Synthesis,Assembly And Stimuli-Responsive Properties Of Difluoroboron ?-Diketonate Complexes

Over the past decades,?-conjugated low molecular weight organogelators have gained considerable attention because they have been widely applied in the fields of sensors,display devices,photovoltaic devices,field-effect transistors due to heterocyclic skeleton can enhance both the electron and hole transporting abilities and the chemical stability of materials.Difluoroboron ?-diketonate complexes exhibited excellent properties.In addition,the ?-diketone boron difluoride unit has a six-membered ring structure,which can enhance the planarity of the molecule,and facilitates the formation of an ordered structure through the interaction of the molecules during the deposition.Accordingly,this thesis was focused on the synthesis,self-assembling and photophysical properties of ?-conjugated difluoroboron ?-diketonate complexes.We have fabricated the organogels and mechanofluorochromism materials with near infra-red emission.Some creative results have been obtained,and outlined below.(1)A series of rigid ?-diketone-boron difluoride derivatives have been synthesized,and it is found that only the boomerang shaped compound DTPEB exhibits good gelation ability in some solvents.It suggests that the balanced ?-? interaction,which can be tuned by the molecular conjugation,can lead to the gel formation from rigid ?-conjugated molecules without alkyl chain and H-bonding unit.It was interesting that TPEB,DTPEB and TTPEB all exhibited AIE(aggregation induced emission)activities.DTPEB exhibited strong orange red fluorescence in wet organogel and in xerogel-based films,and the emission was sensitive to organic amines.The xerogel-based film of DTPEB could be quenched significantly upon exposure to TEA vapor.The detection limit of the film towards gaseous TEA was ca.0.1 ppm.We deemed that the high performance of xerogel-based films of DTPEB in probing TEA vapor was originating from the good absorption and diffusion of analytes in 3D networks consisting lots of nanofibers as well as the efficient excition migration in 1D nanofibers.This strategy provides a new perspective not only in designing new rigid ?-gelators from the point of view of atomic economy but also in extending gel-phase material with appealing photonic and electronic functionality.(2)Two spirofluorene-cored bis(difluoroboron ?-diketonate)complexes bearing terminal carbazoles(CbzBSF)and tert-butylcarbazoles(TCbzBSF)have been synthesized.It is found that only TCbzBSF could form organogels directed by ?-? interactions in non-polar solvents.Notably,the emission of TCbzBSF in xerogel-based film could be quenched significantly upon exposure to aniline,N-methylaniline and N,N-dimethylaniline vapors.The detection limit for aniline vapor is as low as 0.56 ppb,which is lower than other reports.We deemed that the high performance of xerogel-based film of TCbzBSF in probing aniline vapor was originated from the good absorption and diffusion of analyst molecules in 3D networks consisting lots of nanofibers as well as the efficient excitation migration in 1D nanostructure.CbzBSF and TCbzBSF provide a strategy for the design of new rigid ?-gelators with thixotropic and sensory properties.(3)The bisphenethyl-substituted ?-diketone boron fluoride complexes MVB,PMVB,MPMVB and BPMVB were synthesized.It was found that the complexes PMVB,MPMVB and BPMVB of phenyl,2-methylphenyl and 4-tert-butylbenzene were introduced on the dioxaborane ?-carbon,and it was shown by repeated grinding/dichloromethane fumigation treatment.Reversible pressure-induced fluorescence discoloration behavior.The grinding causes the yellow-emitting crystal PMVB to become a powder that emits orange fluorescence,and the fluorescence emission spectrum is red-shifted.However,after the crystals MPMVB and BPMVB were ground,the fluorescence spectrum of the sample was blue-shifted,and the luminescent color changed from red to yellow.We speculate that this may be due to the steric effect of the substituents and the addition of substituents to enhance the polarity of the molecule,making it more sensitive to external stimuli.This multicolor pressure-induced fluorescent color-changing material will have application value in anti-counterfeiting marking and mechanical force sensing.(4)We have designed new ?-diketone difluoroboron complexes with terminal tert-butylcarbazole CVB,PCVB,MPCVB and BPCVB.It was found that the fully conjugated BPCVB without traditional gelation group could form organogels in toluene and xylene,etc.,and the balanced ?-? interactions were the driving force for the gelation.The casting film of BPCVB could emit red fluorescence,which was quenched by aniline vapor selectively.The detection limit of the film towards gaseous aniline was as low as 2.0 ppb.In addition,the synthesized complexes exhibit reversible piezochromic behavior in the red and near-infrared regions.This work is helpful for the designing solid Near infrared luminescent dyes with multiple stimuli-responsive abilities.