Research Of Mechanism And Detection For Cu²⁺?Pb²⁺in Environment By Rhodamine Fluorescence Probe

Rhodamine compounds are a kind of basic fluorescent dyes using O-xanthene as a basic moiety.Because this kind of fluorophores has many advantages,such as high fluorescence quantum yield,controllable fluorescence properties and fluorescence emission wavelengths in the visible region,they have been widely used for the design of various fluorescent molecular probes.In recent years,the research of the lactam spiral ring structure of rhodamines becomes a hot topic:the state of lactam spiral ring structure is non-fluorescent,but the opening of lactam ring structure can result in the fluorescence enhancement,to display the "off-on" fluorescent signals.In this essay,using rhodamine B as a starting material,several its derivatives conjugated with di-amino compounds,including rhodamine B-hydrazine,rhodamine B-ethylenediamine,rhodamineB-hexamethylenetriamine_and_rhodamineB-diethylenetria mine were synthesized,and their lactam structure was confirmed.For visible four compounds in different pH conditions?UV-vis?absorption spectra and fluorescence spectra characterization results show that the fluorescence emission of rhodamine compounds is due to the formation of Luo rhodamine B by the opening and deamination of spiraclactam under acidic conditions.The formation of the transition state with amino participation is conducive to the ammonia removal process.The synthesis of rhodamine B-hydrazine fluorescence probe was used in aqueous solution of pH=7.2 copper???ions,were investigated at different reaction time,different solvents,solvent ratio,and mixing the probe of different ions on copper???ion fluorescence response,and the reaction mechanism was presumed with the job's analysis.The results showed that rhodamineB-hydrazine reacted with Cu²⁺ to form a 1:1 type complex,which could reach the maximun value in the reaction of 2min,and the concentration of rhodamine B-hydrazine was highly selective for Cu²⁺,and the detection range was 5-250?mol/L.The synthesis of rhodamine B-ethylenediamine fluorescence probe was used in aqueous solution of pH=7.2 lead???ions,were investigated at different reaction time,different solvents,solvent ratio,and mixing the probe of different ions on lead???fluorescence response,and the reaction mechanism was presumed with the job's analysis.The results showed that rhodamineB-ethylenediamine reacted with Pb²⁺ to form a 1:1 type complex,which could reach the maximum value in the reaction of 2min,and the concentration of rhodamine B-ethylenediamine was highly selective for Pb²⁺,and the detection range was 5-300?mol/L.