Novel Purely Organic Room Temperature Phosphorescence Materials And The Investigation Of Their Property,Luminous Mechanism

Organic luminescent materials enjoyed advantages such as synthesis convenience,abundant sources,low toxicity,process simplicity and so on.Thus,organic luminescent materials have extensively developed among both academic researchers and industrial circle.Traditional organic luminescent materials suffered a decrease in luminescence efficiency from its solution state to its aggregated states.This so-called aggregation-caused quenching(ACQ)effect is detrimental to the application of organic luminescent materials.In 2001,professor Ben Zhong Tang from Hong Kong University of Science and Technology had reported an opposite phenomenon with ACQ,showing increased emission efficiency in the aggregated states,which was coined Aggregation-induced emission(AIE).AIE materials overcome the negative influence from aggregation-caused quenching effect,and bring vitality within the research of organic luminescent materials.Different from fluorescent materials,Pure organic phosphorescent materials,whose luminescent lifetime could reach millisecond-level,could continuously emit for some time after the excitation was removed.They may find potential application value in information transmitter,photo response,chemical sensors,and bio imaging field.However,because the emission from the excited triplet state is sensitive to temperature and oxygen,pure organic phosphorescence is normally observed under cryogenic and inert conditions.Design and synthesis of materials with persistent and efficient room-temperature phosphorescence(RTP)hence have drawn extensive attention nowadays.In chapter 2,a series of carbonyl group-containing dibenzofuran derivatives were designed and synthesized,and 11 pure organic single crystal samples with room temperature phosphorescence was obtained.The room temperature phosphorescence lifetime of these samples could achieve up to 185 ms.The phosphorescence could be observed by naked eye after the UV excitation was removed.From the comparison of RTP properties with their corresponding single crystal structures,a few conclusions can be draw as followed: first,the strong ?—? stacking interaction between dibenzofuran planes is critical to the room temperature phosphorescence lifetime;second,chlorine-substituted derivatives possess better RTP property compared with other derivatives;third,according to the correlation of luminescence behavior of different polymorphs of the same compound,the slight angle between different dibenzofuran planes might cause a decrease in emission efficiency;last but not least,asymmetrically substituted compounds emit red-shifted and longer phosphorescence compared with their symmetrically substituted isomers.In chapter 3,4 nylon-69 samples were prepared with different crystallinity and up to 218 ms room temperature phosphorescent lifetime of nylons was measured.Besides,the behavior of RTP is affected by the degree of crystallinity.Through melting the non-freshly prepared samples in a vacuum process,the RTP of nylon samples could be recovered.Further investigation of RTP phenomena in small molecular amides indicated that amide groups was responsible for the RTP phenomena of polyamides.To conclude,10 carbonyl group-containing dibenzofuran derivatives with RTP phenomena was designed and synthesized,and the RTP of polyamides was also studied.Based on that,the design principle,structure-function relationship,and mechanism of pure organic room temperature phosphorescent small molecules and polymers were systematically discussed.This work could enrich the system of pure organic room temperature phosphorescence,which might find its potential in the applications of luminescent materials.