Synthesis And Fluorescence Properties Of Novel Coumarin Hydrazide And Triazole Derivatives

In recent decades,the detection of ions in the environment has become particularly important.The method of using small organic molecules to detect ions in the environment and organisms has attracted widespread attention.Coumarins are a kind of heterocyclic compounds widely found in the plant and have important biological activities and uses.Coumarin derivatives have been widely used in the field of organic fluorescent small molecules due to their unique molecular structures and excellent optical activities.The structure of coumarin contains many positions that can be modified.The main work of this thesis is to synthesize two new fluorescent probes by modifying positions 3 and 7 of coumarin,and further investigating the fluorescent properties and applications of the probes.The main research contents are shown as following:（1）Using 4-ethylenediaminosalicylic aldehyde and aromatic aldehyde as the starting materials,16 novel coumarin derivatives with variant aromatic substituents were synthesized,and the relationship between their structures,optical properties and the selectivity of metals has been studied.Palladium has a strong quenching effect on the compounds with pyridyl groups.Three compounds containing pyridyl groups were analyzed,among which the compound（E）-N′-(（（4-chloropyridin-2-yl）methylene）-7-（diethylamino）-2-oxo-2H-chromene-3-carbohydrazide（CMD₁）has unique specific selectivity.We used compound CMD₁ as a representative fluorescent probe to screen the optimal detection conditions of palladium.Under the best test condition,the probe CMD₁ has a short response time（3min）,a wide p H test range（2.0-10.0）,and a low detection limit(4.45×10^-8mol/L),which achieves efficient and rapid detection of palladium.（2）Three compounds using triazole-coumarin as the skeleton has been designed and synthesized.The N2-substituted triazole in the position 3 of coumarin increases not only the electron withdrawing ability of the third position,but also the conjugate structure of the compound.The protecting group on the hydroxyl group at the position7 reduces its electron donating ability.After the cleavage of Si-O bond,an oxygen anion is formed,increasing its electron-donating ability and the conjugate structure as well.Therefore,after the fluoride ion is added to the probe,the fluorescence shows significant redshift.Because the redshift is large enough,there is no other influence,so it can be used as an"Off-On"probe.At the same time,compound CTA₃ can be used to detect fluoride in the organic phase,and also as a ratio probe to detect fluoride in the water phase.