Design,Assembly And Application Of Stimuliresponsive Supramolecular Organogels

In recent years,supramolecular organogels have attracted increasing attention due to the dynamic reversibility of the formed non-covalent interactions and have potential applications in many fields ranging from medicine to optoelectronics.At the same time,the adaptability,tunability and stimulus responsiveness of supramolecular gels are unmatched by traditional nanomaterials.The sensing of chemical analytes using gels in different applications is a fairly new concept in materials chemistry research.Compared with traditional large-scale instrument detection methods that require highly trained professionals to operate,such as:atomic absorption spectroscopy（AAS）,ultraviolet-visible spectrophotometer（UV-vis）,gel-based fluorescence detection technology because of its simplicity,consumption Short time and low price have attracted the attention of scientists.Furthermore,since gelation requires a high concentration of gelling agent(2×10^-3 M),for the same chemical compound,the gel-phase interaction tends to exhibit better selectivity for the target guest than the solution state.The design of general stimuli-responsive supramolecular gels mainly includes three parts:binding site（or reaction site）,linking group and auxiliary self-assembly group（usually hydrophobic or hydrophilic group）.In this paper,on the basis of summarizing and introducing the research progress of domestic and foreign research groups,three kinds of supramolecular organogels based on aggregation-induced emission（AIE）were designed and constructed,and their applications in water ion and food detection were studied.The discussion of this paper is divided into four parts,the contents of which are as follows:In chapter 1,the design principles of stimulus-responsive supramolecular organic gels are introduced,the design strategies of such materials at home and abroad in recent years are summarized,and their applications in negative and cation detection,biometrics,cell imaging,food detection and other aspects are discussed.Based on the research results obtained by the well-known research group and the preliminary topic exploration of the research group,this paper puts forward its own topic and experimental ideas.In chapter 2,a new quinoline gel molecule MN are designed and synthesized.MN can form supramolecular gel（OMN）in iso-Propyl alcohol（i-Pr OH）byπ-πstacking and intermolecular hydrogen bond self-assembly,and exhibits obvious aggregation-induced induced emission（AIE）properties.In addition,the supramolecular organogel OMN realized the ultra-sensitive detection of Fe³⁺and Cu²⁺in water,showing fluorescence quenching at 427nm in the fluorescence spectrum.On this basis,we prepared stimulus-responsive supramolecular gel OMN film,which can be used as a multi-stimulus-responsive fluorescent display material for the detection of Fe³⁺and Cu²⁺.The intelligent gel has a good application prospect for multi-analyte detection.In chapter 3,the gelator of hydrazone（E）-N-（4-bromobenzyl）-4-methoxybenzoylhydrazone（BM）was tried to synthesize,which has high synthesis yield and does not require complex organic purification methods.The obtained molecule BM can self-assemble in N,N-dimethylformamide（DMF）and form a stable organic gel（OBM）by self-assembly driving force at a critical gel formation concentration of 1%.Interestingly,OBM has a fluorescence off detection signal for Fe³⁺and forms a complex OBM-Fe³⁺complex.When CN^-ions were added to Fe³⁺coordination metal organogel,the fluorescence intensity returned to the initial intensity of supramolecular gel OBM.The sensing mechanism of OBM was determined by the competitive coordination between OBM,Fe³⁺and CN^-.At the same time,the organogel sensor OBM can also be used as an ion response film for the detection of Fe³⁺and continuous recognition of CN^-.In chapter 4,a kind of organic gel factor NA containing naphthalimide group through three steps are successfully synthesized.Through a series of self-assembly driving forces,NA assembled in 1,2-propanediol to form a spongiform supramolecularπ-gel（ONA）,exhibiting bright blue aggregation-induced emission（AIE）fluorescence.Interestingly,ONA showed fluorescence“off”for Fe³⁺in the gel state,and the detection limit for Fe³⁺was as low as 6.96×10^-8 M.In addition,Fe³⁺coordination regulated organogels Fe-ONA can continuously recognize H₂PO₄^-in fluorescence spectra.When Fe³⁺and H₂PO₄^-alternately add ONA,the fluorescence cycle switch can appear four times“on-off-on”phenomenon.More importantly,the supramolecular gel ONA can adsorb Fe³⁺in aqueous solution with a recovery of 92.24%.As a supramolecular gel intelligent material,ONA has greatly enriched its application in the field of environmental detection.In chapter 5,the experiments of these three systems were systematically summarized,and also briefly evaluate the expected results achieved by the experiments of each system.The research changes from simple to complex,which provides a good idea for the field of stimuli-responsive supramolecular organogel smart soft materials.