Construction And Properties Of Luminescent Hydrogels With Rare-earth And Cytidine Ligands

Rare earth ion is a kind of ion widely used in luminescent materials.The unique f-layer structure of rare earth ion leads its excellent luminescent property.The peak shape of emission spectrum is sharp,the Stokes displacement is large,the luminescent intensity is high and the fluorescence life is long.However,the f-orbital of rare earth ion is blocked by the inner layer electrons,which leads to the transition forbidden.In addition,the coordination of rare earth complexes is mostly dynamic and reversible,which makes the rare earth-based luminescent materials have stimulus response.We found that a new rare earth ligand can sensitize rare earth luminescence and form hydrogels.The structure and properties of hydrogels were characterized,their luminescent colors were adjusted,and their thorny response properties were studied.The main research work is summarized as follows:In the first chapter,The properties of rare earth and the construction methods of various rare earth hydrogels are summarized.The multicolor luminescence,stimulation response and application potential of rare earth hydrogel are systematically reviewed,providing theoretical support for the research significance and content of this topic.In the second chapter,a new rare earth ligand cytidine has been discovered,which can sensitize rare earth luminescence and form hydrogels.The structure of the complexes formed and the formation process of the hydrogel were characterized and determined.At the same time,the mechanical properties,optical properties and microstructure of the hydrogel were characterized,and the successful preparation of the rare earth hydrogel with excellent optical properties was demonstrated.It provides a new idea for the synthesis of rare earth hydrogels,and extends the method of synthesizing hydrogels by natural molecules.In the third chapter,the luminescence of hydrogels was adjusted.We adopted the red-green-blue strategy.Based on the red light-emitting hydrogel,we chose the carbon dots as blue emitter and fluorescein isothiocyanate as green emitter,and obtained the white light emitting hydrogels through the stoichiometry adjustment.Calculations and tests show that the quantum yield of the white hydrogel is relatively high,and has the prospect of being applied to the field of illumination.In the fourth chapter,the stimuli responsive properties of white hydrogel were studied,and the response ability of hydrogel to p H,ion and temperature was tested.Acid will make phase change and fluorescence discoloration of hydrogel.Fe³⁺will make the fluorescence of the hydrogel quenched and undergo irreversible phase change.The high temperature will reduce the fluorescence intensity of the hydrogel and has excellent stability and reversibility.It is confirmed that this is a multi-responsive white light hydrogel.The last chapter is the summary and prospect of this field.In this work,a new type of hydrogel was prepared by using cytidine as ligand and europium ion coordination.The rare-earth hydrogel can be adjusted to white luminescence with high quantum yield and good stimulus response behavior.It is expected to be used in biosensor,lighting and other fields.