Design,synthesis And Properties Of Organic Fluorescent Probe For Cu²⁺ And Al³⁺based On Naphthalimid

Organic small molecule fluorescent probes have the advantages of rapid response,high selectivity and good sensitivity,and are widely used in the detection field of biomolecules,metal ions and harmful gases.Naphthalimide has the advantages of high quantum yield,strong light resistance and low toxicity.It is a commonly used fluorophore for designing organic fluorescent probes.At present,there are relatively few naphthalimide metal ion probes with good detection performance,and the detection mechanism combined with theoretical calculation is not deeply studied.It is of great significance to design and synthesize naphthalimide-based metal ion probes and clarify the detection mechanism.In this paper,starting from naphthalimide,we designed and synthesized organic fluorescent small molecule probes that can specifically detect copper ions and aluminum ions,and further explored the detection mechanism through mass spectrometry and theoretical calculations.The specific contents are as follows:1.Design,synthesis and application of water-soluble copper ion organic fluorescent small molecule probe based on naphthalimide.Starting from 4-bromo1.8-naphthalic anhydride,compound 3 was synthesized in a three-step reaction,followed by Schiff base reaction with 8-aminoquinoline.Copper ion fluorescence quenching organic fluorescent probe BNQ was designed and synthesized.The probe BNQ has High selectivity,good water solubility,fast response and other advantages,can complete the detection within 2 minutes,the detection limit is 4.5×10^-8 M.Based on the data of fluorescence titration,job's-plot curve and complexation constant,the detection mechanism of proton transfer in excited molecules is proposed and verified by theoretical calculation.Biological experiments show that the probe has low biological toxicity and good biological penetration,and can complete the fluorescent detection of copper ions in living cells.2.Design and synthesize a fluorescent enhanced aluminum ion fluorescent probe with naphthalimide as fluorophore.Starting from 4-bromo1,8-naphthalic anhydride,compound 3 was synthesized in a three-step reaction,followed by reaction with 2,3-diaminomalonitrile.A fluorescence-enhanced organic fluorescence probe that specifically recognized aluminum ions was designed and synthesized.needle.The probe has the advantages of good selectivity and low detection limit.The detection limit of the probe reaches 7.59×10^-8 M.According to the data of ultraviolet titration and fluorescence titration,the detection mechanism of light-induced electron transfer is proposed.When the probe is coordinated with aluminum ions,the PET effect of the probe disappears and fluorescence is emitted.3.A ratio type aluminum ion fluorescent probe L was designed and synthesized based on naphthalimide and 2-methylthioaniline.The study found that in the presence of other interfering ions,the addition of aluminum ions,the fluorescent probe L can produce fluorescence at different wavelengths,to achieve the ratio of aluminum ions,the detection limit is 2.9×10^-7 M.According to the results of spectral titration experiments and theoretical calculations,the detection mechanism of the probe for aluminum ions is proposed.That is,after the aluminum ion forms a complex with the probe L,the original conjugate system of the probe is destroyed,resulting in the fluorescence emission wavelength of the probe Blue shift.At the same time,using the characteristics of good water solubility and strong fluorescence of the probe,the Al³⁺fluorescence imaging experiment of cells and zebrafish was carried out.The results show that the probe L has good application prospects in real-time monitoring of living organisms aluminum ions.