Study On The Synthesis And Crystallization Of Photomechanical Motion Of Azopyridine Derivatives

The photoresponse and self-assembly properties of azopyridine derivatives have attracted wide attention from researchers around the world.At present,the development and application of azopyridine derivatives are gradually being developed and applied in the field of self-assembled fibers and photoresponsive liquid crystal materials.However,the photomechanical motion of of azopyridine derivatives molecular crystals has not been reported yet,and the application of photomechanical sholud be developed.In this context,systematic studies on the crystallization and photomechanical motion of 4-?4-?6-hydroxyhexyloxy?phenylazo?pyridine?6CAZPY?compounds and their three metal organic complexes were carried out.Firstly,6CAZPY compounds were synthesized.The structures of the synthesized compounds were characterized by fourier transform infrared spectroscopy,1H NMR and elemental analysis.Yellow plate-like 6CAZPY crystals were obtained using a slow evaporation method and the thermal stability of the crystal was investigated.Secondly,combined with the self-assembly properties of 6CAZPY,Zn?acetylacetone?₂·H₂O as the ligand,three novel metal-organic complexes were prepared and characterized.The crystal morphology and thermal stability of the crystals were analyzed and it was found that??Zn?acetylacetone?₂·H₂O??6CAZPY???complex-??crystals could be crystallized as?Zn?acetylacetone?₂??6CAZPY??complex-??crystals during the heating process.In addition,single crystal of complex-? and complex-? were obtained,and the crystal structures were analyzed from the molecular arrangement and intermolecular interaction.Photoisomerization and photomechanical bending motions of 6CAZPY and three metal-organic complexes were studied.The phenomena of photoisomerization of the above four substances were analyzed by UV-visible spectroscopy.It was found that the photoisomerization reaction of the four compounds in the toluene solution follows the first-order kinetics.The photomechanical bending motion of 6CAZPY crystals were studied.It was found that the tip distance of bending motion was influenced by the crystal size and the UV light intensity.Photomechanical bending motions of three kinds of metal organic complexes crystals were studied,and it was found that metal complexes crystals can also exhibit obvious photomechanical bending motions in thicker cases,combining the stability and photomechanical properties of various substances,complex-? crystals were found to have stronger photomechanical properties.Finally,the mechanism of photomechanical bending motion of four azopyridine derivatives was explained.The powder X-ray diffractometer?PXRD?was used to measure the position and intensity of the diffraction peaks of the four crystals before and after UV irradiation.It was found that the occurrence of photoisomerization of the compound leads to a decrease in crystallinity,but no new crystals were formed.Atomic force microscopy?AFM?was used to test the changes of the topological structures of the four crystals before and after UV irradiation.It was found that the occurrence of photoisomerization reaction caused short-range disorder on the crystal surface.None relevant publications about investigation on the crystallization of 6CAZPY,the synthesis and crystallization of metal-organic complexes,the photoisomerization of azopyridines,the photomechanical motion and the mechanism of azopyridines have been found in the literature.