Design And Synthesis Of The Fluorescent Chemosensor Based On A Water-Soluble Cationic Bis-Porphyrin And Its Application In Cu²⁺ Detection

Development of reliable sensing platforms for monitoring metal ions is of great importance because of their widespread distribution in environmental systems and biological processes.Comparing with the conventional techniques,fluorescent chemosensors has the advantages of low cost,high sensitivity,and simplified operation.Much attention has been focus on the development of the chemosensors with high sensitivity,selectivity and applicability in recent years.Porphyrin analogues possess inherently many advantageous features,including attractive photophysical properties?large Stokes shifts and relatively long excitation[>400 nm]and emission[>600 nm]wavelengths?,good metal-ion-binding ability and recognition specificity,and modification flexibility of peripheral substituents,making them highly promising for the design of ion probe.The following aspects were included in this thesis:1.A new water-soluble,cationic bis-porphyrin4,4-bis[10,15,20-tris[4-[2-?1-methyl-1-piperidinyl? ethoxy] phenyl]porphyrin] ?Bis-TMPipEOPP? was synthesized and characterized by IR,MS and NMR.2.The optical properties of Bis-TMPipEOPP with different metal ions were investigated,and its fluorescence was found to be specifically quenched by paramagnetic Cu²⁺ions via forming Bis-TMPipEOPP-Cu²⁺complex.Based on these findings,a sensing platform was developed for the“turn-off”detection of Cu²⁺.Such a platform could achieve sensitive Cu²⁺quantitation at a detection limit of 8.8 nM with high ion selectivity,and can be applied to the detection of Cu²⁺in actual water samples.3.Compared to the optical properties of Bis-TMPipEOPP and its monomeric counterpart TMPipEOPP,Bis-TMPipEOPP exhibited a higher tendency to self-aggregate due to the synergy between the two porphine rings.This characteristics conferred the proposed Bis-TMPipEOPP-based Cu²⁺-sensing platform with a sensitive fluorescent response to low concentrations of Cu²⁺in a linear detection range of between 10 nM and 300 nM.However,the TMPipEOPP-based method provided observable changes in the fluorescent signal only at Cu²⁺concentrations>200 nM.