The Synthesis And Self-Assembly Properties Of New Amphiphilic BF₂-azadipyrromethene Dyes

The BF₂-azadipyrromethene?aza-BODIPY?dyes exhibit near-infared?NIR?,long absorption wavelength,high molar absorption coefficient as well as high stability.This class of dyes have been applied in the fields of biological probe,cell imaging and photodynamic therapy.On the other hand,self-assembly could provide properties and functionalities that individual molecules did not have.However,the thermodynamics and the structure for the self-assembly process of aza-BODIPY dyes still need to be elucidated for the application of these dyes.In this thesis,a series of novel amphiphilic aza-BODIPY dyes were designed and synthesized.Their chemical structures were fully characterized and their self-assembly properties were investigated in detail.The main content of this thesis include:1.A series of amphiphilic aza-BODIPY bearing hydrophilic and hydrophobic chains of different lengths were obtained through Cu-catalyzed"click chemistry"reactions.The chemical structures of the dyes were characterized by ¹H NMR,¹³C NMR,High resolution Mass Spectrometer?HRMS?,UV/Vis absorption spectrocopy and fluorescence spectrocopy.2.The supramolecular dye aggregates were prepared in methanol.The self-assembly process properties of the dyes were studied by concentration and temperature–depend UV/Vis spectroscopy.The morphology and nonstructure of aggregates were studied by atomic force microscopy?AFM?,scanning electron microscopy?SEM?and transmission electron microscopy?TEM?.The experimental results indicated that these dyes formed two types of aggregates in methanol,i.e.Agg ?and Agg?.The Agg ?displayed red-shifted and broaden absorption with respect to that of monomeric dye molecule.Meanwhile,the Agg ?shows nanosphere morphology with diameter of c.a.20-60 nm.The agg? was characterized by a red-shifted and extremely narrow absorption band(?_max=799 nm)with high molar absorption coefficient(2.1×10⁵ M^-1cm^-1),indicating the formation of J-type aggregates of this class of dyes.The Agg ?exhibited nanorod-like morphology with a diameter of c.a.7 nm and a length of several hundred nonometers.More importantly,we found that the formation process of Agg ?was kinetically controlled.After a long period of time,the Agg ?can slowly transform to Agg?.3.Owing to the complex self-assembly process of the new aza-BODIPY,we proposed a new competition-cooperative mathematical model to describe such aggregation process.Using this model,we analyzed the concentration–depend UV/Vis absorption spectroscopy of the self-assembly process,such as equilibrium constant,nucleation size and so on.4.In aqueous solution,we found that the new aza-BODIPY can also form Agg ?and Agg?.The Agg ?was characterized by the red-shifted and broaden absorption band.While the Agg? was characterized by the red-shifted and extremely narrowed absorption band(?_max=799 nm)with high molar absorption coefficient(2.2×10⁵ M^-1cm^-1).The Agg ?exhibit nanosphere morphology while Agg? exhibit a worm-like nanowire morphology.We found that the formation process of Agg ?was kinetically controlled.After a long period of time,the Agg ?could slowly transform to Agg?.