Preparation And Applications Of NIR Fluorescence,Colorimetric Dual-mode Cu²⁺/Cl^-Probe Based On Phthalocyanine

With the development of society and industry,large amounts of residential and industrial wastewater are delivered into the environment,leading to serious pollution of water by copper ions(Cu2+)and chloride ions(Cl-).As an essential element required for cofactors and enzymes during metabolic process for human life,copper ions(Cu2+)play a significant role to the health of human body.On the other hand,chloride ion(Cl-)in human body has important physiological functions,these ions have an important role to contribute to human health.Fluorescence or colorimetric approaches have attracted ever growing attention due to their intuitive visibility and inherent ease of operation and high sensitivity.Therefore,the combinational fluorescence and colorimetric dual-mode sensor will greatly improve detecting accuracy and sensitivity.In particular,the NIR fluorescence and colorimetric probe is more attracting due to its deep tissue penetration as well as avoiding self-interference from autofluorescence of tissues.Phthalocyanine(Pc)is a macromolecule with an 18π-electron conjugated planar structure that enables it to have distinctive photophysical and photochemical properties in the red to nearinfrared region.Phthalocyanine as an organic fluorescent material has the advantages of easy preparation,low cost,high molar absorbance coefficient,good biocompatibility,reproducibility,excellent photostability and thermal stability,low toxicity and the ability to achieve visible excitation and emission wavelength variable to near infrared,making it a more ideal chemical sensor.To the extent we are aware,simple and convenient fluorescent or colorimetric sensor have been reported relatively rarely so far,especially for the determination of the ions of heavy metals.Encouraged by the existence of cis-/trans-conformtion of silicon phthalocyanine(SiPc),herein,SiPc based fluorescence and colorimetric dual-mode probe for selective detect Cu2+and Cl-was developed through coordination induced conformation change from trans-SiPc-NH2 to cis-SiPc-NH2.SiPc-NH2 exhibited extremely high sensitivity and selectivity for recognition of Cu2+and Cl-with significant visible color and fluorescence response as well as high antiinterference in the coexistence of other metal ions and anions.The recognition and binding mechanisms of Cu2+ and Cl-are systematically revealed and used to detect Cu2+ and Cl-in natural environments or biological systems.The main contents of the paper are as follows:1.The two products with different polarities,cis-SiPc-NH2 and trans-SiPc-NH2,were separated by the column chromatography method.The structural differences between cis-SiPc-NH2 and trans-SiPc-NH2 were investigated by nuclear magnetic hydrogen spectroscopy(1H NMR),and the interconversion between cis-SiPc-NH2 and transSiPc-NH2 was studied;the optical features of cis-SiPc-NH2 and trans-SiPc-NH2 were investigated and described by UV absorption spectroscopy and fluorescence emission spectroscopy;the single-linear state oxygen consumption rates of both were compared using the DPBF indirect method.The experimental results show that cis-SiPc-NH2 and trans-SiPc-NH2 can be interconverted under certain conditions,which provides us with the feasibility of studying metal ion-induced conformational interconversion.2.A NIR fluorescent and colorimetric dual-mode probe was prepared using SiPc-NH2.The selectivity and anti-interference of this dual-mode probe for Cu2+ were investigated,and to our surprise,we found that Cl-plays a key role in the Cu2+-induced quenching reaction.Thus,a new near-infrared fluorescent and colorimetric probe SiPc-NH2-Cu2+ was prepared using Cu(NO3)2 as an inert copper source,and the selectivity of the new probe for Cl-as well as the anti-interference properties were investigated.The experimental results showed that the probe SiPc-NH2 exhibited extremely high sensitivity and selectivity in the recognition of Cu2+ and Cl-,a fastly visible color and fluorescence response,and a high resistance to interference in the coexistence of other metal ions and anions.3.The stoichiometric ratios of SiPc-NH2 and Cu2+coordination was verified by concentration titration,Job’s plot and NMR titration.SiPc-NH2-CuCl2 complexes were obtained by the coordination reaction of SiPc-NH2 with Cu2+and Cl-.The stoichiometric ratios of SiPc-NH2 and Cu2+ coordination was verified again by using fourier transform infrared spectroscopy(FT-IR),elemental analysis,mass spectrometry(ESI-MS),and X-ray photoelectron spectroscopy(XPS);the UV absorption spectra and fluorescence emission spectra of the complex SiPc-NH2-CuCl2 were tested to study the SiPc-NH2 coordination with Cu2+and Cl-conformational transitions after coordination.The results showed that the coordination ratio of SiPcNH2 to Cu2+ was 1:1.Not only a promising linear relationship was obtained,but the calculated detection limit is 2.79×10-7 M and the "naked eye" detection limit is 1.4μM.SiPc-NH2 formed a cis-configuration with Cu2+after coordination.4.Two fluorescent and colorimetric sensors were designed,one with an excess of Clin SiPc-NH2 to detect Cu2+ and the other with an excess of Cu2+ in SiPc-NH2 to detect Cl-.The bioimaging tests were carried out by performing bioimaging in live MCF-7 cells.The experimental results show that the two designed fluorescent and colorimetric sensors can effectively detect Cu2+(Cl-)without considering the corresponding anions(cations)in the system,and in addition,SiPc-NH2 can provide efficient detection performance for Cu2+ in biological systems.