Synthesis And Photophysical Properties Of Novel Organic Boron Complex Conjugated Fluorescent Dyes

Organic conjugated fluorescent dyes showed attractive application prospects in organic light-emitting diodes,chemical sensors,organic lasers and other fields.Among them,the design and synthesis of organic boron complex fluorescent dyes with excellent solution and solid state luminescent properties that centered on tetrahedral boron have been favored by chemists at home and abroad which promote them sustainable development.This thesis takes the design and synthesis of organic boron complexes with excellent properties and novel structures as the strat point.A series of functional organic boron complex fluorescent dyes with high solubility or solid-state fluorescence emission properties were prepared and studied their photophysical properties in solution and in solid state.The innovative studies are as follows:(1)Novel Bis(difluoroboron)-1,2-bis((1H-pyrrole-2-yl)methylene)hydrazine(BOPHY)fluorescent dyes(F-BOPHY1-3)were prepared.Their photophysical properties were studied by UV-Vis absorption spectra and fluorescence spectra.It was found that the ?-conjugate length of the molecule was greatly extended due to the fused effect of the furan ring,which resulted in a larger red shift of the absorption and fluorescence emission bands than unmodified BOPHY nucleus.F-BOPHY1-3 showed large molar extinction coefficient(109700-123000 M-1cm-1),deep-red fluorescence emission(646-667 nm),a moderate solution fluorescence quantum yield(0.30-0.45),and High light stability,which provide possibilities for its application in the fields of luminescent materials and biofluorescence probes.(2)Triphenylamine functionalized ?-ketimine boron complex BF2-TPA was designed and synthesized.We studied the properties of aggregation-induced fluorescence emission and mechanofluorochromism.The results showed that BF2-TPA has significant aggregation-induced luminescence properties and reversible mechanofluorochromic behavior.BF2-TPA exhibits a very weak fluorescence emission in solution,but has strong fluorescence emission in solid state,and its solid fluorescence quantum yield is 0.49.The crystal powder of BF2-TPA could emit bright yellow fluorescence(549 nm).After grinding,its fluorescence emission becomes orange(590 nm),and the spectral band has a red shift(41 nm).After fuming by dichloromethane vapor,the fluorescence emission was restored,indicating that the mechanofluorochromic behavior of BF2-TPA is reversible.This study provides an important idea for the design of novel mechanofluorochromic materials with AIE properties.(3)A series of triphenylamine-functionalized ?-ketimine boron fluorescent dyes BF2-TT-CN,BPh2-TT-CN,BF2-TT and BPh2-TT based on benzothiazole were designed and synthesized.We studied the properties of aggregation-induced fluorescence emission and mechanofluorochromism.The results showed that these compounds exhibited strong cyano-dependent aggregation-induced emission and mechanofluorochromic behavior.As for cyano-substituted molecules BF2-TT-CN and BPh2-TT-CN,the steric hindrance of the cyano group makes the molecule have more twisted conformation,formating loose accumulation in the crystalline state,which endue them high solid fluorescence quantum yield(0.86 and 0.79),significant aggregation-induced emission characteristics and mechanofluorochromic behavior.The crystal powders of BF2-TT-CN and BPh2-TT-CN were able to emit bright yellow fluorescence(542 and 549 nm).After grinding,the fluorescence emission became orange(599 nm and 566 nm),respectively.The fluorescence emission of BF2-TT-CN and BPh2-TT-CN was reversible by the fuming of dichloromethane vapor.In contrast,BF2-TT and BPh2-TT without cyano groups did not show high solid-state fluorescence quantum yields,aggregation-induced emission and mechanofluorochromic properties.