Controllable Preparation Of Low-Dimensional Structures Of Organic Fluorescent Dye Molecules And Their Photofunctional Applications

Low-dimensional structures of organic fluorescent dye molecules,as excellent optical crystalline materials,can be introduced into textile fibers to broaden the application field of organic low-dimensional crystalline materials and facilitate the production of more colorful and functional textiles.In particular,organic low-dimensional crystals with complex structures provide new avenues for photon modulation and information encryption.However,weak non-covalent interactions between molecules can make it difficult to control the nucleation and growth of organic crystals.Therefore,it is necessary to develop controllable construction strategies for low-dimensional crystalline structures and reveal their structure-property relationships for the development of high-performance organic fluorescent materials.In this paper,a series of organic cocrystal and alloy materials with tunable fluorescence emission were prepared by a simple and efficient solution self-assembly method.Furthermore,nano-fiber-doped films and heterogeneous microwires were prepared from the perspective of meeting the needs of different application scenarios,and their optical functional applications in functional fabrics and optical waveguides were explored.The main research contents are as follows:（1）In this paper,a series of organic cocrystal materials were designed and synthesized through a simple and efficient solution self-assembly method.The effects of organic donor-acceptor molecular interactions on the preparation and optical properties of organic cocrystals were explored,revealing the structure-property relationship between molecular structure and crystal optical properties.Based on the regulation of organic molecular energy level structure and intermolecular interactions,a series of organic cocrystal materials were constructed,achieving flexible control of absorption range between 300-1800 nm and fluorescence emission range between 400-1015 nm.Furthermore,based on the similar intermolecular distance,stacking mode,and competitive intermolecular interactions of organic cocrystals,organic alloy materials with tunable fluorescence emission and enhanced fluorescence quantum yield were controllably prepared.（2）Starting from the application perspective of constructing functional fabrics,this study explores the feasibility of compositing organic cocrystal or alloy materials into polyurethane（PU）nanofiber membranes through electrospinning technology,achieving thin film materials with visible to near-infrared fluorescence emission.The preparation conditions of doped nanofiber membranes and the existence form of crystals in fibers were investigated.Furthermore,organic cocrystal with near-infrared absorption was doped into PU nanofiber membranes,achieving excellent performance with a photothermal conversion efficiency of 60%.This study demonstrates the feasibility of compositing organic low-dimensional crystals with textile fiber materials,filling the gap in the research field of organic crystal materials doped nanofiber membranes.（3）To address the issue of single-structured organic cocrystals being unable to meet the requirements of photon modulation at the microscale,an investigation was conducted into the crystal structure and surface adsorption energy of organic cocrystals during the process of self-assembly with multiple components.This led to the proposal of a strategy for the controlled preparation of organic heterostructures with ultra-low lattice mismatch through epitaxial growth.Using this strategy,microwires with ultra-low lattice mismatch rates（η）were prepared,including three-block copolymers（η₁=0.7%）,branched structures（η₂=0.8%）,and core/shell structures（η₃=0.6%）.Finally,based on the position-dependent luminescent properties of the heterostructure microwires,active and passive optical waveguides and logical gates were realized.（4）To address the issue of the inability to mass-produce organic heterostructure microwires,which limits their practical applications,a concept of lattice-mismatch-free growth based on organic co-crystals and alloys was proposed,enabling the large-scale production of organic heterostructure microwires.Furthermore,precise construction of three-block copolymer and core/shell structure microwires was achieved by adjusting the material proportions.The universality of this strategy was investigated,and it was found that by choosing the appropriate organic molecules,over a dozen types of heterostructure microwires could be prepared.Finally,using a template method,fluorescent two-dimensional barcode patterns were prepared by growing block copolymer microwires with confined segment structures,and the unique structure and spectral features of the segment structure microwires were utilized to achieve triple encryption of the barcode pattern.This strategy provides a new way to mass-produce and control the preparation of organic heterostructure microwires,and the anti-counterfeiting encryption performance of the fluorescent two-dimensional barcode provides material basis and theoretical basis for optical information encryption.