Configuration-Structure-Activity Study Of Excitation Dependent Molecules And Four-Dimensional Security Of Multi-Channel Cellulose Hydrogels

Excitation wavelength dependent photoluminescence（Ex-De）materials have the characteristics of rapid,convenient,sensitive and non-destructive operation,which can change the luminescence color with the change of excitation energy,and have potential applications in anti-counterfeiting labels,photoelectric devices,etc.The excited wavelength dependent materials reported so far are mainly silicon and carbon dots（size effect,element doping and surface functional group modification can effectively introduce new level structure of electron transition）and metal complexes（metal atomic energy can effectively promote the organic ligand electron transition from singlet to triplet state）.The design strategy of the above traditional materials realizes the excitation wavelength dependent emission behavior,but there are some problems such as high biological toxicity,harsh preparation conditions,difficult post-processing,poor material stability and high cost.In contrast,organic luminescent materials have the inherent advantages of good biocompatibility,excellent machining properties,abundant energy level structure and tunable excited state processes.According to Kasha’s rule,photons in organic compounds can only be emitted by the lowest excited state（S₁ or T₁）,and the emission wavelength is independent of the excitation wavelength.In particular,the aggregation state generally exhibits a rapid vibration relaxation process from S_n to S₁.Therefore,the excitation wavelength-dependent luminescence behavior of pure organic compounds is rarely observed,which greatly limits the development of organic luminescent materials in the field of excitation wavelength-dependent photoluminescence.Excitation-state dimers formed by excimer association and excimer complex have significantly different luminescence properties from monomers:large redshift,no fine structure and wide emission spectrum,which show potential application value in organic optoelectronic devices,stimulus response and other fields.However,to develop multicolor luminescent materials,it is necessary to study the luminescence mechanism of molecules deeply,and establish the research strategy of molecular configuration-structure-activity for the excited state processes and molecular configurational forces.In this paper,the molecular design,luminescence mechanism and excited state configuration of organic molecule TPy-CHO forming dimer accumulation were systematically studied,and the excited state mechanism of organic molecule TPy-CHO was revealed,focusing on the luminescence behavior with excitation wavelength dependence and the mechanism process of excited state of excimer association and excimer complex dimer.Multicolor luminous materials have great potential applications in the field of intelligent anti-counterfeiting.However,in the practical application of traditional anti-counterfeiting,the state of materials（powder,solution,etc.）greatly hinders the development and application of intelligent anti-counterfeiting.Hydrogel materials meet the needs of application scenarios in practical application due to its excellent structure and functional coordination characteristics.Natural polymer-based hydrogels have attracted much attention from scientists in recent years due to their advantages such as wide sources,low cost,environmental protection and abundant chemical sites.This paper mainly completed the following aspects:1)Based on the anti-Kasha rule molecular monomer/dimer system,TPy-CHO,an organic compound whose excitation wavelength depends on solid polychromatic luminescence,was designed and synthesized for the first time.Through a series of experiments such as single crystal diffraction test and transient spectrum,the relationship between molecular configuration-structure-activity was deeply explored,and the luminescence performance of the material was regulated from the structural information.The multi-channel excited state luminescence behavior was determined.2)Through chemical modification of abundant cellulose in nature,covalent grafting of chromophores with wavelength-dependent excitation behavior onto the modified cellulose chain,and further through ATRP polymerization reaction to obtain interpenetration of double-network photo-stimulating response hydrogels,the introduction of lanthanide ions for coordination,multi-level transition of lanthanide ions and long-range ordered aggregation of chromophore.The distance between molecules is closer than that of free molecules,which is conducive to the combination of their constituent molecules and the formation of excited states more easily.The behavior of improving the Ex-De of lanthanide hydrogels can achieve a wide emission range and even appear white light with a tiny excitation wavelength gap.3)The non-contact photo-responsive light-emitting hydrogel material based on the excitation wavelength dependence characteristics,compared with the contact chemical anti-counterfeiting means,has the advantages of fast decryption,pollution-free encoding information,excellent reversibility,green environmental protection,simple photochromic molecular synthesis,and excellent photostability of the hydrogel materials.At the same time,the deformation characteristics of the spatial dimension of the temperature response of the hydrogel material,the designed 4-dimensional space security material,can increase the spatial visual information protection on the level of the traditional 3-dimensional security field,improve the security performance after information theft and leakage.The intelligent anti-counterfeiting strategy of orthogonal optical encryption is designed to realize multi-optical color and 4-dimensional space deformation multi-storage intelligent anti-counterfeiting hydrogel materials and intelligent encryption strategy.Combined with the reversible light-color change characteristic of the hydrogel material in response to temperature,the reversible disappearance and recovery of coded information after reading are realized.Instantaneous decryption and encryption greatly improve the security performance and multiple utilization of information after reading.