Synthesis And Properties Studies Of New Naphthalimide Derivative Fluorescent Ion Probe

Heavy metal ions,if accumulated in the body,will seriously threaten the safety of various living organisms,so the detection of these metal ions have important practical significance.Compared with the traditional detection and analytical methods?atomic absorption spectrometry,inductively coupled plasma atomic emission spectroscopy,electrochemical sensing,gas chromatography?,fluorescent ion probe technology possesses the multiple advantages of high selectivity,high sensitivity,simple operation,low cost and rapid analysis detection and others,and its usage has,therefore,aroused widespread concern among researchers both at home and abroadAs a class of excellent fluorescent chromophores,naphthalimide derivatives have become a household name in fluorescence ion probe research because of their superior photophysical and photochemical properties.From the structural point of view,the molecular structure of one end of the "imide" strong electron withdrawing group,and the other end?4-bit?anchor a strong electron donor group,so easy to form intramolecular charge transfer system,easily transduced by light,producing a rich color,and hence a strong fluorescence phenomenon.In this study,the anionic / cationic fluorescent probes with high sensitivity and high selectivity were designed by transforming these two groups and thereby applying them to liquid crystal displays,laser active media,biological fluorescent labels,light induced electron transfer sensors,luminescent materials and fluorescent co nverters,probes and other research areas.In this paper,four naphthalimide derivatives were designed and synthesized using 1,8-naphthalimide as a fluorescent group and Schiff base as recognition group : N-n-butyl-4-[2-??ethylimino?methyl?phenol]-1,8-napthalimide?L¹?,N-n-butyl-4-[2-??aminoethyl?methyl?-6-methoxyphenol]-1,8-napthalimide?L²?,N-n-butyl-4-[3,3'-??2-aminoethyl?azanediyl?bis?N'-?2-hydroxy-3-methoxybenzylidene?-propa nehydrazide?]-1,8-naphthalimide?L³?,N-n-butyl-4-[3,3'-??2-aminoethyl?azanediyl?bis?N'-?2-hydroxybenzylidene?propanehy-drazide?]-1,8-naphthalimide?L⁴?,and the recognition properties of the probe to metal ions were studied.This paper is divided into four parts:Part ?: The research progress of fluorescent ion probe was introduced.Part ?: Two naphthalimide derivatives,copper?II?ion fluorescent probes L¹ and L² were designed and synthesized,and their structures were characterized.When the concentration of Cu²⁺ is between 0.5 and 5.0 ?M,both the probes L¹ and L² can quantitatively detect Cu²⁺,and the binding constants of probes L¹ and L² towards C u²⁺ are 4.76×1011M-1 and 4.97×1011 M-1,respectively.The difference was that the probe L¹ showed a high selectivity to Cu²⁺ in the acetonitrile-HEPES?v/v 1:1?buffer system?the fluorescence intensity was reduced by 12 times?and the probe L² was in the range of methanol-HEPES?v/v 1:1?.The effect of the detection of Cu²⁺ in the buffer system was not significant?the fluorescence intensity was reduced by 6 times?;the detection limits of the probes L¹ and L² were 3.3×10-8 M and 5.67×10-7 M,respectively.The sensitivity of probe L¹ to detect Cu²⁺ is higher,which is of great potential for the detection of Cu²⁺ in practical samples.The results of UV titration,fluorescence titration and Job titration showed that both L¹ and L² and Cu²⁺ were coordinated in a 2: 1 mode.Part ?: Two naphthalimide derivatives,aluminum?III?ion fluorescent probes L³ and L⁴ were designed and synthesized with 1,8-naphthalimide as the parent moiety.The probes L³ and L⁴ were identified to detect Al³⁺ in DMF-HEPES?pH=7.4?and methanol-Tris-HCl?pH=7.2?buffer systems,respectively,and emitted strong green fluorescence.The difference is that Cu²⁺,Co²⁺,Ni²⁺ and Cd²⁺ interfere with Al³⁺ recognition of probe L³,which affects the recognition of Al³⁺ by probe L³;and probe L⁴ is highly specific to Al³⁺ recognition.When the amount of Al³⁺ in the environment is 3.0-10.0?M,the detection limit of Al³⁺ for probe L⁴ is 1.78×10-7 M,which can be used for the detection of Al³⁺ in the actual sample.The binding constant of probe L⁴ and Al³⁺ is 5.49×104 M-1,indicating that there is a strong binding ability between probe L⁴ and Al³⁺.The results of UV titration,fluorescence titration and Job titration showed that a 1: 1 complex was formed between probe L⁴ and Al³⁺.Part ?: The anti-free radical activity?anti-hydroxyl radical and anti-superoxide radical?of ligands L¹,L²,L³ and L⁴ were studied.The experimental results show that the IC50 values of L¹,L²,L³ and L⁴ are in the order of 10-6¹0-5,have a strong anti-free radical activity,and can be used as a potential anti-hydroxyl radical and as well as anti-superoxide radical inhibitors.