Construction Of Low Mass Molecules For Fluorescent Sensor And Room-Temperature Phosphorescent Encryption

Organic luminescent materials have drawn tremendous attention because of their integrated advantages including abundant sources,low toxicity,simple preparation,easy modification and processing.However,the“Aggregation-caused quenching(ACQ)”effect of traditional organic luminescent materials is not favorable for their practical application in the aggregate and solid state.In 2001,Professor Ben Zhong Tang coined a new concept of“Aggregation-induced emission(AIE)”,which can fundamentally overcome the ACQ effect and bring new vitality into the development of organic luminescent materials.Organic luminescent materials with AIE features enjoy the merits of quick response,high sensitivity,good photostability and anti-background fluorescence interference,which can be used as fluorescent sensors to detect trace metal ions.As an extension to AIE,pure organic room-temperature phosphorescence(RTP)materials have become a hot research topic,which can be widely applied in data encryption,anti-counterfeiting,bioimaging,and so on.Currently,the organic RTP materials have been realized by the introduction of halogen bonding,H-aggregation,molecular packing,co-crystallization,host-guest interaction etc.However,the complicated synthesis and high expenditure are still inevitable in these systems.In addition,their performances in air are not satisfactory.Therefore,a new facile and robust host-guest strategy utilizing commercially available molecules is a promising alternative for constructing efficient organic RTP systems.In the second chapter,we designed and synthesized three kinds of fluorescent probe with AIE features,named TPQ,TPEQ and TPAQ,which can realize the detection of trace zinc,aluminum and cadmium ions in aqueous solution.The detection performance of TPQ is the best,whose limit of detection toward zinc ion is as low as 5.7×10^-10 M.Fluorescent probes can further aggregate to restrict their intramolecular motion by coordination with metal ions,thus realizing the fluorescence-enhanced detection of metal ions.In the third chapter,we developed a series of novel host–guest organic RTP systems,in which N,N,N',N'-tetraphenylbenzidine(TPB)acts as a guest,triphenylphosphine(TPP)or triphenylamine(TPA)serves as a host.The maximum phosphorescence efficiency and the longest lifetime of TPB/TPP could reach 23.6%and 362 ms,respectively.At the same time,triple data encryption processes were realized via a simple preparation procedure.Experimental results and theoretical calculation revealed that the host molecules not only play a vital role in providing a rigid environment to suppress the non-radiative decay and the quenching effect of oxgen and water in air,but also show a synergistic effect to the guest in the photophysical process to facilitate the intersystem crossing(ISC)through F(?)rster resonance energy transfer(FRET).