The Studies On 7-methoxychromone-3-carbaldehyde Shiff-bases As Metal Ions(Cd²⁺,Zn²⁺,Mg²⁺,Cu²⁺)probes

In this paper,four ligands rely on 7-methoxychromone-3-carbaldehyde have been synthesized and characterized.Then we have studied their sensing properties of metal ions and recognition mechanisms.Finally,we conclude that these ligands can be used as Cd2+,Zn2+,Mg2+,Cu2+ ions fluorescent chemosensors.The thesis is divided into five chapters and the main contents are as follows:In the first chapter,we give a brief introduction to the pharmacological activities and chemical application of the chromone Shiff-bases.And then the characteristics of fluorescent probes and their working mechanisms have been summarized.Moreover,we have presented some research status of various metal ion fluorescenct chemosensors.In the second chapter,we have designed a new chromone Schiff-base chemosensor 7’-methoxychromone-3’-methylidyne-1,2,4-triazole-3-imine(L1)that allows the Cd2+ to be differentiated on the basis of distinct fluorescence responses in ethanol.And the C=N isomerization can be used to explain this phenomenon.In the third chapter,we have developed a novel chemosensor 7-methoxychromone-3-carbaldehyde-(3’-hydroxy-2’-naphthaleneformyl)hydrazone(L2)based on the C=N isomerization and PET mechanism.The probe has exhibited high selectivity for Zn2+ over other metal ions with a strong fluorescence enhancement.Moreover,the probe has strong anti-interference ability and can be tested in the presence of most other interfering metal ions.And the probe still shows excellent restorability that can be used repeatedly.We believe that this probe has good potential to be used widely in the future.In the fourth chapter,a new dual recognition fluorescent probe 7-methoxychromone-3-carbaldehyde-(3’,4’,5’-tris(benzyloxy)benzoyl)hydrazone(L3)has been designed and synthesized.The probe shows good selectivity for Zn2+ in 75% ethanol aqueous solution,and shows excellent selectivity for Mg2+ in pure ethanol solution.This phenomenon can be explained by PET mechanism.The probe has strong anti-interference ability and high sensitivity with the detection limit reaching at 10-7 M level.What’s more,the probe shows excellent restorability that can be used repeatedly.In the last chapter,we have designed a new quenching fluorescent probe 7-methoxychromone-3-carbaldehyde-(7’-diethylaminocoumarin-3’-formyl)hydrazone(L4)for Cu2+.Furthermore,we reach the conclusion that the binding ratio between L4 and Cu2+ was determined to be 1.And also the probe has strong anti-interference ability and can be tested in the presence of most other common metal ions.