Aggregation Structure Control And Luminescence Properties Of Pyrazoline Derivatives

Organic fluorescent materials have good luminous performance and carrier mobility.which provide abundant raw materials for the development and manufacture of high-performance organic optoelectronic devices.However,due to organic fluorescent materials exist in an aggregated state on organic optoelectronic devices.it is particularly important to study the relationship between the aggregated structure of organic fluorescent molecules and the luminescent behavior in order to get organic fluorescent materials with high-performance aggregation state.In this paper,polycrystalline and co-crystals of pyrazoline derivatives were obtained by using crystal engineering.and the relationship between their molecular structure and their thermodynamic and optical properties were investigated.(1)1-acetyl-3-(3-hydroxyphenyl)-5-(9-anthracenyl)-pyrazoline(AHAP)and 1-acetyl-3-phenyl-5-(9-anthracenyl)-pyrazoline(APAP)were synthesized through Clasien-Schmidt condensation and other reactions.The structures of the above compounds were characterized by 'H NMR and 13C NMR.And the influence of reaction time,material molar ratio and other factors was also explored.Thus,the optimal reaction conditions were established as the reflux temperature,the molar ratio of N2H4 H2O and raw materials was 2:1,the reaction time was 6 h,the yield of AHAP was 67.2%,and the yield of APAP was 60.0%.In addition,the polymorph and co-crystal of the above two pyrazoline derivatives were prepared by crystal engineering strategy.At the same time,X-ray single crystal diffraction was used to determine that the structure of the a crystal type in the polycrystalline type is a one-dimensional chain structure and the structure of the ? crystal form is a cyclic tetramer,and the racemic APAP was successfully divided into R-and S-enantiomers in the eutectic.(2)? and ? crystal forms of 1-acetyl-3-(3-hydroxyphenyl)-5-(9-anthryl)-pyrazoline(AHAP)were studied.The crystal structures show that the AHAP molecules are connected in a head-to-tail manner through the O-H··O hydrogen bond between the carbonyl group and the hydroxyl group,One-dimensional chains are formed in the a crystal form,and cyclic tetramers are formed in the ? crystal form,and the crystal structure is formed in the form of units.Compared with the solvent-free a crystal form,a small part of disordered solvent molecules are contained by the unit cell of the ? crystal form.The Crystal Explorer program.differential scanning calorimetry(DSC)and thermos gravimetric analysis(TGA)experiments show that there are holes in the tetramer,and each hole contains a solvent molecule.1H NMR spectroscopy confirms that the type of disordered solvent molecule is consistent with the crystallization solution.The optical and physical properties of these two crystal forms are studied by us.Due to the accumulation of anthracene fluorophore monomers,they emit a fluorescence spectrum similar to that of anthracene fluorophore monomers(3)Co-crystals of R-and S-binaphthol with 1-acyl-3-phenyl-5-(9-anthryl)-pyrazoline(APAP)molecule were studied,respectively.The crystal structures show.O-H··O hydrogen bonds are formed between the carbonyl group on APAP and the phenolic hydroxyl group on binaphthol in the eutectic and the racemic APAP is resolved into R-and S-enantiomers.Our experiments using 1H NMR,Crystal Explorer program,circular dichroism and circular polarized fluorescence spectroscopy show that each co-crystal contains only one APAP molecule and binaphthol molecule which are crystallographically independent,and the molecular configurations in the two co-crystals are opposite.According to the circular dichroism and circular polarized light emission properties,their luminescence asymmetry factor(glum)under the solid is increased by 34 times compared with the solution state because of R-/S-APAP molecules form a helical aggregate structure in the eutectic.The results of the photophysical properties of the two eutectes show that the weak C-H··? interaction between the anthracene rings in the eutectic can effectively stabilize the anthracene fluorophore and reduce the energy loss of the excited state caused by the conformational change in the process of luminescence,so its luminescence intensity is higher than that of the monomer emission of anthracene.