Synthesis And Properties Of Ferrocene-containing Naphthalimide Derivatives

1,8-naphthalimide derivatives are widely used in fluorescent probes because of their excellent optical properties such as high photostability,large Stokes shift and high fluorescence quantum yields.Various functionalities of 1,8-naphthalimide can be imparted by modifying its 4-position.Ferrocene based compounds are considered to be ideal ion sensing materials due to their stability,favourable electrochemical property,and reaction activity.Ferrocene has good lipophilicity and can easily pass through the cell membrane,which lays the foundation for future application in living cells.We envision the introduction of ferrocene in naphthalimide ligands.Because ferrocene is a fluorescent quencher group,the naphthalimide ligand is quenched by fluorescence.When the ligand contacts metal ions,negative ions or reactive oxygen species,it inhibits the PET effect of ferrocene,naphthalimide ligand restores fluorescence.To confirm our vision,we synthesized four classes of compounds.First of all,a fluorescent probe with ferrocene and 1,8-naphthalimide connected by piperazine were successfully synthesized and characterized.It was found that the compound exhibits a strong fluorescence peak at 520 nm when it exposed to metal ions Cu²⁺,Ag⁺,Al³⁺and hypochlorous acid.Hypochlorous acid and metal ions Cu²⁺,Ag⁺,Al³⁺inhibit the PET effect of ferrocene,naphthalimide ligand restores fluorescence.The compound is highly selective for hypochlorous acid and can form an off-on detection mode.A fluorescent probe with ferrocene and 1,8-naphthalimide connected by hydrazine were successfully synthesized and characterized.In contact with hypochlorous acid,the compound exhibits a strong fluorescence peak at 525 nm,and the compound is highly selective for hypochlorous acid,which can form an off-on detection mode.Through the changes of ultraviolet spectrum and electrochemical signals,the compounds can effectively identify the metal ions Cu²⁺,Ag⁺and anions F^-,CH3COO^-,and the detection of double signals can be achieved for Cu²⁺.A fluorescent probe with ferrocene and 1,8-naphthalimide connected by carbon-nitrogen double bond were successfully synthesized and characterized.In contact with hypochlorous acid,the compound exhibits a strong fluorescence peak at 530 nm,and the compound is highly selective for hypochlorous acid,which can form an off-on detection mode.Through the changes of ultraviolet spectrum and electrochemical signals,the compounds can effectively identify the metal ions Cu²⁺and anions F^-,CH3COO^-.A fluorescent probe with ferrocene and 1,8-naphthalimide connected by ethylenediamine were successfully synthesized and characterized.Because the distance between ferrocene and naphthalimide ligand is extended,fluorescence quenching of ferrocene is inhibited,the compound is in a fluorescent"turn on"state,normally.The compound is highly selective for hypochlorous acid,and the strong fluorescence peak of the compound at 530 nm is enhanced when exposed to hypochlorous acid.When most of the metal ions are contacted,the fluorescence peak of the compound at 530 nm is enhanced,but the selectivity is poor.