Fluorescence Emission Of Linear Aliphatic Amide Salts And Their Applications

Due to the great potential of luminescent materials in optoelectronic devices,fluorescent probes,biosensors,etc.the research and development of new efficient luminescent materials are a hot spot worldwide.Traditional luminescent materials often have fluorescence quenching in high concentration or aggregation state,thise the phenomenon is named as"aggregation caused quenching"(ACQ),which limits the application of such materials in many fields.Traditional fluorescent materials containing conjugated structures have a wide range of applications in chemical detection,energy conversion,cell imaging and other aspects.They are usually composed of conjugated structures and?electron systems.These structures inevitably bring poor stability,high cytotoxicity,non-biodegradation,poor water solubility and other shortcomings.Compared with the classical luminescent polymers,a new class of luminescent polymers,which does not contain conjugated?electron system elements,and they are consisting of only chemical groups such as-COONH,-C=O,-COOR and aliphatic amines,is found to be fluorescent emissive.Because the chemical structure of these polymers is more or less similar to the common polymers with good water solubility and biocompatibility,their chemical preparation process is simple,environmental friendly,and they show obvious advantages in bioluminescence imaging and other aspects.At present,most of the studies on fluorescent materials without typical chromophore are focused on the polymer field,and their luminescence mechanism has been in debate for the last decades.Therefore,the development of new fluorescent compounds,especially small molecular fluorescent materials,is of great significance for the exploration of the fluorescence mechanism of non-traditional fluorescent compounds.This paper mainly studies the luminescence mechanism of linear aliphatic amide salts and discusses their applications.The specific content is as follows:1.An unconventional fluorescent material was synthesized by mixing methanol solution of short-chain fatty acids with another methanol solution of aliphatic amines to obtain a water-soluble straight-chain aliphatic amide salt luminescent material.Nuclear magnetic resonance spectroscopy(NMR)and Fourier transform infrared spectroscopy(FTIR)were used to characterize the structure of these amide salts.The fluorescence performance in aqueous solution,and dependence on temperature,p H,and solvent concentration were tested.It is concluded that the amide fluorescence enhanced with the increase of the concentration of the salt because of the form cluster in aqueous solution these salts.2.For the mixed solution of PA26S and uracil,the fluorescence intensity of the solution was increasing with increase in uracil concentration when it was below 10^-2 M.It was found that the detection limit uracil was 1.69×10^-4 M,when the concentration of PA26S was 50mg/m L.Through DLS,¹H-NMR,UV-Vis,FTIR and other test,it was suggested that uracil moiecules were adhere onto the surface of the amide salt aggregates through electron interaction.The amide salts solution was also used to detect tetracycline.The fluorescence intensity of the mixed solution of PA26S and tetracycline decreased gradually with the increase in tetracycline concentration.It was found that the fluorescence intensity of the mixed solution decreased linearly with the increase of tetracycline concentration,with the concentration of tetracycline below 6×10^-5 M.By DLS,¹H-NMR,UV-Vis,and FTIR test,it was confirmed that energy resonance transfer occurred between amide salts and tetracycline in their aqueous solution,leading to fluorescence quenching of the amide salt.