Synthesis And Properties Of Bis-β-diketone Derivatives Based On Carbazole Structure

Carbazole compounds have multiple active sites,and their molecular structure can be modified by introducing different functional groups.Carbazole derivatives are widely used in solar cells,photoelectric materials,drug synthesis and other fields because of their large conjugated system,good stability and strong intramolecular charge transfer.In this paper,seven bis-β-diketones based on carbazole structure,seven bis-1H-pyrazole compounds and seven bis-β-diketone-boron difluoride complexes were synthesized and their structures and properties were explored.The thesis is mainly composed of the following four parts:1.Seven bis-β-diketones(1a-1g)based on carbazole structure were synthesized from N-ethylcarbazole via Friedel-Crafts acetylation with acetyl chloride using aluminum chloride as catalyst and followed by Claisen condensation with aromatic ester.Their structures were characterized by ~1H NMR,EI-MS,FT-IR and elemental analysis,and the optical properties were studied by ultraviolet absorption spectra and fluorescence spectra.The results showed that bis-β-diketones existed mainly as enol form in solid state and solution.2.Seven bis-1H-pyrazole compounds(2a-2g)were synthesized from bis-β-diketones by cyclization with hydrazine hydrate.The structures of these bis-1H-pyrazoles were confirmed by ~1H NMR,IR,ESI-MS and elemental analysis.Their antibacterial activities against E.coli,S.aureus,P.oryzae and R.solani were tested for MIC by using the double tube dilution method.The results exhibited that the bis-1H-pyrazole 2a with trifluoromethyl group had the highest antibacterial activities among these compounds.3.Seven difluoroboron bis-β-diketonate complexes(3a-3g)were synthesized by chelation of bis-β-diketones(1a-1g)with boron trifluoride-diethyl etherate in dichloromethane and their structures were characterized by ~1H NMR,FT-IR,EI-MS and elemental analysis.The photophysical and electrochemical properties were measured by UV–vis absorption,fluorescence spectroscopy and cyclic voltammetry.The results revealed that all difluoroboron complexes had the higher fluorescence quantum yields(Φ_u=0.35-0.95)and complex 3a exhibited the longest fluorescence lifetime.In addition,these difluoroboron complexes show positive solvent effect with the increase of solvent polarity.4.The photophysical behavior of difluoroboron complexes(3a-3g)in solid powder and PMMA polymer film was also investigated.The results showed that complex 3c had the strongest fluorescence emission and complexes 3a and 3c revealed the longer fluorescence lifetime.