Study On Photostabilityand Quantitative Structure-activity Relationship Of Hemicyanine Fluorescent Dye

DHEASPBr-C2 is a dye which has great fluorescence and important application in the field of textile, but the poor photostability affects its application greatly. In this thesis, the main photodegradation mechanism had been concluded based on experiments and quantum chemistry methods.First, we use self-made DHEASPBr-C2 as hemicyanine fluorescent dye and fluorescent Yellow X-10 GFF as reference sample in acrylic fabrics dyeing and compared the photostability under xenon lamp light irradiation; Meanwhile, we studied the photostability and photolysis kinetics of this two dyes in aqueous solution under Hg lamp light irradiation and xenon lamp light irradiation respectively, the K/S、Lab、reflectance、ultraviolet absorption spectrum and single-photon fluorescence spectrum were measured at different irradiation time and the photodegradation products were identified with the aid of high performance liquid chromatography-mass spectrometry(HPLC/MS). It was found that the photostability of dyed acrylic fabrics with DHEASPBr-C2 is weaker than that of Yellow X-10 GFF and so is in aqueous solution of this two dyes under two lamp source, moreover,dyes were destroyed easier under Hg lamp light irradiation and some photodegradation products appeared during irradiation.Second, the molecular geometries and electronic structures of this two dyes had been calculated using ab initio methods、Density Functional Theory methods and the secondary perturbation method, the photodegradation mechanism of DHEASPBr-C2 had been concluded based on the frontier molecular orbital theory and the three bonding principles and could agree well with the experiments; Meanwhile, the geometry of DHEASP-C2+wasmodified by substituting atoms with donors or acceptors to get better photostability dye structure by using Density Functional Theory methods. In addition, we studied the relationship between the fractal dimension value of four kinds of simplified model of DHEASP-C2+and the fractal dimension value of the corresponding fragments using fractal harmonic law and brachistofractality and the results could agree well with the experiments.