Design,Synthesis And Properties Of Difluoroboron ?-diketonate Complexes

Organic functional materials constructed by ?-conjugated molecules have shown great potentials in nonlinear optics,solar cells,molecule/ion recognition,self-assembly,piezallochromy and other fields.As a kind of important fluorescent complexes,difluoroboron ?-diketonate complexes(BF2bdks)exhibit intriguing properties,including large molar extinction coefficients,high quantum yields and electron affinities,large Stokes shift and high sensitivity.These desirable features make them as promising functional materials and have attracted special attention.In addition,triphenylamine(TPA)and five-membered furan/thiophene derivatives,due to their unique electronic properties,are important structural motifs in numerous organic electroluminescence materials.However,there are few studies on the properties and applications of ?-diketone-boron difluoride derivatives constructed by TPA and five-membered furan/thiophene units.Hence,enrichment and development of this type of materials are of great significance.Accordingly,a series of novel ?-diketonate derivatives based on TPA and furan/thiophene units were constructed in this thesis.Their photophysical properites and electrochemical behaviors were systematically studied.The relationships between the molecular structures and their properties were revealed.The main contents are as follows:1.Two novel triphenylamine-modified D-?-A difluoroboron ?-diketonate derivatives H2 and H3 were synthesized by the Suzuki-Miyaura cross-coupling reaction and the Claisen condensation reaction.It is found that new complexes H2 and H3 exhibit long-wavelength absorption and strong intramolecular charge transfer emission and reversible oxidation and reduction waves in cyclic voltammetry experiments.They were also highly fluorescent in toluene with large Stokes shifts comparable to their parent BF2 nucleus H1.Among them,H3 is able to monitor the ethanol contents in toluene with a limit of detection up to 0.0091% due to its good electron transfer ability.2.Novel difluoroboron ?-diketonate derivatives H5-H8 containing a furan unit were synthesized and fully characterized.The relationships between the molecular structures and their properties were investigated in detail.It was found that these solid state emitters covering green,yellow and blue fluorescence were achieved by tuning the molecular structures.Among them,the complexes H6 with a rigid naphthalene moiety and H7 with an electron donating methoxyl group demonstrated stronger fluorescent emission intensity,much higher quantum yields,and longer lifetime values relative to other complexes.The longest absorption and emission maxima of H6 and H7 were red-shifted markedly,whose maximal emission bands were located at 510 nm and 533 nm,respectively.The introduction of electron withdrawing group F atom had little effect on the photophysical and electrochemical properties of the corresponding complex.3.Two novel D-?-A difluoroboron ?-diketonate derivatives H9 and H11 containing a TPA moiety and a five-membered furan/thiophene unit have been synthesized.It was found that the effect of TPA on the photophysical and electrochemical properties of BF2 complex was significant,while replacing furan with thiophene in the BF2 complex showed slight effects.The two complexes H9 and H11 showed significant red-shift absorptions and intense emission bands in toluene with high fluorescence quantum yields,large Stokes shifts,and longer lifetime values in comparison to those of the corresponding reference complexes H4 and H10.Compared with the furan-based H9,H11 with a thiophene unit exhibited a larger Stokes shift and a higer oxidation potential,but a weaker light harvesting ability.