks when embedding in 1 and 2.The difference is that the heavy atomic effect makes the lifetime of the organics in 2 shorter than that in 1,but the quantum yield is further improved.?2?N-substituted 1,8-naphthalimide?Naba-x?,N-substituted 2,3-naphthalimide?Npaba-x?and N-substituted carbazole derivatives?Caba-x??x=o,m or p?containing benzoic acid groups were designed and synthesized.The results found that they showed strong RTP emission in 1and 2,exhibiting bright afterglow with colors of yellow,green and blue,respectively.The lifetime of Npaba-p/-Cl?1.2 s?is by far the longest among N-substituted naphthalimides-based RTP materials.Beside,we obtained a white light single crystal complex Naba-p/-Cl by incorporating Naba-p into 1,showing photoluminescent quantum yield of 29.5%.What is more gratifying is that Naba-p/-Br shows the highest afterglow quantum yield?58.3%?among the reported yellow RTP materials.At last,six halogen-substituted naphthalimide derivatives were synthesized to investigate the effect of intramolecular heavy atomic action on RTP emission.?3?The delayed white-ligh RTP emission was constructed by doping two guest molecules in matrix 1.Among them,complex W1 and W2 have the phenomenon of initial white light RTP and intermediate white light RTP emission,respectively.This is the first method to adjust the doping ratio of two organics in the same matrix to achieve the white-light RTP emission visible to naked eyes.We also successfully used these unique phenomena to achieve data information encryption and decryption.The excellent RTP emission phenomenon is attributed to the inherent characteristics of the matrices:1)the crystal defects and the closed-packed structures of the matrices enable the compatibility of guest molecules and the inhibition of thermal motion;2)DMSO realizes the dispersion of guest molecules in the reaction system,and the sufficient hydrogen bond sites promote the host-guest interactions;3)the matrices are rich in various heavy atoms,thus facilitating the ISC process of the system.